CMP Journal 2025-01-22

Statistics

Nature: 25

Nature Materials: 2

Nature Physics: 2

Nature Reviews Physics: 2

Physical Review Letters: 14

Physical Review X: 1

Review of Modern Physics: 1

arXiv: 155

Nature

Neuromorphic computing at scale

Review Paper | Electrical and electronic engineering | 2025-01-21 19:00 EST

Dhireesha Kudithipudi, Catherine Schuman, Craig M. Vineyard, Tej Pandit, Cory Merkel, Rajkumar Kubendran, James B. Aimone, Garrick Orchard, Christian Mayr, Ryad Benosman, Joe Hays, Cliff Young, Chiara Bartolozzi, Amitava Majumdar, Suma George Cardwell, Melika Payvand, Sonia Buckley, Shruti Kulkarni, Hector A. Gonzalez, Gert Cauwenberghs, Chetan Singh Thakur, Anand Subramoney, Steve Furber

Neuromorphic computing is a brain-inspired approach to hardware and algorithm design that efficiently realizes artificial neural networks. Neuromorphic designers apply the principles of biointelligence discovered by neuroscientists to design efficient computational systems, often for applications with size, weight and power constraints. With this research field at a critical juncture, it is crucial to chart the course for the development of future large-scale neuromorphic systems. We describe approaches for creating scalable neuromorphic architectures and identify key features. We discuss potential applications that can benefit from scaling and the main challenges that need to be addressed. Furthermore, we examine a comprehensive ecosystem necessary to sustain growth and the new opportunities that lie ahead when scaling neuromorphic systems. Our work distils ideas from several computing sub-fields, providing guidance to researchers and practitioners of neuromorphic computing who aim to push the frontier forward.

Nature 637, 801-812 (2025)

Electrical and electronic engineering, Electronic devices, Learning algorithms, Network models

Extended quantum anomalous Hall states in graphene/hBN moiré superlattices

Original Paper | Quantum Hall | 2025-01-21 19:00 EST

Zhengguang Lu, Tonghang Han, Yuxuan Yao, Zach Hadjri, Jixiang Yang, Junseok Seo, Lihan Shi, Shenyong Ye, Kenji Watanabe, Takashi Taniguchi, Long Ju

Electrons in topological flat bands can form new topological states driven by correlation effects. The pentalayer rhombohedral graphene/hexagonal boron nitride (hBN) moiré superlattice was shown to host fractional quantum anomalous Hall effect (FQAHE) at approximately 400 mK (ref. ¹), triggering discussions around the underlying mechanism and role of moiré effects^2,3,4,5,6. In particular, new electron crystal states with non-trivial topology have been proposed^{3,4,7,8,<a data-test="citation-ref" data-track="click" data-track-action="reference anchor" data-track-label="link" href="https://www.nature.com/articles/s41586-024-08470-1#ref-CR9" id="ref-link-section-d21764472e492_2" title="Tešanović, Z., Axel, F. & Halperin, B. I. "Hall crystal" versus Wigner crystal. Phys. Rev. B 39, 8525-8551 (1989).">9,10,11,12,13,14,15}. Here we report electrical transport measurements in rhombohedral pentalayer and tetralayer graphene/hBN moiré superlattices at electronic temperatures down to below 40 mK. We observed two more fractional quantum anomalous Hall (FQAH) states and smaller R_xx values in pentalayer devices than those previously reported. In the new tetralayer device, we observed FQAHE at moiré filling factors v = 3/5 and 2/3. With a small current at the base temperature, we observed a new extended quantum anomalous Hall (EQAH) state and magnetic hysteresis, where R_xy = h/e² and vanishing R_xx spans a wide range of v from 0.5 to 1.3. At increased temperature or current, EQAH states disappear and partially transition into the FQAH liquid^16,17,18. Furthermore, we observed displacement field-induced quantum phase transitions from the EQAH states to the Fermi liquid, FQAH liquid and the likely composite Fermi liquid. Our observations established a new topological phase of electrons with quantized Hall resistance at zero magnetic field and enriched the emergent quantum phenomena in materials with topological flat bands.

Nature (2025)

Quantum Hall, Topological matter

Resolving native GABAA receptor structures from the human brain

Original Paper | Cryoelectron microscopy | 2025-01-21 19:00 EST

Jia Zhou, Colleen M. Noviello, Jinfeng Teng, Haley Moore, Bradley Lega, Ryan E. Hibbs

Type A GABA (γ-aminobutyric acid) receptors (GABA_A receptors) mediate most fast inhibitory signalling in the brain and are targets for drugs that treat epilepsy, anxiety, depression and insomnia and for anaesthetics^1,2. These receptors comprise a complex array of 19 related subunits, which form pentameric ligand-gated ion channels. The composition and structure of native GABA_A receptors in the human brain have been inferred from subunit localization in tissue^1,3, functional measurements and structural analysis from recombinant expression^4,5,6,7 and in mice⁸. However, the arrangements of subunits that co-assemble physiologically in native human GABA_A receptors remain unknown. Here we isolated α1 subunit-containing GABA_A receptors from human patients with epilepsy. Using cryo-electron microscopy, we defined a set of 12 native subunit assemblies and their 3D structures. We address inconsistencies between previous native and recombinant approaches, and reveal details of previously undefined subunit interfaces. Drug-like densities in a subset of these interfaces led us to uncover unexpected activity on the GABA_A receptor of antiepileptic drugs and resulted in localization of one of these drugs to the benzodiazepine-binding site. Proteomics and further structural analysis suggest interactions with the auxiliary subunits neuroligin 2 and GARLH4, which localize and modulate GABA_A receptors at inhibitory synapses. This work provides a structural foundation for understanding GABA_A receptor signalling and targeted pharmacology in the human brain.

Nature (2025)

