CMP Journal 2025-09-03
Statistics
Nature: 28
Nature Physics: 1
Physical Review Letters: 18
Physical Review X: 2
arXiv: 167
Nature
Cas9 senses CRISPR RNA abundance to regulate CRISPR spacer acquisition
Original Paper | Bacteria | 2025-09-02 20:00 EDT
Xufei Zhou, Rucheng Diao, Xin Li, Christine A. Ziegler, Max J. Gramelspacher, Lydia Freddolino, Zhonggang Hou, Yan Zhang
Prokaryotes create adaptive immune memories by acquiring foreign DNA snippets, known as spacers, into the CRISPR array1. In type II CRISPR-Cas systems, the RNA-guided effector Cas9 also assists the acquisition machinery by selecting spacers from protospacer adjacent motif (PAM)-flanked DNA2,3. Here, we uncover the first biological role for Cas9 that is independent of its dual RNA partners. Following depletion of crRNA and/or tracrRNA, Neisseria apoCas9 stimulates spacer acquisition efficiency. Physiologically, Cas9 senses low levels of crRNA in cells with short CRISPR arrays - such as those undergoing array neogenesis or natural array contractions - and dynamically upregulates acquisition to quickly expand the small immune memory banks. As the CRISPR array expands, rising crRNA abundance in turn reduces apoCas9 availability, thereby dampening acquisition to mitigate autoimmunity risks associate with elevated acquisition. While apoCas9’s nuclease lobe alone suffices for stimulating acquisition, only full-length Cas9 responses to crRNA levels to boost acquisition in cells with low immunity depth. Finally, we show that this activity is evolutionarily conserved across multiple type II-C Cas9 orthologs. Altogether, we establish an auto-replenishing feedback mechanism in which apoCas9 safeguards CRISPR immunity depth by acting as both a crRNA sensor and a regulator of spacer acquisition.
Bacteria, Genetics
Latent resistance mechanisms of steel truss bridges after critical failures
Original Paper | Civil engineering | 2025-09-02 20:00 EDT
Juan C. Reyes-Suárez, Manuel Buitrago, Brais Barros, Safae Mammeri, Nirvan Makoond, Carlos Lázaro, Belén Riveiro, Jose M. Adam
Steel truss bridges are constructed by connecting many different types of bars (components) to form a load-bearing structural system. Several disastrous collapses of this type of bridge have occurred as a result of initial component failure(s) propagating to the rest of the structure1,2,3. Despite the prevalence and importance of these structures, it is still unclear why initial component failures propagate disproportionately in some bridges but barely affect functionality in others4,5,6,7. Here we uncover and characterize the fundamental secondary resistance mechanisms that allow steel truss bridges to withstand the initial failure of any main component. These mechanisms differ substantially from the primary resistance mechanisms considered during the design of (undamaged) bridges. After testing a scaled-down specimen of a real bridge and using validated numerical models to simulate the failure of all main bridge components, we show how secondary resistance mechanisms interact to redistribute the loads supported by failed components to other parts of the structure. By studying the evolution of these mechanisms under increasing loads up to global failure, we are able to describe the conditions that enable their effective development. These findings can be used to enhance present bridge design and maintenance strategies, ultimately leading to safer transport networks.
Civil engineering, Engineering
DNA2 enables growth by restricting recombination-restarted replication
Original Paper | Checkpoint signalling | 2025-09-02 20:00 EDT
Jessica J. R. Hudson, Rowin Appanah, David Jones, Kathryn Davidson, Alice M. Budden, Alina Vaitsiankova, Kok-Lung Chan, Keith W. Caldecott, Antony M. Carr, Ulrich Rass
Nuclease-helicase DNA2 is a multifunctional genome caretaker that is essential for cell proliferation in a range of organisms, from yeast to human1,2,3,4. Bi-allelic DNA2 mutations that reduce DNA2 concentrations cause a spectrum of primordial dwarfism disorders, including Seckel and Rothmund-Thomson-related syndromes5,6,7. By contrast, cancer cells frequently express high concentrations of DNA2 (refs. 8,9,10,11). The mechanism that precludes cell proliferation in the absence of DNA2 and the molecular aetiology of DNA2-linked diseases remain elusive. Here we used yeast and human cells to demonstrate that DNA2 suppresses homologous recombination-restarted replication and checkpoint activation at stalled DNA replication forks. Loss of this control mechanism upon degradation of DNA2 in human cells causes recombination-dependent DNA synthesis and build-up of RPA-bound single-stranded DNA in the G2 phase of the cell cycle. Consequently, DNA2 deprivation triggers the DNA damage checkpoint and invariably leads to ATR-p21-dependent cell-cycle exit before mitosis. These findings explain why DNA2 is essential for cell proliferation and reveal that replication fork processing to restrict recombination is indispensable for avoiding cellular senescence. Stochastic entry into senescence stifles the proliferative potential of cells following the expression of a Seckel syndrome patient-derived DNA2 hypomorph or partial degradation of DNA2, providing a conceptual framework to explain global growth failure in DNA2-linked primordial dwarfism disorders.
Checkpoint signalling, DNA recombination, Neurodevelopmental disorders, Senescence, Stalled forks
A prudent planetary limit for geologic carbon storage
Original Paper | Climate-change mitigation | 2025-09-02 20:00 EDT
Matthew J. Gidden, Siddharth Joshi, John J. Armitage, Alina-Berenice Christ, Miranda Boettcher, Elina Brutschin, Alexandre C. Köberle, Keywan Riahi, Hans Joachim Schellnhuber, Carl-Friedrich Schleussner, Joeri Rogelj
Geologically storing carbon is a key strategy for abating emissions from fossil fuels and durably removing carbon dioxide (CO2) from the atmosphere1,2. However, the storage potential is not unlimited3,4. Here we establish a prudent planetary limit of around 1,460 (1,290-2,710) Gt of CO2 storage through a risk-based, spatially explicit analysis of carbon storage in sedimentary basins. We show that only stringent near-term gross emissions reductions can lower the risk of breaching this limit before the year 2200. Fully using geologic storage for carbon removal caps the possible global temperature reduction to 0.7 °C (0.35-1.2 °C, including storage estimate and climate response uncertainty). The countries most robust to our risk assessment are current large-scale extractors of fossil resources. Treating carbon storage as a limited intergenerational resource has deep implications for national mitigation strategies and policy and requires making explicit decisions on priorities for storage use.
Climate-change mitigation, Climate sciences, Planetary science
A brain-wide map of neural activity during complex behaviour
Original Paper | Decision | 2025-09-02 20:00 EDT
Leenoy Meshulam, Dora Angelaki, Julius Benson, Isaiah McRoberts, Jean-Paul Noel, Jaime Arlandis, Niccolò Bonacchi, Kcenia Bougrova, Joana A. Catarino, Fanny Cazettes, Davide Crombie, Eric EJ DeWitt, Laura Freitas-Silva, Inês C. Laranjeira, Zachary F. Mainen, Guido T. Meijer, Pranav Rai, Georg Raiser, Florian Rau, Michael M. Schartner, Olivier Winter, Anne E. Urai, Valeria Aguillon-Rodriguez, Cristian Soitu, Anthony M. Zador, Christopher S. Krasniak, Yang Dan, Fei Hu, Brandon Benson, Surya Ganguli, Luigi Acerbi, Gaelle A. Chapuis, Charles Findling, Berk Gercek, Felix Huber, Alexandre Pouget, Hailey Barrell, Dan Birman, Kim Miller, Kai Nylund, Noam Roth, Nicholas A. Steinmetz, Matthew Tucker, Kenneth Yang, Ila Rani Fiete, Ari Liu, Rylan Schaeffer, Anne K. Churchland, Felicia Davatolhagh, Anup Khanal, Maxwell Melin, Masayoshi Murakami, Sophie Denève, Ivan Gordeliy, Mandana Ahmadi, Jaweria Amjad, Naoki Hiratani, Sanjukta Krishnagopal, Peter Latham, Alberto Pezzotta, Zekai Xu, Kush Banga, Jai Bhagat, Mayo Faulkner, Kenneth D. Harris, Michael Krumin, Samuel Picard, Carolina Quadrado, Cyrille Rossant, Miles J. Wells, Lauren E. Wool, Matteo Carandini, Agnès Landemard, Karolina Z. Socha, Sebastian A. Bruijns, Peter Dayan, Julia M. Huntenburg, Debottam Kundu, Farideh Oloomi, Charline Tessereau, Zoe C. Ashwood, Tatiana Engel, Robert Fetcho, Laura M. Haetzel, Christopher Langdon, Brenna McMannon, Zeinab Mohammadi, Alejandro Pan Vazquez, Jonathan W. Pillow, Nicholas A. Roy, Yanliang Shi, Ilana B. Witten, Robert Campbell, Naureen Ghani, Sonja B. Hofer, Hernando Martinez-Vergara, Nathaniel J. Miska, Thomas Mrsic-Flogel, Steven J. West, Yaxuan Yang, Karel Svoboda, Marsa Taheri, Michael Häusser, Petrina Y. P. Lau, Amalia Makri-Cottington, Sabrina Perrenoud, Larry Abbot, Hannah M. Bayer, Julien Boussard, E. Kelly Buchanan, Michele Fabbri, Cole Hurwitz, Christopher Langfield, Hyun Dong Lee, Catalin Mitelut, Liam Paninski, Kamron Saniee, Erdem Varol, Shuqi Wang, Matthew R. Whiteway, Charles Windolf, Han Yu, Yizi Zhang, Dora Angelaki, Brandon Benson, Julius Benson, Daniel Birman, Niccolò Bonacchi, Kcénia Bougrova, Sebastian A. Bruijns, Matteo Carandini, Joana A. Catarino, Gaelle A. Chapuis, Anne K. Churchland, Yang Dan, Felicia Davatolhagh, Peter Dayan, Eric EJ DeWitt, Tatiana A. Engel, Michele Fabbri, Mayo Faulkner, Ila Rani Fiete, Charles Findling, Laura Freitas-Silva, Berk Gerçek, Kenneth D. Harris, Michael Häusser, Sonja B. Hofer, Fei Hu, Félix Hubert, Julia M. Huntenburg, Anup Khanal, Christopher S. Krasniak, Christopher Langdon, Christopher Langfield, Petrina Y. P. Lau, Zachary F. Mainen, Guido T. Meijer, Nathaniel J. Miska, Thomas D. Mrsic-Flogel, Jean-Paul Noel, Kai Nylund, Alejandro Pan-Vazquez, Liam Paninski, Alexandre Pouget, Cyrille Rossant, Noam Roth, Rylan Schaeffer, Michael Schartner, Yanliang Shi, Karolina Z. Socha, Nicholas A. Steinmetz, Karel Svoboda, Anne E. Urai, Miles J. Wells, Steven J. West, Matthew R. Whiteway, Olivier Winter, Ilana B. Witten
A key challenge in neuroscience is understanding how neurons in hundreds of interconnected brain regions integrate sensory inputs with previous expectations to initiate movements and make decisions1. It is difficult to meet this challenge if different laboratories apply different analyses to different recordings in different regions during different behaviours. Here we report a comprehensive set of recordings from 621,733 neurons recorded with 699 Neuropixels probes across 139 mice in 12 laboratories. The data were obtained from mice performing a decision-making task with sensory, motor and cognitive components. The probes covered 279 brain areas in the left forebrain and midbrain and the right hindbrain and cerebellum. We provide an initial appraisal of this brain-wide map and assess how neural activity encodes key task variables. Representations of visual stimuli transiently appeared in classical visual areas after stimulus onset and then spread to ramp-like activity in a collection of midbrain and hindbrain regions that also encoded choices. Neural responses correlated with impending motor action almost everywhere in the brain. Responses to reward delivery and consumption were also widespread. This publicly available dataset represents a resource for understanding how computations distributed across and within brain areas drive behaviour.
Decision, Neural decoding, Sensory processing
Divergent evolutionary strategies pre-empt tissue collision in gastrulation
Original Paper | Evolutionary developmental biology | 2025-09-02 20:00 EDT
Bipasha Dey, Verena Kaul, Girish Kale, Maily Scorcelletti, Michiko Takeda, Yu-Chiun Wang, Steffen Lemke
Metazoan development proceeds through a series of morphogenetic events that sculpt body plans and organ structures1,2. In the early embryo, these processes occur concurrently such that forces generated in neighbouring tissues can impose mechanical stresses on each other3,4,5, potentially disrupting development and consequently decreasing fitness. How organisms evolved mechanisms to mitigate inter-tissue mechanical conflicts remains unclear. Here, we combined phylogenetic survey, quantitative live imaging and functional mechanical perturbation to investigate mechanical stress management during gastrulation across the insect order of flies (Diptera). We identify two distinct cellular mechanisms that prevent tissue collision between the expanding head and trunk. In Cyclorrhapha, a monophyletic subgroup including Drosophila melanogaster, active out-of-plane deformation of a transient epithelial fold, called the cephalic furrow, acts as a mechanical sink to pre-empt head-trunk collision. Genetic and optogenetic ablation of the cephalic furrow leads to accumulation of compressive stress, tissue buckling at the head-trunk boundary and late-stage embryonic defects in the head and nervous system. By contrast, the non-cyclorrhaphan Chironomus riparius lacks cephalic furrow formation and instead undergoes widespread out-of-plane division that reduces the duration and spatial extent of head expansion. Re-orienting head mitosis from in-plane to out-of-plane in Drosophila partially suppresses tissue buckling, showing that it can function as an alternative mechanical sink. Our data suggest that mechanisms of mechanical stress management emerge and diverge in response to inter-tissue conflicts during early embryonic development.
Evolutionary developmental biology, Gastrulation
Analog optical computer for AI inference and combinatorial optimization
Original Paper | Computational science | 2025-09-02 20:00 EDT
Kirill P. Kalinin, Jannes Gladrow, Jiaqi Chu, James H. Clegg, Daniel Cletheroe, Douglas J. Kelly, Babak Rahmani, Grace Brennan, Burcu Canakci, Fabian Falck, Michael Hansen, Jim Kleewein, Heiner Kremer, Greg O’Shea, Lucinda Pickup, Saravan Rajmohan, Ant Rowstron, Victor Ruhle, Lee Braine, Shrirang Khedekar, Natalia G. Berloff, Christos Gkantsidis, Francesca Parmigiani, Hitesh Ballani
Artificial intelligence (AI) and combinatorial optimization drive applications across science and industry, but their increasing energy demands challenge the sustainability of digital computing. Most unconventional computing systems1,2,3,4,5,6,7 target either AI or optimization workloads and rely on frequent, energy-intensive digital conversions, limiting efficiency. These systems also face application-hardware mismatches, whether handling memory-bottlenecked neural models, mapping real-world optimization problems or contending with inherent analog noise. Here we introduce an analog optical computer (AOC) that combines analog electronics and three-dimensional optics to accelerate AI inference and combinatorial optimization in a single platform. This dual-domain capability is enabled by a rapid fixed-point search, which avoids digital conversions and enhances noise robustness. With this fixed-point abstraction, the AOC implements emerging compute-bound neural models with recursive reasoning potential and realizes an advanced gradient-descent approach for expressive optimization. We demonstrate the benefits of co-designing the hardware and abstraction, echoing the co-evolution of digital accelerators and deep learning models, through four case studies: image classification, nonlinear regression, medical image reconstruction and financial transaction settlement. Built with scalable, consumer-grade technologies, the AOC paves a promising path for faster and sustainable computing. Its native support for iterative, compute-intensive models offers a scalable analog platform for fostering future innovation in AI and optimization.
Computational science, Optics and photonics, Physics
Single-cell transcriptomic and genomic changes in the ageing human brain
Original Paper | Neural ageing | 2025-09-02 20:00 EDT
Ailsa M. Jeffries, Tianxiong Yu, Jennifer S. Ziegenfuss, Allie K. Tolles, Christina E. Baer, Cesar Bautista Sotelo, Yerin Kim, Zhiping Weng, Michael A. Lodato
Over time, cells in the brain and in the body accumulate damage, which contributes to the ageing process1. In the human brain, the prefrontal cortex undergoes age-related changes that can affect cognitive functioning later in life2. Here, using single-nucleus RNA sequencing (snRNA-seq), single-cell whole-genome sequencing (scWGS) and spatial transcriptomics, we identify gene-expression and genomic changes in the human prefrontal cortex across lifespan, from infancy to centenarian. snRNA-seq identified infant-specific cell clusters enriched for the expression of neurodevelopmental genes, as well as an age-associated common downregulation of cell-essential homeostatic genes that function in ribosomes, transport and metabolism across cell types. Conversely, the expression of neuron-specific genes generally remains stable throughout life. These findings were validated with spatial transcriptomics. scWGS identified two age-associated mutational signatures that correlate with gene transcription and gene repression, respectively, and revealed gene length- and expression-level-dependent rates of somatic mutation in neurons that correlate with the transcriptomic landscape of the aged human brain. Our results provide insight into crucial aspects of human brain development and ageing, and shed light on transcriptomic and genomic dynamics.
Neural ageing, Sequencing, Transcriptomics
A circuit that integrates drive state and social contact to gate mating
Original Paper | Sensory processing | 2025-09-02 20:00 EDT
Lindsey D. Salay, Doris Y. Tsao, David J. Anderson
Internal motive states, such as sexual arousal, drive behaviour in response to social cues. However, little is known about how internal states and external cues are integrated to release appropriate behaviours at the correct moment during a social interaction, such as the transition from the appetitive to the consummatory phases of mating1,2. Here we identify a neural circuit in male mice that gates the onset of consummatory reproductive behaviours on contact with a mating partner. Stimulating MPOAEsr1∩Vgat hypothalamic neurons promotes mounting of conspecifics and three-dimensional dummy objects3. We find that such mounting depends on mechanosensory but not visual cues. Through a large-scale electrophysiological screen, we identify neurons in the subparafascicular thalamic nucleus that nonlinearly integrate medial preoptic area of the hypothalamus (MPOA) and mechanosensory input to encode contact with a potential mate. Circuit tracing and perturbations demonstrated that this conjunctive coding occurs by means of convergent disinhibition from MPOA and excitation from the spinal trigeminal nucleus. Functional manipulations and calcium recordings showed these social-contact neurons, marked by parathyroid hormone 2, were essential for and able to promote mounting. These data indicate that subparafascicular thalamic nucleus-parathyroid hormone 2 neurons integrate internal drive with social touch to trigger mounting at opportune moments during mating. More generally, our findings uncover a brain mechanism whereby an internal state can attribute a social quality to a generic touch to initiate purposeful reproductive actions.
Sensory processing, Sexual behaviour
Spatial joint profiling of DNA methylome and transcriptome in tissues
Original Paper | Epigenomics | 2025-09-02 20:00 EDT
Chin Nien Lee, Hongxiang Fu, Angelysia Cardilla, Wanding Zhou, Yanxiang Deng
The spatial resolution of omics analyses is fundamental to understanding tissue biology1,2,3. The capacity to spatially profile DNA methylation, which is a canonical epigenetic mark extensively implicated in transcriptional regulation4,5, is lacking. Here we introduce a method for whole-genome spatial co-profiling of DNA methylation and the transcriptome of the same tissue section at near single-cell resolution. Applying this technology to mouse embryogenesis and the postnatal mouse brain resulted in rich DNA-RNA bimodal tissue maps. These maps revealed the spatial context of known methylation biology and its interplay with gene expression. The concordance and distinction in spatial patterns of the two modalities highlighted a synergistic molecular definition of cell identity in spatial programming of mammalian development and brain function. By integrating spatial maps of mouse embryos at two different developmental stages, we reconstructed the dynamics that underlie mammalian embryogenesis for both the epigenome and transcriptome, revealing details of sequence-, cell-type- and region-specific methylation-mediated transcriptional regulation. This method extends the scope of spatial omics to include DNA cytosine methylation, enabling a more comprehensive understanding of tissue biology across development and disease.
Epigenomics, Genomic analysis, RNA sequencing
Patterned invagination prevents mechanical instability during gastrulation
Original Paper | Biophysics | 2025-09-02 20:00 EDT
Bruno C. Vellutini, Marina B. Cuenca, Abhijeet Krishna, Alicja Szałapak, Carl D. Modes, Pavel Tomancak
Mechanical forces are crucial for driving and shaping tissue morphogenesis during embryonic development1,2,3. However, their relevance for the evolution of development remains poorly understood4. Here we show that an evolutionary novelty of fly embryos–the patterned embryonic invagination known as the cephalic furrow5,6,7–has a mechanical role during Drosophila gastrulation. By integrating in vivo experiments and in silico simulations, we demonstrate that the head-trunk boundary of the embryo is under increased compressive stress due to the concurrent formation of mitotic domains and germ band extension and that the cephalic furrow counteracts these stresses, preventing mechanical instabilities during gastrulation. Then, by comparing the genetic patterning of species with and without the cephalic furrow, we find evidence that changes in the expression of the transcription factor buttonhead are associated with the evolution of the cephalic furrow. These results suggest that the cephalic furrow may have evolved through the genetic stabilization of morphogenesis in response to the mechanical challenges of dipteran gastrulation. Together, our findings uncover empirical evidence for how mechanical forces can influence the evolution of morphogenetic innovations in early development.
Biophysics, Evolutionary developmental biology, Gastrulation
Brain-wide representations of prior information in mouse decision-making
Original Paper | Bayesian inference | 2025-09-02 20:00 EDT
Charles Findling, Felix Hubert, Luigi Acerbi, Brandon Benson, Julius Benson, Daniel Birman, Niccolò Bonacchi, E. Kelly Buchanan, Sebastian Bruijns, Matteo Carandini, Joana A. Catarino, Gaelle A. Chapuis, Anne K. Churchland, Yang Dan, Felicia Davatolhagh, Eric E. J. DeWitt, Tatiana A. Engel, Michele Fabbri, Mayo A. Faulkner, Ila Rani Fiete, Laura Freitas-Silva, Berk Gerçek, Kenneth D. Harris, Michael Häusser, Sonja B. Hofer, Fei Hu, Julia M. Huntenburg, Anup Khanal, Chris Krasniak, Christopher Langdon, Christopher A. Langfield, Peter E. Latham, Petrina Y. P. Lau, Zach Mainen, Guido T. Meijer, Nathaniel J. Miska, Thomas D. Mrsic-Flogel, Jean-Paul Noel, Kai Nylund, Alejandro Pan-Vazquez, Liam Paninski, Jonathan Pillow, Cyrille Rossant, Noam Roth, Rylan Schaeffer, Michael Schartner, Yanliang Shi, Karolina Z. Socha, Nicholas A. Steinmetz, Karel Svoboda, Charline Tessereau, Anne E. Urai, Miles J. Wells, Steven Jon West, Matthew R. Whiteway, Olivier Winter, Ilana B. Witten, Anthony Zador, Yizi Zhang, Peter Dayan, Alexandre Pouget
The neural representations of prior information about the state of the world are poorly understood1. Here, to investigate them, we examined brain-wide Neuropixels recordings and widefield calcium imaging collected by the International Brain Laboratory. Mice were trained to indicate the location of a visual grating stimulus, which appeared on the left or right with a prior probability alternating between 0.2 and 0.8 in blocks of variable length. We found that mice estimate this prior probability and thereby improve their decision accuracy. Furthermore, we report that this subjective prior is encoded in at least 20% to 30% of brain regions that, notably, span all levels of processing, from early sensory areas (the lateral geniculate nucleus and primary visual cortex) to motor regions (secondary and primary motor cortex and gigantocellular reticular nucleus) and high-level cortical regions (the dorsal anterior cingulate area and ventrolateral orbitofrontal cortex). This widespread representation of the prior is consistent with a neural model of Bayesian inference involving loops between areas, as opposed to a model in which the prior is incorporated only in decision-making areas. This study offers a brain-wide perspective on prior encoding at cellular resolution, underscoring the importance of using large-scale recordings on a single standardized task.
Bayesian inference, Decision, Learning algorithms, Neural decoding, Sensory processing
A nanobody specific to prefusion glycoprotein B neutralizes HSV-1 and HSV-2
Original Paper | Cryoelectron microscopy | 2025-09-02 20:00 EDT
Benjamin Vollmer, Henriette Ebel, Renate Rees, Julia Nentwig, Thomas Mulvaney, Jürgen Schünemann, Jens Krull, Maya Topf, Dirk Görlich, Kay Grünewald
The nine human herpesviruses, including herpes simplex virus 1 and 2, human cytomegalovirus and Epstein-Barr virus, present a significant burden to global public health1. Their envelopes contain at least ten different glycoproteins, which are necessary for host cell tropism, attachment and entry2. The best conserved among them, glycoprotein B (gB), is essential as it performs membrane fusion by undergoing extensive rearrangements from a prefusion to postfusion conformation. At present, there are no antiviral drugs targeting gB or neutralizing antibodies directed against its prefusion form, because of the difficulty in structurally determining and using this metastable conformation. Here we show the isolation of prefusion-specific nanobodies, one of which exhibits strong neutralizing and cross-species activity. By mutational stabilization we solved the herpes simplex virus 1 gB full-length prefusion structure, which allowed the bound epitope to be determined. Our analyses show the membrane-embedded regions of gB and previously unresolved structural features3,4, including a new fusion loop arrangement, providing insights into the initial conformational changes required for membrane fusion. Binding an epitope spanning three domains, proximal only in the prefusion state, the nanobody keeps wild-type HSV-2 gB in this conformation and enabled its native prefusion structure to be determined. This also indicates the mode of neutralization and an attractive avenue for antiviral interventions.
Cryoelectron microscopy, Herpes virus, Membrane fusion, Membrane proteins, Viral infection
Training of physical neural networks
Review Paper | Electronics, photonics and device physics | 2025-09-02 20:00 EDT
Ali Momeni, Babak Rahmani, Benjamin Scellier, Logan G. Wright, Peter L. McMahon, Clara C. Wanjura, Yuhang Li, Anas Skalli, Natalia G. Berloff, Tatsuhiro Onodera, Ilker Oguz, Francesco Morichetti, Philipp del Hougne, Manuel Le Gallo, Abu Sebastian, Azalia Mirhoseini, Cheng Zhang, Danijela Marković, Daniel Brunner, Christophe Moser, Sylvain Gigan, Florian Marquardt, Aydogan Ozcan, Julie Grollier, Andrea J. Liu, Demetri Psaltis, Andrea Alù, Romain Fleury
Physical neural networks (PNNs) are a class of neural-like networks that make use of analogue physical systems to perform computations. Although at present confined to small-scale laboratory demonstrations, PNNs could one day transform how artificial intelligence (AI) calculations are performed. Could we train AI models many orders of magnitude larger than present ones? Could we perform model inference locally and privately on edge devices? Research over the past few years has shown that the answer to these questions is probably “yes, with enough research”. Because PNNs can make use of analogue physical computations more directly, flexibly and opportunistically than traditional computing hardware, they could change what is possible and practical for AI systems. To do this, however, will require notable progress, rethinking both how AI models work and how they are trained–primarily by considering the problems through the constraints of the underlying hardware physics. To train PNNs, backpropagation-based and backpropagation-free approaches are now being explored. These methods have various trade-offs and, so far, no method has been shown to scale to large models with the same performance as the backpropagation algorithm widely used in deep learning today. However, this challenge has been rapidly changing and a diverse ecosystem of training techniques provides clues for how PNNs may one day be used to create both more efficient and larger-scale realizations of present-scale AI models.
Electronics, photonics and device physics, Mathematics and computing
Adaptive and context-aware volumetric printing
Original Paper | Biomaterials | 2025-09-02 20:00 EDT
Sammy Florczak, Gabriel Größbacher, Davide Ribezzi, Alessia Longoni, Marième Gueye, Estée Grandidier, Jos Malda, Riccardo Levato
We introduce Generative, Adaptive, Context-Aware 3D Printing (GRACE), a new approach combining 3D imaging, computer vision and parametric modelling to create tailored, context-aware geometries using volumetric additive manufacturing. GRACE rapidly and automatically generates complex structures capable of conforming directly around features ranging from cellular to macroscopic scales with minimal user intervention. Here we demonstrate its versatility in applications ranging from synthetic objects to biofabrication, including adaptive vascular-like geometries around cell-laden bioinks, resulting in improved functionality. GRACE also enables precise alignment of sequential prints, as well as the detection and overprinting of opaque surfaces through shadow correction. Compatible with various printing modalities1,2,3,4, GRACE transcends traditional additive manufacturing limitations in automating overprinting and adapting the printed designs to the content of the printable material. This opens new possibilities in tissue engineering and regenerative medicine.
Biomaterials, Biomedical engineering, Engineering, Techniques and instrumentation, Tissue engineering
3D-printed micro ion trap technology for quantum information applications
Original Paper | Design, synthesis and processing | 2025-09-02 20:00 EDT
Shuqi Xu, Xiaoxing Xia, Qian Yu, Abhinav Parakh, Sumanta Khan, Eli Megidish, Bingran You, Boerge Hemmerling, Andrew Jayich, Kristin Beck, Juergen Biener, Hartmut Häffner
Trapped-ion applications, such as in quantum information processing1, precision measurements2,3,4,5, optical clocks6 and mass spectrometry7, rely on specialized high-performance ion traps. The last three of these applications typically use traditional machining to customize macroscopic 3D Paul traps8, whereas quantum information processing experiments usually rely on photolithographic techniques to miniaturize the traps and meet scalability requirements9,10. Using photolithography, however, it is challenging to fabricate the complex 3D electrode structures required for optimal confinement. Here we demonstrate a high-resolution 3D printing technology based on two-photon polymerization (2PP)11 that is capable of fabricating large arrays of high-performance miniaturized 3D traps. We show that 3D-printed ion traps combine the advantages, such as strong radial confinement, of traditionally machined 3D traps with on-chip miniaturization. We trap calcium ions in 3D-printed ion traps with radial trap frequencies ranging from 2 MHz to 24 MHz. The tight confinement eases ion cooling requirements and allows us to implement high-quality Rabi oscillations with Doppler cooling only. Also, we demonstrate a two-qubit gate with a Bell-state fidelity of 0.978 ± 0.012. With 3D printing technology, the design freedom is greatly expanded without sacrificing scalability and precision, so that ion trap geometries can be optimized for higher performance and better functionality.
Design, synthesis and processing, Quantum information
Supervised learning in DNA neural networks
Original Paper | DNA computing | 2025-09-02 20:00 EDT
Kevin M. Cherry, Lulu Qian
Learning enables biological organisms to begin life simple yet develop immensely diverse and complex behaviours. Understanding learning principles in engineered molecular systems could enable us to endow non-living physical systems with similar capabilities. Inspired by how the brain processes information, the principles of neural computation have been developed over the past 80 years1, forming the foundation of modern machine learning. More than four decades ago, connections between neural computation and physical systems were established2. More recently, synthetic molecular systems, including nucleic acid and protein circuits, have been investigated for their abilities to implement neural computation3,4,5,6,7. However, in these systems, learning of molecular parameters such as concentrations and reaction rates was performed in silico to generate desired input-output functions. Here we show that DNA molecules can be programmed to autonomously carry out supervised learning in vitro, with the system learning to perform pattern classification from molecular examples of inputs and desired responses. We demonstrate a DNA neural network trained to classify three different sets of 100-bit patterns, integrating training data directly into memories of molecular concentrations and using these memories to process subsequent test data. Our work suggests that molecular circuits can learn tasks more complex than simple adaptive behaviours. This opens the door to molecular machines capable of embedded learning and decision-making in a wide range of physical systems, from biomedicine to soft materials.
DNA computing, Synthetic biology
Commensal yeast promotes Salmonella Typhimurium virulence
Original Paper | Bacterial host response | 2025-09-02 20:00 EDT
Kanchan Jaswal, Olivia A. Todd, Roberto C. Flores Audelo, William Santus, Saikat Paul, Ciera M. Duffy, Edward T. Eshoo III, Manmeet Singh, Jian Miao, David M. Underhill, Brian M. Peters, Judith Behnsen
Enteric pathogens engage in complex interactions with the host and the resident microbiota to establish gut colonization1,2,3. Although mechanistic interactions between enteric pathogens and bacterial commensals have been extensively studied, whether and how commensal fungi affect enteric infections remain largely unknown1. Here we show that colonization with the common human gut commensal fungus Candida albicans worsened infections with the enteric pathogen Salmonella enterica subsp. enterica serovar Typhimurium. The presence of C. albicans in the mouse gut increased Salmonella caecal colonization and systemic dissemination. We investigated the underlying mechanism and found that Salmonella binds to C. albicans via type 1 fimbriae and uses its type 3 secretion system to deliver effector proteins into C. albicans. A specific effector, SopB, was sufficient to manipulate C. albicans metabolism and trigger the release of millimolar amounts of arginine into the extracellular environment. The released arginine, in turn, induced expression of the type 3 secretion system in Salmonella, increasing its invasion of epithelial cells. C. albicans deficient in arginine production was unable to increase Salmonella virulence. Arginine-producing C. albicans also dampened the inflammatory response during Salmonella infection. Arginine supplementation in the absence of C. albicans increased the systemic spread of Salmonella and decreased the inflammatory response, phenocopying the presence of C. albicans. In summary, we identified C. albicans colonization as a susceptibility factor for disseminated Salmonella infection and arginine as a central metabolite in the cross-kingdom interaction between fungi, bacteria and host.
Bacterial host response, Bacterial pathogenesis, Fungi, Microbiome
PICALM Alzheimer’s risk allele causes aberrant lipid droplets in microglia
Original Paper | Alzheimer’s disease | 2025-09-02 20:00 EDT
Alena Kozlova, Siwei Zhang, Ari Sudwarts, Hanwen Zhang, Stanislau Smirnou, Seul Kee Byeon, Christina Thapa, Xiaotong Sun, Kimberley Stephenson, Xiaojie Zhao, Brendan Jamison, Moorthi Ponnusamy, Xin He, Julie A. Schneider, Akhilesh Pandey, David A. Bennett, Zhiping P. Pang, Alan R. Sanders, Hugo J. Bellen, Gopal Thinakaran, Jubao Duan
Despite genome-wide association studies (GWAS) of late-onset Alzheimer’s disease (LOAD) having identified many genetic risk loci1,2,3, the underlying disease mechanisms remain largely unclear. Determining causal disease variants and their LOAD-relevant cellular phenotypes has been a challenge. Here, using our approach for identifying functional GWAS risk variants showing allele-specific open chromatin, we systematically identified putative causal LOAD-risk variants in human induced pluripotent stem (iPS)-cell-derived neurons, astrocytes and microglia, and linked a PICALM LOAD-risk allele to a microglial-specific role of PICALM in lipid droplet (LD) accumulation. Allele-specific open-chromatin mapping revealed functional risk variants for 26 LOAD-risk loci, mostly specific to microglia. At the microglial-specific PICALM locus, the LOAD-risk allele of the single-nucleotide polymorphism rs10792832 reduced transcription factor (PU.1) binding and PICALM expression, impairing the uptake of amyloid beta (Aβ) and myelin debris. Notably, microglia carrying the PICALM risk allele showed transcriptional enrichment of pathways for cholesterol synthesis and LD formation. Genetic and pharmacological perturbations of microglia further established a causal link between reduced PICALM expression, LD accumulation and phagocytosis deficits. Our work elucidates the selective LOAD vulnerability in microglia at the PICALM locus through detrimental LD accumulation, providing a neurobiological basis that can be exploited for developing clinical interventions.