Cryoelectron microscopy, Ion channels in the nervous system

Genomics yields biological and phenotypic insights into bipolar disorder

Original Paper | Bipolar disorder | 2025-01-21 19:00 EST

Kevin S. O'Connell, Maria Koromina, Tracey van der Veen, Toni Boltz, Friederike S. David, Jessica Mei Kay Yang, Keng-Han Lin, Xin Wang, Jonathan R. I. Coleman, Brittany L. Mitchell, Caroline C. McGrouther, Aaditya V. Rangan, Penelope A. Lind, Elise Koch, Arvid Harder, Nadine Parker, Jaroslav Bendl, Kristina Adorjan, Esben Agerbo, Diego Albani, Silvia Alemany, Ney Alliey-Rodriguez, Thomas D. Als, Till F. M. Andlauer, Anastasia Antoniou, Helga Ask, Nicholas Bass, Michael Bauer, Eva C. Beins, Tim B. Bigdeli, Carsten Bøcker Pedersen, Marco P. Boks, Sigrid Børte, Rosa Bosch, Murielle Brum, Ben M. Brumpton, Nathalie Brunkhorst-Kanaan, Monika Budde, Jonas Bybjerg-Grauholm, William Byerley, Judit Cabana-Domínguez, Murray J. Cairns, Bernardo Carpiniello, Miquel Casas, Pablo Cervantes, Chris Chatzinakos, Hsi-Chung Chen, Tereza Clarence, Toni-Kim Clarke, Isabelle Claus, Brandon Coombes, Elizabeth C. Corfield, Cristiana Cruceanu, Alfredo Cuellar-Barboza, Piotr M. Czerski, Konstantinos Dafnas, Anders M. Dale, Nina Dalkner, Franziska Degenhardt, J. Raymond DePaulo, Srdjan Djurovic, Ole Kristian Drange, Valentina Escott-Price, Ayman H. Fanous, Frederike T. Fellendorf, I. Nicol Ferrier, Liz Forty, Josef Frank, Oleksandr Frei, Nelson B. Freimer, John F. Fullard, Julie Garnham, Ian R. Gizer, Scott D. Gordon, Katherine Gordon-Smith, Tiffany A. Greenwood, Jakob Grove, José Guzman-Parra, Tae Hyon Ha, Tim Hahn, Magnus Haraldsson, Martin Hautzinger, Alexandra Havdahl, Urs Heilbronner, Dennis Hellgren, Stefan Herms, Ian B. Hickie, Per Hoffmann, Peter A. Holmans, Ming-Chyi Huang, Masashi Ikeda, Stéphane Jamain, Jessica S. Johnson, Lina Jonsson, Janos L. Kalman, Yoichiro Kamatani, James L. Kennedy, Euitae Kim, Jaeyoung Kim, Sarah Kittel-Schneider, James A. Knowles, Manolis Kogevinas, Thorsten M. Kranz, Kristi Krebs, Steven A. Kushner, Catharina Lavebratt, Jacob Lawrence, Markus Leber, Heon-Jeong Lee, Calwing Liao, Susanne Lucae, Martin Lundberg, Donald J. MacIntyre, Wolfgang Maier, Adam X. Maihofer, Dolores Malaspina, Mirko Manchia, Eirini Maratou, Lina Martinsson, Manuel Mattheisen, Nathaniel W. McGregor, Melvin G. McInnis, James D. McKay, Helena Medeiros, Andreas Meyer-Lindenberg, Vincent Millischer, Derek W. Morris, Paraskevi Moutsatsou, Thomas W. Mühleisen, Claire O'Donovan, Catherine M. Olsen, Georgia Panagiotaropoulou, Sergi Papiol, Antonio F. Pardiñas, Hye Youn Park, Amy Perry, Andrea Pfennig, Claudia Pisanu, James B. Potash, Digby Quested, Mark H. Rapaport, Eline J. Regeer, John P. Rice, Margarita Rivera, Eva C. Schulte, Fanny Senner, Alexey Shadrin, Paul D. Shilling, Engilbert Sigurdsson, Lisa Sindermann, Lea Sirignano, Dan Siskind, Claire Slaney, Laura G. Sloofman, Olav B. Smeland, Daniel J. Smith, Janet L. Sobell, Maria Soler Artigas, Dan J. Stein, Frederike Stein, Mei-Hsin Su, Heejong Sung, Beata Świątkowska, Chikashi Terao, Markos Tesfaye, Martin Tesli, Thorgeir E. Thorgeirsson, Jackson G. Thorp, Claudio Toma, Leonardo Tondo, Paul A. Tooney, Shih-Jen Tsai, Evangelia Eirini Tsermpini, Marquis P. Vawter, Helmut Vedder, Annabel Vreeker, James T. R. Walters, Bendik S. Winsvold, Stephanie H. Witt, Hong-Hee Won, Robert Ye, Allan H. Young, Peter P. Zandi, Lea Zillich, Byung-Chul Lee, Ji-Woong Kim, Young Kee Lee, Joon Ho Kang, Myeong Jae Cheon, Dong Jun Kim, Mihaela Aslan, Philip D. Harvey, Grant D. Huang, Rolf Adolfsson, Martin Alda, Lars Alfredsson, Lena Backlund, Bernhard T. Baune, Frank Bellivier, Susanne Bengesser, Wade H. Berrettini, Joanna M. Biernacka, Michael Boehnke, Anders D. Børglum, Gerome Breen, Vaughan J. Carr, Stanley Catts, Sven Cichon, Aiden Corvin, Nicholas Craddock, Udo Dannlowski, Dimitris Dikeos, Bruno Etain, Panagiotis Ferentinos, Mark Frye, Janice M. Fullerton, Micha Gawlik, Elliot S. Gershon, Fernando S. Goes, Melissa J. Green, Maria Grigoroiu-Serbanescu, Joanna Hauser, Frans A. Henskens, Jens Hjerling-Leffler, David M. Hougaard, Kristian Hveem, Nakao Iwata, Ian Jones, Lisa A. Jones, René S. Kahn, John R. Kelsoe, Tilo Kircher, George Kirov, Po-Hsiu Kuo, Mikael Landén, Marion Leboyer, Qingqin S. Li, Jolanta Lissowska, Christine Lochner, Carmel Loughland, Jurjen J. Luykx, Nicholas G. Martin, Carol A. Mathews, Fermin Mayoral, Susan L. McElroy, Andrew M. McIntosh, Francis J. McMahon, Sarah E. Medland, Ingrid Melle, Lili Milani, Philip B. Mitchell, Gunnar Morken, Ole Mors, Preben Bo Mortensen, Bertram Müller-Myhsok, Richard M. Myers, Woojae Myung, Benjamin M. Neale, Caroline M. Nievergelt, Merete Nordentoft, Markus M. Nöthen, John I. Nurnberger, Michael C. O'Donovan, Ketil J. Oedegaard, Tomas Olsson, Michael J. Owen, Sara A. Paciga, Christos Pantelis, Carlos N. Pato, Michele T. Pato, George P. Patrinos, Joanna M. Pawlak, Josep Antoni Ramos-Quiroga, Andreas Reif, Eva Z. Reininghaus, Marta Ribasés, Marcella Rietschel, Stephan Ripke, Guy A. Rouleau, Panos Roussos, Takeo Saito, Ulrich Schall, Martin Schalling, Peter R. Schofield, Thomas G. Schulze, Laura J. Scott, Rodney J. Scott, Alessandro Serretti, Jordan W. Smoller, Alessio Squassina, Eli A. Stahl, Hreinn Stefansson, Kari Stefansson, Eystein Stordal, Fabian Streit, Patrick F. Sullivan, Gustavo Turecki, Arne E. Vaaler, Eduard Vieta, John B. Vincent, Irwin D. Waldman, Cynthia S. Weickert, Thomas W. Weickert, Thomas Werge, David C. Whiteman, John-Anker Zwart, Howard J. Edenberg, Andrew McQuillin, Andreas J. Forstner, Niamh Mullins, Arianna Di Florio, Roel A. Ophoff, Ole A. Andreassen, Tracey van der Veen, Dan Siskind

Bipolar disorder is a leading contributor to the global burden of disease¹. Despite high heritability (60-80%), the majority of the underlying genetic determinants remain unknown². We analysed data from participants of European, East Asian, African American and Latino ancestries (n = 158,036 cases with bipolar disorder, 2.8 million controls), combining clinical, community and self-reported samples. We identified 298 genome-wide significant loci in the multi-ancestry meta-analysis, a fourfold increase over previous findings³, and identified an ancestry-specific association in the East Asian cohort. Integrating results from fine-mapping and other variant-to-gene mapping approaches identified 36 credible genes in the aetiology of bipolar disorder. Genes prioritized through fine-mapping were enriched for ultra-rare damaging missense and protein-truncating variations in cases with bipolar disorder⁴, highlighting convergence of common and rare variant signals. We report differences in the genetic architecture of bipolar disorder depending on the source of patient ascertainment and on bipolar disorder subtype (type I or type II). Several analyses implicate specific cell types in the pathophysiology of bipolar disorder, including GABAergic interneurons and medium spiny neurons. Together, these analyses provide additional insights into the genetic architecture and biological underpinnings of bipolar disorder.