Alzheimer’s disease, Genetics of the nervous system
Infrastructure deficits and informal settlements in sub-Saharan Africa
Original Paper | Computational science | 2025-09-02 20:00 EDT
Luís M. A. Bettencourt, Nicholas Marchio
Sustainable development is an imperative worldwide1,2,3 but metrics and data on poverty and quality of life have remained too coarse and abstract to characterize challenges adequately and guide practical progress4,5. Nowhere is this challenge greater than in Africa4,5,6, where we still know little about the spatial details of development3,7,8,9. Here we leverage a comprehensive, high-precision dataset of building footprints to identify infrastructure deficits and infer informal settlements down to the street block level10,11,12 everywhere in sub-Saharan Africa. We identify a general pattern of informality with cities showing, on average, greater access to infrastructure and services than rural and peri-urban areas. We show that such patterns of informality are characterized by consistent statistical distributions reflecting uneven local development2,13,14. We also show that these physical measures of informality are systematically associated with many indicators of human deprivation, which form a single principal component co-varying predictably with specific changes in street access to buildings. These results demonstrate that the localization of sustainable development is possible down to the street level at a continental scale and provide a general distributed strategy for accelerating progress in infrastructure and service expansion that taps local innovations in systematic, equitable and context-appropriate ways7,11,12,15.
Computational science, Developing world, Sustainability
Amygdala-liver signalling orchestrates glycaemic responses to stress
Original Paper | Homeostasis | 2025-09-02 20:00 EDT
J. R. E. Carty, K. Devarakonda, R. M. O’Connor, A. Krek, D. Espinoza, M. Jimenez-Gonzalez, A. Alvarsson, R. F. Hampton, R. Li, Y. Qiu, S. Petri, A. Shtekler, A. Rajbhandari, K. Conner, M. Bayne, D. Garibay, J. Martin, V. Lehmann, L. Wang, K. Beaumont, I. Kurland, G. C. Yuan, P. J. Kenny, S. A. Stanley
Behavioural adaptations to environmental threats are crucial for survival1,2 and necessitate rapid deployment of energy reserves3,4,5. The amygdala coordinates behavioural adaptations to threats6, but little is known about its involvement in underpinning metabolic adaptations. Here we show that acute stress activates medial amygdala (MeA) neurons that innervate the ventromedial hypothalamus (MeAVMH neurons), which precipitates hyperglycaemia and hypophagia. The glycaemic actions of MeAVMH neurons occur independently of adrenal or pancreatic glucoregulatory hormones. Using whole-body virus tracing, we identify a polysynaptic connection from MeA to the liver that promotes the rapid synthesis of glucose by hepatic gluconeogenesis. Repeated stress exposure disrupts MeA control of blood glucose, resulting in diabetes-like dysregulation of glucose homeostasis. Our findings reveal an amygdala-liver axis that regulates rapid glycaemic adaptations to stress and links recurrent stress to metabolic dysfunction.
Homeostasis, Hypothalamus
Multiple overlapping binding sites determine transcription factor occupancy
Original Paper | Gene regulation | 2025-09-02 20:00 EDT
Shubham Khetan, Brent S. Carroll, Martha L. Bulyk
Transcription factors (TFs) regulate gene expression by interacting with DNA in a sequence-specific manner. High-throughput in vitro technologies, such as protein-binding microarrays1,2,3,4,5,6 and HT-SELEX (high-throughput systematic evolution of ligands by exponential enrichment)7,8, have revealed the DNA-binding specificities of hundreds of TFs. However, they have limited ability to reliably identify lower-affinity DNA binding sites, which are increasingly recognized as important for precise spatiotemporal control of gene expression9,10,11,12,13,14,15,16,17,18,19. Here, to address this limitation, we developed protein affinity to DNA by in vitro transcription and RNA sequencing (PADIT-seq), with which we comprehensively assayed the binding preferences of six TFs to all possible ten-base-pair DNA sequences, detecting hundreds of novel, lower-affinity binding sites. The expanded repertoire of lower-affinity binding sites revealed that nucleotides flanking high-affinity DNA binding sites create overlapping lower-affinity sites that together modulate TF genomic occupancy in vivo. We propose a model in which TF binding is not determined by individual binding sites, but rather by the sum of multiple, overlapping binding sites. The overlapping binding model explains how competition between paralogous TFs for shared high-affinity binding sites is determined by flanking nucleotides that create differential numbers of overlapping, lower-affinity binding sites. Critically, the model transforms our understanding of noncoding-variant effects, revealing how single nucleotide changes simultaneously alter multiple overlapping sites to additively influence gene expression and human traits, including diseases.
Gene regulation, Genomics
Genetic suppression features ABHD18 as a Barth syndrome therapeutic target
Original Paper | Genetic interaction | 2025-09-02 20:00 EDT
Sanna N. Masud, Anchal Srivastava, Patricia Mero, Victoria Saba Echezarreta, Eve Anderson, Lennard van Buren, Jiarun Wei, David Thomson Taylor, Adrian Granda Farias, Nicholas Mikolajewicz, Angela Shaw, Brandon M. Murareanu, Michelle Lohbihler, Olivia Sniezek Carney, Simon van Heeringen, Linda Clijsters, Olga Sizova, Jeroen van Ameijde, Freya Nye, Andrea Habsid, Lucy Nedyalkova, Laura McDonald, Craig Simpson, Leanne Wybenga-Groot, Kevin R. Brown, Nhi Nho, Radu M. Suciu, Katherine Chan, Amy H. Y. Tong, Frédéric M. Vaz, Bastiaan Evers, Robert Lesurf, Tanya Papaz, Lauryl M. J. Nutter, Stephanie Protze, Maximilian Billmann, Michael Costanzo, Brenda J. Andrews, Chad L. Myers, Seema Mital, Hilary Vernon, Thijn R. Brummelkamp, Charles Boone, Ian C. Scott, Micah J. Niphakis, Douglas Strathdee, Sebastian M. B. Nijman, Vincent A. Blomen, Jason Moffat
Cardiolipin (CL) is the signature phospholipid of the inner mitochondrial membrane, where it stabilizes electron transport chain protein complexes1. The final step in CL biosynthesis relates to its remodelling: the exchange of nascent acyl chains with longer, unsaturated chains1. However, the enzyme responsible for cleaving nascent CL (nCL) has remained elusive. Here, we describe ABHD18 as a candidate deacylase in the CL biosynthesis pathway. Accordingly, ABHD18 converts CL into monolysocardiolipin (MLCL) in vitro, and its inactivation in cells and mice results in a shift to nCL in serum and tissues. Notably, ABHD18 deactivation rescues the mitochondrial defects in cells and the morbidity and mortality in mice associated with Barth syndrome. This rare genetic disease is characterized by the build-up of MLCL resulting from inactivating mutations in TAFAZZIN (TAZ), which encodes the final enzyme in the CL-remodelling cascade1. We also identified a selective, covalent, small-molecule inhibitor of ABHD18 that rescues TAZ mutant phenotypes in fibroblasts from human patients and in fish embryos. This study highlights a striking example of genetic suppression of a monogenic disease revealing a canonical enzyme in the CL biosynthesis pathway.
Genetic interaction, Hydrolases, Metabolic disorders
One mother for two species via obligate cross-species cloning in ants
Original Paper | Evolutionary biology | 2025-09-02 20:00 EDT
Y. Juvé, C. Lutrat, A. Ha, A. Weyna, E. Lauroua, A. C. Afonso Silva, C. Roux, E. Schifani, C. Galkowski, C. Lebas, R. Allio, I. Stoyanov, N. Galtier, B. C. Schlick-Steiner, F. M. Steiner, D. Baas, B. Kaufmann, J. Romiguier
Living organisms are assumed to produce same-species offspring1,2. Here, we report a shift from this norm in Messor ibericus, an ant that lays individuals from two distinct species. In this life cycle, females must clone males of another species because they require their sperm to produce the worker caste. As a result, males from the same mother exhibit distinct genomes and morphologies, as they belong to species that diverged over 5 million years ago. The evolutionary history of this system appears as sexual parasitism3 that evolved into a natural case of cross-species cloning4,5, resulting in the maintenance of a male-only lineage cloned through distinct species’ ova. We term females exhibiting this reproductive mode as xenoparous, meaning they give birth to other species as part of their life cycle.
Evolutionary biology, Evolutionary ecology, Genetic hybridization, Phylogenomics, Population genetics
Dynamic fibroblast-immune interactions shape recovery after brain injury
Original Paper | Neuroimmunology | 2025-09-02 20:00 EDT
Nathan A. Ewing-Crystal, Nicholas M. Mroz, Amara Larpthaveesarp, Carlos O. Lizama, Remy Pennington, Pailin Chiaranunt, Jason I. Dennis, Anthony A. Chang, Eric Dean Merrill, Sofia E. Caryotakis, Nikhita Kirthivasan, Leon Teo, Tatsuya Tsukui, Aditya Katewa, Gabriel L. McKinsey, Sophia C. K. Nelson, Agnieszka Ciesielska, Nicole C. Lummis, Lucija Pintarić, Madelene W. Dahlgren, Amha Atakilit, Helena Paidassi, Saket Jain, Xiaodan Liu, Duan Xu, Manish K. Aghi, James A. Bourne, Jeanne T. Paz, Richard Daneman, Fernando F. Gonzalez, Dean Sheppard, Anna V. Molofsky, Thomas D. Arnold, Ari B. Molofsky
Fibroblasts and immune cells coordinate tissue regeneration and necessary scarring after injury. In the brain, fibroblasts are border-enriched cells whose dynamic molecular states and immune interactions after injury remain unclear1. Here we define the shared fibroblast-immune response to brain injury. Early profibrotic myofibroblasts develop from pre-existing brain fibroblasts and infiltrate brain lesions, orchestrated by fibroblast TGFβ signalling, profibrotic macrophages and microglia, and perilesional glia. Myofibroblasts transition into several late fibroblast states, including lymphocyte-interactive fibroblasts. Interruption of the early myofibroblast state exacerbated sub-acute brain injury, tissue loss and secondary neuroinflammation, with increased mortality in the transient middle cerebral artery occlusion stroke model. Disruption of late lymphocyte-fibroblast niches via selective loss of fibroblast chemokine CXCL12 led to late brain-specific innate inflammation and lymphocyte dispersal with increased IFNγ production. These data indicate the response to brain injury is coordinated by evolving temporal and spatial fibroblast states that limit functional tissue loss and chronic neuroinflammation.
Neuroimmunology, Regeneration and repair in the nervous system, Stroke
Rewiring of cortical glucose metabolism fuels human brain cancer growth
Original Paper | Cancer metabolism | 2025-09-02 20:00 EDT
Andrew J. Scott, Anjali Mittal, Baharan Meghdadi, Alexandra O’Brien, Justine Bailleul, Palavalasa Sravya, Abhinav Achreja, Weihua Zhou, Jie Xu, Angelica Lin, Kari Wilder-Romans, Ningning Liang, Ayesha U. Kothari, Navyateja Korimerla, Donna M. Edwards, Zhe Wu, Jiane Feng, Sophia Su, Li Zhang, Peter Sajjakulnukit, Anthony C. Andren, Junyoung O. Park, Johanna ten Hoeve, Vijay Tarnal, Kimberly A. Redic, Nathan R. Qi, Joshua L. Fischer, Ethan Yang, Michael S. Regan, Sylwia A. Stopka, Gerard Baquer, Krithika Suresh, Jann N. Sarkaria, Theodore S. Lawrence, Sriram Venneti, Nathalie Y. R. Agar, Erina Vlashi, Costas A. Lyssiotis, Wajd N. Al-Holou, Deepak Nagrath, Daniel R. Wahl
The brain avidly consumes glucose to fuel neurophysiology1. Cancers of the brain, such as glioblastoma, relinquish physiological integrity and gain the ability to proliferate and invade healthy tissue2. How brain cancers rewire glucose use to drive aggressive growth remains unclear. Here we infused 13C-labelled glucose into patients and mice with brain cancer, coupled with quantitative metabolic flux analysis, to map the fates of glucose-derived carbon in tumour versus cortex. Through direct and comprehensive measurements of carbon and nitrogen labelling in both cortex and glioma tissues, we identify profound metabolic transformations. In the human cortex, glucose carbons fuel essential physiological processes, including tricarboxylic acid cycle oxidation and neurotransmitter synthesis. Conversely, gliomas downregulate these processes and scavenge alternative carbon sources such as amino acids from the environment, repurposing glucose-derived carbons to generate molecules needed for proliferation and invasion. Targeting this metabolic rewiring in mice through dietary amino acid modulation selectively alters glioblastoma metabolism, slows tumour growth and augments the efficacy of standard-of-care treatments. These findings illuminate how aggressive brain tumours exploit glucose to suppress normal physiological activity in favour of malignant expansion and offer potential therapeutic strategies to enhance treatment outcomes.
Cancer metabolism, CNS cancer, Translational research
Seismic detection of a 600-km solid inner core in Mars
Original Paper | Astronomy and planetary science | 2025-09-02 20:00 EDT
Huixing Bi, Daoyuan Sun, Ningyu Sun, Zhu Mao, Mingwei Dai, Douglas Hemingway
For rocky planets, the presence of a solid inner core has notable implications on the composition and thermal evolution of the core and on the magnetic history of the planet1,2,3. On Mars, geophysical observations have confirmed that the core is at least partially liquid4,5,6,7, but it is unknown whether any part of the core is solid. Here we present an analysis of seismic data acquired by the InSight mission, demonstrating that Mars has a solid inner core. We identify two seismic phases, the deep core-transiting phase, PKKP, and the inner core boundary reflecting phase, PKiKP, indicative of the inner core. Our inversions constrain the radius of the Martian inner core to about 613 ± 67 km, with a compressional velocity jump of around 30% across the inner core boundary, supported by additional inner-core-related seismic phases. These properties imply a concentration of distinct light elements in the inner core, segregated from the outer core through core crystallization. This finding provides an anchor point for understanding the thermal and chemical state of Mars. Moreover, the relationship between inner core formation and the Martian magnetic field evolution could provide insights into dynamo generation across planetary bodies.
Astronomy and planetary science, Planetary science, Seismology
Ancient DNA connects large-scale migration with the spread of Slavs
Original Paper | Archaeology | 2025-09-02 20:00 EDT
Joscha Gretzinger, Felix Biermann, Hellen Mager, Benedict King, Denisa Zlámalová, Luca Traverso, Guido A. Gnecchi Ruscone, Sanni Peltola, Elina Salmela, Gunnar U. Neumann, Rita Radzeviciute, Pavlína Ingrová, Radosław Liwoch, Iwona Wronka, Radomir Jurić, Anna Hyrchała, Barbara Niezabitowska-Wiśniewska, Bartłomiej Bartecki, Beata Borowska, Tomasz Dzieńkowski, Marcin Wołoszyn, Michał Wojenka, Jarosław Wilczyński, Małgorzata Kot, Eric Müller, Jörg Orschiedt, Gunita Zariņa, Päivi Onkamo, Falko Daim, Arnold Muhl, Ralf Schwarz, Marek Majer, Michael McCormick, Jan Květina, Tivadar Vida, Patrick J. Geary, Jiří Macháček, Mario Šlaus, Harald Meller, Walter Pohl, Zuzana Hofmanová, Johannes Krause
The second half of the first millennium ce in Central and Eastern Europe was accompanied by fundamental cultural and political transformations. This period of change is commonly associated with the appearance of the Slavs, which is supported by textual evidence1,2 and coincides with the emergence of similar archaeological horizons3,4,5,6. However, so far there has been no consensus on whether this archaeological horizon spread by migration, Slavicisation or a combination of both. Genetic data remain sparse, especially owing to the widespread practice of cremation in the early phase of the Slavic settlement. Here we present genome-wide data from 555 ancient individuals, including 359 samples from Slavic contexts from as early as the seventh century ce. Our data demonstrate large-scale population movement from Eastern Europe during the sixth to eighth centuries, replacing more than 80% of the local gene pool in Eastern Germany, Poland and Croatia. Yet, we also show substantial regional heterogeneity as well as a lack of sex-biased admixture, indicating varying degrees of cultural assimilation of the autochthonous populations. Comparing archaeological and genetic evidence, we find that the change in ancestry in Eastern Germany coincided with a change in social organization, characterized by an intensification of inter- and intra-site genetic relatedness and patrilocality. On the European scale, it appears plausible that the changes in material culture and language between the sixth and eighth centuries were connected to these large-scale population movements.
Archaeology, Genetics, Population genetics
Nature Physics
Accelerator technologies for proton and ion beam therapy
Review Paper | Applied physics | 2025-09-02 20:00 EDT
Vivek Maradia, Benjamin Clasie, Emma Snively, Katia Parodi, Marco Schwarz, Marco Durante
Over the past 75 years, proton beam therapy has emerged as a promising modality for cancer treatment, boasting precise targeting and reduced collateral damage to healthy tissue. Here we discuss the evolution of accelerator technology in proton therapy, examining advancements in cyclotron, synchrotron and linear accelerator technology, and their implications for modern treatment delivery. Additionally, we explore advances in delivering accelerated carbon or helium ions for therapeutic treatments. We also discuss the integration of advanced imaging modalities, such as multienergy X-ray, magnetic resonance imaging and ion-based imaging, for real-time monitoring and adaptive radiotherapy. These advancements position particle therapy to offer personalized and effective cancer treatment strategies, heralding improved patient outcomes.
Applied physics, Particle physics
Physical Review Letters
Heisenberg-Limited Continuous-Variable Distributed Quantum Metrology with Arbitrary Weights
Research article | Optical interferometry | 2025-09-02 06:00 EDT
Wenchao Ge and Kurt Jacobs
Distributed quantum metrology (DQM) enables the estimation of global functions of $d$ distributed parameters beyond the capability of separable sensors. Continuous-variable DQM involves using a linear network with at least one nonclassical input. Here, we fully elucidate the structure of linear networks with two nonvacuum inputs, which allows us to prove a number of fundamental properties of continuous-variable DQM. While measuring the sum of $d$ parameters at the Heisenberg limit can be achieved with a single nonvacuum input, we show that two inputs, one of which can be classical, are required to measure an arbitrary linear combination of $d$ parameters and an arbitrary global function of the parameters. We obtain a universal and tight upper bound on the sensitivity of DQM networks with two inputs, and completely characterize the properties of the nonclassical input required to obtain a quantum advantage. This reveals that a wide range of nonclassical states makes this possible, including a squeezed vacuum. We also show that, for a class of nonclassical inputs, local photon number detection will achieve the maximum sensitivity. Finally we show that a general DQM network has two distinct regimes. The first achieves Heisenberg scaling. In the second the nonclassical input is much weaker than the coherent input, nevertheless providing a multiplicative enhancement to the otherwise classical sensitivity.
Phys. Rev. Lett. 135, 100801 (2025)
Optical interferometry, Quantum metrology, Quantum states of light
Ultralight Dark Matter Statistics for Pulsar Timing Detection
Dark matter | 2025-09-02 06:00 EDT
Kimberly K. Boddy, Jeff A. Dror, and Austin Lam
Fluctuations in ultralight dark matter produce significant metric perturbations, which may be detected by monitoring the arrival times of light from millisecond pulsars. While searches using this technique are already underway, they do not consistently account for the statistical properties of the dark matter field. The statistics of this field depend on the velocity dispersion of dark matter and, consequently, its coherence length. In the mass range relevant for pulsar timing arrays, the coherence length is comparable to separations between pulsars, making it crucial to incorporate its effects into the analysis. This Letter presents a consistent statistical method for gravitational direct detection of ultralight dark matter. Our key result is the derivation of the two-point function of the metric fluctuations, which we apply to pulsar timing and discuss its implementation in future searches.
Phys. Rev. Lett. 135, 101001 (2025)
Dark matter, Dark matter direct detection, Gravitational waves, Neutron stars & pulsars, Gravitational wave detectors
Universal Bound on the Duration of a Kination Era
Research article | Cosmology | 2025-09-02 06:00 EDT
Cem Eröncel, Yann Gouttenoire, Ryosuke Sato, Géraldine Servant, and Peera Simakachorn
We show that primordial adiabatic curvature fluctuations generate an instability of the scalar field sourcing a kination era. We demonstrate that the generated higher Fourier modes constitute a radiationlike component dominating over the kination background after about 11 e-folds of cosmic expansion. Current constraints on the extra number of neutrino flavors $\mathrm{\Delta }{N}_{\mathrm{eff}}$ thus imply the observational bound of approximately 10 e-folds, representing the most stringent bound to date on the stiffness of the equation of state of the pre–Big Bang–nucleosynthesis universe.
Phys. Rev. Lett. 135, 101002 (2025)
Cosmology, Evolution of the Universe, Gravitational waves, Particle production
Unveiling the Electrodynamic Nature of Spacetime Collisions
Research article | Classical black holes | 2025-09-02 06:00 EDT
Siddharth Boyeneni, Jiaxi Wu, and Elias R. Most
Gravitational field equations describing binary black holes can be recast in a form resembling coupled Maxwell’s equations for electrodynamics.
Phys. Rev. Lett. 135, 101401 (2025)
Classical black holes, Fluid-gravity correspondence, General relativity formalism, Maxwell’s equations, Numerical relativity
Localization of the M2-Brane
Gauge-gravity dualities | 2025-09-02 06:00 EDT
Friðrik Freyr Gautason and Jesse van Muiden
We study quantum M2-branes in holographic backgrounds and show that their moduli spaces of zero modes are localized according to an R-symmetry Killing vector. We discuss the relation with recent results in the context of equivariant localization in gauged supergravity and argue its origin within M-theory path integrals expanded in saddle points over M2-branes. We argue that the M2-brane partition function, including its nonperturbative corrections, should be compared to the field theory grand canonical partition function. Our results extend recent observations in the context of the giant graviton expansion of superconformal indices to generic supersymmetric anti–de Sitter boundary conditions. As a byproduct we predict nonperturbative corrections to a variety of supersymmetric observables of the Aharony-Bergman-Jafferis-Maldacena theory.
Phys. Rev. Lett. 135, 101601 (2025)
Gauge-gravity dualities, M-theory, Quantum gravity, Strings & branes, Supersymmetry
Electroweak Symmetry Restoration and Radiation Amplitude Zeros
Research article | Electroweak phase transition | 2025-09-02 06:00 EDT
Rodolfo Capdevilla and Tao Han
In high-energy collisions far above the electroweak scale, the effects of electroweak symmetry breaking are expected to become parametrically small $\delta \sim {M}_{W}/E$. This defines the extent to which the electroweak gauge symmetry is restored: (i) the physics of the transverse gauge bosons and fermions is described by a massless theory in the unbroken phase; (ii) the longitudinal gauge bosons behave like the Goldstone bosons and join the Higgs boson to restore the unbroken O(4) symmetry in the original Higgs sector. Using the unique feature of the radiation amplitude zeros in gauge theory, we propose to study the electroweak symmetry restoration quantitatively by examining the processes for the gauge boson pair production ${W}^{\pm{}}\gamma ,{W}^{\pm{}}Z$, and ${W}^{\pm{}}H$ at the LHC and muon colliders.
Phys. Rev. Lett. 135, 101801 (2025)
Electroweak phase transition, Electroweak symmetry breaking, W & Z bosons
Measurement of the Positive Muon Anomalous Magnetic Moment to 127 ppb
Research article | Leptonic, semileptonic & radiative decays | 2025-09-02 06:00 EDT
D. P. Aguillard et al. (Muon Collaboration)
*et al.*The final results from the Muon g - 2 experiment agree with the latest predictions of the muon’s magnetic properties–letting down hopes that the particle would upset the standard model’s applecart.
Phys. Rev. Lett. 135, 101802 (2025)
Leptonic, semileptonic & radiative decays, Magnetic moment, Accelerators & storage rings, Muons, Precision measurements
Single-Inclusive Hadron Production in Electron-Positron Annihilation at Next-to-Next-to-Next-to-Leading Order in QCD
Research article | Fragmentation functions | 2025-09-02 06:00 EDT
Chuan-Qi He, Hongxi Xing, Tong-Zhi Yang, and Hua Xing Zhu
Single-inclusive hadron production in electron-positron annihilation (SIA) represents the cleanest process for investigating the dynamics of parton hadronization, as encapsulated in parton fragmentation functions. In this Letter, we present, for the first time, the analytical computation of quantum chromodynamics corrections to the coefficient functions for SIA at next-to-next-to-next-to-leading order (${\mathrm{N}}^{3}\mathrm{LO}$) accuracy, achieving the highest precision to date for hadron production processes. Utilizing the BABAR measurement as a benchmark, we assess the phenomenological implications of this high-precision calculation. Our findings demonstrate a substantial reduction in scale uncertainties at ${\mathrm{N}}^{3}\mathrm{LO}$ and offer an improved description of the experimental data compared to lower-order calculations. This advancement underscores the importance of higher-order corrections in achieving a more accurate understanding of hadronization processes.
Phys. Rev. Lett. 135, 101901 (2025)
Fragmentation functions, Perturbative QCD, QCD phenomenology
Magnifying the Wave Function of Interacting Fermionic Atoms
Research article | Cold atoms & matter waves | 2025-09-02 06:00 EDT
Sandra Brandstetter, Carl Heintze, Paul Hill, Philipp M. Preiss, Maciej Gałka, and Selim Jochim
A new technique allows the imaging of an atomic system in which the interatomic spacing is smaller than the optical-resolution limit.
Phys. Rev. Lett. 135, 103401 (2025)
Cold atoms & matter waves, Fermi gases
High-Throughput Search for Metallic Altermagnets by Embedded Dynamical Mean Field Theory
Research article | Altermagnetism | 2025-09-02 06:00 EDT
Xuhao Wan, Subhasish Mandal, Yuzheng Guo, and Kristjan Haule
We introduce a high-fidelity high-throughput screening (HTS) strategy to accelerate the discovery of altermagnets by combining density functional theory (DFT) with embedded dynamical mean-field theory. Our approach improves over the HTS with the conventional DFT method in the accuracy of predicting metallicity and spin splitting, especially in transition-metal-rich compounds. Our method is based on an automated workflow that incorporates prescreening and symmetry analysis and can be applied to a variety of correlated materials. This approach identified two previously unreported metallic altermagnets, CrSe and ${\mathrm{CaFe}}{4}{\mathrm{Al}}{8}$ (in addition to one known altermagnet CrSb), as well as a dozen semiconducting altermagnets among over 2000 magnetic materials. Our findings reveal that while altermagnets are abundant among magnetic materials, only a tiny fraction are metallic.
Phys. Rev. Lett. 135, 106501 (2025)
Altermagnetism, Electronic structure of atoms & molecules, First-principles calculations, Dynamical mean field theory
Non-Hermitian Floquet Topological Sensors for Ultrasensitive Detection of Dynamic Signals
Research article | Quantum sensing | 2025-09-02 06:00 EDT
Xiaoqi Zhou, Weixuan Zhang, Wenhui Cao, and Xiangdong Zhang
Non-Hermitian systems, distinguished by the presence of exceptional points and non-Hermitian topological states, have transformed sensing technologies through the implementation of novel physical mechanisms. However, despite their demonstrated potential, existing non-Hermitian sensors are predominantly limited to static operational configurations, which substantially restricts their effects in detecting time-varying signals. Here, we transcend this limitation by introducing a new sensing framework: non-Hermitian Floquet topological sensors (NHFTSs). This approach harnesses the synergistic interplay among time-periodic driving, nonlinear dynamics, and non-Hermitian topology to enable ultrasensitive detection of dynamic signals. NHFTSs establish nonlinear non-Hermitian Floquet topological zero modes as robust global attractors. These modes manifest extraordinary sensitivity to dynamic boundary perturbations, exhibiting frequency shifts that scale exponentially with system size. Moreover, NHFTSs possess exceptional resilience against both background noise and structural perturbations, a feature enabled by the dual protective mechanisms of nonlinear stability and topological band gaps. Notably, the signal-to-noise ratio of NHFTSs can be exponentially amplified through sensor size scaling. We experimentally validate the NHFTS using time-varying topolectrical circuits, demonstrating their unparalleled capability in detecting dynamic electrical signals with high sensitivity and signal-to-noise ratios. This Letter not only establishes a new paradigm for non-Hermitian dynamical sensing but also paves the way for exploring non-Hermitian topological phenomena in Floquet nonlinear systems, with profound implications for the development of next-generation non-Hermitian sensors and beyond.
Phys. Rev. Lett. 135, 106601 (2025)
Quantum sensing, Topolectrical circuits, Non-Hermitian systems, Nonlinear waves, Topological insulators
Quantum Geometry and the Electric Magnetochiral Anisotropy in Noncentrosymmetric Polar Media
Research article | Electrical conductivity | 2025-09-02 06:00 EDT
Pierpaolo Fontana, Victor Velasco, Chang Niu, Peide D. Ye, Pedro V. Lopes, Kaio E. M. de Souza, Marcus V. O. Moutinho, Caio Lewenkopf, and Marcello B. Silva Neto
The electric magnetochiral anisotropy is a nonreciprocal phenomenon accessible via second harmonic transport in noncentrosymmetric, time-reversal invariant materials, in which the rectification of current, $\mathbf{I}$, can be controlled by an external magnetic field, $\mathbf{B}$. Quantum geometry, which characterizes the topology of Bloch electrons in a Hilbert space, provides a powerful description of the nonlinear dynamics in topological materials. Here, we demonstrate that the electric magnetochiral anisotropy in noncentrosymmetric polar media owes its existence to the quantum metric, arising from the spin-orbit coupling, and to large Born effective charges. In this context, the reciprocal magnetoresistance $\beta {\mathbf{B}}^{2}$ is modified to $R(I,P,B)=\phantom{\rule{0ex}{0ex}}{R}_{0}[1+\beta {B}^{2}+{\gamma }^{\pm{}}\mathbf{I}\cdot{}(\mathbf{P}\times{}\mathbf{B})]$, where the chirality dependent ${\gamma }^{\pm{}}$ is determined by the quantum metric dipole and $\mathbf{P}$ is the polarization. In 2D, we predict a universal scaling ${\gamma }^{\pm{}}(V)\sim {V}^{- 5/2}$, which we compare to available phase sensitive, second harmonic transport measurements on hydrothermally grown tellurium films under applied gate voltage, $V$. The control of rectification by varying $\mathbf{I}$, $\mathbf{P}$, $\mathbf{B}$, and $V$, demonstrated in this work, opens up new avenues for the building of ultrascaled complementary metal-oxide-semiconductor circuits.
Phys. Rev. Lett. 135, 106602 (2025)
Electrical conductivity, Geometric & topological phases, Magnetoresistance, Topological phases of matter, Noncentrosymmetric materials, Weyl semimetal, Boltzmann theory, k dot p method
Anomalous Hall Effect in the Dirac Semimetal ${\mathrm{Cd}}{3}{\mathrm{As}}{2}$ Probed by In-Plane Magnetic Field
Research article | Hall effect | 2025-09-02 06:00 EDT
Shinichi Nishihaya, Hiroaki Ishizuka, Yuki Deguchi, Ayano Nakamura, Tadashi Yoneda, Hsiang Lee, Markus Kriener, and Masaki Uchida
Intrinsic anomalous Hall effect (AHE) formulated by geometric properties of Bloch wave functions is a ubiquitous transport phenomenon not limited to magnetic systems but also allowed in nonmagnetic ones under an external field breaking time-reversal symmetry. On the other hand, detection of field-induced AHE is practically challenging because the band modulation through the Zeeman and spin-orbit couplings is typically small compared to other contributions as induced by the Lorentz force. Here, we demonstrate on Dirac semimetal ${\mathrm{Cd}}{3}{\mathrm{As}}{2}$ films that the field-induced AHE in nonmagnetic systems can be quantitatively probed by applying and rotating the magnetic field within the Hall deflection plane. Measurements on the ${\mathrm{Cd}}{3}{\mathrm{As}}{2}$ (112) plane reveal that AHE emerges as a clear threefold symmetric component for the in-plane field rotation. This intrinsic response becomes more pronounced in ultralow-electron-density films where significant variations in the geometric properties are expected under the magnetic field. Our findings open new opportunities in the research of Hall responses manifested as orbital magnetization in nonmagnetic systems.
Phys. Rev. Lett. 135, 106603 (2025)
Hall effect, Dirac semimetal, Thin films, Molecular beam epitaxy
Mixing of Surface and Bulk Optical Nonlinearities via Surface Plasmon Polaritons
Research article | Nonlinear optical susceptibility | 2025-09-02 06:00 EDT
Guy Sayer, Matan Iluz, Amit Kam, and Guy Bartal
We present controlled interplay between the surface second-order and bulk third-order nonlinearities of gold, utilizing wave mixing between surface plasmons on the metal-air interface and free-space photons. By tuning the nonlinear interactions, we demonstrate experimentally that photons emerging from these inherently different mechanisms can interfere, while both their relative amplitude and phase are controlled solely by the pump beam. These results provide a foundation for engineering plasmonic nonlinearities and open new possibilities for quantum photonic applications.
Phys. Rev. Lett. 135, 106901 (2025)
Nonlinear optical susceptibility, Second order nonlinear optical processes, Third order nonlinear optical processes, Four-wave mixing
Diffusive Nature of Housing Prices
Research article | Complex systems | 2025-09-02 06:00 EDT
Antoine-Cyrus Becharat, Michael Benzaquen, and Jean-Philippe Bouchaud
We analyze the French housing market prices in the period 1970–2022, with high-resolution data from 2018 to 2022. The spatial correlation of the observed price field exhibits logarithmic decay characteristic of the two-dimensional random diffusion equation—local interactions may create long-range correlations. We introduce a stylized model, used in the past to model spatial regularities in voting patterns, that accounts for both spatial and temporal correlations with reasonable values of parameters, some fitted on impulse response data. Our analysis reveals that price shocks are persistent in time and their amplitude is strongly heterogeneous in space. Our study quantifies the diffusive nature of housing prices that was anticipated in the 1990s, albeit on much restricted local datasets.
Phys. Rev. Lett. 135, 107401 (2025)
Complex systems, Diffusion, Physics & society
Particle Scale Anisotropy Controls Bulk Properties in Sheared Granular Materials
Research article | Granular materials | 2025-09-02 06:00 EDT
Carmen L. Lee, Ephraim Bililign, Emilien Azéma, and Karen E. Daniels
The bulk dynamics of dense granular materials arise through a combination of particle-scale and mesoscale effects. Theoretical and numerical studies have shown that collective effects are created by particle-scale anisotropic structures such as grain connectivity, force transmission, and frictional mobilization, all of which influence bulk properties like bulk friction and the stress tensor through the stress-force-fabric (SFF) relationship. To date, establishing the relevance of these effects to laboratory systems has remained elusive due to the challenge of measuring both normal and frictional contact forces at the particle scale. In this study, we perform experiments on a sheared photoelastic granular system in a quasi-2D annular cell. During these experiments, we measure particle locations, contacts, and normal and frictional forces vectors during loading. We reconstruct the angular distributions of the contact and force vectors, and extract the corresponding emergent anisotropies for each of these metrics. Finally, we show for the first time in an experimental system that the SFF relation quantitatively predicts the relationship between particle scale anisotropies, the stress tensor components, and the bulk friction coefficient, capturing even transient behaviors—closing the gap between experimental measurements and prior theoretical and numerical models.
Phys. Rev. Lett. 135, 108201 (2025)
Granular materials, Microstructure, Shear deformation
Anomalous Shear Stress Growth during Relaxation of a Soft Glass
Research article | Non-Newtonian fluids | 2025-09-02 06:00 EDT
Crystal E. Owens
We show experimentally that multiple soft glassy fluids are capable of storing directional rheological signatures from past shear history, evidenced during stress growth and overall nonmonotonic stress relaxation after small steps in strain. We illustrate theoretically that these responses can be reproduced without requiring thixotropy or shear banding, which are typically implicated in time-dependent rheological complexities. Instead, we use a simple elastoplastic rheological model with power-law yielding that incorporates a distribution of local strain states. Using insight from the model, we suggest a mechanism for the experimentally observed stress increase to be driven by residual anisotropy in strain states that are relaxed at different rates. We demonstrate that these effects persist even after material is stressed beyond the yield stress, indicating that past deformation may have more influence than previously thought.
Phys. Rev. Lett. 135, 108202 (2025)
Non-Newtonian fluids, Plastic deformation, Rheology, Foams, Gels
Cell Stiffness-Mediated Mechanochemical Waves in Three-Dimensional Tissues
Research article | Cellular organization, physiology & dynamics | 2025-09-02 06:00 EDT
Pengyu Yu, Rui Zhang, and Bo Li
Tissue development, physiological or pathological, commonly involves stiffness alterations in the constituent cells. Here, we develop a three-dimensional (3D) active vertex model incorporating mechanical feedback from extracellular signal-regulated kinase (ERK) to explore mechanochemical waves in tissues with varying cell stiffness. Combining theory and simulations, we show that rich cell oscillations, mediated by cell stiffness and its spatial heterogeneity, can arise from mechanochemical instability. Increasing cell stiffness promotes the long-range force transmission and synchronization of collective waves, which exhibit robustness against cell heterogeneity of both size and stiffness. These mechanochemical waves can propagate around the locally stiffened inclusions or traverse stiff walls but retain their intrinsic modes. We further generate and interpret the ERK edge wave in 3D multicellular spheroids with stiffness variation, consistent with previous experiments. Our work uncovers the multifaceted roles of mechanics in self-organized mechanochemical dynamics within 3D multicellular tissues.
Phys. Rev. Lett. 135, 108401 (2025)
Cellular organization, physiology & dynamics, Living matter & active matter, Collective dynamics
Physical Review X
Criticality Enhances the Reinforcement of Disordered Networks by Rigid Inclusions
Research article | Composite materials | 2025-09-02 06:00 EDT
Jordan L. Shivers, Jingchen Feng, and Fred C. MacKintosh
Near a mechanical critical point, adding even a small amount of rigid material to soft fiber networks causes unexpectedly large stiffness increases, revealing new ways to design tunable, responsive materials.
Phys. Rev. X 15, 031061 (2025)
Composite materials, Polymer networks, Critical phenomena
Single-Shot Reconstruction of Electron Beam Longitudinal Phase Space in a Laser Wakefield Accelerator
Research article | Beam diagnostics | 2025-09-02 06:00 EDT
Y. Ma et al.
*et al.*A technique for fully mapping the ultrashort electron beams for laser wakefield acceleration eases the path to creating compact next-generation x-ray free-electron lasers.
Phys. Rev. X 15, 031062 (2025)
Beam diagnostics, Laser wakefield acceleration, Laser-plasma interactions, Plasma-beam interactions, Particle-in-cell methods
arXiv
Photothermomechanicaly Efficient, Low-Cost, High-Cycle-Life, Hybrid MXene-Polymer Actuators
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Ken Iiyoshi, Georgios Korres, Orsolya Nagy, Gabriel Roldán, Panče Naumov, Stefan Schramm, Mohamad Eid
Photothermomechanical polymer film actuators stand out among the dynamic components available for soft robotics due to a combination of assets, such as capability for rapid energy transduction, wireless control, and ease of miniaturization. Despite their anticipated superior performance, several design challenges remain. These include high operational temperatures, inadequate mechanical output relative to the radiation energy provided, limited durability during repeated use, and high production costs; such factors hinder the scalability of these actuating materials in practical applications. Here, we report a viable solution by substituting performance-enhancing nanoparticles with MXenes–carbon-based, two-dimensional materials known for their theoretical photothermal conversion efficiency of up to 100%. This led to the development of MXene-dispersed polymer trilayer actuators (MPTAs). Extensive photothermal and thermomechanical characterization demonstrated superior performance compared to previously reported actuators, with a reduced shed power demand (0.1 mW cm$ ^{-2}$ $ ^\circ$ C$ ^{-1}$ ), substantial bending capacity per irradiation power per time (0.1$ ^\circ$ mW$ ^{-1}$ cm$ ^{2}$ s$ ^{-1}$ ), and enhanced cyclic longevity, with fatigueless operation of at least 1,000 cycles. We demonstrate three applications: A kirigami-inspired flower, parallel manipulator, and soft gripper. Additionally, these materials are cost-effective; thus, they are the optimal choice for long-term, reversible operation with efficient heat-to-work transduction.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
27 pages, 5 figures Supplementary materials link: Supplementary Text Supplementary Figs. 1 to 6 Supplementary Movie 1 to 4 Source Data 1 this https URL
Poroelasticity of bottlebrush and linear polymer networks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Nolan A. Miller, Alfred J. Crosby
The transport of solvent molecules through soft, swollen networks is critical in both natural and engineered systems. While this poroelastic flow has traditionally been explored in networks where the mesh size is comparable to the solvent molecule size, the effect of network architecture on permeability remains underexplored. Here we investigate solvent transport in linear polymer networks (LPN) and highly elastic bottlebrush elastomer networks (BBN), where the presence of densely grafted sidechains allows for control over swelling and mechanical properties. By synthesizing BBNs with systematically varied crosslinking density while maintaining constant sidechain length and grafting density, we probe the poroelastic response in the stretched backbone regime (SBB). Poroelastic relaxation indentation experiments, performed in toluene, reveal how permeability scales with crosslink density and polymer volume fraction. Compared to LPN with identical chemistry, the BBN exhibited a lower permeability scaling exponent with polymer volume fraction that closely matches the theoretical exponent. Despite architectural differences, permeability data for both networks collapse onto a single curve when plotted against dry shear modulus. Our findings demonstrate that molecular network architecture significantly influences permeability, offering new routes to tailor solvent transport in soft, swollen networks. These insights highlight BBNs as a promising platform for applications in permeable membranes, filtration, and microfluidic systems, and pave the way for further studies on how network parameters, such as sidechain length, impact permeability in these highly tunable materials.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
10 pages, 4 figures, submitted to Soft Matter, published by Royal Society of Chemistry
When wall slip wins over shear flow: A temperature-dependent Eyring slip law and a thermal multiscale model for diamond-like carbon lubricated by a polyalphaolefin oil
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Stefan Peeters, Edder J. García, Franziska Stief, Thomas Reichenbach, Kerstin Falk, Gianpietro Moras, Michael Moseler
The quantitative description of lubricant flow in nanoscale channels is complicated by various finite-size effects that are not taken into account in conventional thermo-elasto-hydrodynamic lubrication (TEHL) models. One of these effects is wall slip, a phenomenon that has been extensively studied both theoretically and experimentally. The relationship between wall slip and thermal effects is intricate, and some authors debate whether the friction reduction observed in their experiments in the TEHL regime can be explained by either slip or viscosity reduction in heated lubricants. To disentangle these mechanisms, a comprehensive molecular dynamics study of the relationship between temperature and slip in the shear flow of a 4 cSt polyalphaolefin (PAO4) base oil in a nanoscale diamond-like carbon (DLC) channel is performed here. An Eyring law describes the relationship between slip velocity and shear stress at the solid-liquid interface for a given temperature and pressure. The same simulation campaign provides a pressure-dependent law for the interface thermal resistance (ITR) between DLC and PAO4. These constitutive laws are employed in a continuum model for lubricated parallel channels. By taking heat conduction into account and combining the slip and ITR laws with a temperature- and pressure-dependent Eyring viscosity law, questions about the competition of slip and thermal thinning of the lubricant can be answered. For DLC film thicknesses compatible with tribological experiments and applications, this model shows that slip is only relevant for very thin lubricant films that are typical of boundary lubrication, suggesting the dominance of thermal thinning in the TEHL regime.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Main text: 39 pages and 10 figures. Supporting information: 21 pages and 11 figures
Homogenization framework for rigid and non-rigid foldable origami metamaterials
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Xuwen Li, Amin Jamalimehr, Mathias Legrand, Damiano Pasini
Origami metamaterials typically consist of folded sheets with periodic patterns, conferring them with remarkable mechanical properties. In the context of Continuum Mechanics, the majority of existing predictive methods are mechanism analogs which favor rigid folding and panel bending. While effective in predicting primary deformation modes, existing methods fall short in capturing the full spectrum of deformation of non-rigid foldable origami, such as the emergence of curvature along straight creases, local strain at vertices and warpage in panels. To fully capture the entire deformation spectrum and enhance the accuracy of existing methods, this paper introduces a homogenization framework for origami metamaterials where the faces are modeled as plate elements. Both asymptotic and energy-based homogenization methods are formulated and implemented. As a representative crease pattern, we examine the Miura origami sheet homogenized as an equivalent Kirchhoff-Love plate. The results reveal that certain effective elastic properties are nonlinearly related to both the initial fold angle and the crease stiffness. When benchmarked with results from fully resolved simulations, our framework yields errors up to 12.9%, while existing models, including the bar-and-hinge model and the rigid-panel model, show up to 161% error. The differences in errors are associated with the complex modes of crease and panel deformation in non-rigid origami, unexplored by the existing models. This work demonstrates a precise and efficient continuum framework for origami metamaterials as an effective strategy for predicting their elastic properties, understanding their mechanics, and designing their functionalities.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Ostwald Ripening in Underground Gas Storage
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Mohammad Salehpour, Tian Lan, Nicolas Bueno, Md Zahidul Islam Laku, Yashar Mehmani, Benzhong Zhao
Underground gas storage is central to both climate mitigation and energy transition strategies, supporting both long-term carbon sequestration and seasonal hydrogen storage. A key mechanism governing the fate of injected gases is Ostwald ripening, the curvature-driven mass transfer between trapped gas ganglia in porous media. While ripening is well understood in open systems, its behavior in geometrically confined porous structures remains poorly characterized, especially over long timescales relevant to subsurface operations. Here, we present ultra-high-resolution microfluidic experiments that capture the evolution of residually trapped hydrogen over weeks in realistic, heterogeneous pore geometries under well-defined boundary conditions. We observe a distinct two-stage dynamic: a rapid local equilibration among neighboring bubbles, followed by slow global depletion driven by long-range diffusion toward low-chemical potential boundaries. Building on these insights, we develop and validate a continuum model that couples microscale capillary pressure-saturation (Pc-s) relationships, extracted via the pore-morphology method, with macroscopic diffusive transport. The model accurately predicts gas saturation evolution without fitting parameters and collapses experimental results across a range of experimental conditions. Extending the model to reservoir scales, we estimate equilibration timescales for CO2 and H2 in homogeneous sandstone aquifers. We find that ripening occurs much faster than convective dissolution in CO2 sequestration, and on timescales comparable to seasonal H2 storage operations. These findings establish a quantitative framework linking pore-scale heterogeneity to field-scale gas redistribution, with implications for the design and longevity of subsurface storage strategies.
Soft Condensed Matter (cond-mat.soft)
Phase-Field Modeling of Two-Phase Flows: A Projection-Based Cahn-Hilliard-Navier-Stokes Framework
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Sukriti Manna, Constantine M Megaridis, Subramanian KRS Sankaranarayanan
The coupled Cahn-Hilliard and Navier-Stokes (CH-NS) equations provide a powerful framework for modeling multiphase flows with diffuse interfaces, enabling simulations of droplet breakup, bubble dynamics, and hydrodynamic instabilities. These capabilities are vital in boiling heat transfer, microfluidics, coating, additive manufacturing, and oil-water separation, where resolving fluid-fluid interactions is essential. Numerically, the CH-NS system is challenging: the Cahn-Hilliard equation involves higher-order derivatives and nonlinearities, and coupling with Navier-Stokes introduces strong two-way interactions. The velocity field advects the phase field, while the evolving interface alters density and viscosity, feeding back into the flow. Variable-density and variable-viscosity systems further increase complexity, requiring accurate treatment of property contrasts without losing stability or mass conservation. To address this, we employ a decoupled pressure-projection method with finite differences on staggered grids and explicit Euler time stepping. Our formulation extends the CH-NS system to homogeneous and variable-property fluids with consistent hydrodynamic-phase-field coupling. Validation against canonical benchmarks-including bubble rise and Plateau-Taylor instability shows excellent agreement in rise velocity, interface shape, and instability wavelength. This framework establishes a reproducible foundation for multiphysics extensions such as heat transfer, phase change, and electrohydrodynamics in boiling, droplet manipulation, and electronics cooling
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Fluid Dynamics (physics.flu-dyn)
Self-organized learning emerges from coherent coupling of critical neurons
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-09-03 20:00 EDT
Deep artificial neural networks have surpassed human-level performance across a diverse array of complex learning tasks, establishing themselves as indispensable tools in both social applications and scientific research.
Despite these advances, the underlying mechanisms of training in artificial neural networks remain elusive.
Here, we propose that artificial neural networks function as adaptive, self-organizing information processing systems in which training is mediated by the coherent coupling of strongly activated, task-specific critical neurons.
We demonstrate that such neuronal coupling gives rise to Hebbian-like neural correlation graphs, which undergo a dynamic, second-order connectivity phase transition during the initial stages of training.
Concurrently, the connection weights among critical neurons are consistently reinforced while being simultaneously redistributed in a stochastic manner.
As a result, a precise balance of neuronal contributions is established, inducing a local concentration within the random loss landscape which provides theoretical explanation for generalization capacity.
We further identify a later on convergence phase transition characterized by a phase boundary in hyperparameter space, driven by the nonequilibrium probability flux through weight space.
The critical computational graphs resulting from coherent coupling also decode the predictive rules learned by artificial neural networks, drawing analogies to avalanche-like dynamics observed in biological neural circuits.
Our findings suggest that the coherent coupling of critical neurons and the ensuing local concentration within the loss landscapes may represent universal learning mechanisms shared by both artificial and biological neural computation.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Neurons and Cognition (q-bio.NC)
A correction tensor for approximating drag on slow-moving particles of arbitrary shape
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
A new form of the Cunningham correction factor is presented that requires no experimental fitting. It is expanded to provide a predictive heuristic for non-spherical particles, via definition of a “correction tensor’’. Its accuracy is tested against experiments and kinetic theory for the sphere, and stochastic solutions to the Boltzmann equation for a range of spheroids. It represents a simple, general tool for approximating transport properties of non-spherical micro/nano particles in a gas.
Soft Condensed Matter (cond-mat.soft)
6 pages, 3 figures
Statistical Mechanics of Paraparticles
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Quantum mechanics broadly classifies the particles into two categories: $ (1)$ fermions and $ (2)$ bosons. Fermions are half-integer spin particles, obeying Pauli’s exclusion principle and Fermi-Dirac statistics. Whereas bosons are integer spin particles, not obeying Pauli’s exclusion principle, and obeying Bose-Einstein statistics. However, there are two exceptions to this standard case: first, anyons, which exist in 2-dimensional systems, and secondly, paraparticles, which can exist in any dimension. Paraparticles follow their non-trivial parastatistics, obeying their generalised exclusion principle. In this paper, we provide a detailed review of the foundations of paraparticle statistics established in \cite{wang2025particle}. We extend this work further and then derive an important expression for the heat capacity of paraparticles for a specific case, which would provide a handle for the experimental detection of paraparticles in appropriate systems.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 1 figure
Majorana edge modes in number-conserving models with long-range interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Jaden Thomas-Markarian, Kartiek Agarwal, Ivar Martin
Topological superconductors are believed to host exotic quasiparticle excitations known as Majorana zero-modes, with much of the evidence based on BCS mean-field theory. The direct application of mean-field arguments is tenuous in finite, isolated systems relevant in some experiments. Here, we numerically study fermion number-conserving models with long-range interactions, which under periodic boundary conditions exhibit robust topological and non-topological superconductivity, tuned by the strength of interaction [1]. We find evidence that, on the topological side, Majorana edge modes appear in open chains, manifesting as the vanishing of the energy splitting between odd- and even-parity ground states with increasing system size. Additionally, off-diagonal two-point correlation functions show nonlocal, parity-dependent edge effects consistent with Majorana phenomenology. We develop a correlation-based method revealing the spatial structure of Majorana modes in this fully interacting many-body setting.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
4.5 pages main text; 5 pages supplementary; 13 figures
Nonadiabatic Wave-Packet Dynamics: Nonadiabatic Metric, Quantum Geometry, and Analogue Gravity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Yafei Ren, M. E. Sanchez Barrero
We develop a unified theory for the nonadiabatic wave-packet dynamics of Bloch electrons subject to slowly varying spatial and temporal perturbations. Extending the conventional wave-packet ansatz to include interband contributions, we derive equations for the interband coefficients using the time-dependent variational principle, referred to as the wave-packet coefficient equation. Solving these equations and integrating out interband contributions yields the leading-order nonadiabatic corrections to the wave-packet Lagrangian. These corrections appear in three forms: (i) a nonadiabatic metric in real and momentum space, which we identify with the energy-gap-renormalized quantum metric, (ii) modified Berry connections associated with the motion of the wave-packet center, and (iii) an energy correction arising from spatial and temporal variations of the Hamiltonian. This metric reformulates the wave-packet dynamics as geodesic motion in phase space, enabling an analogue-gravity perspective in condensed matter systems. As an application, we analyze one-dimensional Dirac electron systems under a slowly varying exchange field $ \bm{m}$ . Our results demonstrate that variations in the magnitude of $ \bm{m}$ are important to nonadiabatic dynamics, in sharp contrast to the adiabatic regime where directional variations of $ \bm{m}$ are crucial.
Materials Science (cond-mat.mtrl-sci)
10 pages, 0 figures, comments are welcome
Percolation transition in entangled granular networks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Seongmin Kim, Daihui Wu, Yilong Han
Highly nonconvex granular particles, such as staples and metal shavings, can form solid-like cohesive structures through geometric entanglement (interlocking). The network structure formed by this entanglement, however, remains largely unexplored. Here we utilize network science to investigate the entanglement networks of C-shaped granular particles under vibration through experiments and simulations. By analyzing key network properties, we demonstrate that these networks undergo a percolation transition as the number of links increases logarithmically over time; the entangled particles form a giant cluster when the number of links exceeds a critical threshold. We propose a continuum percolation model of rings that effectively describes the observed transition. Additionally, we find that particle’s opening angle significantly affects mechanical bonding and, consequently, the network structure. This work highlights the potential of network-based approaches to study entangled materials, paving the way for advancements in applications ranging from mechanical metamaterials to entangled robot swarms.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
Pattern formation in a coupled driven diffusive system
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
G. E. Freire Oliveira, R. Dickman, M. O. Lavrentovich, R. K. P. Zia
We investigate pattern formation in a driven mixture of two repulsive particles by introducing a Field-based Lattice Model (FLM), a hybrid model that combines aspects of the driven Widom-Rowlison lattice gas (DWRLG) and its statistical field theory \cite{DWRLG1,DWRLG2}. We find that the FLM effectively captures the bulk behavior of the DWRLG in both low- and high-density phases, suggesting that phase transitions in these models may share a universality class. Under the effect of the drive, the FLM additionally reveals an intermediate regime, not reported in the previous DWRLG studies, characterized by irregular stripes" with widely fluctuating widths, contrasting with the regular”, well-ordered stripes found at higher densities. In this intermediate phase, the system exhibits long-range order, predominantly perpendicular to the drive direction. To construct a continuum description, we derive two coupled partial differential equations via a gradient expansion of the FLM mean mass-transfer equations, supplemented with additive noise. Designing a numerical solver using the pseudospectral method with dealiasing and stochastic time differencing, we reproduce the low-density microemulsion phase (characterized by a non-zero characteristic wavenumber $ q^\ast$ ) and perpendicular stripes at high density. We identify the non-zero difference in the characteristic velocities of the fields as a necessary condition for perpendicular stripe formation in the high-density phase. The continuum model also uncovers novel behaviors not previously observed in the FLM, such as stripes aligned parallel to the drive and chaotic patterns. This work highlights how the interplay of external drive, particle interactions, and noise can lead to a rich phenomenology in strongly driven binary mixtures.
Statistical Mechanics (cond-mat.stat-mech)
43 pages, 13 figures
Universal Mott quantum criticality in a modified periodic Anderson model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Sujan K. K., N. S. Vidhyadhiraja
Mott quantum criticality is a central theme in correlated electron physics, observed in systems featuring both continuous zero-temperature transitions and those with finite-temperature critical endpoints. Within dynamical mean-field theory (DMFT), the paradigmatic single-band Hubbard model (SBHM) displays such criticality only above a finite-temperature endpoint. In contrast, the modified periodic Anderson model (MPAM) is a rare example known to host a surface of genuinely continuous Mott quantum critical points (QCPs) at zero temperature. Using DMFT with the numerical renormalization group as an impurity solver, we investigate the finite-temperature, real-frequency properties of the MPAM. Our central finding is the emergence of quantum critical scaling in the electrical resistivity, with critical exponents $ z_{\text{met}} = 0.76$ and $ z_{\text{ins}} = 0.66$ on the metallic and insulating sides, respectively. These values fall within the range reported for the SBHM, suggesting that both transitions are governed by a common universality class. We further substantiate the presence of local quantum criticality by demonstrating robust $ \omega/T$ scaling in single- and two-particle correlation functions. Finally, we identify novel transport signatures in the optical conductivity, where the distinct evolution of two isosbestic points serves as a unique fingerprint of the QCP. These results establish the MPAM as a canonical model for investigating genuine Mott quantum criticality and support the existence of a universal framework for this fundamental phenomenon.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 13 figures
Impact of periodic thermal driving on heat fluctuations in a harmonic system
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Felipe P. Abreu, Welles A. M. Morgado
The thermodynamics of mesoscopic systems driven by time-varying temperatures is crucial for understanding biological systems, designing nanoscale engines, and performing micro-particle cooling. In this work, we analyze an underdamped Brownian particle in a harmonic trap under a sinusoidal thermal protocol. Through analytical methods and numerical simulations, we analyze the system’s dynamics and heat statistics. We report the emergence of resonant position-velocity correlations and a non-Gaussian, asymmetric heat distribution consistent with the Fluctuation Theorem. We demonstrate that inertia is a key parameter, damping the system’s response and slowing its relaxation to a periodic non-equilibrium steady state. Our results show that oscillatory thermal driving is a powerful tool for controlling nanoscale energy flow.
Statistical Mechanics (cond-mat.stat-mech)
Disorder-Induced Damping of Spin Excitations in Cr-Doped BaFe$_2$As$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
Marli R. Cantarino, Rafael M. P. Teixeira, R. Pakuszewski, Wagner R. da Silva Neto, Juliana G. de Abrantes, Mirian Garcia-Fernandez, P. G. Pagliuso, C. Adriano, Claude Monney, Thorsten Schmitt, Eric C. Andrade, Fernando A. Garcia
Partial chemical substitution inevitably introduces disorder. In doped Hund’s metals, such as the iron-based superconductors, effects like charge doping and chemical pressure are often considered dominant. Here, we investigate spin excitations in Ba(Fe$ _{1-x}$ Cr$ _x$ )$ _2$ As$ _{2}$ (CrBFA) by high-resolution Resonant inelastic X-ray scattering (RIXS) for samples with $ x = 0, 0.035,$ and $ 0.085$ . In CrBFA, Cr acts as a hole dopant, but also introduces localized spins that compete with Fe-derived magnetic excitations. We found that the Fe-derived magnetic excitations are softened primarily by damping, becoming overdamped for $ x = 0.085$ . At this doping level, complementary angle-resolved photoemission spectroscopy measurements (ARPES) show the absence of electronic structure reconstruction effects such as the nematic band splitting. We propose a localized spin model that explicitly incorporates substitutional disorder and Cr local moments, successfully reproducing our key observations. These results reveal a case where disorder dominates over charge doping in the case of a correlated Hund’s metal.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 4 figures and a supplemental material: 8 pages, 11 figures
Follow the curvature of viscoelastic stress: Insights into the steady arrowhead structure
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Pierre-Yves Goffin, Yves Dubief, Vincent E. Terrapon
Focusing on simulated dilute polymer solutions, this letter investigates the interactions between flow structures and organized polymer stress sheets for the steady arrowhead coherent structure in a two-dimensional periodic channel flow. Formulating the problem in a frame of reference moving with the arrowhead velocity, streamlines, which are also pathlines in this frame, enables the identification of two distinct topological regions linked to two stagnation points. The streamlines help connecting the spatial distribution of polymer stress within the sheets and the dynamics of polymers transported by the flow. Using stresslines, lines parallel to the eigenvectors of polymer stress, a novel formulation of the viscoelastic stress term in the momentum transport equation proposes a more intuitive interpretation of the relation between the curvature of the stresslines, and the variation of stress along these lines, with the local flow topology. An approximation of this formulation is shown to explain the pressure jump observed in the arrowhead structure as a function of the local curvature of the polymer stress sheet.
Soft Condensed Matter (cond-mat.soft)
Submitted to Physical Review Fluids
Strange diffusivity of incoherent metal in half-filled two-dimensional Hubbard model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Youngmin Eom, Igor S. Tupitsyn, Nikolay V. Prokof’ev, Boris Svistunov, Evgeny Kozik, Aaram J. Kim
We study charge transport across the metal-insulator crossover in the half-filled two-dimensional Hubbard model, with particular emphasis on precision control. The dynamic current-current correlation function is obtained directly in the thermodynamic limit, and the optical conductivity is extracted using numerical analytic continuation. To achieve this, we develop a multiscale approach: the non-perturbative low-frequency behavior is computed using the unbiased diagrammatic Monte Carlo technique, while the high-frequency physics is captured via a self-consistent (semi-)analytic diagrammatic theory. We found that across a broad temperature range where the DC resistivity displays anomalous scaling, $ \sim T^\alpha$ with $ 0<\alpha\lesssim 1$ , the Nernst-Einstein relation implies the diffusion constant with the characteristic $ \sim 1/\sqrt{T}$ “strange metal” behavior. It was also revealed that the insulating regime is entered through a peculiar non-Fermi liquid state-which we call a Pseudogap Metal-characterized by insulating charge compressibility coexisting with metallic transport. Diagrammatically, the high-temperature incoherent transport is captured by the dressed polarization bubble, whereas near the metal-insulator crossover, the effective interaction vertex between opposite-spin particles is responsible for transferring the Drude weight to a high-frequency continuum.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas)
14 pages, 12 figures
Reexamining Machine Learning Models on Predicting Thermoelectric Properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Thermoelectric materials can generate clean energy by transforming waste heat into electricity. The effectiveness of thermoelectric materials is measured by the dimensionless figure of merit, ZT. The quest for high ZT materials has drawn extensive research experimentally and theoretically. However, due to the vast material space, finding high ZT materials is time-consuming and costly. To improve the efficiency of discovering new thermoelectric materials, recent studies have employed machine learning with databases to search for high ZT candidates. In this work, we examine the effects of adding various physical concepts on the performance of machine learning models in predicting TE properties. The objective is to improve the model ability to capture the underlying physics in designing TE materials. These concepts include short range order and crystal structure class. Results show some improvements in accuracy. However, the current models do not distinguish between dilute alloys and concentrated alloys, rendering them inadequate in predicting doping effects. To better capture the electronic band structure effect from doping, we included various dopant properties as features. This increases the prediction accuracy in doped materials. Furthermore, we used a genetic algorithm to rank features for various thermoelectric properties to provide physical insight into key parameters in designing thermoelectric materials.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Free-carrier screening unlocks high electron mobility in ultrawide bandgap semiconductor CaSnO$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Jiayi Gong, Chuanyu Zhang, Wenjie Hu, Jin-Jian Zhou
Alkaline earth stannates have emerged as promising transparent conducting oxides due to their wide band gaps and high room-temperature electron mobilities. Among them, CaSnO$ _3$ possesses the widest band gap, yet reported mobilities vary widely and are highly sample-dependent, leaving its intrinsic limit unclear. Here, we present ab initio calculations of electron mobility in CaSnO$ _3$ across a range of temperatures and doping levels, using state-of-the-art methods that explicitly account for free-carrier screening in electron-phonon interactions. We identify the dominant limiting mechanism to be the long-range longitudinal optical phonon scattering, which is significantly suppressed at high doping due to free-carrier screening, leading to enhanced phonon-limited mobility. While ionized impurity scattering emerges as a competing mechanism at carrier concentrations up to ~10$ ^{20}$ cm$ ^{-3}$ , the phonon scattering reduction dominates, yielding a net mobility increase with predicted room-temperature values reaching about twice the highest experimental report. Our work highlights the substantial untapped conductivity in CaSnO$ _3$ , establishing it as a compelling ultrawide bandgap semiconductor for transparent and high-power electronic applications.
Materials Science (cond-mat.mtrl-sci)
5 pages, 4 figures, accepted by Appl. Phys. Lett
Capturing the fractocohesive length scale through a gradient-enhanced damage model for elastomers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
S. Mohammad Mousavi, Jason Mulderrig, Brandon Talamini, Nikolaos Bouklas
This study aims to unravel the micro-mechanical underpinnings of the emergence of the fractocohesive length scale as a central concept in modern fracture mechanics. A thermodynamically consistent damage and fracture model for elastomers is developed, incorporating elements of polymer chain statistical mechanics. This approach enables the direct incorporation of polymer chain response into a continuum gradient enhanced damage formulation, that in turn allows a physically meaningful description of diffuse chain damage and corresponding fracture events. Through a series of numerical experiments, we simulate crack propagation and extract the fracture energy as an output of the model, while keeping track of the micromechanical signatures of diffuse chain damage that accommodate fracture propagation. Furthermore, we investigate flaw sensitivity and demonstrate that when flaw sizes are smaller than a critical length scale, the material response becomes largely insensitive to notch size. Finally, by combining the fracture toughness and the work to rupture, we identify a fractocohesive length of the material, corresponding to the full width of the damage zone and representing the region where the irreversible dissipation process (i.e., bond scission) is happening. As this region is dictated in the proposed FED model through the introduction of a length scale associated with the non-local nature of the damage and fracture process, the emerging relationship of the two length scales is discussed, effectively connecting the microscopic characteristics of damage to the effective macroscopic response.
Soft Condensed Matter (cond-mat.soft)
Landau-de Gennes Modelling of Confinement Effects and Cybotactic Clusters in Bent-Core Nematic Liquid Crystals
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Yucen Han, Prabakaran Rajamanickam, Bedour Alturki, Apala Majumdar
We study bent-core nematic (BCN) systems in two-dimensional (2D) and three-dimensional (3D) settings, focusing on the role of cybotactic clusters, phase transitions, confinement effects and applied external fields. We propose a generalised version of Madhusudhana’s two-state model for BCNs in [Madhusudana NV, Physical Review E, 96(2), 022710] with two order parameters: $ \mathbf{Q}_g$ to describe the ambient ground-state (GS) molecules and $ \mathbf{Q}_c$ to describe the ordering within the cybotactic clusters. The equilibria are modelled by minimisers of an appropriately defined free energy, with an empirical coupling term between $ \mathbf{Q}_g$ and $ \mathbf{Q}_c$ . We demonstrate two phase transitions in spatially homogeneous 3D BCN systems at fixed temperatures: a first-order nematic-paranematic transition followed by a paranematic-isotropic phase transition driven by the GS-cluster coupling. We also numerically compute and give heuristic insights into solution landscapes of confined BCN systems on 2D square domains, tailored by the GS-cluster coupling, temperature and external fields. This benchmark example illustrates the potential of this generalised model to capture tunable director profiles, cluster properties and macroscopic biaxiality.