Nature (2025)

Bipolar disorder, Genetics of the nervous system, Genetics research, Genome-wide association studies

Experience-dependent dopamine modulation of male aggression

Original Paper | Neural circuits | 2025-01-21 19:00 EST

Bing Dai, Bingqin Zheng, Xiuzhi Dai, Xiaoyang Cui, Luping Yin, Jing Cai, Yizhou Zhuo, Nicolas X. Tritsch, Larry S. Zweifel, Yulong Li, Dayu Lin

Numerous studies support the role of dopamine in modulating aggression^1,2, but the exact neural mechanisms remain elusive. Here we show that dopaminergic cells in the ventral tegmental area (VTA) can bidirectionally modulate aggression in male mice in an experience-dependent manner. Although VTA dopaminergic cells strongly influence aggression in novice aggressors, they become ineffective in expert aggressors. Furthermore, eliminating dopamine synthesis in the VTA prevents the emergence of aggression in naive mice but leaves aggression intact in expert aggressors. VTA dopamine modulates aggression through the dorsal lateral septum (dLS), a region known for aggression control. Dopamine enables the flow of information from the hippocampus to the dLS by weakening local inhibition in novice aggressors. In expert aggressors, dLS local inhibition naturally weakens, and the ability of dopamine to modulate dLS cells diminishes. Overall, these results reveal a sophisticated role of dopamine in the rise of aggression in adult male mice.

Nature (2025)

Neural circuits, Social behaviour, Synaptic plasticity

Superconductivity in 5.0° twisted bilayer WSe2

Original Paper | Electronic properties and materials | 2025-01-21 19:00 EST

Yinjie Guo, Jordan Pack, Joshua Swann, Luke Holtzman, Matthew Cothrine, Kenji Watanabe, Takashi Taniguchi, David G. Mandrus, Katayun Barmak, James Hone, Andrew J. Millis, Abhay Pasupathy, Cory R. Dean

The discovery of superconductivity in twisted bilayer and trilayer graphene^1,2,3,4,5 has generated tremendous interest. The key feature of these systems is an interplay between interlayer coupling and a moiré superlattice that gives rise to low-energy flat bands with strong correlations⁶. Flat bands can also be induced by moiré patterns in lattice-mismatched and/or twisted heterostructures of other two-dimensional materials, such as transition metal dichalcogenides (TMDs)^7,8. Although a wide range of correlated phenomena have indeed been observed in moiré TMDs^{9,10,11,12,13,14,15,16,17,18,19}, robust demonstration of superconductivity has remained absent⁹. Here we report superconductivity in 5.0° twisted bilayer WSe₂ with a maximum critical temperature of 426 mK. The superconducting state appears in a limited region of displacement field and density that is adjacent to a metallic state with a Fermi surface reconstruction believed to arise from AFM order²⁰. A sharp boundary is observed between the superconducting and magnetic phases at low temperature, reminiscent of spin fluctuation-mediated superconductivity²¹. Our results establish that moiré flat-band superconductivity extends beyond graphene structures. Material properties that are absent in graphene but intrinsic among TMDs, such as a native band gap, large spin-orbit coupling, spin-valley locking and magnetism, offer the possibility of accessing a broader superconducting parameter space than graphene-only structures.

Nature 637, 839-845 (2025)

Electronic properties and materials, Superconducting properties and materials

Tissue-resident memory CD8 T cell diversity is spatiotemporally imprinted

Original Paper | Adaptive immunity | 2025-01-21 19:00 EST

Miguel Reina-Campos, Alexander Monell, Amir Ferry, Vida Luna, Kitty P. Cheung, Giovanni Galletti, Nicole E. Scharping, Kennidy K. Takehara, Sara Quon, Peter P. Challita, Brigid Boland, Yun Hsuan Lin, William H. Wong, Cynthia S. Indralingam, Hayley Neadeau, Suzie Alarcón, Gene W. Yeo, John T. Chang, Maximilian Heeg, Ananda W. Goldrath

Tissue-resident memory CD8 T (T_RM) cells provide protection from infection at barrier sites. In the small intestine, T_RM cells are found in at least two distinct subpopulations: one with higher expression of effector molecules and another with greater memory potential¹. However, the origins of this diversity remain unknown. Here we proposed that distinct tissue niches drive the phenotypic heterogeneity of T_RM cells. To test this, we leveraged spatial transcriptomics of human samples, a mouse model of acute systemic viral infection and a newly established strategy for pooled optically encoded gene perturbations to profile the locations, interactions and transcriptomes of pathogen-specific T_RM cell differentiation at single-transcript resolution. We developed computational approaches to capture cellular locations along three anatomical axes of the small intestine and to visualize the spatiotemporal distribution of cell types and gene expression. Our study reveals that the regionalized signalling of the intestinal architecture supports two distinct T_RM cell states: differentiated T_RM cells and progenitor-like T_RM cells, located in the upper villus and lower villus, respectively. This diversity is mediated by distinct ligand-receptor activities, cytokine gradients and specialized cellular contacts. Blocking TGFβ or CXCL9 and CXCL10 sensing by antigen-specific CD8 T cells revealed a model consistent with anatomically delineated, early fate specification. Ultimately, our framework for the study of tissue immune networks reveals that T cell location and functional state are fundamentally intertwined.

Nature (2025)

Adaptive immunity, Mucosal immunology

Field-particle energy transfer during chorus emissions in space

Original Paper | Astrophysical magnetic fields | 2025-01-21 19:00 EST

C. M. Liu, B. N. Zhao, J. B. Cao, C. J. Pollock, C. T. Russell, Y. Y. Liu, X. N. Xing, P. A. Linqvist, J. L. Burch

Chorus waves are some of the strongest electromagnetic emissions naturally occurring in space and can cause radiation that is hazardous to humans and satellites^1,2,3. Although chorus waves have attracted extreme interest and been intensively studied for decades^4,5,6,7, their generation and evolution remain highly debated⁷. Here, in contrast to the conventional expectation that chorus waves are governed by planetary magnetic dipolar fields^5,7, we report observations of repetitive, rising-tone chorus waves in the terrestrial neutral sheet, where the effects of the magnetic dipole are absent. Using high-cadence data from NASA's MMS mission, we present ultrafast measurements of the wave fields and three-dimensional electron distributions within the waves, which provides evidence for chorus-electron interactions and the development of electron holes in the wave phase space. We found that the waves are associated with resonant currents antiparallel to the wave magnetic field, as predicted by nonlinear wave theory. We estimated the nonlinear field-particle energy transfer inside the waves, finding that the waves extract energy from local thermal electrons, in line with the positive growth rate of the waves derived from an instability analysis. Our observations may help to resolve long-standing controversies regarding chorus emissions and in gaining an understanding of the energy transport observed in space and astrophysical environments.

Nature 637, 813-820 (2025)

Astrophysical magnetic fields, Aurora

Global 3D model of mantle attenuation using seismic normal modes

Original Paper | Geophysics | 2025-01-21 19:00 EST

Sujania Talavera-Soza, Laura Cobden, Ulrich H. Faul, Arwen Deuss

Seismic tomographic models based only on wave velocities have limited ability to distinguish between a thermal or compositional origin for Earth's 3D structure¹. Complementing wave velocities with attenuation observations can make that distinction, which is fundamental for understanding mantle convection evolution. However, global 3D attenuation models are only available for the upper mantle at present^2,3,4,5. Here we present a 3D global model of attenuation for the whole mantle made using whole-Earth oscillations, constraining even spherical harmonics up to degree four. In the upper mantle, we find that high attenuation correlates with low velocity, indicating a thermal origin, in agreement with previous studies^6,7. In the lower mantle, we find the opposite and observe the highest attenuation in the ‘ring around the Pacific', which is seismically fast, and the lowest attenuation in the large low-seismic-velocity provinces (LLSVPs). Comparing our model with wave speeds and attenuation predicted by a laboratory-based viscoelastic model⁸ suggests that the circum-Pacific is a colder and small-grain-size region⁹, surrounding the warmer and large-grain-size LLSVPs. Viscosities calculated for the inferred variations in grain size and temperature confirm LLSVPs as long-lived, stable features¹⁰.