Soft Condensed Matter (cond-mat.soft), Mathematical Physics (math-ph)
Dimensional hierarchy of topological bound states in the continuum
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Shunda Yin, Zhenyu Wang, Liping Ye, Hailong He, Manzhu Ke, Weiyin Deng, Jiuyang Lu, Zhengyou Liu
Bound states in the continuum (BICs), with the ability of trapping and manipulating waves within the radiation continuum, have gained significant attention for their potential applications in optics and acoustics. However, challenges arise in reducing wave leakage and noise from fabrication imperfections. The emergence of robust wave manipulations based on topological BICs (TBICs) offers promising solutions. Traditionally, TBICs of different dimensions are observed separately in distinct systems. Here, we report the experimental discovery of the coexistence of two-dimensional surface TBICs and one-dimensional hinge TBICs in a single three-dimensional phononic crystal system. Such an unprecedented dimensional hierarchy of TBICs is triggered by the mechanism of separability and protected by the valley Chern numbers. Notably, these TBICs inherit dispersive propagation characteristics from valley topology and can propagate robustly against defects without leakage. Our findings offer an efficient approach to multidimensional TBICs and can be applied in designing highly efficient acoustic devices for wave trapping and manipulation in multidimensional environments.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 7 figures
Simulations of grain growth in tungsten armor materials under ARC plasma edge operation conditions using an integrated plasma-edge/materials model
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Jinxin Yu, Nithin Mathew, Sophie Blondel, Ane Lasa, Jon Hillesheim, Lauren Garrison, Brian D. Wirth, Jaime Mariana
An integrated model of grain growth deuterium-exposed tungsten polycrystals, consisting of a two-dimensional vertex dynamics model fitted to atomistic data, has been developed to assess the grain growth kinetics of deuterium-exposed polycrystalline tungsten (W). The model tracks the motion of grain boundaries under the effect of driving forces stemming from grain boundary curvature and differential deuterium concentration accumulation. We apply the model to experimentally-synthesized W polycrystals under deuterium saturated conditions consistent with those of the ARC concept design, and find fast grain growth kinetics in the material region adjacent to the plasma (at 1400 K, <100 seconds for full transformation), while the microstructure is stable deep inside the material (several days to complete at a temperature of 1000 K). Our simulations suggest that monolithic W fabricated using conventional techniques will be highly susceptible to grain growth in the presence of any driving force at temperatures above 1000 K.
Materials Science (cond-mat.mtrl-sci)
21 pages, 12 figures
Hidden ferromagnetism of centrosymmetric antiferromagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
The time-reversal symmetry ($ \mathcal{T}$ ) breaking is a signature of ferromagnetism, giving rise to such phenomena as the anomalous Hall effect (AHE) and orbital magnetism (OM). Nevertheless, $ \mathcal{T}$ can be also broken in certain classes of antiferromagnets, such as weak ferromagnets or altermagnets, which remain invariant under the spatial inversion. In the light of this similarity with the ferromagnetism, it is tempting to ask whether such anomalous antiferromagnetic (AFM) state can be presented as a simplest ferromagnetic one, i.e. within a minimal unit cell containing only one magnetic cite. We show that such presentation is possible due to the special form of the spin-orbit (SO) interaction in an antiferroelectrically distorted lattice hosting this AFM state. The inversion symmetry, combined with the lattice translations, imposes a severe constraint on the form of the SO interaction, which becomes invariant under the symmetry operation $ { \mathcal{S}| {\bf t} }$ , combining the $ 180^{\circ}$ rotation of spins ($ \mathcal{S}$ ) with the lattice shift $ {\bf t}$ , connecting antiferromagnetically coupled sublattices. This is the fundamental symmetry property of centrosymmetric antiferromagnets, which justifies the use of the generalized Bloch theorem and transformation to the local coordinate frame with one magnetic cite per cell. It naturally explains the emergence of AHE and OM, and provides transparent expressions for these properties in terms of the electron hoppings and SO interaction operating between nearest neighbors as well as the orthorhombic strain of the next-nearest-neighbor hoppings. The idea is illustrated on a number of examples, using realistic models derived from first-principles calculations. These examples include two-dimensional square lattice, monoclinic VF$ _4$ and CuF$ _2$ , and RuO$ _2$ -type materials with the tetragonal symmetry.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 9 figures
Activity-driven sorting, approach to criticality and turbulent flows in dense persistent active fluids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Suman Dutta, Pinaki Chaudhuri, Madan Rao, Chandan Dasgupta
We show that dense active fluids comprising interacting particles with persistent self-propulsion are driven to a non-equilibrium steady state consisting of co-moving particles with co-aligned active forces. This velocity and force sorting appears to be associated with a critical state where the length scales associated with spatial correlations of the velocity and the propulsive force grow with system size. At large system sizes, these growing velocity domains are accompanied by the appearance of dynamic macroscopic voids in the steady state, associated with large density fluctuations. The dynamics of the macroscopic voids drives a new kind of turbulent state.
Soft Condensed Matter (cond-mat.soft)
Role of lattice structure and breaking of antiferromagnetic spin order in enhancement of ferromagnetic, electronic, and magneto-electric properties in Fe$_{2-x}$Sc$_x$O$_3$ system
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
R. N. Bhowmik, Bipin Kumar Parida, Amit Kumar, P.D. Babu, S. M. Yusuf
The strategy of breaking AFM ground state of alpha-Fe2O3 by doping non-magnetic Sc3+ (3d0) ions at the Fe3+ (3d5) sites has been used to understand modified lattice-structure, magnetic spin order, and charge-spin coupling in Fe$ _{2-x}$ Sc$ _x$ O$ _3$ system ($ x =$ 0.2, 0.5, 1.0). The material has been stabilized in single-phased (rhombohedral $ \alpha$ -Fe$ _2$ O$ _3$ ) or mix-phased (rhombohedral alpha-Fe$ _2$ O$ _3$ and cubic Sc$ _2$ O$ _3$ -types) structures by varying the Sc content and heat treatment temperature. Neutron diffraction confirmed magnetic moment approximately 2.75-4.68 Bohr-magneton per Fe site and spin reorientation from in-plane to out of plane direction below the Morin transition approximately 260 K. The material showed magnetic coercivity (0.2 to 6 kOe). The electrical properties transformed from insulating state (conductivity 10-14-10-10 S/cm and polarization 0.5-2 micro-C/cm$ ^2$ ) to high conductive state (conductivity approximately 10-10 -10-7 S/cm and polarization greater than 2 micro-C/cm$ ^2$ ) above Morin transition. The material at 300 K produced the maximum current density 20-95 micro-A/cm$ ^2$ , ferroelectric polarization 2.7-15.6 micro-C/cm$ ^2$ , ME voltage up to 5 mV with coupling coefficient 0.53 mV/Oe/cm and huge negative magnetoconductance up to 90%. The results in the present hematite based canted ferromagnetic materials are expected to be useful for applying in low power spintronic devices.
Materials Science (cond-mat.mtrl-sci)
pages 26, 11 figures, 4 tables
Recent Advances in Unconventional Ferroelectrics and Multiferroics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Hongyu Yu, Junyi Ji, Wei Luo, Xingao Gong, Hongjun Xiang
Emerging ferroic materials may pave a new way to next-generation nanoelectronic and spintronic devices due to their interesting physical properties. Here, we systematically review unconventional ferroelectric systems, from Hf-based and elementary ferroelectrics to stacking ferroelectricity, polar metallicity, fractional quantum ferroelectricity, wurtzite-type ferroelectricity, and freestanding membranes ferroelectricity. Moreover, multiferroic materials are reviewed, particularly the interplay between novel magnetic states and ferroelectricity, as well as ferrovalley-ferroelectric coupling. Finally, we conclude by discussing current challenges and future opportunities in this field.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
62 pages, 13 figures
Stabilization of Ferroelectric Hafnia and Zirconia through Y2O3 doping
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
We investigate the possible stabilization of ferroelectricity in bulk Y2O3-doped hafnia and zirconia. We use density functional theory (DFT) with large random supercells of hafnia and zirconia and study the relative phase stability of the centrosymmetric cubic and monoclinic phases compared with the polar orthorhombic phase. We find that Y2O3-doping stabilizes the polar ferroelectric phase over the monoclinic baddeleyite phase in both hafnia and zirconia.
Materials Science (cond-mat.mtrl-sci)
5 pages, 4 figures
Extreme dynamics and relaxation of quantum gases: A hydrodynamic approach
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Ritwik Mukherjee, Abhishek Dhar, Manas Kulkarni, Samriddhi Sankar Ray
The evolution of quantum gases, released from traps, are studied through hydrodynamics, both analytically and numerically, in one and two dimensions. In particular, we demonstrate the existence of long time self-similar solutions of the Euler equations, for the density and velocity fields, and derive the scaling exponents as well as the scaling functions. We find that the expanding gas develops a shock front and the size of the cloud grows in time as a powerlaw. We relate the associated exponent to that appearing in the corresponding equation of state of the quantum gas. Furthermore, we study the relaxation dynamics of a trapped quantum gas and show that the resulting steady state is in excellent agreement with that derived analytically. Our hydrodynamic approach is versatile and can be used to unravel several other far-from-equilibrium collective phenomenon of extreme nature, relevant to the growing experimental interests in quantum gases.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech)
13 pages, 8 figures
Discovery of nodal-line superconductivity in chiral crystals
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
Tian Shang, Jianzhou Zhao, Lun-Hui Hu, Weikang Wu, Keqi Xia, Mukkattu O. Ajeesh, Michael Nicklas, Yang Xu, Qingfeng Zhan, Dariusz J. Gawryluk, Ming Shi, Toni Shiroka
Chiral crystals, whose key feature is the structural handedness, host exotic quantum phenomena driven by the interplay of band topology, spin-orbit coupling (SOC), and electronic correlations. Due to the limited availability of suitable chiral-crystal materials, their unconventional superconductivity (SC) remains largely unexplored. Here, we report the discovery of unconventional SC in the La(Rh,Ir)Si family of materials by combining muon-spin spectroscopy, band-structure calculations, and perturbation theory. This family, characterized by a double-helix chiral structure, hosts exotic multifold fermions that are absent in other topological chiral crystals. While LaRhSi behaves as a fully-gapped superconductor, the substitution of 4$ d$ -Rh by 5$ d$ -Ir significantly enhances the SOC and leads to the emergence of topological nodal-line SC in LaIrSi. The developed model shows that the nodal-line SC arises from an isotropic SOC with a specific strength. Such an exotic mechanism expands our conventional understanding of material candidates for unconventional SC, which typically rely on a significantly anisotropic SOC to promote the triplet pairing. Our work establishes a new type of phase diagram, which provides a comprehensive roadmap for identifying and engineering unconventional SC in chiral crystals. Furthermore, it calls for renewed investigations of unconventional SC in other widely studied superconductors with a chiral structure.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
accepted version; 20 pages, 5 figures
From diamond to BC8 to simple cubic and back: kinetic pathways to post-diamond carbon phases from metadynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Roman Martoňák, Sergey Galitskiy, Azat Tipeev, Joseph M. Gonzalez, Ivan I. Oleynik
The experimental observation of elusive post-diamond carbon phases at extreme pressures remains a major challenge in high-pressure science. Using metadynamics with coordination-number-based collective variables and SNAP machine-learned interatomic potential, we uncover atomistic mechanisms governing the transformation of cubic and hexagonal diamond into post-diamond phases above 1.5 TPa. The transition initiates via homogeneous nucleation of nanoscale liquid droplets, which rapidly crystallize into either BC8 (below 1.8 TPa) or simple cubic phases (above 2.1 TPa), once the liquid nucleus surpasses a critical size. Favorable conditions for synthesizing BC8 are identified near 1.8 TPa and 3500–5000 K. Decompression pathways from simple cubic and BC8 phases were also simulated to study possible experimental recovery of post-diamond carbon allotropes at ambient conditions. We also find a new metastable low-enthalpy structure with four-coordinated carbon atoms and space group P222. Our insights provide a theoretical foundation for experimental discovery of ultra-dense carbon phases under extreme conditions.
Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
6 pages, 7 figures, Supplemental Material
Sliding-induced ferrovalley polarization and possible antiferromagnetic half-metal in bilayer altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Altermagnets, a newly discovered class of materials, exhibit zero net magnetization while hosting spin-split electronic bands. However, monolayer altermagnets maintain degenerate band gaps at the high-symmetry X and Y points in the Brillouin zone, manifesting a paravalley phase characterized by unpolarized valley states. In this work, we demonstrate that spontaneously broken valley degeneracy can be achieved through interlayer sliding in engineered M$ _2$ A$ _2$ B and M$ _2$ AA$ ‘$ B bilayer altermagnets by first-principles calculations and minimal microscopic model. We propose a promising route to achieve antiferromagnetic half-metal driven by sliding and emergent ferrovalley phase without applied electric field, which is realized in the V$ _2$ SSeO engineered bilayer. Our calculations also reveal that Mo$ _2$ O$ _2$ O exhibits the largest valley splitting gap of ~0.31 eV, making it a promising candidate for valley-spin valve devices. Furthermore, band structure calculations on Mo$ _2$ AA$ ‘$ O materials demonstrate that increasing the difference in atomic number ($ \Delta$ Z) between A and A$ ‘$ site atoms effectively enhances valley polarization. This work establishes a novel platform for discovering and controlling ferrovalley states in altermagnetic systems.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 5 figures
Probing the Nanoscale Excitonic Landscape and Quantum Confinement of Excitons in Gated Monolayer Semiconductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Yueh-Chun Wu, Bogdan Dryzhakov, Huan Zhao, Ivan Vlassiouk, Kyle Kelley, Takashi Taniguchi, Kenji Watanabe, Jun Yan, Benjamin Lawrie
Engineering and probing excitonic properties at the nanoscale remains a central challenge in quantum photonics and optoelectronics. While exciton confinement via electrical control and strain engineering has been demonstrated in 2D semiconductors, substantial nanoscale heterogeneity limits the scalability of 2D quantum photonic device architectures. In this work, we use cathodoluminescence spectroscopy to probe the excitonic landscape of monolayer $ WS_2$ under electrostatic gating. Exploiting the high spatial resolution of the converged electron beam, we resolve a homojunction arising between gated and ungated regions. Moreover, we reveal an exciton confinement channel arising from an unconventional doping mechanism driven by the interplay between the electron beam and the applied gate fields. These findings offer new insights into the optoelectronic behavior of monolayer semiconductors under the combined influence of electron-beam excitation and electrostatic gating. Our approach provides a pathway for exciton manipulation at the nanoscale and opens opportunities for controlling quantum-confined exciton transport in two-dimensional materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Energy non-equipartition in vibrofluidized particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Alok Tiwari, Manaswita Bose, V. Kumaran
The aim of the present work is to investigate the influence of the realistic model parameters on the equipartition of energy in a vibrofluidized system. To achieve this, a three-dimensional vertically vibrated granular system consisting of spherical particles is simulated using the discrete element method (DEM) using the open-source software LAMMPS. Interparticle and wall-particle interactions are determined using the linear-spring dashpot model. Simulations are performed for nearly perfectly smooth to nearly perfectly rough particles. Two different values for the ratio of the tangential to normal spring stiffness coefficient $ \kappa$ ($ 2/7$ and $ 3/4$ ) are chosen. Non-equipartition of energy between the translational and rotational modes is observed for all realistic values in the parametric range.
Soft Condensed Matter (cond-mat.soft)
8 pages, 6 figures
Shot noise as a probe for Andreev reflection in graphene-based heterojunctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Shahrukh Salim, Poornima Shakya
Shot noise emerges due to the discrete nature of charge transport and provides direct access to the underlying microscopic transport mechanisms governing current flow in mesoscopic conductors. In this work, we demonstrate that quantum shot noise offers a direct and robust fingerprint of Andreev reflection, distinguishing between retro and specular processes in graphene-superconductor, graphene-superconductor-graphene, and superconductor-graphene-superconductor junctions. At the graphene-superconductor interface, exact reflection amplitudes obtained from full wavefunction matching within the Bogoliubov-de Gennes formalism capture retro and specular regimes. The associated Fano factor exhibits distinct Fermi-level-dependent signatures, with retro Andreev reflection suppressing and specular Andreev reflection enhancing the shot noise. Extensions to graphene-superconductor-graphene and superconductor-graphene-superconductor configurations reveal how the transmission spectrum and, consequently, the noise profile are modified in the presence of multiple interfaces, coherent quasiparticle interference, and superconducting phase variations. Our findings establish shot noise spectroscopy as a potent and experimentally viable probe for differentiating Andreev reflection types in graphene-based quantum devices, providing complementary insights beyond conventional conductance measurements.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
Dynamically generated correlations in a trapped bosonic gas via frequency quenches
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Nikhil Mesquita, Manas Kulkarni, Satya N. Majumdar, Sanjib Sabhapandit
We study a system of $ N$ noninteracting bosons in a harmonic trap subjected to repeated quantum quenches, where the trap frequency is switched from one value to another after a random time duration drawn from an exponential distribution. Each cycle contains two steps: (i) changing the trap frequency to enable unitary evolution under a Hamiltonian, and (ii) reapplying the original trap at stochastic times to cool the gas back to its initial state. This protocol effectively makes it an open quantum system and drives it into a unique nonequilibrium steady state (NESS). We analytically and numerically characterize the NESS, uncovering a conditionally independent and identically distributed (CIID) structure in the joint probability density function (JPDF) of the positions. The JPDF in the CIID structure is a product of Gaussians with a common random variance, which is then averaged with respect to its distribution, making the JPDF non-factorizable, giving rise to long-range emergent dynamical correlations. The average density profile of the gas shows significant deviations from the initial Gaussian shape. We further compute the order and the gap statistics, revealing universal scaling in both bulk and edge regimes. We also analyze the full counting statistics, exposing rich parameter-dependent structure. Our results demonstrate how stochastic quenches can generate nontrivial correlations in quantum many-body systems.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech)
8 pages, 5 figures
Stochastic Two-temperature Nonequilibrium Ising model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Debraj Dutta, Ritwick Sarkar, Urna Basu
We investigate the nonequilibrium stationary state (NESS) of the two-dimensional Ising model under a stochastic dichotomous modulation of temperature, which alternates between $ T_c \pm \delta$ around the critical temperature $ T_c$ at a rate $ \gamma$ . Both magnetization and energy exhibit non-monotonic dependence on $ \gamma$ , explained by a renewal approach in the slow-switching limit, while for small $ \delta$ dynamical response theory quantitatively captures the $ \gamma$ -dependence of the observables. In the fast-switching regime, the NESS appears Boltzmann-like with a $ \gamma$ -dependent effective temperature. However, a finite energy current flowing through the system from hot to cold reservoir confirms the intrinsic nonequilibrium nature of the dynamics.
Statistical Mechanics (cond-mat.stat-mech)
19 pages, 10 figures; comments and suggestions are welcome
“One defect, one potential” strategy for accurate machine learning prediction of defect phonons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Junjie Zhou, Xinpeng Li, Menglin Huang, Shiyou Chen
Atomic vibrations play a critical role in phonon-assisted electron transitions at defects in solids. However, accurate phonon calculations in defect systems are often hindered by the high computational cost of large-supercell first-principles calculations. Recently, foundation models, such as universal machine learning interatomic potentials (MLIPs), emerge as a promising alternative for rapid phonon calculations, but the quantitatively low accuracy restricts its fundamental applicability for high-level defect phonon calculations, such as nonradiative carrier capture rates. In this paper, we propose a “one defect, one potential” strategy in which an MLIP is trained on a limited set of perturbed supercells. We demonstrate that this strategy yields phonons with accuracy comparable to density functional theory (DFT), regardless of the supercell size. The predicted accuracy of defect phonons is validated by phonon frequencies, Huang-Rhys factors, and phonon dispersions. Further calculations of photoluminescence (PL) spectra and nonradiative capture rates based on this defect-specific model also show good agreements with DFT results, meanwhile reducing the computational expenses by more than an order of magnitude. Our approach provides a practical pathway for studying defect phonons in 10$ ^4$ -atom large supercell with high accuracy and efficiency.
Materials Science (cond-mat.mtrl-sci)
Magnetic dynamics in NiTiO3 honeycomb antiferromagnet using neutron scattering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Srimal Rathnayaka, Luke Daemen, Tao Hong, Songxue Chi, Stuart Calder, John A. Schneeloch, Yongqiang Cheng, Bing Li, Despina Louca
The ilmenite NiTiO3 consists of a buckled honeycomb lattice, with the Ni spins aligned ferromagnetically in-plane and antiferromagnetically out-of-plane. Using neutron spectroscopy, the magnetic structure and the dynamics were investigated as a function of temperature. Dispersive acoustic bands and nearly dispersionless optical bands at ~3.7 meV are described by a highly anisotropy Heisenberg model with stronger antiferromagnetic (AFM) out-of-plane, weaker ferromagnetic (FM) in-plane interactions and an anisotropy gap of 0.95 meV. The order parameter yields a critical exponent between the Heisenberg and two-dimensional Ising models, consistent with highly anisotropic Heisenberg systems. The frustration parameter ~ 2 supports a weakly frustrated system.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 10 figures
Real-space observation of the low-temperature Skyrmion lattice in Cu2OSeO3(100) single crystal
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Gerald Malsch, Peter Milde, Dmytro Ivaneiko, Andreas Bauer, Christian Pfleiderer, H. Berger, Lukas M. Eng
Cu2OSeO3 is a skyrmion host material in which two distinct thermodynamically stable skyrmion phases were identified. We report magnetic force microscopy imaging of the low-temperature magnetic phases in bulk Cu2OSeO3(100) single crystal. Tuning the external magnetic field over the various phase transition at a temperature of 10 K, we observe the formation of helical, conical, tilted conical and skyrmion lattice domains in real space.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Theory of Emergent Trionic Order in One-Dimensional Bose-Fermi Mixtures
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Yan-Guang Yue, Qi Song, Jie Lou, Yan Chen
We study a one-dimensional (1D) lattice mixture of hard-core bosons and spinless fermions with attractive interspecies interaction and correlated fermion pair hopping. Using Schrieffer-Wolff (SW) transformation and bosonization, we derive an effective low-energy theory that reveals a density-induced resonance mechanism. When the filling ratio satisfies $ \rho_{c0}:\rho_{b0} = 2:1$ , a non-oscillatory cosine term emerges in the bosonized theory. This term favors the formation of trions, i.e., bound states of two fermions and one boson. By performing a renormalization-group (RG) analysis, we identify a phase transition from a gapless two-component Luttinger liquid to a partially gapped trionic phase, where trionic correlations exhibit dominant quasi-long-range order. Our findings provide a microscopic understanding of composite superfluidity and offer experimentally relevant signatures for Bose-Fermi mixtures in 1D lattices.
Strongly Correlated Electrons (cond-mat.str-el)
Josephson Dynamics in 2D Ring-shaped Condensates
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Koon Siang Gan, Vijay Pal Singh, Luigi Amico, Rainer Dumke
We investigate Josephson transport in a fully closed, two-dimensional superfluid circuit formed by a ring-shaped 87Rb Bose-Einstein condensate that contains two optical barriers acting as movable weak links. Translating these barriers at controlled speeds imposes a steady bias current, enabling direct mapping of the current-chemical-potential (I-{\Delta}{\mu}) characteristics. For narrow junctions (w \approx 1{\mu}m) the circuit exhibits a pronounced dc branch that terminates at a critical current I_c = 9(1) x 10^3 s^{-1}; above this threshold the system switches to an ac, resistive regime. Classical-field simulations that include the moving barriers quantitatively reproduce both the nonlinear I-{\Delta}{\mu} curve and the measured I_c, validating the underlying microscopic picture. Analysis of the ensuing phase dynamics shows that dissipation is mediated by the nucleation and traversal of vortex-antivortex pairs through the junctions, while the bulk condensate remains globally phase-locked \textemdash direct evidence of the ring’s topological constraint enforcing quantized circulation. These results establish a cold-atom analogue of a SQUID in which Josephson dynamics can be resolved at the single-vortex level, providing a versatile platform for atomtronic circuit elements, non-reciprocal Josephson devices, and on-chip Sagnac interferometers for multi-axis rotation sensing.
Quantum Gases (cond-mat.quant-gas)
7 pages, 4 figures
Unveiling Insulating Ferro and Ferrimagnetism in Double-Double Perovskite Oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Monirul Shaikh, Fengyi Zhou, Sathiyamoorthy Buvaneswaran, Rajan Gowsalya, Trilochan Sahoo, Duo Wang, Saurabh Ghosh
The emergence of ferro- and ferrimagnetic behavior in insulating materials is uncommon, largely due to Hund’s rules. Utilizing symmetry analysis, first-principles methods, and classical Monte Carlo simulations, \textcolor{black}{we report technologically important insulating ferro and ferrimagnetic double-double perovskite oxides. Our study predicts LaA$ ^{\prime}$ MnNiO$ _6$ (A$ ^{\prime}$ = V, Cr, Mn, Co, and Ni) as promising candidates for spintronic and optical applications exhibiting band gaps between 1.3 eV and 1.9 eV. We explain the mechanisms driving band gap openings and magnetic exchange interactions in these ferro and ferrimagnetic compounds. Monte Carlo simulations, together with state-of-the-art orbital-decomposed exchange parameter analysis, reveal intriguing variations in magnetic transition temperatures (up to 242 K) and the corresponding exchange mechanisms in all LaA$ ^{\prime}$ MnNiO$ _6$ compounds.} In addition, we assess the thermodynamic and dynamic stability of these compounds to comment on the feasibility of these systems.
Materials Science (cond-mat.mtrl-sci)
Radio-Frequency Method for Detecting Superconductivity Under High Pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
Dmitrii V. Semenok, Di Zhou, Jianbo Zhang, Toni Helm, Yang Ding, Ho-kwang Mao, Viktor V. Struzhkin
We introduce a contactless technique for probing superconductivity, metal-insulator transitions, and magnetic ordering in micron-sized samples under extreme pressure. Utilizing a multistage Lenz lens system, directly sputtered onto diamond anvils, we realize a radio-frequency (RF, 50 kHz - 200 MHz) transformer with a sample, of 50-100 microns in diameter, as its core. This configuration enables efficient transfer and focusing of an electromagnetic field within the diamond anvil cell’s chamber. Consequently, the transmitted RF signal exhibits high sensitivity to variations in the sample’s surface conductivity and magnetic permeability. We validate this method by determining the critical temperatures ($ T_{\text{c}}$ ) of known superconductors, including NbTi, MgB$ 2$ , Hg-1223, BSCCO, and REBCO in various magnetic fields, as well as the magnetic ordering temperatures of Gd and Tb, and the metal-insulator transition in VO$ 2$ . Notably, we apply this technique to the (La,Ce)H$ {10-12}$ superhydride at a pressure of about 150 GPa. The observed superconducting transition, at 215-220 K, is noticeably higher than the $ T{\text{c}}$ determined via traditional electrical-resistance measurements (200-205 K), demonstrating the method’s enhanced sensitivity. Moreover, we show how multiple repetitions of the RF experiment with the La-Ce superhydride make it possible to detect the increase in $ T{\text{c}}$ over time up to 260-270 K. This finding opens a pathway towards reaching a critical $ T{\text{c}}$ above 0$ ^\circ$ C in the La-based superhydrides.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Sub-GHz Breathing Dynamics of Magnetic Hopfions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Magnetic hopfions are three-dimensional topological solitons whose static stability has recently been confirmed in experiments, yet their dynamical modes remain largely unexplored. Here we combine micromagnetic simulations and analytical modelling to characterise the fundamental breathing excitation of hopfions. We show that the breathing mode corresponds to a coherent oscillation of both the hopfion core diameter and the shell width, while preserving the topological charge. An analytical domain-wall interaction model explains the weak field dependence of the shell thickness and yields a closed-form expression for the restoring stiffness. From this curvature and the collective-coordinate inertia, we derive an estimated breathing frequency in excellent agreement with micromagnetic spectra. The ability to capture the hopfion dynamics quantitatively from material constants highlights a direct route to experimental detection by ferromagnetic resonance or Brillouin light scattering, and establishes a framework for frequency-encoded control in reconfigurable spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 Pages, 7 Figures
Topology of Fermi seas and geometry of their boundaries for free particles in one and two-dimensional lattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Free gases of spinless fermions moving on a geometric background with lattice symmetries are considered. Their Fermi seas and corresponding boundaries may be classified according to their topological properties at zero temperature. This is accomplished by considering the flat orbifolds $ R^{d}/\Gamma$ , with $ \Gamma$ being the crystallographic group of symmetry in $ d$ -dimensional momentum space. For $ d=1$ , there are 2 topological classes: a circumference, corresponding to an insulator and an interval, identified as a conductor. For $ d=2$ , the number of topological classes extends to 17: there are 8 with the topology of a disk identified as conductors and 4 corresponding to a 2-sphere matching insulators, both sets eventually including finite numbers of conical singularities and reflection corners at the boundaries. The rest of the listing includes single cases corresponding to insulators (2-torus, real projective plane, Klein bottle) and conductors (annulus, Möbius strip). Physical interpretations of the singularities are provided, as well as examples that fit within this listing. Given the topological nature of this classification, its results are expected to be robust against small perturbative interactions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), High Energy Physics - Theory (hep-th)
10 pages, 2 tables
Fully-chromophoric ferroelectric nematics for electronic electro-optics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Xi Chen (1), Andrew Bradfield (1), Chirag Patel (2), Pavel Savechenkov (2), Jason W. Sickler (2), Gianlorenzo Masini (2), Joseph E. Maclennan (1), Noel A. Clark (1), Cory Pecinovsky (2), Matthew A. Glaser (1) ((1) Department of Physics, University of Colorado Boulder, CO, USA (2) Polaris Electro-Optics, Inc., Broomfield, CO, USA)
Electronic electro-optic (EEO) phase modulation is a key emerging technology for the chip-scale inter-conversion of signals between the electronic and photonic domains. The recent discovery of the ferroelectric nematic ($ N_F$ ) liquid crystal phase, a three dimensional fluid of rod-shaped organic molecules having near-perfect equilibrium polar molecular orientational order, offers attractive opportunities for the creation of second-order nonlinear optical materials for EEO. Here we propose and realize a design motif for NF EEO molecules in which few-nanometer-long molecular rods are functionalized both for electro-static end-to-end association, facilitating NF phase formation, and for chromophoric optical nonlinearity, enabling high EEO efficiency, a combination enabling an active second-order nonlinear EEO medium that is 100% chromophoric.
Soft Condensed Matter (cond-mat.soft)
Surface Effects on the Magnetocrystalline Anisotropy of IrMn$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Robert A. Lawrence, Matt I.J. Probert
Magnetic anisotropy is a key parameter to describe the exchange bias effect in heterostructures. In this paper, we describe explicit density functional calculations of the magnetic structure of an interface between the industrially critically antiferromagnetic material, IrMn, and Fe, which together form a simple ferromagnet-antiferromagnet heterostructure. Additionally, the magnetic anisotropy was evaluated for several terminations of the IrMn. It was found that the [111] surface had a perpendicular anisotropy of 1.62 meV/$ \textÅ^2$ , whereas the two possible [100] surfaces (Ir-rich and Mn-rich) had in-plane anisotropies of 0.13 meV/$ \textÅ^2$ and 1.39 meV/$ \textÅ^2$ respectively. The affect of the magnetic order of the easy and hard configurations were calculated and used to explain the relative values of the anisotropies.
Materials Science (cond-mat.mtrl-sci)
14 pages, 7 figures
Electronic frictional effects near metal surfaces with strong correlations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
The electronic friction-Langevin dynamics (EF-LD) offers a simplified framework for describing nonadiabatic effects at metal surfaces, particularly in electrochemical and molecular electronic applications. We investigate the electronic friction behavior for the Hubbard-Holstein model using density matrix renormalization group (DMRG) theory. We show that electron-electron interactions lead to the formation of two energy levels in the impurity, resulting in two peaks in the electronic friction at the resonances of electron attachment or detachment with the metal’s Fermi level. We further benchmark our results against mean field theory (MFT) and exact diagonalization (ED). The results calculated by ED and DMRG show strong agreement at high temperatures, suggesting the results from DMRG are reliable; however, at low temperatures, ED exhibits significant deviations relative to DMRG due to the finite-size limitations inherent in ED calculations. MFT completely fails to recover Fermi resonance in electronic friction. Moreover, we investigate the dynamics of the electronic friction using EF-LD. Simulations reveal differences between the electronic population and kinetic energy dynamics predicted by MFT and DMRG approaches, suggesting that MFT approach is unreliable for nonadiabatic dynamics of strongly correlated systems.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
9 pages, 3 figures
Parametrically Driven Superradiance of an Interacting Tavis-Cummings Model
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Wen-Jie Geng, Yiwen Han, Wei Yi
We consider the superradiant transition of a generalized Tavis-Cummings model, where a number of two-level qubits are coupled to a dissipative cavity. The cavity is coherently driven through a parametric medium, and all-to-all interactions between the qubits are introduced. While the nonlinear gain from the parametric drive breaks the U(1) symmetry of the standard Tavis-Cummings model, thus giving rise to superradiance with squeezed cavity fields, we show that the interactions impact the collective excitations and significantly modify the superradiant transition. Insights to the superradiant phase transitions, as well as the interaction effects, are obtained through effective models involving only a handful of low-lying collective states, under which the steady-state phase diagram of the hybrid system is faithfully reproduced. Our study is relevant to Rydberg-atom arrays coupled to a parametrically driven cavity, where the long-range interactions derive from the dipole-dipole interatomic interactions.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
Domain-Wall Mediated Polarization Switching in Ferroelectric AlScN: Strain Relief and Field-Dependent Dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Xiangyu Zheng, Charles Paillard, Dawei Wang, Peng Chen, Hong Jian Zhao, Yu Xie, Laurent Bellaiche
Aluminum nitride is a traditional wide-bandgap semiconductor that has been widely used in high-power electronic and optoelectronic devices. Recently, scandium-doped aluminum nitride (AlScN) was shown to host ferroelectricity with high remnant polarization and excellent thermal stability. However, its practical use is currently limited by its high coercive field, $ E_c$ . Understanding the atomic-scale switching mechanism is essential to guide strategies for reducing $ E_c$ . Here, we combine density functional theory and machine-learning molecular dynamics to investigate polarization switching mechanisms in AlScN over various Sc concentrations and applied electric fields. We find that collective switching induces excessive lattice strain and is therefore unlikely to occur. Rather, pre-existing domain walls relieve strain and lead to a distinct switching dynamics, with the associated switching mechanism being field dependent. More precisely, at low electric fields, switching proceeds via gradual domain-wall propagation, well described by the Kolmogorov-Avram-Ishibashi model; meanwhile high fields trigger additional nucleation events, producing rapid and more homogeneous reversal, whose mixed switching process is better described by the simultaneous non-linear nucleation and growth model. These findings highlight the critical role of domain-wall dynamics in nitride ferroelectrics and suggest that domain engineering provides a viable route to control coercive fields and enhance device performance.