Nature (2025)

Geophysics, Mineralogy, Seismology

The maternal X chromosome affects cognition and brain ageing in female mice

Original Paper | Cognitive ageing | 2025-01-21 19:00 EST

Samira Abdulai-Saiku, Shweta Gupta, Dan Wang, Francesca Marino, Arturo J. Moreno, Yu Huang, Deepak Srivastava, Barbara Panning, Dena B. Dubal

Female mammalian cells have two X chromosomes, one of maternal origin and one of paternal origin. During development, one X chromosome randomly becomes inactivated^1,2,3,4. This renders either the maternal X (X_m) chromosome or the paternal X (X_p) chromosome inactive, causing X mosaicism that varies between female individuals, with some showing considerable or complete skew of the X chromosome that remains active^5,6,7. Parent-of-X origin can modify epigenetics through DNA methylation^8,9 and possibly gene expression; thus, mosaicism could buffer dysregulated processes in ageing and disease. However, whether X skew or its mosaicism alters functions in female individuals is largely unknown. Here we tested whether skew towards an active X_m chromosome influences the brain and body--and then delineated unique features of X_m neurons and X_p neurons. An active X_m chromosome impaired cognition in female mice throughout the lifespan and led to worsened cognition with age. Cognitive deficits were accompanied by X_m-mediated acceleration of biological or epigenetic ageing of the hippocampus, a key centre for learning and memory, in female mice. Several genes were imprinted on the X_m chromosome of hippocampal neurons, suggesting silenced cognitive loci. CRISPR-mediated activation of X_m-imprinted genes improved cognition in ageing female mice. Thus, the X_m chromosome impaired cognition, accelerated brain ageing and silenced genes that contribute to cognition in ageing. Understanding how X_m impairs brain function could lead to an improved understanding of heterogeneity in cognitive health in female individuals and to X-chromosome-derived pathways that protect against cognitive deficits and brain ageing.

Nature (2025)

Cognitive ageing, Hippocampus, Spatial memory

RELMβ sets the threshold for microbiome-dependent oral tolerance

Original Paper | Microbiome | 2025-01-21 19:00 EST

Emmanuel Stephen-Victor, Gavin A. Kuziel, Monica Martinez-Blanco, Bat-Erdene Jugder, Mehdi Benamar, Ziwei Wang, Qian Chen, Gabriel L. Lozano, Azza Abdel-Gadir, Ye Cui, Jason Fong, Elisa Saint-Denis, Iris Chang, Kari C. Nadeau, Wanda Phipatanakul, Angela Zhang, Farida Abi Farraj, Faye Holder-Niles, Daniel Zeve, David T. Breault, Klaus Schmitz-Abe, Rima Rachid, Elena Crestani, Seth Rakoff-Nahoum, Talal A. Chatila

Tolerance to dietary antigens is critical for avoiding deleterious type 2 immune responses resulting in food allergy (FA) and anaphylaxis^1,2. However, the mechanisms resulting in both the maintenance and failure of tolerance to food antigens are poorly understood. Here we demonstrate that the goblet-cell-derived resistin-like molecule β (RELMβ)^3,4 is a critical regulator of oral tolerance. RELMβ is abundant in the sera of both patients with FA and mouse models of FA. Deletion of RELMβ protects mice from FA and the development of food-antigen-specific IgE and anaphylaxis. RELMβ disrupts food tolerance through the modulation of the gut microbiome and depletion of indole-metabolite-producing Lactobacilli and Alistipes. Tolerance is maintained by the local production of indole derivatives driving FA protective RORγt⁺ regulatory T (T_reg) cells⁵ through activation of the aryl hydrocarbon receptor. RELMβ antagonism in the peri-weaning period restores oral tolerance and protects genetically prone offspring from developing FA later in life. Together, we show that RELMβ mediates a gut immune-epithelial circuit regulating tolerance to food antigens--a novel mode of innate control of adaptive immunity through microbiome editing--and identify targetable candidates in this circuit for prevention and treatment of FA.

Nature (2025)

Microbiome, Mucosal immunology, Peripheral tolerance

A map of the rubisco biochemical landscape

Original Paper | Enzymes | 2025-01-21 19:00 EST

Noam Prywes, Naiya R. Phillips, Luke M. Oltrogge, Sebastian Lindner, Leah J. Taylor-Kearney, Yi-Chin Candace Tsai, Benoit de Pins, Aidan E. Cowan, Hana A. Chang, Renée Z. Wang, Laina N. Hall, Daniel Bellieny-Rabelo, Hunter M. Nisonoff, Rachel F. Weissman, Avi I. Flamholz, David Ding, Abhishek Y. Bhatt, Oliver Mueller-Cajar, Patrick M. Shih, Ron Milo, David F. Savage

Rubisco is the primary CO₂-fixing enzyme of the biosphere¹, yet it has slow kinetics². The roles of evolution and chemical mechanism in constraining its biochemical function remain debated^3,4. Engineering efforts aimed at adjusting the biochemical parameters of rubisco have largely failed⁵, although recent results indicate that the functional potential of rubisco has a wider scope than previously known⁶. Here we developed a massively parallel assay, using an engineered Escherichia coli⁷ in which enzyme activity is coupled to growth, to systematically map the sequence-function landscape of rubisco. Composite assay of more than 99% of single-amino acid mutants versus CO₂ concentration enabled inference of enzyme velocity and apparent CO₂ affinity parameters for thousands of substitutions. This approach identified many highly conserved positions that tolerate mutation and rare mutations that improve CO₂ affinity. These data indicate that non-trivial biochemical changes are readily accessible and that the functional distance between rubiscos from diverse organisms can be traversed, laying the groundwork for further enzyme engineering efforts.

Nature (2025)

Enzymes, Rubisco

Precise modelling of mitochondrial diseases using optimized mitoBEs

Original Paper | Animal disease models | 2025-01-21 19:00 EST

Xiaoxue Zhang, Xue Zhang, Jiwu Ren, Jiayi Li, Xiaoxu Wei, Ying Yu, Zongyi Yi, Wensheng Wei

The development of animal models is crucial for studying and treating mitochondrial diseases. Here we optimized adenine and cytosine deaminases to reduce off-target effects on the transcriptome and the mitochondrial genome, improving the accuracy and efficiency of our newly developed mitochondrial base editors (mitoBEs)¹. Using these upgraded mitoBEs (version 2 (v2)), we targeted 70 mouse mitochondrial DNA mutations analogous to human pathogenic variants², establishing a foundation for mitochondrial disease mouse models. Circular RNA-encoded mitoBEs v2 achieved up to 82% editing efficiency in mice without detectable off-target effects in the nuclear genome. The edited mitochondrial DNA persisted across various tissues and was maternally inherited, resulting in F₁ generation mice with mutation loads as high as 100% and some mice exhibiting editing only at the target site. By optimizing the transcription activator-like effector (TALE) binding site, we developed a single-base-editing mouse model for the mt-Nd5 A12784G mutation. Phenotypic evaluations led to the creation of mouse models for the mt-Atp6 T8591C and mt-Nd5 A12784G mutations, exhibiting phenotypes corresponding to the reduced heart rate seen in Leigh syndrome and the vision loss characteristic of Leber's hereditary optic neuropathy, respectively. Moreover, the mt-Atp6 T8591C mutation proved to be more deleterious than mt-Nd5 A12784G, affecting embryonic development and rapidly diminishing through successive generations. These upgraded mitoBEs offer a highly efficient and precise strategy for constructing mitochondrial disease models, laying a foundation for further research in this field.

Nature (2025)

Animal disease models, Biotechnology, Genetic engineering, Mutation

Multiscale footprints reveal the organization of cis-regulatory elements

Original Paper | Epigenomics | 2025-01-21 19:00 EST

Yan Hu, Max A. Horlbeck, Ruochi Zhang, Sai Ma, Rojesh Shrestha, Vinay K. Kartha, Fabiana M. Duarte, Conrad Hock, Rachel E. Savage, Ajay Labade, Heidi Kletzien, Alia Meliki, Andrew Castillo, Neva C. Durand, Eugenio Mattei, Lauren J. Anderson, Tristan Tay, Andrew S. Earl, Noam Shoresh, Charles B. Epstein, Amy J. Wagers, Jason D. Buenrostro

Cis-regulatory elements (CREs) control gene expression and are dynamic in their structure and function, reflecting changes in the composition of diverse effector proteins over time¹. However, methods for measuring the organization of effector proteins at CREs across the genome are limited, hampering efforts to connect CRE structure to their function in cell fate and disease. Here we developed PRINT, a computational method that identifies footprints of DNA-protein interactions from bulk and single-cell chromatin accessibility data across multiple scales of protein size. Using these multiscale footprints, we created the seq2PRINT framework, which uses deep learning to allow precise inference of transcription factor and nucleosome binding and interprets regulatory logic at CREs. Applying seq2PRINT to single-cell chromatin accessibility data from human bone marrow, we observe sequential establishment and widening of CREs centred on pioneer factors across haematopoiesis. We further discover age-associated alterations in the structure of CREs in murine haematopoietic stem cells, including widespread reduction of nucleosome footprints and gain of de novo identified Ets composite motifs. Collectively, we establish a method for obtaining rich insights into DNA-binding protein dynamics from chromatin accessibility data, and reveal the architecture of regulatory elements across differentiation and ageing.

Nature (2025)

Epigenomics, Gene regulatory networks, Machine learning

Rapid and scalable personalized ASO screening in patient-derived organoids

Original Paper | Antisense oligonucleotide therapy | 2025-01-21 19:00 EST

John C. Means, Anabel L. Martinez-Bengochea, Daniel A. Louiselle, Jacqelyn M. Nemechek, John M. Perry, Emily G. Farrow, Tomi Pastinen, Scott T. Younger

Personalized antisense oligonucleotides (ASOs) have achieved positive results in the treatment of rare genetic disease¹. As clinical sequencing technologies continue to advance, the ability to identify patients with rare disease harbouring pathogenic genetic variants amenable to this therapeutic strategy will probably improve. Here we describe a scalable platform for generating patient-derived cellular models and demonstrate that these personalized models can be used for preclinical evaluation of patient-specific ASOs. We describe protocols for delivery of ASOs to patient-derived organoid models and confirm reversal of disease-associated phenotypes in cardiac organoids derived from a patient with Duchenne muscular dystrophy (DMD) with a structural deletion in the gene encoding dystrophin (DMD) that is amenable to treatment with existing ASO therapeutics. Furthermore, we designed novel patient-specific ASOs for two additional patients with DMD (siblings) with a deep intronic variant in the DMD gene that gives rise to a novel splice acceptor site, incorporation of a cryptic exon and premature transcript termination. We showed that treatment of patient-derived cardiac organoids with patient-specific ASOs results in restoration of DMD expression and reversal of disease-associated phenotypes. The approach outlined here provides the foundation for an expedited path towards the design and preclinical evaluation of personalized ASO therapeutics for a broad range of rare diseases.

Nature (2025)

Antisense oligonucleotide therapy, Reprogramming, Stem-cell biotechnology, Stem-cell differentiation

Leveraging a phased pangenome for haplotype design of hybrid potato

Original Paper | Agricultural genetics | 2025-01-21 19:00 EST

Lin Cheng, Nan Wang, Zhigui Bao, Qian Zhou, Andrea Guarracino, Yuting Yang, Pei Wang, Zhiyang Zhang, Dié Tang, Pingxian Zhang, Yaoyao Wu, Yao Zhou, Yi Zheng, Yong Hu, Qun Lian, Zhaoxu Ma, Ludivine Lassois, Chunzhi Zhang, William J. Lucas, Erik Garrison, Nils Stein, Thomas Städler, Yongfeng Zhou, Sanwen Huang

The tetraploid genome and clonal propagation of the cultivated potato (Solanum tuberosum L.)^1,2 dictate a slow, non-accumulative breeding mode of the most important tuber crop. Transitioning potato breeding to a seed-propagated hybrid system based on diploid inbred lines has the potential to greatly accelerate its improvement³. Crucially, the development of inbred lines is impeded by manifold deleterious variants; explaining their nature and finding ways to eliminate them is the current focus of hybrid potato research^{4,5,6,7,8,9,10}. However, most published diploid potato genomes are unphased, concealing crucial information on haplotype diversity and heterozygosity^11,12,13. Here we develop a phased potato pangenome graph of 60 haplotypes from cultivated diploids and the ancestral wild species, and find evidence for the prevalence of transposable elements in generating structural variants. Compared with the linear reference, the graph pangenome represents a broader diversity (3,076 Mb versus 742 Mb). Notably, we observe enhanced heterozygosity in cultivated diploids compared with wild ones (14.0% versus 9.5%), indicating extensive hybridization during potato domestication. Using conservative criteria, we identify 19,625 putatively deleterious structural variants (dSVs) and reveal a biased accumulation of deleterious single nucleotide polymorphisms (dSNPs) around dSVs in coupling phase. Based on the graph pangenome, we computationally design ideal potato haplotypes with minimal dSNPs and dSVs. These advances provide critical insights into the genomic basis of clonal propagation and will guide breeders to develop a suite of promising inbred lines.

Nature (2025)

Agricultural genetics, Genomics, Plant breeding, Plant domestication, Structural variation

Immune evasion through mitochondrial transfer in the tumour microenvironment

Original Paper | Cancer metabolism | 2025-01-21 19:00 EST

Hideki Ikeda, Katsushige Kawase, Tatsuya Nishi, Tomofumi Watanabe, Keizo Takenaga, Takashi Inozume, Takamasa Ishino, Sho Aki, Jason Lin, Shusuke Kawashima, Joji Nagasaki, Youki Ueda, Shinichiro Suzuki, Hideki Makinoshima, Makiko Itami, Yuki Nakamura, Yasutoshi Tatsumi, Yusuke Suenaga, Takao Morinaga, Akiko Honobe-Tabuchi, Takehiro Ohnuma, Tatsuyoshi Kawamura, Yoshiyasu Umeda, Yasuhiro Nakamura, Yukiko Kiniwa, Eiki Ichihara, Hidetoshi Hayashi, Jun-ichiro Ikeda, Toyoyuki Hanazawa, Shinichi Toyooka, Hiroyuki Mano, Takuji Suzuki, Tsuyoshi Osawa, Masahito Kawazu, Yosuke Togashi

Cancer cells in the tumour microenvironment use various mechanisms to evade the immune system, particularly T cell attack¹. For example, metabolic reprogramming in the tumour microenvironment and mitochondrial dysfunction in tumour-infiltrating lymphocytes (TILs) impair antitumour immune responses^2,3,4. However, detailed mechanisms of such processes remain unclear. Here we analyse clinical specimens and identify mitochondrial DNA (mtDNA) mutations in TILs that are shared with cancer cells. Moreover, mitochondria with mtDNA mutations from cancer cells are able to transfer to TILs. Typically, mitochondria in TILs readily undergo mitophagy through reactive oxygen species. However, mitochondria transferred from cancer cells do not undergo mitophagy, which we find is due to mitophagy-inhibitory molecules. These molecules attach to mitochondria and together are transferred to TILs, which results in homoplasmic replacement. T cells that acquire mtDNA mutations from cancer cells exhibit metabolic abnormalities and senescence, with defects in effector functions and memory formation. This in turn leads to impaired antitumour immunity both in vitro and in vivo. Accordingly, the presence of an mtDNA mutation in tumour tissue is a poor prognostic factor for immune checkpoint inhibitors in patients with melanoma or non-small-cell lung cancer. These findings reveal a previously unknown mechanism of cancer immune evasion through mitochondrial transfer and can contribute to the development of future cancer immunotherapies.