Materials Science (cond-mat.mtrl-sci)
6 pages, 4 figures
Edge states, pairing, and sorting of motile chiral particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Raushan Kant, Ananyo Maitra, A K Sood, Sriram Ramaswamy
We present experiments on chiral active polar particles, realized as vibrated granular rods, revealing the formation of robust ``skipping orbits’’ at hard boundaries. These edge states exhibit a net circulation opposite to the particles’ intrinsic rotation and lead to a pronounced accumulation at the boundary, stronger than for their achiral counterparts. The directed nature of these orbits provides a simple yet high-fidelity mechanism for chiral sorting – even for solitary particles, unlike in T Barois et al., Phys. Rev. Lett. 125 , 238003 (2020). We propose a unified theoretical framework for boundary interactions of both chiral and achiral particles. In this model, an effective outward radial force, proportional to motility and chirality, explains the observed boundary-hugging. Our theory predicts, and our experiments confirm, a transition in the pairing of two particles of the same chirality, from apolar spinners to polar circle walkers, with increasing packing fraction of an ambient medium of beads.
Soft Condensed Matter (cond-mat.soft)
This article consists of eight pages and five figures. For supplementary videos, please click on the link below, this https URL and description of movies see supplementary file below, this https URL
Self-Organising Memristive Networks as Physical Learning Systems
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-09-03 20:00 EDT
Francesco Caravelli, Gianluca Milano, Adam Z. Stieg, Carlo Ricciardi, Simon Anthony Brown, Zdenka Kuncic
Learning with physical systems is an emerging paradigm that seeks to harness the intrinsic nonlinear dynamics of physical substrates for learning. The impetus for a paradigm shift in how hardware is used for computational intelligence stems largely from the unsustainability of artificial neural network software implemented on conventional transistor-based hardware. This Perspective highlights one promising approach using physical networks comprised of resistive memory nanoscale components with dynamically reconfigurable, self-organising electrical circuitry. Experimental advances have revealed the non-trivial interactions within these Self-Organising Memristive Networks (SOMNs), offering insights into their collective nonlinear and adaptive dynamics, and how these properties can be harnessed for learning using different hardware implementations. Theoretical approaches, including mean-field theory, graph theory, and concepts from disordered systems, reveal deeper insights into the dynamics of SOMNs, especially during transitions between different conductance states where criticality and other dynamical phase transitions emerge in both experiments and models. Furthermore, parallels between adaptive dynamics in SOMNs and plasticity in biological neuronal networks suggest the potential for realising energy-efficient, brain-like continual learning. SOMNs thus offer a promising route toward embedded edge intelligence, unlocking real-time decision-making for autonomous systems, dynamic sensing, and personalised healthcare, by enabling embedded learning in resource-constrained environments. The overarching aim of this Perspective is to show how the convergence of nanotechnology, statistical physics, complex systems, and self-organising principles offers a unique opportunity to advance a new generation of physical intelligence technologies.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Soft Condensed Matter (cond-mat.soft), Emerging Technologies (cs.ET), Machine Learning (cs.LG)
Perspective paper on SOMN; 20 pages double columns, 5 figures, 2 boxes;
First principles study on the oxidation resistance of two-dimensional intrinsic and defective GeO2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Xixiang Zhang, Xinmei Yu, Liang Ma, Yanfeng Ge, Yong Liu, Wenhui Wan
Although two-dimensional (2D) oxide semiconductors exhibit remarkable oxidation resistance compared to conventional 2D materials, the microscopic physical processes that govern this behavior at the atomic scale remains elusive. Using first-principles calculations, we investigated the defect formation and oxidation dynamics of the GeO$ {_2}$ monolayer (ML). The investigations reveal that the intrinsic GeO$ {_2}$ ML is resistant to oxidation due to strong electrostatic repulsion between surface oxygen ions and approaching O$ _2$ molecules, effectively suppressing chemisorption. In contrast, defective GeO$ _2$ ML with surface O vacancies shows vulnerability to oxidation with the O$ _2$ molecule occupying the vacancy through a low-energy activation energy ($ E_a$ ) of 0.375 eV. Remarkably, the subsequent O$ _2$ dissociation into atomic species faces a higher activation barrier ($ E_a$ = 1.604 eV), suggesting self-limiting oxidation behavior. Electronic structure analysis demonstrates that oxidation primarily modifies the valence bands of defective GeO$ {_2}$ MLs through oxygen incorporation, while the conduction bands and electron effective mass recover to pristine-like characteristics. We further proved that the high O$ _2$ pressure hinders the formation of the O vacancy, while high temperature increases the oxidation rate in GeO$ _2$ ML. These atomic-level insights not only advance our understanding of oxidation resistance in 2D oxides but also provide guidelines for developing stable GeO$ {_2}$ -based nanoelectronic devices.
Materials Science (cond-mat.mtrl-sci)
Surfaces and Interfaces, 69, 106648(2025)
Integration of promising piezoelectric and photocatalytic properties in Janus In$XY$ ($X$ = S, Se, Te; $Y$ = Cl, Br, I) monolayers and their heterojunctions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Xinyue Liu, Ziqiang Li, Yanfeng Ge, Yong Liu, Xing Wang, Wenhui Wan
Two-dimensional (2D) Janus materials show great promise as piezoelectric materials and photocatalysts for water splitting. In this work, we systematically investigated the piezoelectric and photocatalytic properties of the hexagonal Janus InXY (X = S, Se, Te; Y = Cl, Br, I) monolayers (MLs) using first-principles calculations. Except for InSeCl ML, the remaining eight InXY MLs are stable and exhibit exceptionally high in-plane piezoelectric coefficients ($ |d_{22}| = $ 6.07–155.27 pm/V), which exceed those of most known 2D materials. InXY MLs possess band edges straddling the water redox potentials at pH = 0. Their intrinsic vertical polarization induces an intralayer polarization field $ E_{\rm intra}$ , leading to low exciton binding energies (0.44–0.78 eV). Moreover, their strong vertical piezoelectric responses ($ |d_{32}|$ = 0.34–0.65 pm/V) suggest that in-plane stress can further enhance $ E_{\rm intra}$ to facilitate the separation of photogenerated carriers. Additionally, these InXY MLs exhibit high electron mobility (101–899 cm$ ^2$ /V/s) and a pronounced anisotropy ratio in carrier mobility, which effectively suppresses charge recombination. To optimize performance, we constructed a van der Waals heterojunction (InSI/InSeBr), which demonstrates remarkable photocatalytic properties, including enhanced redox ability, a direct Z-scheme charge transfer pathway, strong visible-light absorption, high carrier mobility, and excellent photocorrosion resistance. Our results indicate that hexagonal Janus InXY MLs and their heterojunctions are multifunctional materials integrating piezoelectricity and photocatalysis, paving the way for energy conversion applications.
Materials Science (cond-mat.mtrl-sci)
First-principles investigation of Sr-Ce-M-O perovskites for solar thermochemical water splitting
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Sachin Kumar, Pritam Ghosh, Gopalakrishnan Sai Gautam
Using density functional theory based calculations, we systematically examine the utility of Sr-M-O and Sr-Ce-M-O perovskites for solar thermochemical water splitting, a promising route for sustainable hydrogen production. Importantly, we identify Sr$ _{0.5}$ Ce$ _{0.5}$ MnO$ _3$ and Sr$ _{0.5}$ Ce$ _{0.5}$ CrO$ _3$ to be promising candidates, exhibiting optimal oxygen vacancy formation energy and 0 K thermodynamic stability.
Materials Science (cond-mat.mtrl-sci)
Interplay of energy and charge transfer in WSe2/CrSBr heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
José Roberto de Toledo, Caique Serati de Brito, Barbara L. T. Rosa, Alisson R. Cadore, César Ricardo Rabahi, Paulo E. Faria Junior, Ana Carolina Ferreira de Brito, Talieh S. Ghiasi, Josep Ingla-Aynés, Christian Schüller, Herre S. J. van der Zant, Stephan Reitzenstein, Ingrid D. Barcelos, Florian Dirnberger, Yara Galvão Gobato
Van der Waals heterostructures (vdWHs) composed of transition-metal dichalcogenides (TMDs) and layered magnetic semiconductors offer great opportunities to manipulate exciton and valley properties of TMDs. Here, we present magneto-photoluminescence (PL) studies in a WSe2 monolayer (ML) on a CrSBr crystal, an anisotropic layered antiferromagnetic semiconductor. Our results reveal unique behavior of each of the ML-WSe2 PL peaks under magnetic field that is distinct from the pristine case. An intriguing feature is the clear enhancement of the PL intensity that we observe each time the external magnetic field tunes the energy of an exciton in CrSBr into resonance with one of the optical states of WSe2. This result suggests a magnetic field-controlled resonant energy transfer (RET) beyond other effects reported in similar structures. Our work provides deep insight on the importance of different mechanisms into magnetic vdWHs and underscores its great potential for light harvesting and emission enhancement of two-dimensional materials.
Materials Science (cond-mat.mtrl-sci)
Nano Lett. 2025, XXXX, XXX, XXX-XXX
Topological switching in bilayer magnons via electrical control
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Xueqing Wan, Quanchao Du, Jinlian Lu, Zhenlong Zhang, Jinyang Ni, Lei Zhang, Zhijun Jiang, Laurent Bellaiche
Topological magnons, quantized spin waves featuring nontrivial boundary modes, present a promising route toward lossless information processing. Realizing practical devices typically requires magnons excited in a controlled manner to enable precise manipulation of their topological phases and transport behaviors. However, their inherent charge neutrality and a high frequency nature pose a significant challenge for nonvolatile control, especially via electric means. Herein, we propose a general strategy for electrical control of topological magnons in bilayer ferromagnetic insulators. With strong spin-layer coupling, an applied vertical electric field induces an interlayer potential imbalance that modifies intralayer Heisenberg exchanges between adjacent layers. This electric-field-driven modulation competes with the bilayer’s intrinsic Dzyaloshinskii-Moriya interaction, enabling the accurate tuning of the band topology and nonreciprocal dynamics of magnons. More importantly, such an electric control mechanism exhibits strong coupling with external magnetic fields, unveiling new perspectives on magnetoelectric coupling in charge-neutral quasiparticles
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
4 figures,
Infinite-temperature quantum phases and phase transitions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Tengzhou Zhang, Zhizhen Chen, Zi Cai
In this study, we reveal nontrivial quantum physics in an infinite-temperature system. By performing an unbiased quantum Monte Carlo simulation, we study a hybrid model composed of hard-core bosons, whose hopping amplitude is mediated by the density of another type of soft-core bond bosons that can absorb entropy indefinitely. It is shown that the Bose-Einstein condensate can persist in three dimensions even when the temperature approaches the infinite-temperature limit. In contrast, in two dimensions, the quasi-superfluid is depleted by the fluctuations of the bond bosons, which, on the other hand, enhance the conductivity of the hard-core bosons in the normal phase. A generalization to the fermionic model has also been discussed.
Statistical Mechanics (cond-mat.stat-mech)
6 pages
Dissipation in passive non-reciprocal microwave devices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Non-reciprocal devices are key components in both classical and quantum electronics. One approach to realizing passive non-reciprocal microwave devices is through capacitive coupling between external electrodes and materials exhibiting non-reciprocal conductance. In this work, we develop an analytic framework that captures the response of such devices in the presence of dissipation while accounting for the full AC dynamics of the material. Our results yield an effective circuit model that accurately describes the device response in experimentally relevant regimes even at small dissipation levels. Furthermore, our analysis reveals counterpropagating features arising from the intrinsic AC response of the material that could be exploited to dynamically switch the non-reciprocity of the device, opening pathways for tunable non-reciprocal microwave technologies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Observation of moiré trapped biexciton through sub-diffraction-limit probing using hetero-bilayer on nanopillar
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Mayank Chhaperwal, Suman Chatterjee, Suchithra Puliyassery, Jyothsna Konkada Manattayil, Rabindra Biswas, Patrick Hays, Seth Ariel Tongay, Varun Raghunathan, Kausik Majumdar
The ability to tune the degree of interaction among particles at the nanoscale is highly intriguing. The spectroscopic signature of such interaction is often subtle and requires special probes to observe. To this end, inter-layer excitons trapped in the periodic potential wells of a moiré superlattice offer rich interaction physics, specifically due to the presence of both attractive and repulsive components in the interaction. Here we show that the Coulomb force between two inter-layer excitons switches from repulsive to attractive when the length scale reduces from inter-moiré-pocket to intra-moiré-pocket in a WS$ _2$ /WSe$ _2$ hetero-bilayer - thanks to the complex competition between direct and exchange interaction. The finding is a departure from the usual notion of repelling inter-layer excitons due to layer polarization. This manifests as the simultaneous observation of an anomalous superlinear power-law of moiré exciton and a stabilization of moiré trapped biexciton. The experimental observation is facilitated by placing the hetero-bilayer on a polymer-nanopillar/gold-film stack which significantly reduces the inhomogeneous spectral broadening by selectively probing a smaller ensemble of moiré pockets compared with a flat sample. This creates an interesting platform to explore interaction among moiré trapped excitons and higher order quasiparticles.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Optics (physics.optics), Quantum Physics (quant-ph)
Möbius-topological auxiliary function for $f$ electrons
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
$ f$ -electron systems exhibit a subtle interplay between strong spin–orbit coupling and crystal-field effects, producing complex energy landscapes that are somewhat cumbersome to compute. We introduce auxiliary functions, constructed by extending hydrogen-like wave functions through a modification of the Legendre function. These functions often possess a Möbius-like topology, satisfying $ \psi(\varphi) = -\psi(\varphi + 2\pi)$ , while their squared modulus respects inversion symmetry. By aligning $ |\psi|^2$ with the symmetry of the crystal field, they allow rapid determination of eigenstate structures without the need for elaborate calculations. The agreement with established results indicates that these functions capture the essential physics while offering considerable computational simplification.
Strongly Correlated Electrons (cond-mat.str-el)
Quantum action of the Josephson dynamics
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Cesare Vianello, Sofia Salvatore, Luca Salasnich
We study the beyond-mean-field Josephson dynamics of the relative phase between two coupled macroscopic quantum systems. Using a covariant background field method, we derive the one-loop only-phase quantum effective action and the corresponding equation of motion for the quantum average of the phase. These analytical results are benchmarked against the exact quantum dynamics of the two-site Bose-Hubbard model, demonstrating a relevant improvement over the standard mean-field predictions across a wide range of interaction strengths.
Quantum Gases (cond-mat.quant-gas), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
15 pages, 3 figures
Role of correlations in Ruddlesden-Popper bilayer nickelates under compressive strain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Logan Bleys, Nicholas Corkill, Yi-Feng Zhao, Gheorghe Lucian Pascut, Harrison LaBollita, Antia S. Botana, Khandker F. Quader
The recent discovery of superconductivity in thin films of the bilayer Ruddlesden-Popper (RP) nickelate La$ _3$ Ni$ _2$ O$ 7$ (La327) under compressive strain has generated enormous interest, opening up further opportunities to stabilize superconductivity in this class of materials at ambient pressure. To better understand the many-body normal state from which superconductivity arises, it is important to ascertain the nature and role of correlations in its electronic structure. To provide insights into this question, we use a fully charge self-consistent DFT+e-DMFT (eDMFT) approach to study La327 at several compressive strain levels. At the strain level where superconductivity has been observed experimentally (-2%), in contrast with DFT and DFT+$ U$ results, the so-called $ \gamma$ pocket emerges and the associated band, of mostly $ d{z^2}$ character, crosses the Fermi level exhibiting `flat band’’-like features when dynamical correlations are included. Larger strain levels suppress the $ \gamma$ pocket, which may have implications for superconductivity or its pairing symmetry.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
11 pages, 5 figures
Superconducting Diode Effect in Gradiently Strained Nb0.5Ti0.5N Films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
Zherui Yang, Shengyao Li, Shaoqin Peng, Xueyan Wang, Liang Wu, Ri He, Zhen Wang, Yanwei Cao, Xiao Renshaw Wang
The superconducting diode effect (SDE), combining superconductivity with diode-like nonreciprocal current flow, recently emerges as an ideal candidate for zero-dissipation electronic circuits. Such technologically advantageous diodes are achieved by intricate material engineering to disrupt inversion symmetry, which leads to the production challenges as well as a limited pool of viable materials. Here we exploit the gradient interfacial strain to experimentally induce the SDE in Nb0.5Ti0.5N (NTN) films grown on MgO substrates. Additionally, the SDE is tunable with an in-plane magnetic field and can be further enhanced by introducing an interfacial anisotropic pinning potential. Our findings establish interfacial strain gradient as a versatile tool for creating and enhancing tunable SDE.
Superconductivity (cond-mat.supr-con)
4 figures
Appl. Phys. Rev. 12, 031411 (2025)
Protocol for Clustering 4DSTEM Data for Phase Differentiation in Glasses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Phase-change materials (PCMs) such as Ge-Sb-Te alloys are widely used in non-volatile memory applications due to their rapid and reversible switching between amorphous and crystalline states. However, their functional properties are strongly governed by nanoscale variations in composition and structure, which are challenging to resolve using conventional techniques. Here, we apply unsupervised machine learning to 4-dimensional scanning transmission electron microscopy (4D-STEM) data to identify compositional and structural heterogeneity in Ge-Sb-Te. After preprocessing and dimensionality reduction with principal component analysis (PCA), cluster validation was performed with t-SNE and UMAP, followed by k-means clustering optimized through silhouette scoring. Four distinct clusters were identified which were mapped back to the diffraction data. Elemental intensity histograms revealed chemical signatures change across clusters, oxygen and germanium enrichment in Cluster 1, tellurium in Cluster 2, antimony in Cluster 3, and germanium again in Cluster 4. Furthermore, averaged diffraction patterns from these clusters confirmed structural variations. Together, these findings demonstrate that clustering analysis can provide a powerful framework for correlating local chemical and structural features in PCMs, offering deeper insights into their intrinsic heterogeneity.
Materials Science (cond-mat.mtrl-sci), Computer Vision and Pattern Recognition (cs.CV), Machine Learning (cs.LG)
Transitioning from Silicon to Carbon Nanotube based transistors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Suhas Bharadwaj, Reuben Thomas Thovelil, Rohith Chembattammal, Sradha Mishra, Sunit Sahoo, Himnish Dave, Karthik S., Kabir Jaisinghani
Carbon Nanotubes have shown to be an attractive option in the race to find a replacement to silicon-based transistors, due to its high electrical conductivity, extraordinary mechanical strength, and thermal conductivity. However, challenges with regards to controlling the purity and chirality of CNTs have raised doubts if the mass production of these transistors are even viable. This paper explores the challenges of scalability and proposes methods such as Liquid and Gas phase oxidative methods and microwave heating to tackle the problem of metal impurities found within CNTs and the methods of Catalyst Engineering and Chemical Vapor Deposition to control the chirality of CNTs. It also suggests techniques such as Lithography, Screen Printing and Stack Engineering to facilitate the large-scale production of CNT transistors. This paper also attempts to explore the methods of Laser Ablation and Arc Discharge that allows for the synthesis of CNTs of pure quality and high yield further facilitating the rise of mass production of CNT transistors. The feasibility and challenges relating to the integration of CNT transistors with already pre-existing circuitry was also investigated and the methods of annealing and potassium doping were studied and analyzed. The main aim of this paper is providing a comprehensive guide to allow for the mass production and rapid integration of CNT transistors into the semi-conductor market.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
11 pages, 20 figures
Performance Improvement of Deorbitalized Exchange-Correlation Functionals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
H. Francisco, B. Thapa, S.B. Trickey, A.C. Cancio
Deorbitalization of a conventional meta-generalized-gradient exchange-correlation approximation replaces its dependence upon the Kohn-Sham kinetic energy density with a dependence on the density gradient and Laplacian. In principle, that simplification should provide improved computational performance relative to the original meta-GGA form because of the shift from an orbital-dependent generalized Kohn-Sham potential to a true KS local potential. Often that prospective gain is lost because of problematic roughness in the density caused by the density Laplacian and consequent roughness in the exchange-correlation potential from the resulting higher-order spatial derivatives of the density in it. We address the problem by constructing a deorbitalizer based on the RPP deorbitalizer [Phys. Rev. Mater. 6, 083803 (2022)] with comparative smoothness of the potential along with retention of constraint satisfaction as design goals. Applied to the r^2SCAN exchange-correlation functional [J. Phys. Chem. Lett. 11, 8208 (2020)], we find substantial timing improvements for solid-state calculations over both r^2SCAN and its earlier deorbitalization for high precision calculations of structural properties, while improving upon the accuracy of RPP deorbitalization for both solids and molecules.
Materials Science (cond-mat.mtrl-sci)
22 pages, 8 figures
Common errors in BoltzTraP-based calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Øven A. Grimenes, Kristian Berland
Boltzmann transport calculations based on band structures computed from first principles play an important role in modern thermoelectric materials research. Among available codes, the \textsc{BoltzTraP} code is the most widely adopted, but many recent studies contain systematic mistakes. We identify three error modes: (1) inserting the electronic thermal conductivity at zero electric field, $ \kappa_0$ , in place of the electronic thermal conductivity at zero electric current, $ \kappa_e$ , (2) computing the figure of merit $ zT$ by combining a constant relaxation time of unity while keeping the lattice thermal conductivity $ \kappa_\ell$ in standard units, and (3) doing both errors at once. We have found many examples of the third error, but since the first two are simpler, we suspect they are also present in the literature. For the single parabolic band model, we derive exact analytical limits in the non-degenerate and near-degenerate regimes, and we show how mistakes appear for the realistic case study of ZrNiSn. Our results illustrate how faulty calculations can appear reasonable at certain temperatures and Fermi levels, and we provide practical guidance for identifying faulty results and avoiding such pitfalls in thermoelectric transport studies.
Materials Science (cond-mat.mtrl-sci)
Calculations of current in the cotunneling regime using Lindblad equations
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Kian Maleki, Michael E. Flatté
Transport through zero-dimensional states in a tunneling barrier can occur via co-tunneling, wherein a carrier occupying a state outside the range of energies between the chemical potentials of the two leads hops to a lead, and within the brief time permitted by the energy-time uncertainty relationship the occupancy is replenished from the other lead. Here, we calculate the current in such junctions using a Lindblad formalism within the Markovian approximation. We consider transport in the Coulomb blockade regime with spin-polarized leads and a magnetic field smaller than the coercive field of either lead. Dependences on magnetic field and lead spin polarization of the spin blockade, decoherence, and spin lifetime of the subsystems of this model are calculated.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Emergent Rotational Order and Re-entrant Global Order of Vicsek Agents in a Complex Noise Environment
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Noisy pursuit in complex environments drives emergent collective behaviors in active matter systems. A compelling platform to study the impact of environment cues is provided by the standard Vicsek model for studying flocking and swarming phenomena. In this study, we explore the collective dynamics of Vicsek agents in a complex noise environment, featuring a noiseless circular region ($ \eta_{\text{c}} = 0.0$ ) surrounded by a noisy outer region ($ \eta_{\text{b}} = 1.0$ , tunable), with a mutually repelling interactions. By varying the outer noise intensity, we observe an emergent rotational order ($ \phi_r$ ) that peaks at higher noise levels ($ \eta_{\text{b}}\sim 1$ ), as revealed by phase and susceptibility plots. Global order follows ($ \phi$ ) follows a `U’ shaped curve, $ \phi \sim 0.965$ at $ \eta_b=0$ , dies down to $ \phi \sim 0.57$ at $ \eta_b=0.9$ and re-enters at $ \eta_b > 1$ and peaks $ \phi \sim 0.960$ at $ \eta_b=1.5$ . The latter rise attributing to $ \phi_r$ increase. Higher particle velocities enhance escape rates ($ \kappa$ ) from the circular region, with slower-moving agents exhibiting greater virtual confinement. We quantify escape dynamics through time-averaged and first-passage escape rates, demonstrating velocity-dependent retention on the probability of finding the bi-motility agent flocks at a give time resulting in segregation and trapping. Introducing a gradual noise increase from the circle’s center to the outer region reduces both global ($ \phi$ ) and rotational ($ \phi_r$ ) order, underscoring the impact of environmental heterogeneity and sudden annealing over gradual change. These findings offer insights into predicting and manipulating active agent dynamics in heterogeneous environments, with applications in biological and synthetic swarming systems.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Computational Physics (physics.comp-ph)
Control of Covalent Bond Enables Efficient Magnetic Cooling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Xin Tang, Yoshio Miura, Noriki Terada, Enda Xiao, Shintaro Kobayashi, Allan Doring, Terumasa Tadano, Andres Martin-Cid, Takuo Ohkochi, Shogo Kawaguchi, Yoshitaka Matsushita, Tadakatsu Ohkubo, Tetsuya Nakamura, Konstantin Skokov, Oliver Gutfleisch, Kazuhiro Hono, Hossein Sepehri-Amin
Magnetic cooling, harnessing the temperature change in matter when exposed to a magnetic field, presents an energy-efficient and climate-friendly alternative to traditional vapor-compression refrigeration systems, with a significantly lower global warming potential. The advancement of this technology would be accelerated if irreversible losses arising from hysteresis in magnetocaloric materials were minimized. Despite extensive efforts to manipulate crystal lattice constants at the unit-cell level, mitigating hysteresis often compromises cooling performance. Herein, we address this persistent challenge by forming Sn(Ge)3/Sn(Ge)3 bonds within the unit cell of the Gd5Ge4 compound. Our approach enables an energetically favorable phase transition, leading to the elimination of thermal hysteresis. Consequently, we achieve a synergistic improvement of two key magnetocaloric figures of merit: a larger magnetic entropy change and a twofold increase in the reversible adiabatic temperature change (from 3.8 to 8 K) in the Gd5Sn2Ge2 compound. Such synergies can be extended over a wide temperature range. This study demonstrates a paradigm shift in mastering hysteresis toward simultaneously achieving exceptional magnetocaloric metrics and opens up promising avenues for gas liquefaction applications in the longstanding pursuit of sustainable energy solutions.
Materials Science (cond-mat.mtrl-sci)
Luminescence-Induced Tunable Superconductivity in BSCCO via GaP Quantum Dots
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
Qingyu Hai, Duo Chen, Ruiyuan Bi, Yao Qi, Lifeng Xun, Xiaoyan Li, Xiaopeng Zhao
The enhancement of superconducting properties in high-temperature copper-oxide superconductor B(P)SCCO remains a hot research topic in the field of superconducting materials. Building on previous research, here we introduce GaP quantum dots as an heterophase into the B(P)SCCO superconductor, aiming to enhance its superconductivity through the luminescent properties of GaP quantum dots. The experimental results demonstrate that the introduction of GaP quantum dots into B(P)SCCO generates significant tunable superconducting effects, leading to enhanced critical transition temperature (Tc), critical current density (Jc), and Meissner field (Hc) of B(P)SCCO with increasing luminescent intensity of the GaP quantum dots. The enhancement effect induced by GaP quantum dots exhibits a positive correlation with luminescent intensity, meaning samples with the addition of GaP quantum dots exhibiting higher luminescent intensity show elevated Tc, Jc, and Hc values. Unlike impurity effects, a distinct critical concentration dependency is observed. Notably, this GaP quantum dot modification strategy is not only effective in conventional superconductors but also applicable to high-temperature oxide superconductors.
Superconductivity (cond-mat.supr-con)
Topological characterization of phase transitions and critical edge states in one-dimensional non-Hermitian systems with sublattice symmetry
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Longwen Zhou, Rujia Jing, Shenlin Wu
Critical edge states appear at the bulk gap closing points of topological transitions. Their emergence signify the existence of topologically nontrivial critical points, whose descriptions fall outside the scope of gapped topological matter. In this work, we reveal and characterize topological critical points and critical edge states in non-Hermitian systems. By applying the Cauchy’s argument principle to two characteristic functions of a non-Hermitian Hamiltonian, we obtain a pair of winding numbers, whose combination yields a complete description of gapped and gapless topological phases in one-dimensional, two-band non-Hermitian systems with sublattice symmetry. Focusing on a broad class of non-Hermitian Su-Schrieffer-Heeger chains, we demonstrate the applicability of our theory for characterizing gapless symmetry-protected topological phases, topologically distinct critical points, phase transitions along non-Hermitian phase boundaries and their associated topological edge modes. Our findings not only generalize the concepts of topologically nontrivial critical points and critical edge modes to non-Hermitian setups, but also yield additional insights for analyzing topological transitions and bulk-edge correspondence in open systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
16 pages, 11 figures
Effective diffusion of Brownian motion in spatially quasi-periodic noise
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
The effective diffusion of Brownian particles in periodic potential has been a central topic in nonequilibrium statistical physcis. A classical result is the Lifson formula which provides the effective diffusion constant in periodic potentials. Extending beyong periodicity, our recent work [arXiv:2504.16527] has demonstrated that a modified Lifson expression remains valid for Brownian motion in quasi-periodic potentials. In this work, we extend our previous results by incorporating spatial quasi-periodic noise and examining different stochastic interpretations, $ \alpha\in[0,1]$ . The proposed framework is simple, computationally efficient, and unifies the treatment of diffusion in both periodic and quasi-periodic systems.
Statistical Mechanics (cond-mat.stat-mech)
5pages,1 figures
Phase Diagram and Spectral Function of the Two-Dimensional Disordered Bose-Hubbard Model: A Real-Space Dynamical Mean-Field Theory Analysis
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Bastian Schindler, Renan da Silva Souza, Walter Hofstetter
We numerically investigate the two-dimensional Bose-Hubbard model with local onsite disorder, where the competition between disorder and short-range interactions leads to the emergence of a Bose glass (BG) phase between the Mott insulator (MI) and superfluid (SF) phases. In order to analyze the inhomogeneous system we employ real-space bosonic dynamical mean-field theory and perform an ensemble average over disorder realizations. To distinguish the MI from the BG phase, we compare the Edwards-Anderson order parameter and the compressibility with the energy gap condition. To identify the insulator to SF transition, we apply a percolation analysis to the condensate order parameter. In qualitative accordance with the theorem of inclusions we always find an intermediate BG phase between the SF and MI. However, the quantitative comparison indicates significant deviations between the MI to BG phase boundary expected in the thermodynamic limit and the one obtained for a finite system size. Analyzing the spectral function in the strong-coupling regime reveals evidence for analytically predicted damped localized modes in the dispersion relation.
Quantum Gases (cond-mat.quant-gas)
4 pages (main text), 7 pages (total), 4 figures, submitted to Physical Review Letters, manuscript in review
Odd-Parity Selection in Parity-Forbidden Electronic Transitions Revealed by Mn4+ Fluorescence Spectroscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Yitong Wang, Fei Tang, Jiqiang Ning, Shijie Xu
Mn4+-doped fluoride phosphors represent a significant class of narrow band red-emitting materials, whose luminescent properties are profoundly influenced by electron-phonon coupling. However, the parity-forbidden nature of these electronic transition systems is incompatible with the conventional Condon approximation, which is widely adopted in the classic theories such as the Huang-Rhys theory, a framework established on the assumption of parity-allowed electric dipole transitions. This results in a critical knowledge gap regarding the principles governing the phonon sidebands of parity-forbidden electronic transitions. This study experimentally reveals a pronounced parity-dependent intensity distribution in the phonon sidebands of these systems: significantly suppressed even-order sidebands and normally observed odd-order sidebands. To elucidate the phenomenon, we extend the Huang-Rhys theory to parity-forbidden systems by incorporating the Herzberg-Teller approximation into the treatment of the transition matrix elements. The improved theory successfully uncovers the physical mechanism behind the strong suppression of the even-order sidebands in the parity-forbidden systems, in which the Huang-Rhys factor is derived as S=((2I_3)/(9I_1 ))^(1/2). This work not only reveals new findings regarding the phonon sidebands of the parity-forbidden electronic transition systems, but also establishes an improved theoretical framework for understanding the electron-phonon coupling mechanisms of color centers in solids.
Materials Science (cond-mat.mtrl-sci)
Short-time blowup statistics of a Brownian particle in repulsive potentials
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
We study the dynamics of an overdamped Brownian particle in a repulsive scale-invariant potential $ V(x) \sim -x^{n+1}$ . For $ n > 1$ , a particle starting at position $ x$ reaches infinity in a finite, randomly distributed time. We focus on the short-time tail $ T \to 0$ of the probability distribution $ P(T, x, n)$ of the blowup time $ T$ for integer $ n > 1$ . Krapivsky and Meerson [Phys. Rev. E \textbf{112}, 024128 (2025)] recently evaluated the leading-order asymptotics of this tail, which exhibits an $ n$ -dependent essential singularity at $ T = 0$ . Here we provide a more accurate description of the $ T \to 0$ tail by calculating, for all $ n = 2, 3, \dots$ , the previously unknown large pre-exponential factor of the blowup-time probability distribution. To this end, we apply a WKB approximation – at both leading and subleading orders – to the Laplace-transformed backward Fokker–Planck equation governing $ P(T, x, n)$ . For even $ n$ , the WKB solution alone suffices. For odd $ n$ , however, the WKB solution breaks down in a narrow boundary layer around $ x = 0$ . In this case, it must be supplemented by an ``internal’’ solution and a matching procedure between the two solutions in their common region of validity.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Probability (math.PR)
6 pages, 2 figures
Identification of the transport regimes of the one-dimensional Holstein model
New Submission | Other Condensed Matter (cond-mat.other) | 2025-09-03 20:00 EDT
Suzana Miladić, Nenad Vukmirović
The Holstein model is a benchmark model of systems with electron-phonon interaction. However, its electrical transport properties are not yet fully understood. In this work, we performed numerically exact calculations of imaginary-time current-current correlation function of the Holstein Hamiltonian for a broad range of model parameters. These calculations were performed using a path-integral based Quantum Monte Carlo method. We compared these results with the results obtained under the assumption of conventional band transport, small polaron hopping and polaron band transport. From this comparison we identified the regions in parameter space where each of these transport regimes is valid. In some cases when imaginary-time comparison of current-current correlation functions could not give conclusive results, we complemented them with real-time comparisons or the comparison with literature data on numerically exact dc mobilities. Overall, we found that the parameter space is almost completely covered by the three mentioned transport regimes.