Nature (2025)

Cancer metabolism, Cancer microenvironment, Tumour immunology

Complete human recombination maps

Original Paper | Computational biology and bioinformatics | 2025-01-21 19:00 EST

Gunnar Palsson, Marteinn T. Hardarson, Hakon Jonsson, Valgerdur Steinthorsdottir, Olafur A. Stefansson, Hannes P. Eggertsson, Sigurjon A. Gudjonsson, Pall I. Olason, Arnaldur Gylfason, Gisli Masson, Unnur Thorsteinsdottir, Patrick Sulem, Agnar Helgason, Daniel F. Gudbjartsson, Bjarni V. Halldorsson, Kari Stefansson

Human recombination maps are a valuable resource for association and linkage studies and crucial for many inferences of population history and natural selection. Existing maps^1,2,3,4,5 are based solely on cross-over (CO) recombination, omitting non-cross-overs (NCOs)--the more common form of recombination⁶--owing to the difficulty in detecting them. Using whole-genome sequence data in families, we estimate the number of NCOs transmitted from parent to offspring and derive complete, sex-specific recombination maps including both NCOs and COs. Mothers have fewer but longer NCOs than fathers, and oocytes accumulate NCOs in a non-regulated fashion with maternal age. Recombination, primarily NCO, is responsible for 1.8% (95% confidence interval: 1.3-2.3) and 11.3% (95% confidence interval: 9.0-13.6) of paternal and maternal de novo mutations, respectively, and may drive the increase in de novo mutations with maternal age. NCOs are substantially more prominent than COs in centromeres, possibly to avoid large-scale genomic changes that may cause aneuploidy. Our results demonstrate that NCOs highlight to a much greater extent than COs the differences in the meiotic process between the sexes, in which maternal NCOs may reflect the safeguarding of oocytes from infancy until ovulation.

Nature (2025)

Computational biology and bioinformatics, DNA recombination, Genomics

Synthesis of a semimetallic Weyl ferromagnet with point Fermi surface

Original Paper | Electronic properties and materials | 2025-01-21 19:00 EST

Ilya Belopolski, Ryota Watanabe, Yuki Sato, Ryutaro Yoshimi, Minoru Kawamura, Soma Nagahama, Yilin Zhao, Sen Shao, Yuanjun Jin, Yoshihiro Kato, Yoshihiro Okamura, Xiao-Xiao Zhang, Yukako Fujishiro, Youtarou Takahashi, Max Hirschberger, Atsushi Tsukazaki, Kei S. Takahashi, Ching-Kai Chiu, Guoqing Chang, Masashi Kawasaki, Naoto Nagaosa, Yoshinori Tokura

Quantum materials governed by emergent topological fermions have become a cornerstone of physics. Dirac fermions in graphene form the basis for moiré quantum matter and Dirac fermions in magnetic topological insulators enabled the discovery of the quantum anomalous Hall (QAH) effect^1,2,3. By contrast, there are few materials whose electromagnetic response is dominated by emergent Weyl fermions^4,5,6. Nearly all known Weyl materials are overwhelmingly metallic and are largely governed by irrelevant, conventional electrons. Here we theoretically predict and experimentally observe a semimetallic Weyl ferromagnet in van der Waals (Cr,Bi)₂Te₃. In transport, we find a record bulk anomalous Hall angle of greater than 0.5 along with non-metallic conductivity, a regime that is strongly distinct from conventional ferromagnets. Together with symmetry analysis, our data suggest a semimetallic Fermi surface composed of two Weyl points, with a giant separation of more than 75% of the linear dimension of the bulk Brillouin zone, and no other electronic states. Using state-of-the-art crystal-synthesis techniques, we widely tune the electronic structure, allowing us to annihilate the Weyl state and visualize a unique topological phase diagram exhibiting broad Chern insulating, Weyl semimetallic and magnetic semiconducting regions. Our observation of a semimetallic Weyl ferromagnet offers an avenue towards new correlated states and nonlinear phenomena, as well as zero-magnetic-field Weyl spintronic and optical devices.

Nature (2025)

Electronic properties and materials, Surfaces, interfaces and thin films, Topological matter

Mapping cells through time and space with moscot

Original Paper | Chromatin | 2025-01-21 19:00 EST

Dominik Klein, Giovanni Palla, Marius Lange, Michal Klein, Zoe Piran, Manuel Gander, Laetitia Meng-Papaxanthos, Michael Sterr, Lama Saber, Changying Jing, Aimée Bastidas-Ponce, Perla Cota, Marta Tarquis-Medina, Shrey Parikh, Ilan Gold, Heiko Lickert, Mostafa Bakhti, Mor Nitzan, Marco Cuturi, Fabian J. Theis

Single-cell genomic technologies enable the multimodal profiling of millions of cells across temporal and spatial dimensions. However, experimental limitations hinder the comprehensive measurement of cells under native temporal dynamics and in their native spatial tissue niche. Optimal transport has emerged as a powerful tool to address these constraints and has facilitated the recovery of the original cellular context^1,2,3,4. Yet, most optimal transport applications are unable to incorporate multimodal information or scale to single-cell atlases. Here we introduce multi-omics single-cell optimal transport (moscot), a scalable framework for optimal transport in single-cell genomics that supports multimodality across all applications. We demonstrate the capability of moscot to efficiently reconstruct developmental trajectories of 1.7 million cells from mouse embryos across 20 time points. To illustrate the capability of moscot in space, we enrich spatial transcriptomic datasets by mapping multimodal information from single-cell profiles in a mouse liver sample and align multiple coronal sections of the mouse brain. We present moscot.spatiotemporal, an approach that leverages gene-expression data across both spatial and temporal dimensions to uncover the spatiotemporal dynamics of mouse embryogenesis. We also resolve endocrine-lineage relationships of delta and epsilon cells in a previously unpublished mouse, time-resolved pancreas development dataset using paired measurements of gene expression and chromatin accessibility. Our findings are confirmed through experimental validation of NEUROD2 as a regulator of epsilon progenitor cells in a model of human induced pluripotent stem cell islet cell differentiation. Moscot is available as open-source software, accompanied by extensive documentation.

Nature (2025)

Chromatin, Machine learning, Organogenesis, Software, Transcriptomics

Ultrabroadband integrated electro-optic frequency comb in lithium tantalate

Original Paper | Frequency combs | 2025-01-21 19:00 EST

Junyin Zhang, Chengli Wang, Connor Denney, Johann Riemensberger, Grigory Lihachev, Jianqi Hu, Wil Kao, Terence Blésin, Nikolai Kuznetsov, Zihan Li, Mikhail Churaev, Xin Ou, Gabriel Santamaria-Botello, Tobias J. Kippenberg

The integrated frequency comb generator based on Kerr parametric oscillation¹ has led to chip-scale, gigahertz-spaced combs with new applications spanning hyperscale telecommunications, low-noise microwave synthesis, light detection and ranging, and astrophysical spectrometer calibration^2,3,4,5,6. Recent progress in lithium niobate (LiNbO₃) photonic integrated circuits (PICs) has resulted in chip-scale, electro-optic (EO) frequency combs^7,8, offering precise comb-line positioning and simple operation without relying on the formation of dissipative Kerr solitons. However, current integrated EO combs face limited spectral coverage due to the large microwave power required to drive the non-resonant capacitive electrodes and the strong intrinsic birefringence of LiNbO₃. Here we overcome both challenges with an integrated triply resonant architecture, combining monolithic microwave integrated circuits with PICs based on the recently emerged thin-film lithium tantalate (LiTaO₃)⁹. With resonantly enhanced EO interaction and reduced birefringence in LiTaO₃, we achieve a fourfold comb span extension and a 16-fold power reduction compared to the conventional, non-resonant microwave design. Driven by a hybrid integrated laser diode, the comb spans over 450 nm (more than 60 THz) with more than 2,000 lines, and the generator fits within a compact 1-cm² footprint. We additionally observe that the strong EO coupling leads to an increased comb existence range approaching the full free spectral range of the optical microresonator. The ultra-broadband comb generator, combined with detuning-agnostic operation, could advance chip-scale spectrometry and ultra-low-noise millimetre wave synthesis^10,11,12,13 and unlock octave-spanning EO combs. The methodology of co-designing microwave and photonics can be extended to a wide range of integrated EOs applications^14,15,16.

Nature (2025)

Frequency combs, Integrated optics

Regional and institutional trends in assessment for academic promotion

Original Paper | Careers | 2025-01-21 19:00 EST

B. H. Lim, C. D'Ippoliti, M. Dominik, A. C. Hernández-Mondragón, K. Vermeir, K. K. Chong, H. Hussein, V. S. Morales-Salgado, K. J. Cloete, J. N. Kimengsi, L. Balboa, S. Mondello, T. E. dela Cruz, S. Lopez-Verges, I. Sidi Zakari, A. Simonyan, I. Palomo, A. Režek Jambrak, J. Germo Nzweundji, A. Molnar, A. M. I. Saktiawati, S. Elagroudy, P. Kumar, S. Enany, V. Narita, M. Backes, V. Siciliano, D. Egamberdieva, Y. Flores Bueso

The assessment of research performance is widely seen as a vital tool in upholding the highest standards of quality, with selection and competition believed to drive progress. Academic institutions need to take critical decisions on hiring and promotion, while facing external pressure by also being subject to research assessment^1,2,3,4. Here we present an outlook on research assessment for career progression with specific focus on promotion to full professorship, based on 314 policies from 190 academic institutions and 218 policies from 58 government agencies, covering 32 countries in the Global North and 89 countries in the Global South. We investigated how frequently various promotion criteria are mentioned and carried out a statistical analysis to infer commonalities and differences across policies. Although quantitative methods of assessment remain popular, in agreement with what is found in more geographically restricted studies^5,6,7,8,9, they are not omnipresent. We find differences between the Global North and the Global South as well as between institutional and national policies, but less so between disciplines. A preference for bibliometric indicators is more marked in upper-middle-income countries. Although we see some variation, many promotion policies are based on the assumption of specific career paths that become normative rather than embracing diversity. In turn, this restricts opportunities for researchers. These results challenge current practice and have strategic implications for researchers, research managers and national governments.

Nature (2025)

Careers, Developing world, Policy, Research management

CD45-PET is a robust, non-invasive tool for imaging inflammation

Original Paper | Acute inflammation | 2025-01-21 19:00 EST

Ali Salehi Farid, Jennifer E. Rowley, Harris H. Allen, Isabella G. Kruger, Soheil Tavakolpour, Kyle Neeley, Min Cong, Haneyeh Shahbazian, Niki Dorafshani, Achraf Berrada, Alexander C. MacDonagh, Robert F. Padera, Pedro Brugarolas, Alan B. Packard, Matthew W. Rosenbaum, Sanjay Divakaran, Marcelo F. Di Carli, Mohammad Rashidian

Imaging inflammation holds immense potential for advancing the diagnosis, treatment and prognosis of many conditions^{1,<a data-test="citation-ref" data-track="click" data-track-action="reference anchor" data-track-label="link" href="https://www.nature.com/articles/s41586-024-08441-6#ref-CR2" id="ref-link-section-d31924266e709_1" title="Bennett, J. M., Reeves, G., Billman, G. E. & Sturmberg, J. P. Inflammation--nature's way to efficiently respond to all types of challenges: implications for understanding and managing "the epidemic" of chronic diseases. Front. Med. 5, 316 (2018).">2,3}. The lack of a specific and sensitive positron emission tomography (PET) probe to detect inflammation is a critical challenge. To bridge this gap, we present CD45-PET imaging, which detects inflammation with exceptional sensitivity and clarity in several preclinical models. Notably, the intensity of the CD45-PET signal correlates robustly with the severity of disease in models of inflammatory lung and bowel diseases, outperforming ¹⁸F-fluorodeoxyglucose PET, the most widely used imaging modality for inflammation globally. Longitudinal CD45-PET imaging further enables precise monitoring of dynamic changes in tissue-specific inflammatory profiles. Finally, we developed a human CD45-PET probe for clinical translation that effectively detects human immune cells in a humanized mouse model. CD45-PET imaging holds substantial clinical promise, offering a tool for guiding diagnostic and therapeutic decisions for inflammatory diseases through a precise, whole-body assessment of the inflammation profiles of individual patients.

Nature (2025)

Acute inflammation, Chronic inflammation, Imaging the immune system, Inflammatory diseases, Translational immunology

Moiré-driven topological electronic crystals in twisted graphene

Original Paper | Electronic properties and materials | 2025-01-21 19:00 EST

Ruiheng Su, Dacen Waters, Boran Zhou, Kenji Watanabe, Takashi Taniguchi, Ya-Hui Zhang, Matthew Yankowitz, Joshua Folk

In a dilute two-dimensional electron gas, Coulomb interactions can stabilize the formation of a Wigner crystal^1,2,3. Although Wigner crystals are topologically trivial, it has been predicted that electrons in a partially filled band can break continuous translational symmetry and time-reversal symmetry spontaneously, resulting in a type of topological electron crystal known as an anomalous Hall crystal^{4,5,6,7,8,9,10,11}. Here we report signatures of a generalized version of the anomalous Hall crystal in twisted bilayer-trilayer graphene, whose formation is driven by the moiré potential. The crystal forms at a band filling of one electron per four moiré unit cells (ν = 1/4) and quadruples the unit-cell area, coinciding with an integer quantum anomalous Hall effect. The Chern number of the state is exceptionally tunable, and it can be switched reversibly between +1 and -1 by electric and magnetic fields. Several other topological electronic crystals arise in a modest magnetic field, originating from ν = 1/3, 1/2, 2/3 and 3/2. The quantum geometry of the interaction-modified bands is likely to be very different from that of the original parent band, which enables possible future discoveries of correlation-driven topological phenomena.

Nature (2025)

Electronic properties and materials, Topological insulators

Scaling and networking a modular photonic quantum computer

Original Paper | Information theory and computation | 2025-01-21 19:00 EST

H. Aghaee Rad, T. Ainsworth, R. N. Alexander, B. Altieri, M. F. Askarani, R. Baby, L. Banchi, B. Q. Baragiola, J. E. Bourassa, R. S. Chadwick, I. Charania, H. Chen, M. J. Collins, P. Contu, N. D'Arcy, G. Dauphinais, R. De Prins, D. Deschenes, I. Di Luch, S. Duque, P. Edke, S. E. Fayer, S. Ferracin, H. Ferretti, J. Gefaell, S. Glancy, C. González-Arciniegas, T. Grainge, Z. Han, J. Hastrup, L. G. Helt, T. Hillmann, J. Hundal, S. Izumi, T. Jaeken, M. Jonas, S. Kocsis, I. Krasnokutska, M. V. Larsen, P. Laskowski, F. Laudenbach, J. Lavoie, M. Li, E. Lomonte, C. E. Lopetegui, B. Luey, A. P. Lund, C. Ma, L. S. Madsen, D. H. Mahler, L. Mantilla Calderón, M. Menotti, F. M. Miatto, B. Morrison, P. J. Nadkarni, T. Nakamura, L. Neuhaus, Z. Niu, R. Noro, K. Papirov, A. Pesah, D. S. Phillips, W. N. Plick, T. Rogalsky, F. Rortais, J. Sabines-Chesterking, S. Safavi-Bayat, E. Sazhaev, M. Seymour, K. Rezaei Shad, M. Silverman, S. A. Srinivasan, M. Stephan, Q. Y. Tang, J. F. Tasker, Y. S. Teo, R. B. Then, J. E. Tremblay, I. Tzitrin, V. D. Vaidya, M. Vasmer, Z. Vernon, L. F. S. S. M. Villalobos, B. W. Walshe, R. Weil, X. Xin, X. Yan, Y. Yao, M. Zamani Abnili, Y. Zhang