Other Condensed Matter (cond-mat.other)
Phys. Rev. B 112, 054314 (2025)
Phase diagram and eigenvalue dynamics of stochastic gradient descent in multilayer neural networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-09-03 20:00 EDT
Chanju Park (Swansea University), Biagio Lucini (Queen Mary University of London), Gert Aarts (Swansea University)
Hyperparameter tuning is one of the essential steps to guarantee the convergence of machine learning models. We argue that intuition about the optimal choice of hyperparameters for stochastic gradient descent can be obtained by studying a neural network’s phase diagram, in which each phase is characterised by distinctive dynamics of the singular values of weight matrices. Taking inspiration from disordered systems, we start from the observation that the loss landscape of a multilayer neural network with mean squared error can be interpreted as a disordered system in feature space, where the learnt features are mapped to soft spin degrees of freedom, the initial variance of the weight matrices is interpreted as the strength of the disorder, and temperature is given by the ratio of the learning rate and the batch size. As the model is trained, three phases can be identified, in which the dynamics of weight matrices is qualitatively different. Employing a Langevin equation for stochastic gradient descent, previously derived using Dyson Brownian motion, we demonstrate that the three dynamical regimes can be classified effectively, providing practical guidance for the choice of hyperparameters of the optimiser.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Machine Learning (cs.LG), High Energy Physics - Lattice (hep-lat)
27 pages, many figures
When Blood Parts Ways: Phase Separation in Microstructured Environments
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Sampad Laha, Ananta Kumar Nayak, Alexander Farutin, Suman Chakraborty, Chaouqi Misbah
Understanding how red blood cell (RBC) suspensions navigate porous materials is critical for for both fundamental physiology, such as maternal-fetal exchange in the placenta, and transformative biomedical applications, including rapid, low-cost disease diagnostics from a single drop of blood in resource-constrained settings. Here we elucidate how RBC movement through fibrous microporous structures is influenced by cell aggregation agents, emphasizing the impact of their clustering, membrane flexibility, and confinement. By varying the volume fraction of the RBC (hematocrit) and aggregation strength, we reveal a surprising phase separation: a dense RBC core surrounded by a cell-free layer, an effect not previously reported in whole blood studies. This separation is shown to be more pronounced with rigidified cells and persists even at high hematocrit levels, unlike in healthy samples. By connecting RBC deformability and aggregability to pore-mediated phase dynamics, our study provides a foundation for new diagnostic tools capable of classifying blood disorders or evaluating blood quality using only a sheet of structured paper, seamlessly integrating fundamental fluid mechanics with translational biomedical innovation in a previously unexplored manner.
Soft Condensed Matter (cond-mat.soft), Cell Behavior (q-bio.CB)
Two-level system loss characterization of NbTi superconducting resonators on Si/SiO2 substrates
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
Superconducting coplanar waveguide (SCPW) resonators, key components for quantum computing and sensing applications, require a high internal quality factor (Qi) for effective qubit readout and quantum sensing applications. Minimizing two-level system (TLS) losses, particularly at material interfaces, is critical for gatemon and topological qubits operating at low temperatures and in high magnetic fields. NbTi, a superconducting alloy with a high upper critical field, enables SCPW resonators resilient to such conditions. We fabricated NbTi SCPW resonators on Si/SiO2 substrates and systematically characterized their TLS-limited quality factors as functions of temperature and microwave photon number. Our results demonstrate that NbTi-based SCPWs on Si/SiO2 substrates provide a promising platform for developing next-generation quantum circuits.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
19 pages, 6 figures
Dipolar Nematic State in Relaxor Ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Yuan-Jinsheng Liu, Tyler C. Sterling, Shi Liu
Relaxor ferroelectrics exhibit exceptional dielectric and electromechanical properties, yet their microscopic origins remain elusive due to the interplay of hierarchical polar structures and chemical complexity. While models based on polar nanoregions or nanodomains offer valuable phenomenological insights, they often lack the first-principles predictive capability necessary for quantitatively describing functional properties such as piezoelectric coefficients. Here, we use large-scale molecular dynamics simulations, enabled by a universal first-principles-based machine-learning interatomic potential, to investigate atomic-scale polar dynamics in canonical Pb-, Bi-, and Ba-based relaxors. Across all systems, we uncover a universal dipolar nematic state, characterized by long-range orientational order of local polarizations without local alignment, challenging conventional polar cluster-based paradigms. We introduce a universal order parameter, derived from the skewness of the distributions of the local polarization autocorrelation functions, that captures the thermal evolution of both lead-based and lead-free systems within a single master curve. This nematic order, and its robust structural memory under electric field cycling, underpins key relaxor phenomena, including diffuse phase transition, frequency-dependent dielectric dispersion, and reversible giant piezoelectricity. Our findings establish a unified microscopic framework for relaxors and present a broadly applicable statistical approach to understanding complex disordered materials.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Quantum Spin Hall effect on planar Archimedean lattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
L. V. Duc Pham, Nicki F. Hinsche, Ingrid Mertig
Archimedean lattices constitute a unique family of two-dimensional tilings formed from regular polygons arranged with uniform vertex configurations. While the kagome lattice has been extensively studied and the snub square lattice has served as a quasicrystal approximant, the broader family remains comparatively unexplored in the context of electronic and topological properties. In this work, we present a systematic tight-binding study of all eight pure Archimedean lattices, incorporating both $ s$ and $ p$ orbitals. We analyze their band structures, investigate topological edge states arising from unconventional nanoribbon geometries, and evaluate $ \mathbb{Z}_2$ invariants as well as intrinsic spin Hall conductivities using the Kubo formalism. Our results reveal that several Archimedean lattices, such as the truncated hexagonal and truncated trihexagonal lattices, host nearly dispersionless flat bands extending across the Brillouin zone, which remain robust even in the presence of next-nearest-neighbor hopping and strong spin-orbit coupling. In particular, the truncated trihexagonal lattice supports topologically protected, highly spin-polarized edge states across multiple ribbon geometries. These states are stable against defects and spin-flip scattering, and they give rise to sizable spin Hall currents.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
The non-perturbative sides of the Kardar-Parisi-Zhang equation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
The Kardar-Parisi-Zhang (KPZ) equation is a celebrated non-linear stochastic equation yielding non-equilibrium universal scaling. It exhibits notorious non-perturbative aspects. The KPZ fixed point is strong-coupling, all the more in $ d>1$ . Strikingly, another, even stronger-coupling fixed point of the KPZ equation, called inviscid Burgers fixed point, has been recently unveiled. These non-pertubative features can be theoretically accessed and studied in a controlled way in all dimensions using the functional renormalisation group. We propose an overview of the related results, which provide the full picture of the fixed-point structure and associated scaling regimes of the KPZ equation in $ d=1$ and in higher dimensions.
Statistical Mechanics (cond-mat.stat-mech)
18 pages, 8 figures, related to StatPhys29 conference
Quality of Helicity-Dependent Magnetization Switching by Phonons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
F.G.N. Fennema, C.S. Davies, A. Tsukamoto, A. Kirilyuk
Optical control of magnetization has emerged as a promising approach to achieve ultrafast and energy-efficient magnetization reversal. Here, we investigate helicity-dependent switching of magne- tization driven by the resonant excitation of circularly-polarized transverse-optical phonons, using a polarization-modulated transient grating. Our results show that the polarized phonons within the sample substrate induce robust, helicity-defined magnetization reversal in the magnetic overlayer. Moreover, the quality of switching remains largely unaffected when the degree of ellipticity of the infrared excitation is varied at frequencies resonant with the targeted phonon modes. Conversely, as the excitation is moved slightly off-resonance, switching quality becomes highly sensitive to the ellipticity of the incident light.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Ideal Optical Flux Lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Ophelia Evelyn Sommer, Nigel R. Cooper
The realization of fractional quantum Hall (FQH) states in cold atomic gases is a long-standing goal in quantum simulation. Established approaches, including rapidly rotating gases and tight-binding lattices, are often hampered by low interaction energies and small many-body energy gaps. While optical flux lattices (OFLs) can achieve higher effective magnetic flux densities, standard two-state configurations generate highly non-uniform fields, and extensions to multi-state systems introduce significant experimental complexity. Here, we present a new paradigm for engineering robust FQH phases in OFLs using only two internal atomic states. We show that the introduction of an additional scalar potential provides a generic mechanism for creating Chern bands that are simultaneously essentially flat and “ideal.” Drawing on concepts from moiré materials, these desirable properties arise by tuning lattice parameters to certain $ N$ -flat manifolds $ (N=1,2,\dots)$ , where the $ 1$ -flat manifold shares its origin with certain “magic-angle” conditions. We provide a variety of examples of how to design optical flux lattices, including dark-state OFLs, to achieve these goals. This method allows for precise tuning of band flatness and stabilizes both Abelian and non-Abelian FQH phases. Our scheme is compatible with existing experimental capabilities using vector polarizability, opening practical routes to exploring strongly correlated topological physics with cold atoms.
Quantum Gases (cond-mat.quant-gas), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
24 pages, 11 figures, 2 tables
Realizing Blume-Capel Degrees of Freedom with Toroidal Moments in a Ruby Artificial Spin Ice
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Luca Berchialla, Gavin M. Macauley, Flavien Museur, Tianyue Wang, Armin Kleibert, Peter M. Derlet, Laura J. Heyderman
Realizing exotic Hamiltonians beyond the Ising model is a key pursuit in experimental statistical physics. One such example is the Blume-Capel model, a three-state spin model, whose phase diagram features a tricritical point where second-order and first-order transition lines converge, leading to a coexistence of paramagnetic, ferromagnetic, and disordered phases. Here, we realize an artificial crystal of single-domain nanomagnets, placed on the links of the Ruby lattice, enabling real-space observation of the Blume-Capel degrees of freedom. These Blume-Capel degrees of freedom are represented by the presence, sign and interactions of the toroidal moments that emerge naturally in plaquettes of nanomagnets in the Ruby artificial spin ice. By precisely tuning the lattice parameters of the Ruby artificial spin ice, we demonstrate control over the two-step ordering process of the toroidal moments, whereby there is a high-temperature crossover from a paramagnetic phase to an intermediate paratoroidic regime, followed by a second-order phase transition to a ferrotoroidic ground state. This sequence of toroidal phases and transitions is accurately captured by the Blume-Capel framework and provides a direct realization of a substantial portion of the phase diagram associated with the model. This establishes a new platform for exploring exotic Hamiltonians in terms of artificial spin ice superstructures, here with groups of nanomagnets forming toroidal moments. The success of this mapping paves the way for an entirely new frontier in artificial spin ice: intentionally engineering lattice designs whose effective Hamiltonians mediate unconventional forms of magnetic order, with new behaviors and functionalities.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Active sorting to boundaries in active nematic – passive isotropic fluid mixtures
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Saraswat Bhattacharyya, Julia M. Yeomans
We use a two-fluid model to study a confined mixture of an active nematic fluid and a passive isotropic fluid. We find that an extensile active fluid preferentially accumulates at a boundary if the anchoring is planar, whereas its boundary concentration decreases for homeotropic anchoring. These tendencies are reversed if the active fluid is contractile. We argue that the sorting results from gradients in the nematic order, and show that the behaviour can be driven by either imposed boundary anchoring or spontaneous anchoring induced by active flows. Our results can be tested by experiments on microtubule-kinesin motor networks, and may be relevant to sorting to the boundary in cell colonies or cancer spheroids.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Electron transfer between surface-acoustic-wave-induced moving and static quantum dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Fast long-range interactions between distant quantum dots in arrays remains an unsolved issue, which can be key to solve scalability issues in quantum simulation and computation processes, particularly related to the overhead associated with quantum error correction schemes. Furthermore, transport between static and moving quantum dots, relevant in surface acoustic wave induced experiments, has not been studied in detail. This article presents a paradigmatic model for picturing this process, where non-adiabatic terms driving a two-state transfer process are derived and discussed. Moreover, the main effects in the spin state of the electron and its effect on the transfer probability of the loading are analyzed including the most relevant interaction in semiconductor heterostructure induced 2 dimensional electron gases i.e. the Rashba-Dresselhaus terms.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Magnetic-Field Control of Emergent Order in a 3D Dipolar Pyramid Artificial Spin Ice
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Luca Berchialla, Gavin M. Macauley, Flavien Museur, Anja Weber, Laura J. Heyderman
We realize a three-dimensional artificial spin ice of disconnected nanomagnets interacting solely via dipolar coupling, patterned on square pyramids. This Pyramid artificial spin ice, with both tilted and in-plane nanomagnets, supports tunable states. Monte Carlo simulations reveal a rich phase diagram and an emergent square ice of vertex-level effective spins. Tailored demagnetization protocols and magnetic force microscopy allow experimental access to low-energy states, establishing a platform for exploring three-dimensional artificial spin ices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Conductive domain walls in ferroelectrics as tunable coherent THz radiation source
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Ramaz Khomeriki, Kathrin Dörr, Jamal Berakdar
THz emission associated with currents in conductive domains in BiFeO$ _3$ following infrared radiation is theoretically investigated. This experimentally observed phenomenon is explained by the domain wall stripes acting as metallic resonators with the oscillating charge accumulation being at the domain wall edges. The charge oscillation frequency is related to the plasma frequency inside the domain wall. The value of plasma frequency determines both the frequency and the amplitude of the emission emanating from the BiFeO$ _3$ lattice. We show that for certain geometries of the domain wall structure and for specific polarization of the incident pulse the THz emission embodies a non-vanishing chirality.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Applied Physics (physics.app-ph)
Geometric phases on graphene from Atiyah-Singer index theorem
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
M. Dantas, A. Carvalho, G. Garcia, C. Furtado
We investigate the emergence of geometric phases in graphene-based nanostructures through the lens of the Atiyah-Singer index theorem. By modeling low-energy quasiparticles in curved graphene geometries as Dirac fermions, we demonstrate that topological defects arising from the insertion of pentagonal or heptagonal carbon rings generate effective gauge fields that induce quantized Berry phases. We derive a compact expression for the geometric phase in terms of the genus and number of open boundaries of the structure, providing a topological classification of zero-energy modes. This framework enables a deeper understanding of quantum holonomies in graphene and their potential application in holonomic quantum computation. Our approach bridges discrete lattice models with continuum index theory, yielding insights that are both physically intuitive and experimentally accessible.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Dynamics of Loschmidt echoes from operator growth in noisy quantum many-body systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
We study the dynamics of Loschmidt echoes in noisy quantum many-body systems without conservation laws. We first show that the operator Loschmidt echo in noisy unitary dynamics is equivalent to the operator norm of the corresponding dissipative dynamics upon noise averaging. We then analyze this quantity in two complementary ways, revealing universal dynamical behavior. First, we develop a heuristic picture for generic Floquet systems that connects Loschmidt echoes, out-of-time-order correlators, and operator growth, which is valid at any dissipation strength. We assert that the Loschmidt echo has two dynamical regimes depending on the time $ t$ and the strength of the noise $ p$ : Gaussian decay for $ pt\ll1$ and exponential decay (with a noise-independent decay rate) for $ pt\gg1$ . Lastly, we rigorously prove all our results for a solvable chaotic many-body quantum circuit, the dissipative random phase model – thus providing exact insight into dissipative quantum chaos.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
7 pages
Disorder-aided Early Warning Signals: Predicting Catastrophic Shifts in Athermal Systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Tapas Bar, Anurag Banerjee, Blai Casals, Gustau Catalan, Javier Rodríguez-Viejo
The early prediction of tipping points, distinguished by sudden and catastrophic shifts from stable states, poses a challenging task that would enable us to assess the impending threat across natural and engineered systems. This threat becomes particularly acute in low-fluctuation environments, where tipping occurs through saddle-node bifurcation without prior warning in noise dynamics. In this study, we investigate the tipping point dynamics of avalanche catastrophes in low-fluctuation domain, employing model system like the zero temperature random field Ising model and thermally deposited cobalt films. As the system approaches the tipping point, avalanche activity reveals pronounced critical behaviour, including critical slowing down, variance enhancement, and a growing spatial correlation length–hallmarks that may serve as early warning signals of impending collapse. Crucially, we demonstrate that increasing disorder in the system reduces its vulnerability to catastrophic failure. In highly disorder regimes, these early warning signals emerge well before the transition, thereby providing a large margin for anticipation and mitigation. This key finding suggests a protective role of disorder offering a novel perspective on resilience in complex systems. Our results not only deepen the understanding of tipping phenomena in disorder materials but also have broader implications for forecasting regime shift in diverse real-world systems.
Statistical Mechanics (cond-mat.stat-mech)
17 pages, 12 figures
Reduced fidelities for free fermions out of equilibrium: From dynamical quantum phase transitions to Mpemba effect
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
We investigate the out-of-equilibrium dynamics after a quantum quench of the reduced fidelities between the states of a subregion $ A$ at different times. Precisely, we consider the fidelity between the time-dependent state of $ A$ and its initial value, as well as with the state at infinite time. We denote these fidelities as the reduced Loschmidt echo (RLE) and the final-state fidelity (FSF), respectively. If region $ A$ is the full systems, the RLE coincide with the standard Loschmidt echo. We focus on quenches from Gaussian states in several instances of the XY spin chain. In the hydrodynamic limit of long times and large sizes of $ A$ , with their ratio fixed, the reduced fidelities admit a quasiparticle picture interpretation. Interestingly, for some quenches in the hydrodynamic regime the RLE features a complicated structure with an infinite sequence of nested lightcones, corresponding to quasiparticles with arbitrary large group velocities. This leads to a ‘’staircase’’ of cusp-like singularities in the time-derivative of the fidelity. At the sub-hydrodynamic regime for some quenches the RLE exhibits cusp-like singularities, similar to the so-called dynamical quantum phase transitions (DQPT). We conjecture a criterion for the occurrence of the DQPT and for the ‘’critical’’ times at which the singularities occur. Finally, we discuss the hydrodynamic limit of the FSF. In particular, we show that it provides a valuable tool to detect the so-called quantum Mpemba effect.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
29 pages, 10 figures
Embodying computation in nonlinear perturbative metamaterials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Sima Zahedi Fard, Paolo Tiso, Parisa Omidvar, Marc Serra-Garcia
Designing metamaterials that carry out advanced computations poses a significant challenge. A powerful design strategy splits the problem into two steps: First, encoding the desired functionality in a discrete or tight-binding model, and second, identifying a metamaterial geometry that conforms to the model. Applying this approach to information-processing tasks requires accurately mapping nonlinearity – an essential element for computation – from discrete models to geometries. Here we formulate this mapping through a nonlinear coordinate transformation that accurately connects tight-binding degrees of freedom to metamaterial excitations in the nonlinear regime. This transformation allows us to design information-processing metamaterials across the broad range of computations that can be expressed as tight-binding models, a capability we showcase with three examples based on three different computing paradigms: a coherent Ising machine that approximates combinatorial optimization problems through energy minimization, a mechanical racetrack memory exemplifying in-memory computing, and a speech classification metamaterial based on analog neuromorphic computing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Emerging Technologies (cs.ET)
Quantum Computation of the Electronic Structure of Some Prototype Solids
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Naman Khandelwal, Nidhi Verma, Pooja Jamdagni, Ashok Kumar
Over the last decade, researchers have been working to improve a crucial aspect of quantum computing to predict Hamiltonian energy of solids. Quantum algorithms such as Variational Quantum Eigensolver (VQE) and Variational Quantum Deflation (VQD) have been used to study the molecular systems. However, there is growing interest in adapting and applying these methods to periodic solid-state materials. In this work, we have integrated first-principles density functional theory with VQE and VQD algorithms and utilizing the Wannier Tight-Binding Hamiltonian (WTBH) method to predict the electronic characteristics of solids. We demonstrate that VQE and VQD algorithms can be used to accurately predict electronic characteristics in a variety of multi-component prototype solid-state materials such as-Silicon (semiconductor), Gold (metallic), Boron Nitrile (insulator), Graphene (semi-metal). Efficient SU2 performs well among all the predefined ansatz used in the study. COBYLA is the fastest optimizer among the classical optimizers with minimum number of iterations for convergence. Results of noise models help to understand the band structure when calculated on real quantum hardware. As quantum hardware advances, our method stands as a prototype for future quantum simulations of materials pushing us closer to autonomous quantum discovery engines.
Materials Science (cond-mat.mtrl-sci)
26 pages, 6 figures
Racetrack computing with a topological boundary ratchet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Parisa Omidvar, Markus Bestler, Sima Zahedi Fard, Oded Zilberberg, Marc Serra-Garcia
Multistable order parameters provide a natural means of encoding non-volatile information in spatial domains, a concept that forms the foundation of magnetic memory devices. However, this stability inherently conflicts with the need to move information around the device for processing and readout. While in magnetic systems, domains can be transported using currents or external fields, mechanisms to robustly shuttle information-bearing domains across neutral systems are scarce. Here, we experimentally realize a topological boundary ratchet in an elastic metamaterial, where digital information is encoded in buckling domains and transported in a quantized manner via cyclic loading. The transport is topological in origin: neighboring domains act as different topological pumps for their Bogoliubov excitations, so their interface hosts topological boundary modes. Cyclic loading renders these modes unstable through inter-domain pressure, which in turn drives the motion of the domain wall. We demonstrate that the direction of information propagation can be controlled through adjustable mechanical constraints on the buckling beams, and numerically investigate buckling-based domain-wall logic circuits in an elastic metamaterial network. The underlying tight-binding structure with low-order nonlinearities makes this approach a general pathway toward racetrack memories in neutral systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Emerging Technologies (cs.ET)
12 pages, 9 figures
Generalized Rényi Entropy Production Rate in Non-equilibrium Systems: From Markov Processes to Chaotic Dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
J.M. Nieto-Villar, R. Mansilla, I. Santamaria-Holek
A generalization of the entropy production rate is proposed $ \Pi_q$ in non-equilibrium systems by extending the formalism of classical stochastic thermodynamics to regimes with non-Gaussian fluctuations. Through the Rényi entropy $ S_q$ , where entropic parameter $ q$ modulates critical fluctuations, it is defined $ \Pi_q$ and the postulated generalized $ q$ -affinity $ {\cal A}_q$ for Markov processes, where it is demonstrated that $ \Pi_q \geq 0$ , generalizing the second thermodynamics this http URL derived formal framework was applied to the Rössler model, a nonlinear dynamical system exhibiting chaos. Numerical simulations show that the entropy production rate $ \Pi_q$ can be used as an index of robustness and complexity by quantitatively corroborating the greater robustness of funnel-type chaos compared to spiral-type chaos. Our results reveal limitations of Gibbs-Shannon entropy in capturing non-Gaussian fluctuations induced by nonlinearity. On the contrary, it is found that $ \Pi_q$ it can be a suitable magnitude to measure the intensity of chaotic dynamics through the entropy parameter $ q$ , indicating a plausible link with Lyapunov exponents. The proposed formal framework extends the scope of stochastic thermodynamics to complex systems, integrating chaotic dynamics and the role of the entropic index q as a source of irreversibility and in capturing non-Gaussian contributions to entropy production.
Statistical Mechanics (cond-mat.stat-mech), Other Condensed Matter (cond-mat.other)
6 pages 4 figures
Direct spatiotemporal imaging of a long-lived bulk photovoltaic effect in $BiFeO_{3}$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Saptam Ganguly, Sebin Varghese, Aaron M. Schankler, Xianfei Xu, Kazuki Morita, Michel Viret, Andrew M. Rappe, Gustau Catalan, Klaas-Jan Tielrooij
The bulk photovoltaic effect (BPVE), a manifestation of broken centrosymmetry, has attracted interest as a probe of the symmetry and quantum geometry of materials, and for use in novel optoelectronic devices. Despite its bulk nature, the BPVE is typically measured with interfaces and metal contacts, raising concerns as to whether the observed signals are genuinely of bulk origin. Here, we use a contactless pump-probe microscopy method to observe the space- and time-resolved dynamics of photoexcited carriers in single-crystal, monodomain $ BiFeO_{3}$ . We observe asymmetric transport of carriers along the polar axis, confirming the intrinsic bulk and symmetry-driven nature of BPVE. This asymmetric transport persists for several nanoseconds after photoexcitation, which cannot be explained by the shift or phonon ballistic current BPVE mechanisms. Monte Carlo simulations show that asymmetric momentum scattering by defects under non-equilibrium conditions explains the long-lived carrier drift, while first principles calculations confirm that oxygen vacancies have an asymmetric electronic state that can cause such asymmetric scattering. Our findings highlight the critical role of defects in long-lived photoresponses.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Quantitative and bond-traceable resonant X-ray optical tensors of organic molecules
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Victor Murcia, Obaid Alqahtani, Harlan Heilman, Brian A. Collins
X-ray scattering at the carbon absorption edge is uniquely sensitive to local molecular bond identity and orientation in organic nanostructures, encoded as a function of photon energy and polarization. However, quantitative analysis is precluded due to the lack of accurate optical models with bond and orientation specificity. We generate such a model through an algorithm that parameterizes and refines density functional theory calculations with angle-resolved absorbance spectroscopy measurements. The resulting optical tensor is shown to reproduce data from samples with domains of different orientation and crystalline packing, enabling label-free orientation analyses of individual chemical moieties within molecular nanostructures using resonant X-rays.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft), Applied Physics (physics.app-ph), Optics (physics.optics)
Topological polar textures on CsPbBr3 nanoplatelets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Monika Bhakar, Pooja Bhardwaj, Gokul M. Anilkumar, Atikur Rahman, Goutam Sheet
Polar topological textures like the bubble domains, flux–closures, and labyrinth etc., unlock functional responses in ferroic systems but are difficult to stabilize and control in chemically simple, solution–grown materials. Here we show that ultra–thin, large–area CsPbBr$ _3$ nanoplatelets host room–temperature ferroelectric bubble domains whose characteristic size is tunable by thickness. Using contact–resonance piezoresponse force microscopy (PFM) across 125ñm–2~$ \mu$ m, we observe a systematic decrease in domain size with decreasing thickness, consistent with a depolarization–field controlled stability window. Repeated scanning transforms bubbles into labyrinthine patterns, indicating metastability under weak mechanical/electrical perturbations. Upon heating, bubbles evolve into labyrinths and vanish at $ T_C!\approx!90^\circ$ C, with domain nucleation recovered on cooling. These results establish a controllable platform for polar topology in a stable, stochiometric perovskite grown via a solvothermal route, and clarify how electrical boundary conditions (set by thickness and temperature) govern texture selection. The thickness–tunable polar textures identified here offer a route to engineer domain–wall–mediated functionalities in halide perovskites.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
AM-DefectNet: Additive Manufacturing Defect Classification Using Machine Learning - A comparative Study
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Mohsen Asghari Ilani, Yaser Mike Banad
Additive Manufacturing (AM) processes present challenges in monitoring and controlling material properties and process parameters, affecting production quality and defect detection. Machine Learning (ML) techniques offer a promising solution for addressing these challenges. In this study, we introduce a comprehensive framework, AM-DefectNet, for benchmarking ML models in melt pool characterization, a critical aspect of AM. We evaluate 15 ML models across 10 metrics using 1514 training and 505 test datasets. Our benchmarking reveals that non-linear tree-based algorithms, particularly CatBoost, LGBM, and XGBoost, outperform other models, achieving accuracies of 92.47%, 91.08%, and 90.89%, respectively. Notably, the Deep Neural Network (DNN) also demonstrates competitive performance with an accuracy of 88.55%. CatBoost emerges as the top-performing algorithm, exhibiting superior performance in precision, recall, F1-score, and overall accuracy for defect classification tasks. Learning curves provide insights into model performance and data requirements, indicating potential areas for improvement. Our study highlights the effectiveness of ML models in melt pool characterization and defect detection, laying the groundwork for process optimization in AM.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Multi-objective Evolutionary Algorithms (MOEAs) in PMEDM - A Comparative Study in Pareto Frontier
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Mohsen Asghari Ilani, Yaser Mike Banad
Electrical discharge machining (EDM) is a crucial process in precision manufacturing, leveraging electro-thermal energy to remove material without electrode contact. In this study, we delve into the realm of Machine Learning (ML) to enhance the efficiency and precision of EDM, particularly focusing on Powder-Mixed Electrical Discharge Machining (PMEDM) with the integration of a vibration system. We comprehensively evaluate four leading ML models - Deep Neural Network (DNN), Extreme Gradient Boosting (XGBoost), Adaptive Gradient Boosting (AdaBoost), and ElasticNet, against a pool of ML models, employing various evaluation metrics including Accuracy, Mean Squared Error (MSE), Root Mean Squared Error (RMSE), and Mean Absolute Error (MAE). Our evaluations, conducted on datasets enriched with features derived from powder addition and electrode vibration, reveal XGBoost superior accuracy, followed by AdaBoost, DNN, and ElasticNet. Furthermore, through the integration of Multi-Objective Evolutionary Algorithms (MOEAs) such as NSGA-II, NSGA-III, UNSGA-III, and C-TAEA, we explore and optimize the Pareto front to attain optimal solutions. Our findings underscore the transformative potential of ML and optimization techniques in advancing EDM processes, offering cost-effective, time-efficient, and reliable solutions for precision manufacturing applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Hidden orders in spin-orbit entangled correlated insulators
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Leonid V. Pourovskii, Dario Fiore Mosca, Lorenzo Celiberti, Sergii Khmelevskyi, Arun Paramekanti, Cesare Franchini
In many materials, ordered phases and their order parameters are easily characterized by standard experimental methods. “Hidden order” refers to a phase transition in which an ordered state emerges without such an easily detectable order parameter, despite clear thermodynamic evidence of the transition. The underlying mechanisms for these unconventional states of matter stem from spin-orbit coupling, which intertwines inter-site exchange, classical electron-magnetic interactions, and electron-lattice effects. This physics is elusive to experimental probes and beyond traditional theories of insulating magnetism, requiring sophisticated methodologies for its exploration. In this Review, we survey exotic hidden-order phases in correlated insulators, particularly focusing on the latest progress in material-specific theories and numerical approaches. The relevant degrees of freedom in these phases are local high-rank multipole moments of magnetic and charge density that emerge from spin-orbit entangled correlated shells of heavy d and f electron ions and interact on the lattice via various mechanisms. We discuss approaches to modelling hidden orders in realistic systems via direct ab initio calculations or by constructing low-energy many-body effective Hamiltonian. We also describe how these new theoretical tools have helped to uncover driving mechanisms for recently discovered multipolar phases in double perovskites of heavy transition metals, and how they have proved instrumental in disentangling the role of various interactions in “traditional” f-electron multipolar materials like actinide dioxides. In both cases, material-specific theories have played a key role in interpreting and predicting experimental signatures of hidden orders.
Strongly Correlated Electrons (cond-mat.str-el)
Nature Reviews Materials volume 10, pages 674-696 (2025)
The Crooks relationship in single molecule pulling simulations of coupled harmonic oscillators
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Julián David Jiménez-Paz, José Daniel Muñoz-Castaño
In this work, we propose two models of coupled harmonic oscillators under Brownian motion to computationally study the applications of fluctuation theorems. This paper also illustrates how to analytically calculate free energy differences for these systems. The computational results clearly show that Crooks relation is able to predict free energy differences between initial and final canonical ensembles with around $ 1%$ accuracy by using probability distributions of cumulative work done during nonequilibrium protocols carried out with velocities up to three orders of magnitude larger than the quasi-stationary evolution velocity. The curves of instantaneous force and cumulative work for the second model resemble those obtained experimentally on the unfolding of ARN molecules. Hence, the proposed systems are not just useful to illustrate the performance and conceptual significance of the fluctuation theorems, but also they could be studied as simplified models for biophysical systems.
Statistical Mechanics (cond-mat.stat-mech)
Intermittent localization and fast spatial learning by non-Markov random walks with decaying memory
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Paulina R. Martí n-Cornejo, Denis Boyer
Random walks on lattices with preferential relocation to previously visited sites provide a simple modeling of the displacements of animals and humans. When the lattice contains a single impurity or resource site where the walker spends more time on average at each visit than on the other sites, the long range memory can suppress diffusion and induce by reinforcement a steady state localized around the resource. This phenomenon can be identified with a spatial learning process by the walker. Here we study theoretically and numerically how the decay of memory impacts learning in these models. If memory decays as $ 1/\tau$ or slower, where $ \tau$ is the time backward into the past, the localized solutions are the same as with perfect, non-decaying memory and they are linearly stable. If forgetting is faster than $ 1/\tau$ , for instance exponential, an unusual regime of intermittent localization is observed, where well localized periods of exponentially distributed duration are interspersed with intervals of diffusive motion. At the transition between the two regimes, for a kernel in $ 1/\tau$ , the approach to the stable localized state is the fastest, opposite to the expected critical slowing down effect. Hence forgetting can allow the walker to save memory without compromising learning and to achieve a faster learning. These findings agree with biological evidence on the benefits of forgetting.
Statistical Mechanics (cond-mat.stat-mech), Neurons and Cognition (q-bio.NC)
23 pages, 7 figures
Spin-orbit torque control of topology in intrinsic antiferromagnetic insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Rajibul Islam, Shakeel Ahmad, Fei Xue
Magnetic topological insulators host exotic phenomena such as the quantum anomalous Hall effect and quantized magnetoelectric responses, but dynamic electrical control of their topological phases remains elusive. Here we demonstrate from first principles that spin-orbit torque enables direct switching of the topological state in the intrinsic antiferromagnetic bilayer MnBi$ _2$ Te$ _4$ . A symmetry-enforced interband (time-reversal even) torque persists inside the bulk gap and deterministically reverses the Néel order and layer-resolved Chern number without free carriers. Upon doping, both interband and intraband torques are amplified, lowering the critical electric field for switching by two orders of magnitude. Together, these results establish two complementary regimes of control, dissipationless in-gap torques without Joule heating and enhanced current-induced torques, providing a robust route to manipulate local Chern numbers, quasi-helical edge states, and topological responses in antiferromagnetic topological insulators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Main text: 6 pages, 4 figures; Supplemental Materials: 3 pages, 6 figures
Optical Voltammetry of redox processes inside a nanohole with Opto-iontronic microscopy
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Zhu Zhang, Haolan Tao, Cheng Lian, René van Roij, Sanli Faez
Cyclic Voltammetry (CV) is the most commonly used method in electrochemistry to characterize electrochemical reactions, usually involving macroscopic electrodes. Here we demonstrate a novel optical CV technique called Opto-iontronic Microscopy, which is capable of monitoring electrochemical processes at the nanoscale. By integrating optical microscopy with nanohole electrodes, we enhance sensitivity in detecting redox reactions within volumes as small as an attoliter ($ (100 \text{~nm})^{3}$ ). This technique uses total internal reflection (TIR) illumination, Electric-double-layer modulation, cyclic voltammetry, and lock-in detection, to probe ion dynamics inside nanoholes. We applied this method to study EDL (dis)charging coupled to ferrocenedimethanol (Fc(MeOH)$ _2$ ) redox reactions. Experimental results were validated against a theoretical Poisson-Nernst-Planck-Butler-Volmer (PNP-BV) model, providing insights into ion concentration changes of reaction species that contribute to the optical contrast. This work opens up opportunities for high-sensitivity, label-free analysis of electrochemical reactions in nanoconfined environments, with potential applications in pure nanocrystal growth and monitoring, and potentially single-molecule electrochemistry.
Soft Condensed Matter (cond-mat.soft)
A Practical Flake Segmentation and Indexing Pipeline for Automated 2D Material Stacking
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Yutao Li, Logan Sherlock, Ryan Benderson, Daniel Ostrom, Huandong Chen, Kazuhiro Fujita, Abhay Pasupathy
A cost-effective and robust image-processing pipeline is presented for the detection and characterization of exfoliated two-dimensional (2D) material flakes in optical microscope images, designed to facilitate automation in van der Waals heterostructure assembly. The system combines shallow machine learning (ML)-based material classification with a precision-first flake detection algorithm driven by edge morphology and color discontinuity. Step edges are resolved when supported by optical contrast, while spurious features such as dust and background texture are reliably rejected. Each identified flake is exported in a structured format that includes centroid coordinates, bounding geometries, average RGB color, and estimated optical thickness, enabling seamless integration into automated pick-up and stacking workflows. The pipeline is hardware-light and operates without the need for deep learning models or nanoscale ground-truth labels, making it practical for scalable front-end wafer processing at a hardware cost of under 30,000 USD. In contrast to prior approaches that focus solely on detection accuracy, the proposed system unifies flake segmentation with indexing, filtering, and blueprint-driven stacking, forming a closed-loop workflow from image acquisition to device planning. Its low annotation requirement and flexible implementation enable rapid deployment across diverse 2D material systems and imaging conditions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Instrumentation and Detectors (physics.ins-det)
Influence of Stretching Boundary Conditions on Fracture in Phantom Star Polymer Networks: From Volume to Cross-sectional Area Conservation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Yuichi Masubuchi, Takato Ishida, Yusuke Koide, Takashi Uneyama
This study systematically investigates the effect of stretching boundary conditions, ranging from conservation of cross-sectional area to conservation of volume, on the rupture behavior of phantom star polymer networks using energy-minimizing coarse-grained molecular simulations. By continuously varying the deformation parameter, the simulations reveal that true stress and rupture characteristics, such as strain and stress at break and work for rupture, systematically decrease as the boundary condition approaches cross-sectional area conservation. In contrast, nominal stress and the corresponding rupture characteristics exhibit near-independence from boundary conditions, indicating that bond tension remains largely unaffected for phantom networks under the examined conditions. These results clarify that volume expansion primarily drives deviations in true stress and highlight a critical distinction between true and nominal stress-strain definitions. The difference between true and nominal stress-strain relations also affected the scaling exponent for strand length dependence on stretch at break. The findings stress the importance of specifying both deformation boundary conditions and stress-strain definitions in polymer network simulations for accurate interpretation of mechanical properties.
Soft Condensed Matter (cond-mat.soft)
16 pages, 5 figures
A Concise Review of Recently Synthesized 2D Carbon Allotropes: Amorphous Carbon, Graphynes, Biphenylene and Fullerene Networks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Ricardo Paupitz, Alexandre F. Fonseca, Mizraim Bessa, Guilherme S. L. Fabris, William F. da Cunha, Leonardo D. Machado, Marcelo L. Pereira Junior, Luiz A. Ribeiro Junior Douglas S. Galvão
Two-dimensional (2D) carbon allotropes have received considerable attention due to their unique properties and potential applications in several fields, including electronics, catalysis, energy storage, and sensing. Following the experimental realization of graphene, numerous other 2D carbon structures have been proposed and, in some cases, successfully synthesized. This work presents a concise review of the recently experimentally realized 2D carbon allotropes, including graphynes, biphenylene-based networks, fullerene networks, and monolayer amorphous carbon. For each class, we discuss structural characteristics, theoretical predictions, and synthesis methods, with emphasis on the interplay between theory and experiment. We also highlight instances where experimental studies overlooked relevant theoretical contributions. Finally, we identify theoretically predicted structures that remain unexplored experimentally, suggesting opportunities for synthesis-driven investigations.
Materials Science (cond-mat.mtrl-sci)
36 pages and six figures
Magnonic radar for dynamic domain walls in synthetic antiferromagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Spin wave and magnetic domain wall are two of basic excitations in magnetic systems, and their spatiotemporal interplay encodes rich information of underlying magnetic interactions. In synthetic antiferromagnets, the domain wall acquires an inertia and the spin wave unlocks the full polarization degree of freedom, lays a salient platform for their interplay. Here we show that both the translational and angular velocities of domain wall in synthetic antiferromagnets can be detected via the scattered spin wave, through the synergy of translational and angular Doppler effects. Following the setup of an electromagnetic or acoustic radar, the time evolution of a domain wall state are accessible via a series of spin wave packets, in both non-invasive and invasive fashion. The inspections in frequency domain, offer new paradigms in exploration and exploitation of magnetic excitations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 7 figures
Raman spectroscopy of graphite with water as the pressure medium
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
K. Perry, A. T. Roy, A. R. Parmenter, Y. J. Ryu, V. B. Prakapenka, J. Lim
We report a high-pressure Raman spectroscopy study of a graphite-water mixture using water as the pressure-transmitting medium up to 9.9 GPa. In the graphite-rich region, three characteristic Raman features-the $ E_{2g}^{(1)}$ shear mode, the G band ($ E_{2g}^{(2)}$ ), and the 2D band-were observed and tracked as a function of pressure. The G band exhibits a pronounced blue shift with increasing pressure, indicating enhanced interlayer coupling between graphite planes. In the water-rich region, the librational band and three distinct O-H stretching modes were identified. Notably, above 8 GPa, the slope of the pressure dependence decreases relative to the earlier report, likely due to the influence of the water pressure medium, emphasizing the need for further investigation at higher pressures.
Materials Science (cond-mat.mtrl-sci)
Defining structural gradient hardening through Type II back stress for heterostructured materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
The recently proposed term “heterostructured (HS) materials” serves as an umbrella classification encompassing a wide range of materials that hold great promise for enhanced mechanical properties. Most HS materials exhibit back-stress strengthening, as is typical for all plastically non-homogeneous materials. To better embody the distinctiveness of materials crafted via innovative heterostructuring, here we introduce the concept of “structural gradient hardening” (SGH), which captures an essential feature of HS materials and complements traditional strengthening mechanisms. SGH refers to the extra strengthening that arises from a characteristic gradient structure introduced by heterostructuring, beyond what is predicted by the rule of mixtures. This distinction is useful, as the overall back stress can in fact be partitioned into Type I and Type II components, with the latter specifically quantifying the extra hardening originating from the structural and strain gradients established by heterostructuring, as articulated in this Viewpoint article.
Materials Science (cond-mat.mtrl-sci)
21 pages, 4 figures
Heavy Fermi polarons in a one-dimensional harmonic trap
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
We provide an analytically tractable toy model of an infinitely heavy impurity interacting with the spin-polarized gas of bath fermions via a contact potential in 1D and placed in a harmonic trap. The solution to this problem requires knowledge of the single-particle fermionic eigenstates in the presence of a harmonic trap and a contact potential. We show how the spectrum can be understood from a perturbative solution of the exact transcendental equation in the weak and strong-coupling regimes. We additionally provide expressions for normalized wavefunctions and different overlaps between the states in the presence and absence of the impurity. Using these exact results, we analyze the energy of the polaron, derive Tan’s contact-like relation for the density at the center of the harmonic trap, and compute the quasiparticle residue.
Quantum Gases (cond-mat.quant-gas)
4+5 pages, 3 figures
High-quality Tungsten-doped Vanadium Dioxide Thin Films Fabricated in an Extremely Low-oxygen Furnace Environment
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Vishwa Krishna Rajan, Ken Araki, Robert Y. Wang, Liping Wang
This work reports the fabrication and characterization of high-quality tungsten-doped vanadium dioxide (WxV1-xO2, x = 0~3 at. %) by thermal oxidation of sputtered tungsten-vanadium alloyed thin films with different atomic percentages and high-temperature annealing in an extremely low oxygen atmosphere (5 to 20 ppm) along with reduction of surface over-oxides in high vacuum (1 mPa). Oxidation parameters such as temperature, time and nitrogen purging rate are first optimized for obtaining high quality undoped VO2 thin film. Insulator-to-metal (IMT) phase transition behavior of VO2 thin films fabricated in a low-O2 environment is characterized with temperature dependent spectral infrared transmittance and electrical resistivity measurements, where there is 15% higher infrared transmittance change and additional 1 order change in resistivity in comparison with VO2 thin films fabricated in a O2-rich environment. Grazing angle X-ray diffraction scan confirms no presence of higher oxides in the VO2 oxidized in low-O2 environment, which improves its quality significantly. Comprehensive studies on thermal annealing and vacuum reduction for tungsten doped VO2 thin films are also carried out to find the optimal fabrication conditions. With the tungsten at. % measured by X-ray photoelectron spectroscopy, the optimal WVO2 thin films fabricated through this streamlined oxidation, annealing and reduction processes in extremely low-O2 furnace environment exhibit lowered IMT temperature at -23°C per at.% of tungsten dopants from 68°C without doping. This low-cost and scalable fabrication method could facilitate the wide development of tunable WVO2 coatings in thermal and energy applications.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Intrinsic nonlinear valley Nernst effect in the strained bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Ying-Li Wu, Jia-Liang Wan, Xiao-Qin Yu
We theoretically analyze the nonlinear valley Nernst effect (NVNE) as the second-order response of temperature gradient through the semiclassical framework of electron dynamics up to second order. Our study shows that an intrinsic nonlinear pure valley current can be generated vertically to the applied temperature in the materials with both inversion and time-reversal symmetries. This intrinsic NVNE has a quantum origin from the quantum metric and shows independence from the relaxation time. It’s found that the local largest symmetry near the valleys for the nonvanishing intrinsic NVNE is a single mirror symmetry in two-dimensional systems. We theoretically investigate the intrinsic NVNE in the uniaxially strained gapless bilayer graphene and find the intrinsic NVNE can emerge when applying the temperature gradient vertically to the direction of strain. Interestingly, a transition from the compressive strain to the tensile one results in the sign reversal of the intrinsic NVNE.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 3 figures, Submitted to Physical Review B on 28 July 2025 (under review)
Thermodynamic uncertainty relation for generalized time-reversal observables
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Tetta Indo, Yoshihiko Hasegawa
Time-reversal symmetry plays an essential role in the thermodynamic uncertainty relation, which bound the fluctuations of observables in terms of the associated dissipation. In fact, thermodynamic uncertainty relations are typically derived under the assumption that the observable of interest is antisymmetric under time reversal. This also suggests that existing thermodynamic uncertainty relations are restricted to a limited class of observables. In this paper, we mitigate this restriction by introducing a new class of observables that do not exhibit the exact antisymmetry but only change the sign under time reversal. We call it generalized time reversal and derive a broadly applicable thermodynamic uncertainty relation for observables with this condition. The generalization is achieved by direct statistical arguments on the probability distributions of dissipation and the observable, and holds for both deterministic and stochastic dynamics. We demonstrate the derived thermodynamic uncertainty relation in a quantum refrigeration model, showing that the precision of generalized observables remains expressible in terms of the heat-dissipation cost. The result extends the scope of thermodynamic uncertainty relations beyond what was reached by frameworks relying on strong symmetries imposed by fluctuation theorems.
Statistical Mechanics (cond-mat.stat-mech)
9 pages, 3 figures
Interfacial Control of both Magnetism and Polarization in a van der Waals Ferromagnet/Ferroelectric Heterostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Priyanshu Raj, Sourav Mal, Rana Saha, Prasenjit Sen
Two-dimensional multiferroic van der Waals heterostructures provide a promising platform for the simultaneous control of distinct ferroic orders, with potential applications in magnetoelectric devices and spintronics. The practical implementation of such technologies requires 2D magnets with high Curie temperatures and strong perpendicular magnetic anisotropy (PMA). Here, based on first-principles calculations, we propose a multiferroic heterostructure composed of the room-temperature ferromagnet $ \text{Fe}_3\text{Ga}\text{Te}_2$ and the ferroelectric $ \text{In}_2\text{Se}_3$ . We show that intercalation of Fe atoms into the van der Waals gap of the $ \text{Fe}_3\text{Ga}\text{Te}_2$ /$ \text{In}_2\text{Se}_3$ heterostructure enhances PMA by nearly an order of magnitude relative to the pristine $ \text{Fe}_3\text{Ga}\text{Te}_2$ monolayer, while simultaneously allowing electric polarization to be modulated through interfacial charge redistribution. The enhancement of PMA arises from interfacial hybridization that modifies the spin-orbit coupling of Fe $ d$ -orbitals. Our results demonstrate an effective pathway to engineer magnetoelectric coupling in two-dimensional multiferroic heterostructures and pave the way toward energy-efficient spintronic devices.
Materials Science (cond-mat.mtrl-sci)
8 pages, 5 figures
Dipolar Self-Interactions Drive Polymer Chain Collapse
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Pratik Khandagale, Gal deBotton, Timothy Breitzman, Carmel Majidi, Kaushik Dayal
We report that a dielectric polymer chain, constrained at both ends, sharply collapses when exposed to a high electric field. The chain collapse is driven by nonlocal dipolar interactions and anisotropic polarization of monomers, a characteristic of real polymers that prior theories were unable to incorporate. Once collapsed, a large number of chain monomers accumulate at the center location between the chain ends, locally increasing the electric field and polarization by orders of magnitude. The chain collapse is sensitive to the orientation of the applied electric field and chain stretch. Our findings not only offer new ways for rapid actuation and sensing but also provide a pathway to discover the critical physics behind instabilities and electrical breakdown in dielectric polymers.
Soft Condensed Matter (cond-mat.soft)
Coordinate space representation of a one dimensional $p$-wave pseudopotential
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Marc Camus-Sais, Abel Rojo-Francàs, Grigori E. Astrakharchik, Bruno Juliá-Díaz
We propose a discrete-space representation of the $ p$ -wave pseudopotential. The proposed representation is validated by applying it to the analytically solvable case of two fermions in a harmonic trap and successfully recovering the exact energy spectrum and eigenfunctions. Furthermore, we use the square-well and modified Pöschl-Teller potentials as finite-range representations of the $ p$ -wave interaction and study their convergence to the contact interaction when the range tends to zero. Finally, we perform natural orbital analysis and compute the eigenvalues of the one-body density matrix for different particle numbers, examining their dependence on the one-dimensional scattering length and identifying distinct physical regimes.
Quantum Gases (cond-mat.quant-gas)
Optically induced spin Hall current in monolayer Janus NbSSe: A first-principles study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Souren Adhikary, Tomoaki Kameda, Katsunori Wakabayashi
Monolayer Janus transition-metal dichalcogenides possess Ising- and Rashba-type spin-orbit-couplings (SOC), leading to intriguing spin splitting effects at K and K$ ‘$ , and around $ \Gamma$ points across the wide energy range. Using first-principles calculations, we unveil these SOC characteristics in metallic Janus NbSSe and demonstrate its potential for optically controlled spin current eneration. On the basis of the symmetry of the system, we show that different linear polarized light can selectively drive spin currents of distinct spin components. Our findings establish NbSSe as a promising candidate for next-generation optospintronic technologies, which is offering a pathway toward the development of polarization-tunable spin-current sources.
Materials Science (cond-mat.mtrl-sci)
7 pages, 5 figures
Extremely Large and Angle-Dependent Magnetoresistance in Kagome Dirac Semimetal RFe$_6$Sn$_6$ (R=Ho, Dy)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Susanta Ghosh, Achintya Low, Nayana Devaraj, Susmita Changdar, Awadhesh Narayan, Setti Thirupathaiah
We report on the electronic, magnetic, and magneto-transport properties of Fe-based kagome Dirac system, RFe$ _6$ Sn$ _6$ (R = Ho, Dy). Magnetic properties study reveals an antiferromagnetic order with N$ \acute{e}$ el temperature of $ T_N \approx$ 570 K. Additionally, a weak ferromagnetic order emerge at low temperatures. Magnetotransport measurements demonstrate an extremely large magnetoresistance (XMR) reaching as high as $ 3\times 10^{3} %$ for HoFe$ _6$ Sn$ _6$ and $ 1\times 10^{3} %$ for DyFe$ _6$ Sn$ _6$ when measured at 2 K with 9 T of magnetic field. The semi-classical two-band model fitting of the Hall conductivity reveals nearly perfect electron-hole compensation and high carrier mobility, which leads to XMR behaviour in these system. Further, we identify large magnetoresistance anisotropy for the magnetic fields applied in different crystallographic orientations. In addition, considerable modification in the angle-dependent magnetoresistance (ADMR) pattern has been noticed between 2 and 50 K, indicating temperature-dependent changes in the Fermi surface topology of these systems.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
18 pages, 15 figures, Accepted for publication in Journal of Alloys and Compounds
Phase field simulation of dendrite growth in solid-state lithium batteries based on mechanical-thermo-electrochemical coupling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Pengyang Hou, Jiamiao Xie, Jingyang Li, Peng Zhang, Zhaokai Li, Wenqian Hao, Jia Tian, Zhe Wang, Fuzheng Li
Solid-state lithium batteries possess numerous advantages, such as high energy density, excellent cycle stability, superior mechanical strength, non-flammability, enhanced safety, and extended service life. These characteristics make them highly suitable for applications in aerospace, new energy vehicles, and portable electronic devices. However, the growth of lithium dendrite at the electrode/electrolyte interface remains a critical challenge, limiting both performance and safety. The growth of lithium dendrites in the electrolyte not only reduces the Coulombic efficiency of the battery but also poses a risk of puncturing the electrolyte, leading to internal short circuits between the anode and cathode. This study is to solve the problem of lithium dendrite growth in solid-state lithium batteries by employing phase-field theory for numerical simulations. A phase-field model is developed by coupling the mechanical stress field, thermal field, and electrochemical field, to investigate the morphology and evolution of lithium dendrites under the condition of different ambient temperatures, external pressures, and their combined effects. The results indicate that higher temperature and greater external pressure significantly suppress lithium dendrite growth, leading to fewer side branches, smoother surfaces, and more uniform electrochemical deposition. Increased external pressure inhibits longitudinal dendrite growth, resulting in a compressed morphology with higher compactness, but at the cost of increased mechanical instability. The combined effect of temperature and pressure exhibits a pronounced inhibitory influence on dendrite growth, with stress concentrating at the dendrite roots. This stress distribution promotes lateral growth, facilitating the formation of flatter and denser lithium deposits.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
28 pages,9 figures
Acta Phys. Sin., 2025, 74(7): 070201
Boundary Renormalization Group Flow of Entanglement Entropy at a (2+1)-Dimensional Quantum Critical Point
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
Zhiyan Wang, Zhe Wang, Yi-Ming Ding, Zenan Liu, Zheng Yan, Long Zhang
We investigate the second order Rényi entanglement entropy at the quantum critical point of spin-1/2 antiferromagnetic Heisenberg model on a columnar dimerized square lattice. The universal constant $ \gamma$ in the area-law scaling $ S_{2}(\ell) = \alpha\ell - \gamma$ is found to be sensitive to the entangling surface configurations, with $ \gamma_{\text{sp}} > 0$ for strong-bond-cut (special) surfaces and $ \gamma_{\text{ord}} < 0$ for weak-bond-cut (ordinary) surfaces, which is attributed to the distinct conformal boundary conditions. Introducing boundary dimerization drives a renormalization group (RG) flow from the special to the ordinary boundary criticality, and the constant $ \gamma$ decreases monotonically with increasing dimerization strength, demonstrating irreversible evolution under the boundary RG flow. These results provide strong numerical evidence for a higher-dimensional analog of the $ g$ -theorem, and suggest $ \gamma$ as a characteristic function for boundary RG flow in (2+1)-dimensional conformal field theory.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
6 pages, 3 figures
Information-Theoretical Approach to Relaxation Time Distribution in Rheology: Log-Normal Relaxation Spectrum Model
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
The relaxation modulus of a viscoelastic fluid can be decomposed into multiple Maxwell models and characterized by the relaxation spectrum for the relaxation time. It is empirically known that the logarithmic relaxation time is useful to express the relaxation spectrum. We use information geometry to analyze the relaxation modulus and shown that the logarithmic relaxation time is the most natural variable for the relaxation spectrum. Then we use information theory to estimate the most probable functional form for the relaxation spectrum. We show that the log-normal distribution is the information-theoretically most probable relaxation spectrum. We analyze the properties of the log-normal relaxation spectrum model and compare it with the fractional Maxwell model. The fractional Maxwell model with a small power-law exponent can be approximated as the log-normal relaxation spectrum model with a large standard deviation. We also compare the log-normal relaxation spectrum model with experimental linear viscoelasticity data for a high-density polyethylene, both at melt and solid states.
Soft Condensed Matter (cond-mat.soft)
16 pages, 11 figures, to appear in Nihon Reoroji Gakkaishi (J. Soc. Rheol. Jpn.)
Reentrant superconductivity and superconductor-to-insulator transition in a naturally occurring Josephson junction array tuned by RF power
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
S. Avraham, S. Sankar, S. Sandik, A. Burshtein, M. Goldstein, E. Sela, Y. Dagan
Superconductivity, characterized by dissipationless current flow with flux expulsion or quantization, is usually muted when the magnetic field or the temperature is sufficiently high. However, in rare instances, superconductivity can reappear upon increasing the temperature or magnetic field, a phenomenon known as reentrant superconductivity. It usually emerges from competing orders in strongly correlated materials. Here we demonstrate reentrant superconductivity as a function of both temperature and magnetic field, tuned by radio frequency (RF) power in a relatively simple system: granular aluminum (grAl), which exhibits the properties of a naturally occurring Josephson junction array. At low temperatures, giant Shapiro steps emerge, exhibiting characteristics of a single Josephson junction. Coherent phase locking across the array’s multiple junctions amplifies the quantized voltage, enabling tunability at radio frequencies, as observed in artificially designed Josephson arrays. We show that our system can be tuned from a coherent superconducting (stiff-phase) to an insulating (phase-fluctuating) state using RF power. We propose that the RF power modulates the Josephson coupling energy, $ E_J$ . Remarkably, at elevated temperatures, the screening of the electron charge suppresses the charging energy, causing superconductivity to reappear. This many-body effect cannot be described within a single junction framework and involves many-body correlations. Our system can therefore be tuned to observe both the single-junction regime and many-body correlation effects, serving as a quantum simulator for complex phenomena in condensed matter physics.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Cryogenic performance of field-effect transistors and amplifiers based on selective area grown InAs nanowires
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Giulia Meucci, Dags Olšteins, Damon J. Carrad, Gunjan Nagda, Daria V. Beznasyuk, Christian E. N. Petersen, Sara Martí-Sánchez, Jordi Arbiol, Thomas Sand Jespersen
Indium-Arsenide (InAs) nanowire field-effect transistors (NWFETs) are promising platforms for high-speed, low power nanoelectronics operating at cryogenic conditions, relevant for quantum information processing. We present selective area growth (SAG) of nanowires, which enable scalability and planar geometries that are compatible with standard semiconductor processing techniques. NWFETs are fabricated and their low temperature characteristics - including ION/IOFF ratios, threshold voltages, sub-threshold slope, interfacial trap density, hysteresis, and mobility - are characterized. The NWFETs operate successfully in integrated circuitry relying on saturation-mode operation. In sub-threshold applications such as amplifiers, we find bandwidths exceeding our cryostat wiring, but the gate hysteresis presents challenges for precise tuning of the amplifier operating point. We discuss the role of crystal imperfections and fabrication processes on the transistor characteristics and propose strategies for further improvements.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Magnetization Dynamics in Quasiperiodic Magnonic Crystals
New Submission | Other Condensed Matter (cond-mat.other) | 2025-09-03 20:00 EDT
Riya Mehta, Bivas Rana, Susmita Saha
Quasiperiodic magnonic crystals, in contrast to their periodic counterparts, lack strict periodicity which gives rise to complex and localised spin wave spectra characterized by numerous band gaps and fractal features. Despite their intrinsic structural complexity, quasiperiodic nature of these magnonic crystals enables better tunability of spin wave spectra over their periodic counterparts and therefore holds promise for the applications in reprogrammable magnonic devices. In this article, we provide an overview of magnetization reversal and precessional magnetization dynamics studied so far in various quasiperiodic magnonic crystals, illustrating how their quasiperiodic nature gives rise to tailored band structure, enabling unparalleled control over spin waves. The review is concluded by highlighting the possible potential applications of these quasiperiodic magnonic crystals, exploring potential avenues for future exploration followed by a brief summary.
Other Condensed Matter (cond-mat.other)
32 pages, 7 figures
Journal of Physics: Condensed Matter. 36, 443003 (2024)
Domain Wall Engineering in Graphene-Based Josephson Junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Xia’an Du, Junjie Qi, Hua Jiang, X. C. Xie
Recent progress has enabled the controlled fabrication of domain walls (DWs) in graphene, which host topological kink states. Meanwhile, reliable techniques for constructing graphene-based Joseph- son junctions have been established. While the experimental prerequisites for combining DWs with Josephson junctions are now available, this direction remains largely unexplored. In this work, we theoretically investigate transport properties in graphene-based Josephson junctions mediated by topological kink states and propose three DW engineering strategies. (i) DW number engineering uncovers a continuous evolution of critical current interference pattern from Aharonov-Bohm oscil- lation to Fraunhofer diffraction with increasing DW number, reproducing experimental observations [Barrier et al., Nature 628, 741 (2024)] and suggesting enhanced sensitivity for magnetometry ap- plications. (ii) DW symmetry engineering demonstrates that an asymmetric configuration of DWs under magnetic field yields an ideal Josephson diode characterized by pronounced nonreciprocal transport. (iii) DW geometry engineering reveals that intersecting DWs enable controllable super- current splitting with ratios among leads tunable through the intersection angle, magnetic field, and superconducting phase difference. Our findings elucidate the rich physics of DW-based Josephson junctions and establish a versatile platform for next-generation quantum devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 7 figures
Wide Electrical Tunability of the Valley Splitting in a Doubly gated Silicon-on-Insulator Quantum Well
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Nathan Aubergier, Vincent T. Renard, Sylvain Barraud, Kei Takashina, Benjamin A. Piot
The valley splitting of 2D electrons in doubly-gated silicon-on-insulator quantum wells is studied by low temperature transport measurements under magnetic fields. At the buried thermal-oxide SiO$ {2}$ interface, the valley splitting increases as a function of the electrostatic bias $ \delta n = n{B}-n_{F}$ (where $ n_{B}$ and $ n_{F}$ are electron densities contributed by back and front gates, respectively) and reaches values as high as $ 6.3$ ~meV, independent of the total carrier concentration of the channel. We show that $ \delta n$ tunes the square of the wave function modulus at the interface and its penetration into the barrier, both of which are key quantities in a theory describing interface-induced valley splitting, and is therefore the natural experimental parameter to manipulate valleys in 2D silicon systems. At the front interface, made of a thin ``high-k’’ dielectric, a smaller valley splitting is observed, adding further options to tune the valley splitting within a single device.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Supporting information available online
Nano Lett. 2025, XXXX, XXX, XXX-XXX
Electromagnetic responses of bilayer excitonic insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
We investigate the electromagnetic responses of a bilayer excitonic insulators (EI) and identify two types of collective modes:
(1) Two gapped plasmon modes couple to the layer symmetric gauge field. The transverse mode is nearly dispersionless in the long-wavelength limit, while the longitudinal mode, accounting for total charge fluctuations, has a linear dispersion with velocity proportional to two dimensional (2D) electrical polarizability.
(2) A gapless phase (Goldstone) mode and a gapped amplitude mode, associated with the fluctuations of EI order parameter, couple to the layer antisymmetric gauge field.
In the long-wavelength limit, the Goldstone mode exhibits linear dispersion with velocity inversely proportional to the square root of exciton compressibility, representing the first sound mode of the exciton condensate
Significantly, its linear dispersion yields a cubic frequency dependence of the real admittance in microwave impedance microscopy (MIM), providing a method to detect the Goldstone mode directly.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Classification of topological insulators and superconductors with multiple order-two point group symmetries
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
We present a method for computing the classification groups of topological insulators and superconductors in the presence of $ \mathbb{Z}_2^{\times n}$ point group symmetries, for arbitrary natural numbers $ n$ . Each symmetry class is characterized by four possible additional symmetry types for each generator of $ \mathbb{Z}_2^{\times n}$ , together with bit values encoding whether pairs of generators commute or anticommute. We show that the classification is fully determined by the number of momentum- and real-space variables flipped by each generator, as well as the number of variables simultaneously flipped by any pair of generators. As a concrete illustration, we provide the complete classification table for the case of $ \mathbb{Z}_2^{\times 2}$ point group symmetry.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages
Three prerequisites for high-temperature superconductivity in t-PtBi$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
Andrii Kuibarov, Susmita Changdar, Riccardo Vocaturo, Oleksandr Suvorov, Alexander Fedorov, Rui Lou, Maxim Krivenkov, Luminita Harnagea, Sabine Wurmehl, Jeroen van den Brink, Bernd Büchner, Sergey Borisenko
Although the generic mechanism behind high-temperature superconductivity remains notoriously elusive, a set of favorable conditions for its occurrence in a given material has emerged: (i) the electronic structure should have a very high density of states near the Fermi level; (ii) electrons need to be susceptible to a sizable interaction with another degree of freedom to ensure pairing themselves; (iii) the ability to fine-tune some of the system properties significantly helps maximising the critical temperature. Here, by means of high-resolution ARPES, we show that all three criteria are remarkably fulfilled in trigonal platinum bismuthide (t-PtBi$ _2$ ). Specifically, this happens on its surface, which hosts topological surface states known as Fermi arcs. Our findings pave the way for the stabilisation and optimisation of high-temperature superconductivity in this topological material.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Impact of early-age exposure to power ultrasound on the micromechanical properties of hardened cement paste
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Martin Chaigne, Sébastien Manneville, Michael Haist, Roland J.-M. Pellenq, Thibaut Divoux
Cement paste serves as the universal binder in concrete, formed by mixing water with Ordinary Portland Cement (OPC). In its fresh state, cement paste is a suspension in which the initial particle inventory continuously dissolves, while simultaneously, a growing population of colloidal calcium silica-hydrate (C-S-H) particles forms and progressively builds a percolated structure that densifies and hardens through hydration. Like most colloidal gels, cement paste is sensitive to external stimuli such as mechanical vibrations and temperature variations. Here, we show that power ultrasound (PUS) applied to OPC paste during the very early stages of hydration significantly alters the mechanical properties of the hardened material. Freshly prepared cement pastes are exposed to PUS at varying durations and intensities before curing for 28 days. Micro-indentation testing at the scale of tens of microns reveals that increasing PUS amplitude and prolonged PUS exposure degrade the micro-mechanical properties of hardened cement paste, making it more ductile. This softening behavior evolves continuously with exposure conditions and is consistent with an increase in porosity, likely caused by micro-cracks induced by PUS. This scenario is further supported by micro-scratch testing, which shows higher levels of acoustic emission in PUS-exposed samples. Finally, nano-indentation confirms that the properties of the individual phases composing the hardened paste – low-density and high-density C-S-H – remain largely unaffected. These findings offer valuable experimental insights into novel pathways for modifying the mechanical properties of reactive colloidal gels.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
14 pages, 9 figures
Mechanical performance of hybrid polymer-lipid vesicles with leaflet asymmetry engineered using microfluidics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Yuting Huang, Arash Manafirad, Simon Matoori, Laura R. Arriaga, Sijie Sun, Anqi Chen, Anthony D. Dinsmore, David J. Mooney, David A. Weitz
Lipid vesicles consist of aqueous cores surrounded by a bilayer of phospholipids. Hybrid polymer-lipid vesicles incorporate both polymers and lipids, offering promising properties for developing pharmaceuticals, biosensors, and artificial cells. The hybrid vesicles can be symmetric, in which their two leaflets contain identical compositions, or asymmetric, in which the leaflets possess dissimilar compositions and can lead to dramatically modified properties. However, methods to produce both symmetric and asymmetric hybrid vesicles result in heterogenous compositions and sizes, making it challenging to quantify the effect of asymmetry and limiting applications. Here, we use a microfluidic approach to produce hybrid vesicles containing symmetric or asymmetric leaflets with precisely engineered compositions. We find the vesicles with asymmetric leaflets are significantly stiffer and tougher than those with symmetric leaflets; moreover, the lateral diffusivity of lipids is greatly decreased. The structure for improved toughness consists of an inner leaflet that is a stretchable lipid leaflet and an outer leaflet that is a fully continuous polymer leaflet. This technique of precisely engineering asymmetric structures may be applied to hybrid vesicles composed of block copolymers and phospholipids dissolvable in chloroform and hexane, further expanding their applications.
Soft Condensed Matter (cond-mat.soft), Applied Physics (physics.app-ph)
A High-Throughput Search for Stable and Magnetically Robust Fe$_3$XY$_2$ Monolayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Soheil Ershadrad, Biplab Sanyal
We present first principles exploration of 529 Fe$ _3$ XY$ _2$ compounds, where $ X$ and $ Y$ elements are selected from the $ p$ -block of the periodic table. Out of the entire set, 31 compounds satisfy all criteria for energetic, dynamic, mechanical, and thermal stability. Our analysis reveals several key trends: halide-containing systems exhibit the highest average magnetic moments and the highest magnetic transition temperatures, highlighting their potential for room-temperature spintronic applications. The majority of stable compounds display perpendicular magnetic anisotropy (PMA), with Fe$ _3$ SiTe$ _2$ exhibiting the strongest PMA among all candidates. Exchange interactions are found to be governed by a dual mechanism, direct exchange between nearest-neighbor Fe atoms and indirect, $ p$ -orbital-mediated exchange for second-nearest neighbors and beyond. Notably, four compounds have non-centrosymmetric crystal structures and exhibit finite spiralization constants. Among them, Fe$ _3$ AsBr$ _2$ is predicted to host Néel-type skyrmions even at zero external magnetic field, as confirmed by micromagnetic simulations. These findings offer a roadmap for experimental realization of novel 2D ferromagnets with enhanced functionalities.
Materials Science (cond-mat.mtrl-sci)
Theoretical calculation of finite-temperature X-ray absorption fine structure: application to sodium K-edge in NaCl
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Philipp Hönicke, Yves Kayser, Pouya Partovi-Azar
We present a comprehensive computational framework for reproducing the full X-ray absorption fine structure (XAFS) through quantum-chemical simulations. The near-edge region is accurately captured using an efficient implementation of time-dependent density-functional perturbation theory applied to core excitations, while ab initio molecular dynamics provides essential sampling of core-excitation energies and interatomic distance distributions for interpreting extended X-ray absorption fine structure (EXAFS) features. Owing to the efficiency of the approach, the total spectrum can be decomposed into contributions from bulk, defective, and surface environments, which commonly coexist in experimental systems. The methodology is demonstrated for sodium at the Na K-edge in NaCl, where the predicted spectra show good agreement with experimental measurements on thin film samples. This strategy offers a practical route to generating chemically specific XAFS cross-section data for elements and species that remain challenging to characterize experimentally, thereby enabling deeper insights into materials of technological importance.
Materials Science (cond-mat.mtrl-sci)
Probing Non-Fermi-Liquid Behaviour of Composite Fermi Liquid via Efficient Thermal Simulations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Bin-Bin Chen, Hongyu Lu, Zi Yang Meng
The two-dimensional electron gas in a perpendicular magnetic field, i.e., the quantum Hall system, is remarkably rich. At half filling of the lowest Landau level, it has been predicted that ``composite fermions’’ – emergent quasiparticle of an electron with two magnetic flux quanta – can experience zero net magnetic field and form a Fermi sea, dubbed composite Fermi liquid (CFL). However, the seemingly simple appearance of CFL is a strongly correlated quantum many-body state in disguise, and to solve it in a controlled manner is extremely difficult, to the level that the thermodynamic properties of CFL is still largely unknown. In this work, we perform state-of-the-art thermal tensor network simulations on the $ \nu=1/2$ Landau level systems, and observe low-temperature power-law behaviour of the specific heat, signaling the gapless nature of CFL. More importantly, the power is extracted to be closed to $ 2/3$ , clearly deviated from the ordinary linear-$ T$ Fermi liquid behaviour, suggesting the coupling between the CFs and the dynamical emergent gauge field and therefore revealed the quantum many-body aspect of the CFL state. Relevance of our methodology to other quantum Hall settings and moiré systems is discussed.
Strongly Correlated Electrons (cond-mat.str-el)
7+3 pages, 4+2 figures
Dual Cross-Linked Hydrogels: Linear Rheology and Fractional Calculus Modeling
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Agniva Dutta, Valeriy V. Ginzburg, Gleb Vasilyev, Eyal Zussman
Hydrogels are increasingly recognized as a versatile platform for applications spanning from tissue engineering to soft robotics or flexible electronics. Recent efforts have focused on enhancing and tailoring their mechanical performance to meet application-specific demands. However, the intricate viscoelastic response of hydrogels remains challenging to capture using conventional phenomenological models. In this study, we prepared a series of tough dual crosslinked hydrogels – poly(methacrylamide-co-acrylic acid)-Fe3+ and systematically tuned their mechanical properties by leveraging the salting-out effect. The viscoelastic behavior of the hydrogels was characterized under shear deformations, and a four-parameter Fractional Maxwell Model (FMM) was constructed to quantitatively describe oscillatory shear, creep, and stress relaxation responses. The influence of salt concentration on each FMM parameter was analyzed and correlated with bulk mechanical performance. This framework provides a first step toward capturing the complex viscoelastic nature of the advanced hydrogels and lays the foundation for developing more comprehensive nonlinear constitutive models.
Soft Condensed Matter (cond-mat.soft)
Non-Ferroelectric to Ferroelectric Phase Transition in epitaxial Y:HfO$_2$ via Rapid Thermal Annealing Induced Nitrogen Doping
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Soumyajyoti Mondal, Asraful Haque, Binoy Krishna De, Shubham Kumar Parate, Pramod Kumar Yadav, Arup Basak, Kaushal Tiwari, Bhagwati Prasad, Pavan Nukala
Oxygen vacancies are often essential for stabilizing the orthorhombic ferroelectric phase in HfO$ _2$ , with cationic doping widely employed to introduce such defects. In contrast, systematic studies on anionic doping to induce ferroelectricity remain largely in nascent stages. On epitaxial Y:HfO$ _2$ grown on ITO buffered YSZ substrates that crystallize in a mixed monoclinic (non-polar) and orthorhombic (polar) phases, we introduce nitrogen doping via post deposition rapid thermal annealing (RTA) in N$ _2$ atmosphere at 900$ ^\circ$ C. As the annealing time increases from 10s to 4min, the monoclinic phase fraction diminishes, enabling the emergence of well-defined ferroelectric loops in films annealed beyond 2min. We clearly show that this is an effect of nitrogen incorporation (doping) into the samples through a suite of structure-property correlation measurements including x-ray photoelectron spectroscopy. These results reveal that nitrogen actively participates in the RTA-induced phase stabilization, enabling ferroelectricity in epitaxial Y:HfO$ _2$ without sacrificing crystallographic coherence, providing a viable pathway for structure-property correlation studies and a model system to study opto-electronic devices integrated with ferroelectrics.
Materials Science (cond-mat.mtrl-sci)
Main article: 10 pages, 3 figures, Supplementary Information: 7 figures
Nanoscale Dipolar Fields in Artificial Spin Ice Probed by Scanning NV Magnetometry
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Ephraim Spindler, Vinayak Shantaram Bhat, Elke Neu, Mathias Weiler, M. Benjamin Jungfleisch
We investigate dipolar coupling fields in two square-lattice artificial spin ice (ASI) systems with different lattice constants using scanning probe microscopy based on a single nitrogen-vacancy (NV) center in diamond. This technique offers unprecedented spatial resolution, operates under ambient condition, and provides quantitative stray field measurements, making it uniquely suited for studying nanoscale magnetic textures. Our approach combines fluorescence quenching imaging and continuous-wave optically detected magnetic resonance (cODMR). A comparison of the two ASI samples, which differ in their lattice constants of 1000 nm and 910 nm respectively, reveals differences in the appearance of ice-rule violations - deviations from the lowest energy configuration in ASI vertices. We attribute these variations to varying coupling strengths dictated by the lattice constant. From the cODMR data, we extract both axial and transverse components of the local magnetic field relative to the NV axis. Micromagnetic modeling of these measurements allows for an iterative determination of the external magnetic field orientation, the detection of subtle magnetization tilts induced by weak external fields (well below the nanomagnets’ switching threshold), and an estimation of the effective saturation magnetization, thereby accounting for deviations in nanomagnet dimensions. These findings provide crucial insights into the tunable magnetic interactions in ASI, paving the way for the design of advanced magnonic and spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
8 pages, 4 figures
Improving atomic force microscopy structure discovery via style-translation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Jie Huang, Niko Oinonen, Fabio Priante, Filippo Federici Canova, Lauri Kurki, Chen Xu, Adam S. Foster
Atomic force microscopy (AFM) is a key tool for characterising nanoscale structures, with functionalised tips now offering detailed images of the atomic structure. In parallel, AFM simulations using the particle probe model provide a cost-effective approach for rapid AFM image generation. Using state-of-the-art machine learning models and substantial simulated datasets, properties such as molecular structure, electrostatic potential, and molecular graph can be predicted from AFM images. However, transferring model performance from simulated to experimental AFM images poses challenges due to the subtle variations in real experimental data compared to the seemingly flawless simulations. In this study, we explore style translation to augment simulated images and improve the predictive performance of machine learning models in surface property analysis. We reduce the style gap between simulated and experimental AFM images and demonstrate the method’s effectiveness in enhancing structure discovery models through local structural property distribution comparisons. This research presents a novel approach to improving the efficiency of machine learning models in the absence of labelled experimental data.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
14 pages, 7 figures
Diamagnetic Meissner response of odd-frequency superconducting pairing from quantum geometry
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-03 20:00 EDT
Ankita Bhattacharya, Annica M. Black-Schaffer
We investigate the role of quantum geometry in the Meissner response for odd-frequency superconducting pairs in multiband systems. Odd-frequency pairing is traditionally associated with a paramagnetic Meissner response, which raises questions about the stability of the superconducting phase, especially in multiband systems where odd-frequency pairing is ubiquitous. Using analytical calculations in a general two-band, we show that the quantum geometric contribution to the Meissner response from odd-frequency pairs is always diamagnetic for its interband processes, while intraband processes always yield a paramagnetic response. With odd-frequency pairing itself generated by interband pairing, an overall diamagnetic response may often be anticipated. We confirm these results with numerical calculations of models with both flat and dispersive bands. In flat band systems, where geometric effects dominate, the diamagnetic odd-frequency response can even exceed the even-frequency contribution, making odd-frequency pairs the primary source of the diamagnetic Meissner response. In a dispersive two-band system with finite quantum geometry, we similarly find a robust diamagnetic contribution from odd-frequency pairing, even when the total response turns paramagnetic due to even-frequency contributions. These results establish that quantum geometry stabilizes odd-frequency superconductivity and also identify flat-band materials as candidates for realizing odd-frequency superconductivity with a diamagnetic Meissner effect.
Superconductivity (cond-mat.supr-con)
11 pages, 5 figures
Intricacies of Frustrated Magnetism in the Kondo Metal YbAgGe
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
D. G. Mazzone, C. B. Larsen, B. Ueland, X. Boraley, D. M. Pajerowski, Y. Skourski, J. Taylor, B. Fak, S. L. Bud’ko, R. McQueeney, P. C. Canfield, O. Zaharko
The combination of localized magnetic moments, their frustration and interaction with itinerant electrons is a key challenge of condensed matter physics. Frustrated magnetic interactions promote degenerate ground states with enhanced fluctuations, a topic that is predominantly studied in magnetic insulators. The coupling between itinerant and localized electrons in metals add complexity to the problem, and presently formulated only for extreme cases in which the itinerant electrons mediate exchange between localized spins (RKKY interaction) or suppress the formation of magnetic moments (Kondo screening). Here, we report an in-depth experimental study of the distorted Kagome metal YbAgGe, unravelling the open questions of how frustration, localized magnetism and itinerant electrons are intertwined in frustrated Kondo metals. We find that coupled itinerant and localized electrons give rise to dynamic magnetic correlations below T\ast ~ 20 K. At lower temperature, frustrated magnetic interactions establish anisotropic magnetic short-range correlations that culminate into antiferromagnetic long-range order below TN = 0.68 K with a significantly reduced modulated magnetic moment. We show that local moment Hamiltonians can yield limited understanding of the microscopic behaviour in frustrated metals, and prompt the extension of more sophisticated model Hamiltonians incorporating itinerant effects.
Strongly Correlated Electrons (cond-mat.str-el)
Unconventional Electromechanical Response in Ferrocene Assisted Gold Atomic Chain
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Biswajit Pabi, Štěpán Marek, Tal Klein, Arunabha Thakur, Richard Korytár, Atindra Nath Pal
Atomically thin metallic chains serve as pivotal systems for studying quantum transport, with their conductance strongly linked to the orbital picture. Here, we report a non-monotonic electro-mechanical response in a gold-ferrocene junction, characterized by an unexpected conductance increase over a factor of ten upon stretching. This response is detected in the formation of ferrocene-assisted atomic gold chain in a mechanically controllable break junction at a cryogenic temperature. DFT based calculations show that tilting of molecules inside the chain modifies the orbital overlap and the transmission spectra, leading to such non-monotonic conductance evolution with stretching. This behavior, unlike typical flat conductance plateaus observed in metal atomic chains, pinpoints the unique role of conformational rearrangements during chain elongation. Our findings provide a deeper understanding of the role of orbital hybridization in transport properties and offer new opportunities for designing nanoscale devices with tailored electro-mechanical characteristics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Transforming tubular packings to bicontinuous surfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Vira Raichenko, Alicja Bukat, Michal Bykowski, Lucja Kowalewska, Myfanwy E. Evans
The link between bicontinuous architectures in biological membranes and triply-periodic minimal surfaces (TPMS) is a well established example of stunning geometric form in nature. The prolamellar body (PLB) in early plant plastid development is a classic example, forming the Diamond TPMS in a lipid-protein-pigment membrane. However, the early development of such spectacular geometric structures is poorly understood. Inspired by the presence of tubules in the micrographs of early plastid membrane formation, we explore here geometric modelling of transformations of packings of cylinders that coalesce together to form bicontinuous structures. Using computational modelling, we find that specific cylinder packings with cubic symmetry transform into highly symmetric TPMS, which now stand as a candidate set of surfaces for further investigation into the PLB, as well as other occurrences of bicontinuous membranes.
Soft Condensed Matter (cond-mat.soft), Differential Geometry (math.DG)
Dynamic structure factor of quantum hard rods from exact form-factors
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-03 20:00 EDT
Stanisław Kiedrzyński, Emilia Witkowska, Miłosz Panfil
We study the quantum hard-rods model and obtain compact analytical expressions for density form factors, and a semi-analytical treatment for dynamic and static structure factors calculations, greatly reducing computational complexity. We identify conditions under which these form factors vanish and analyze real-space correlations, confirming the model’s Tomonaga-Luttinger liquid behavior. The results reveal universal features of low energy physics of gapless quantum fluid and relation to Luttinger liquid theory, providing precise benchmarks for numerical simulations. This work establishes quantum hard rods as an important testbed for theories of strongly correlated one-dimensional systems.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Exactly Solvable and Integrable Systems (nlin.SI)
12 pages, 6 figures
Permeability heterogeneity and bulk linear elasticity determine interfacial pattern morphologies during confined, miscible displacements of clay suspensions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Vaibhav Raj Singh Parmar, Ranjini Bandyopadhyay
When a less viscous Newtonian fluid displaces an aging aqueous clay suspension in a confined space, a rich array of interfacial patterns emerges due to a predominantly viscous instability. In the present work, we controlled the mechanical properties of clay suspensions by incorporating additives and studied the interfacial instabilities that resulted when these suspensions were radially displaced by water in a Hele-Shaw cell. When the elasticity of clay was low, the interfacial dynamics exhibited features of nonlinear viscous fingering in heterogeneous media. By tuning the nature and content of additives that delay clay aging, we uncovered two novel propagation mechanisms: pattern growth via skewering and zig-zag finger propagation. These patterns have hitherto never been observed in experiments with colloidal systems. For moderate clay elasticities, we demonstrate here that shear-thinning-induced flow anisotropy leads to the formation of dendrites with dominant side branches. As clay elasticity increases due to the incorporation of salts, the energy required to create fractures becomes smaller than that for system-wide yielding. This scenario is characterized by the emergence of viscoelastic fractures. Our work demonstrates that incorporating additives is an effective strategy to manipulate the onset and growth of interfacial instabilities during the confined displacement of clay by miscible Newtonian fluids.
Soft Condensed Matter (cond-mat.soft)
21 pages including supplementary information, 7 figures
Transient Dynamical Phase Diagram of the Spin-Boson Model at Finite Temperature
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Olga Goulko, Hsing-Ta Chen, Moshe Goldstein, Guy Cohen
We present numerically exact inchworm quantum Monte Carlo results for the real-time dynamics of the spin polarization in the sub-Ohmic spin–boson model at finite temperature. We focus in particular on the localization and coherence behavior of the model, extending our previous study at low temperature [Phys. Rev. Lett. 134, 056502 (2025)]. As the temperature increases, the system becomes less localized and less coherent. The loss of coherence, which is controlled by two independent mechanisms – a smooth damping-driven crossover and a sharp frequency-driven transition – exhibits a nontrivial temperature dependence. While both types of coherence loss occur at lower coupling in the high temperature regime, the frequency exhibits a sharper drop at high temperatures and this drop is observed for all values of the sub-Ohmic exponent, in contrast to the zero-temperature case. We discuss the full temperature-dependent dynamical phase diagram of the system and the interplay between coherence and localization across a wide range of physical parameters.
Strongly Correlated Electrons (cond-mat.str-el)
Ancillary data file included
Van der Waals Density Functional for Molecular Crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Trevor Jenkins, Kristian Berland, Timo Thonhauser
Since the development of the nonlocal correlation functional vdW-DF, the family of van der Waals density functionals has grown to better describe a wide variety of systems. A recent generation of the vdW-DF family, vdW-DF3, featured a newly-constructed form of the nonlocal correlation that more accurately modeled molecular dimers, layered structures, and surface adsorption. However, it also revealed an intrinsic tradeoff in vdW-DF3’s parametrization and inflexibility of exchange in the generalized gradient approximation (GGA), limiting its accuracy for molecular crystals. In this paper we propose a new optimization of vdW-DF3 that is tailored to 3D molecular crystals. This functional, called vdW-DF3-mc, contains a new, tunable form of the exchange enhancement factor with parameters that directly correspond to physically relevant qualities. In addition, within the nonlocal correlation, we prioritize smoothness of the kernel switching function as a means of restoring flexibility to vdW-DF3’s design. Testing vdW-DF3-mc on several benchmark sets, we achieve highly accurate energetics and geometries for molecular crystals. This is particularly evident for the case of polymorphs of ice, for which errors in the volume and cohesive energy are on the order of only 1%, indicating very promising performance for important subcategories of molecular crystals, such as polymorphism and hydrogen-bonded solids.
Materials Science (cond-mat.mtrl-sci)
All-optical band structure reconstruction and onset of Landau quantization of Dirac fermions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Josef Riepl (1), Marc Aichner (1 and 2), Nikolai N. Mikhailov (3), Sergei A. Dvoretsky (3), Grigory V. Budkin (4), Sergey D. Ganichev (1), Christoph Lange (5), Joshua Mornhinweg (1, 5 and 6), Rupert Huber (1) ((1) Department of Physics, University of Regensburg, Regensburg, Germany, (2) LSI, CNRS, CEA/DRF/IRAMIS, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France, (3) A.V. Rzhanov Institute of Semiconductor Physics, Novosibirsk, Russia, (4) A. F. Ioffe Insitute, Saint Petersburg, Russia, (5) Department of Physics, TU Dortmund University, Dortmund, Germany, (6) Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA, USA)
The nature of relativistic electrons in solids depends on the precise shape of the underlying band structure. Prominently, symmetry-related mechanisms, such as the breaking of time reversal symmetry in topological insulators, can lead to the emergence of band gaps on small energy scales. It is, thus, important to quantify potential gaps of the Dirac cone with meV precision. Yet established band structure measurements are often challenged by their strict surface sensitivity or limited energy resolution. In this work, we use broadband, time-resolved THz magneto-spectroscopy to access the band structure of Dirac electrons in a buried HgTe quantum well by contact-free, all-optical measurements. Optical doping allows us to control the Fermi level without applying any electrical gate voltages. The background-free measurement of the cyclotron resonance of the Dirac system over 2.5 optical octaves, a broad range of magnetic field strengths, and different Fermi energies allows us to reconstruct the band structure near the Dirac point with sub-meV precision, and to observe a crossover of Landau quantization from a quasi-classical to the relativistic regime.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Josef Riepl and Marc Aichner contributed equally
Magnetic Worms: Oscillatory Bimeron Pairing And Collective Transport In Patterned Stripes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Jose Toledo-Marin, Mario Castro, David Galvez-Poblete, Bruno Grossi, Sebastián Castillo-Sepúlveda, Alvaro S. Nunez, Sebastian Allende
Magnetic bimerons in a domain wall provide a practical route for current driven transport in patterned magnetic stripes. However, coupling between bimerons and pinning by defects complicate reliable motion. Here we show that a periodic array of edge defects both stabilizes transport of multiple bimerons and gives rise to a distinctive collective state, the magnetic worm. A single bimeron travels at constant speed; defects lower this speed while preserving an approximately linear relation between velocity $ v$ and current density $ J$ . With two bimerons, the center of mass advances nearly uniformly while their separation exhibits a bounded oscillation whose frequency increases and amplitude decreases with current. For larger trains, these oscillations lose synchrony, producing segmented, worm like motion. The center of mass speed grows with current but decreases as the number of bimerons increases. Notably, eight bimerons cannot be sustained in a smooth stripe but can be stabilized by the periodic defects
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Self-propulsive active nematics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Niels de Graaf Sousa, Simon Guldager Andersen, Aleksandra Ardaševa, Amin Doostmohammadi
Increasing evidence suggests that active matter exhibits instances of mixed symmetry that cannot be fully described by either polar or nematic formalism. Here, we introduce a minimal model that integrates self-propulsion into the active nematic framework. Our linear stability analyses reveal how self-propulsion shifts the onset of instability, fundamentally altering the dynamical landscape. Numerical simulations confirm these predictions, showing that self-propulsion induces anti-hyperuniform fluctuations, anomalous long-range order in vorticity, and non-universal self-similar energy cascades. Notably, these long-range ordered states emerge within the active turbulence regime well before the transition to a flocking state. Additionally, our analyses highlight a non-monotonic dependence of self-organization on self-propulsion, with optimal states characterized by a peak in correlation length. These findings are relevant for understanding of active nematic systems that self-propel, such as migrating cell layers or swarming bacteria, and offer new avenues for designing synthetic systems with tailored collective behaviours, bridging the gap between active nematics and self-propulsive systems.
Soft Condensed Matter (cond-mat.soft)
Accepted in Philosophical Transactions A, Biologically Active Fluids: Emerging Directions issue
Revisiting the diffusion equation derivation in Persson’s theory of contact
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-03 20:00 EDT
Yang Xu, Siyuan Yang, Yunong Zhou, Liang Luo
In Persson’s seminal work on tire-road interaction (Persson, J. Chem. Phys. {\bf 115}(8), 2001), he ingeniously derived a diffusion equation in Appendix B to characterize the evolution of contact pressure between a rigid rough indenter and an elastic half-space with spatial magnification, which constitutes the foundation of Persson’s theory of contact. Persson’s theory has been extensively validated and applied to investigate nearly all critical aspects of tribological problems. In contrast to the well-known Greenwood-Williamson (GW) model, Persson’s theory receives relatively less attention within the tribology community. One contributing factor to this discrepancy is that the original derivation of the diffusion equation in Appendix B is not easily understandable to non-physicists. In this technical note, the authors provide supplementary information for each step of the derivation, aiming to clarify the conceptual foundation for researchers who encounter difficulties in understanding Persson’s theory, thereby encouraging its broader application within and beyond tribology.
Soft Condensed Matter (cond-mat.soft)
Hybrid quantum-classical systems: statistics, entropy, microcanonical ensemble and its connection to the canonical ensemble
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-03 20:00 EDT
J.L. Alonso, C. Bouthelier-Madre, A. Castro, J. Clemente-Gallardo, J. A. Jover-Galtier
We describe in detail a mathematical framework in which statistical ensembles of hybrid classical- quantum systems can be properly described. We show how a maximum entropy principle can be applied to derive the microcanonical ensemble of hybrid systems. We investigate its properties, and in particular how the microcanonical ensemble and its marginal classical and quantum ensembles can be defined for arbitrarily small range of energies for the whole system. We show how, in this situations, the ensembles are well defined for a continuum of energy values, unlike the purely quantum microcanonical ensemble, thus proving that hybrid systems translate properties of classical systems to the quantum realm. We also analyze the relation with the hybrid canonical ensemble by considering the microcanonical ensemble of a compound system composed of a hybrid subsystem weakly coupled to a reservoir and computing the marginal ensemble of the hybrid subsystem. Lastly, we apply the theory to the statistics of a toy model, which gives some insight on the different properties presented along the article.
Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph), Quantum Physics (quant-ph)
15 pages, 2 figures
Pressure-Induced Mechanical Instabilities in Cubic SiC: Structural and Electronic Properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Carlos P. Herrero, Eduardo R. Hernandez, Gabriela Herrero-Saboya, Rafael Ramirez
Silicon carbide is widely used in electronics, ceramics, and renewable energy due to its exceptional hardness and resistance. In this study, we investigate the effects of hydrostatic and uniaxial pressure (both compressive and tensile) on the structural and electronic properties of $ 3C$ -SiC. Our analysis is based on atomistic molecular dynamics (MD) simulations using an efficient tight-binding Hamiltonian, whose accuracy is validated against density functional theory calculations. Moreover, to account for nuclear quantum effects, we employ path-integral MD simulations. Our results show significant changes in the direct electronic gap as a function of temperature and pressure, with a renormalization of about 80 meV due to zero-point motion. Under hydrostatic tensile pressure, the direct band gap $ E_{\Gamma}$ vanishes at the material’s mechanical stability limit (spinodal point, where the bulk modulus $ B \to 0$ ). For uniaxial pressure, we observe instabilities (Young’s modulus $ Y \to 0$ ) at approximately 90 GPa for both tension and compression, where $ E_{\Gamma} \to 0$ . Additionally, we analyze the pressure dependence of the internal energy, lattice parameter, and bond length, along with their finite-temperature fluctuations, which exhibit anomalies near the instability points.
Materials Science (cond-mat.mtrl-sci)
17 pages, 11 figures, 2 tables
Phys. Rev. B 112, 054106 (2025)
Experimental electronic structure of the mineral superconductor covellite CuS
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Alexandre Antezak, Takemi Kato, Pedro Rezende Gonçalves, Franck Fortuna, Marcin Rosmus, Natalia Olszowska, Andrés Felipe Santander-Syro, Emmanouil Frantzeskakis
Covellite (CuS) is the first known natural mineral superconductor. Despite its simple chemical formula, covellite exhibits a rich crystal structure at the origin of several remarkable properties. The ionic arrangement in CuS crystals leads to a mixed valence of Cu and a second-order structural transition at 55 K. Despite the abundance of structural studies and theoretical reports on its electronic structure, there are scarce references on its experimental band structure. By means of Angle Resolved PhotoEmission Spectroscopy (ARPES), we have probed the experimental electronic structure of covellite. We compare our results with the predictions of density-functional theory (DFT) calculations. Our experimental data are in remarkable agreement with the calculations, revealing subtle fingerprints of the structural phase transition, and confirming the quasi-2D nature of the electronic structure of CuS.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
10 pages, 6 figures
Physical Review B 112, 115103 (2025)
Signatures of three-state Potts nematicity in spin excitations of the van der Waals antiferromagnet FePSe$_3$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-03 20:00 EDT
Weiliang Yao, Viviane Peçanha Antonio, Devashibhai Adroja, S. J. Gomez Alvarado, Bin Gao, Sijie Xu, Ruixian Liu, Xingye Lu, Pengcheng Dai
In two-dimensional (2D) nearly square-lattice quantum materials, electron correlations can induce an electronic nematic phase with twofold rotational ($ C_2$ ) symmetry that profoundly impacts their properties. For 2D materials with threefold rotational ($ C_3$ ) symmetry, such as the honeycomb lattice, a vestigial three-state Potts nematic order has been observed in the van der Waals antiferromagnet (AFM) FePSe$ _3$ via optical and thermodynamic methods under uniaxial strain. Here, we use neutron scattering to study the magnetic order and spin excitations of FePSe$ 3$ under uniaxial strain. In the AFM ordered state, we find that $ \sim$ 0.6% tensile strain significantly suppresses one zigzag domain and promotes the other two, lowering the AFM order and spin waves to $ C_2$ symmetry. The broken $ C_3$ symmetry in spin excitations persists slightly above $ T{\rm{N}}\approx 108.6$ K, where the zigzag AFM order is absent. Our results thus provide direct evidence of magnetoelastic coupling and suggest that the three-state Potts nematicity in paramagnetic spin excitations arises from the vestigial order associated with the low-temperature zigzag AFM order.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Medium-range structural order in amorphous arsenic
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Yuanbin Liu, Yuxing Zhou, Richard Ademuwagun, Luc Walterbos, Janine George, Stephen R. Elliott, Volker L. Deringer
Medium-range order (MRO) is a key structural feature of amorphous materials, but its origin and nature remain elusive. Here, we reveal the MRO in amorphous arsenic (a-As) using advanced atomistic simulations, based on machine-learned potentials derived using automated workflows. Our simulations accurately reproduce the experimental structure factor of a-As, especially the first sharp diffraction peak (FSDP), which is a signature of MRO. We compare and contrast the structure of a-As with that of its lighter homologue, red amorphous phosphorus (a-P), identifying the dihedral-angle distribution as a key factor differentiating the MRO in both. The pressure-dependent structural behaviors of a-As and a-P differ as well, which we link to the interplay of ring topology and structural entropy. We finally show that the origin of the FSDP is closely correlated with the size and spatial distribution of voids in the amorphous networks. Our work provides fundamental insights into MRO in an amorphous elemental system, and more widely it illustrates the usefulness of automation for machine-learning-driven atomistic simulations.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
General structure factor and dynamic effects of the Dzyaloshinskii-Moriya interaction in S = 1/2 clusters
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-03 20:00 EDT
Evan M. Wilson, Joseph A. Prescott, Jason T. Haraldsen
Understanding the effects of the Dzyaloshinskii-Moriya interaction (DMI) has become increasingly important in the context of nanoscale magnetism and spintronics. In this study, we derive a general structure factor equation for an S = 1/2 dimer and show that the anisotropic ratio $ D_z/|J|$ and complex phase $ \phi$ of the DMI control the gap energy and intensity of the $ |0,0\rangle \to |1,0\rangle$ transition. {Using exact diagonalization of the Heisenberg spin-spin Hamiltonian that incorporates both isotropic and anisotropic interactions,} as well as the effects of an external magnetic field and an electric field. Our results show that the DM interaction splits energy eigenstates, induces level repulsion, and significantly modifies the spin dimer structure factor. These effects reveal a direct correspondence between thermodynamic anomalies in the heat capacity and spin-resolved selection rules.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Strongly Correlated Electrons (cond-mat.str-el)
11 Pages, 6 Figures
Enhanced Terahertz Thermoelectricity via Engineered van Hove Singularities and Nernst Effect in Moiré Superlattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
L. Elesin, A. L. Shilov, S. Jana, I. Mazurenko, P. A. Pantaleon, M. Kashchenko, N. Krivovichev, V. Dremov, I. Gayduchenko, G. Goltsman, T. Taniguchi, K. Watanabe, Y. Wang, E. I. Titova, D. A. Svintsov, K. S. Novoselov, D. A. Bandurin
Thermoelectric materials, long explored for energy harvesting and thermal sensing, convert heat directly into electrical signals. Extending their application to the terahertz (THz) frequency range opens opportunities for low-noise, bias-free THz detection, yet conventional thermoelectrics lack the sensitivity required for practical devices. Thermoelectric coefficients can be strongly enhanced near van Hove singularities (VHS), though these are usually difficult to access in conventional materials. Here we show that moiré band engineering unlocks these singularities for THz optoelectronics. Using 2D moiré structures as a model system, we observe strong enhancement of the THz photothermoelectric response in monolayer and bilayer graphene superlattices when the Fermi level is tuned to band singularities. Applying a relatively small magnetic field further boosts the response through the THz-driven Nernst effect, a transverse thermoelectric current driven by the THz-induced temperature gradient. Our results establish moiré superlattices as a versatile platform for THz thermoelectricity and highlight engineered band structures as a route to high-performance THz optoelectronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
9 pages, 5 figures
Interaction-limited conductivity of twisted bilayer graphene revealed by giant terahertz photoresistance
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
A. L. Shilov, M. Kravtsov, J. Covey, M. A. Kashchenko, O. Popova, X. Zhou, I. Yahniuk, T. Taniguchi, K. Watanabe, A. I. Berdyugin, Y. Wang, S. D. Ganichev, V. Perebeinos, D. A. Svintsov, A. Principi, K. S. Novoselov, D. L. Maslov, D. A. Bandurin
Identifying the microscopic processes that limit conductivity is essential for understanding correlated and quantum-critical states in quantum materials. In twisted bilayer graphene (TBG) and other twist-controlled materials, the temperature dependence of metallic resistivity follows power-law scaling, with the exponent spanning a broad range, rendering standard transport measurements insufficient to unambiguously identify the dominant scattering processes and giving rise to competing interpretations ranging from phonon-limited transport and umklapp scattering to strange metallicity and heavy fermion renormalization. Here, we use terahertz (THz) excitation to selectively raise the electron temperature in TBG while keeping the lattice cold, enabling a direct separation of electron-electron and electron-phonon contributions to resistivity. We observe a giant THz photoresistance, reaching up to 70% in magic-angle devices, demonstrating that electronic interactions dominate transport even in regimes previously attributed to phonons, including the linear-in-temperature resistivity near the magic angle. Away from the magic angle, we observe coexisting photoresistance and robust quadratic-in-temperature resistivity at extremely low carrier densities where standard electron-electron scattering mechanisms (umklapp and Baber inter-band scattering) are kinematically forbidden. Our analysis identifies the breakdown of Galilean invariance in the Dirac-type dispersion as a possible origin of the interaction-limited conductivity, arising from inter-valley electron-electron collisions. Beyond twisted bilayer graphene, our approach establishes THz-driven hot-electron transport as a general framework for disentangling scattering mechanisms in low-density quantum materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Floquet multiple exceptional points with higher-order skin effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-03 20:00 EDT
Gaurab Kumar Dash, Subhendu Kumar Patra, Diptiman Sen, Manisha Thakurathi
We investigate the rich non-equilibrium physics arising in periodically driven open quantum systems, specifically those realized within microcavity resonators, whose dynamics are governed by a non-Hermitian Hamiltonian hosting Floquet Exceptional Points (FEPs). By introducing a periodically quenched driving protocol, we analytically derive the Floquet effective Hamiltonian and determine the locations of multiple FEPs harbored within the Floquet bulk bands. We demonstrate that the pair-production and annihilation of these FEPs can be precisely controlled by fine-tuning the system parameters, and zero and $ \pi$ FEPs are topologically characterized by robust integer quantized winding numbers. To probe these singularities, we introduce a bi-orthogonal Floquet fidelity susceptibility, whose value exhibits large non-zero peaks at the momentum points hosting FEPs in the Brillouin zone. Furthermore, the momentum-summed susceptibility displays a sharp divergence when the number of FEPs change with respect to the time period of the drive. Our findings also reveal the emergence of Floquet edge states around zero energy and Dirac-like dispersion around $ \pi$ . Moreover, our model reveals a higher-order skin effect, where the periodically driven Hamiltonian hosts skin modes localized at both edges and corners. These insights offer novel avenues for the Floquet engineering of topological singularities in driven dissipative systems, with significant potential for manipulating light and matter at the microscale.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 6 figures (comments are welcomed)