Photonics offers a promising platform for quantum computing^1,2,3,4, owing to the availability of chip integration for mass-manufacturable modules, fibre optics for networking and room-temperature operation of most components. However, experimental demonstrations are needed of complete integrated systems comprising all basic functionalities for universal and fault-tolerant operation⁵. Here we construct a (sub-performant) scale model of a quantum computer using 35 photonic chips to demonstrate its functionality and feasibility. This combines all the primitive components as discrete, scalable rack-deployed modules networked over fibre-optic interconnects, including 84 squeezers⁶ and 36 photon-number-resolving detectors furnishing 12 physical qubit modes at each clock cycle. We use this machine, which we name Aurora, to synthesize a cluster state⁷ entangled across separate chips with 86.4 billion modes, and demonstrate its capability of implementing the foliated distance-2 repetition code with real-time decoding. The key building blocks needed for universality and fault tolerance are demonstrated: heralded synthesis of single-temporal-mode non-Gaussian resource states, real-time multiplexing actuated on photon-number-resolving detection, spatiotemporal cluster-state formation with fibre buffers, and adaptive measurements implemented using chip-integrated homodyne detectors with real-time single-clock-cycle feedforward. We also present a detailed analysis of our architecture's tolerances for optical loss, which is the dominant and most challenging hurdle to crossing the fault-tolerant threshold. This work lays out the path to cross the fault-tolerant threshold and scale photonic quantum computers to the point of addressing useful applications.

Nature (2025)

Information theory and computation, Photonic devices, Quantum information, Quantum optics, Single photons and quantum effects

Nature Materials

Double-sided van der Waals epitaxy of topological insulators across an atomically thin membrane

Original Paper | Design, synthesis and processing | 2025-01-21 19:00 EST

Joon Young Park, Young Jae Shin, Jeacheol Shin, Jehyun Kim, Janghyun Jo, Hyobin Yoo, Danial Haei, Chohee Hyun, Jiyoung Yun, Robert M. Huber, Arijit Gupta, Kenji Watanabe, Takashi Taniguchi, Wan Kyu Park, Hyeon Suk Shin, Miyoung Kim, Dohun Kim, Gyu-Chul Yi, Philip Kim

Atomically thin van der Waals (vdW) films provide a material platform for the epitaxial growth of quantum heterostructures. However, unlike the remote epitaxial growth of three-dimensional bulk crystals, the growth of two-dimensional material heterostructures across atomic layers has been limited due to the weak vdW interaction. Here we report the double-sided epitaxy of vdW layered materials through atomic membranes. We grow vdW topological insulators Sb₂Te₃ and Bi₂Se₃ by molecular-beam epitaxy on both surfaces of atomically thin graphene or hexagonal boron nitride, which serve as suspended two-dimensional vdW substrate layers. Both homo- and hetero-double-sided vdW topological insulator tunnel junctions are fabricated, with the atomically thin hexagonal boron nitride acting as a crystal-momentum-conserving tunnelling barrier with abrupt and epitaxial interfaces. By performing field-angle-dependent magneto-tunnelling spectroscopy on these devices, we reveal the energy-momentum-spin resonance of massless Dirac electrons tunnelling between helical Landau levels developed in the topological surface states at the interfaces.

Nat. Mater. (2025)

Design, synthesis and processing, Electronic and spintronic devices, Surfaces, interfaces and thin films, Topological insulators, Two-dimensional materials

Platinum hydride formation during cathodic corrosion in aqueous solutions

Original Paper | Corrosion | 2025-01-21 19:00 EST

Thomas J. P. Hersbach, Angel T. Garcia-Esparza, Selwyn Hanselman, Oscar A. Paredes Mellone, Thijs Hoogenboom, Ian T. McCrum, Dimitra Anastasiadou, Jeremy T. Feaster, Thomas F. Jaramillo, John Vinson, Thomas Kroll, Amanda C. Garcia, Petr Krtil, Dimosthenis Sokaras, Marc T. M. Koper

Cathodic corrosion is an electrochemical phenomenon that etches metals at moderately negative potentials. Although cathodic corrosion probably occurs by forming a metal-containing anion, such intermediate species have not yet been observed. Here, aiming to resolve this long-standing debate, our work provides such evidence through X-ray absorption spectroscopy. High-energy-resolution X-ray absorption near-edge structure experiments are used to characterize platinum nanoparticles during cathodic corrosion in 10 mol l^-1 NaOH. These experiments detect minute chemical changes in the Pt during corrosion that match first-principles simulations of X-ray absorption spectra of surface platinum multilayer hydrides. Thus, this work supports the existence of hydride-like platinum during cathodic corrosion. Notably, these results provide a direct observation of these species under conditions where they are highly unstable and where prominent hydrogen bubble formation interferes with most spectroscopy methods. Therefore, this work identifies the elusive intermediate that underlies cathodic corrosion.

Nat. Mater. (2025)

Corrosion

Nature Physics

Programmable simulations of molecules and materials with reconfigurable quantum processors

Original Paper | Electronic structure of atoms and molecules | 2025-01-21 19:00 EST

Nishad Maskara, Stefan Ostermann, James Shee, Marcin Kalinowski, Abigail McClain Gomez, Rodrigo Araiza Bravo, Derek S. Wang, Anna I. Krylov, Norman Y. Yao, Martin Head-Gordon, Mikhail D. Lukin, Susanne F. Yelin

Simulations of quantum chemistry and quantum materials are believed to be among the most important applications of quantum information processors. However, realizing practical quantum advantage for such problems is challenging because of the prohibitive computational cost of programming typical problems into quantum hardware. Here we introduce a simulation framework for strongly correlated quantum systems represented by model spin Hamiltonians that uses reconfigurable qubit architectures to simulate real-time dynamics in a programmable way. Our approach also introduces an algorithm for extracting chemically relevant spectral properties via classical co-processing of quantum measurement results. We develop a digital-analogue simulation toolbox for efficient Hamiltonian time evolution using digital Floquet engineering and hardware-optimized multi-qubit operations to accurately realize complex spin-spin interactions. As an example, we propose an implementation based on Rydberg atom arrays. In addition, we show how detailed spectral information can be extracted from the dynamics through snapshot measurements and single-ancilla control, enabling the evaluation of excitation energies and finite-temperature susceptibilities from a single dataset. To illustrate the approach, we show how to use the method to compute key properties of a polynuclear transition-metal catalyst and two-dimensional magnetic materials.

Nat. Phys. (2025)

Electronic structure of atoms and molecules, Magnetic properties and materials, Quantum chemistry, Quantum information, Quantum simulation

Free-electron quantum optics

Review Paper | Matter waves and particle beams | 2025-01-21 19:00 EST

Ron Ruimy, Aviv Karnieli, Ido Kaminer

Recent theoretical and experimental breakthroughs have given rise to the emerging field of free-electron quantum optics, reshaping the understanding of free-electron physics. Traditionally rooted in classical electrodynamics, this field now reveals quantum-mechanical features that necessitate the frameworks of quantum electrodynamics and quantum optics. This shift compels a re-evaluation of well-established areas, bringing quantum-mechanical corrections to accelerator science and to electron-radiation phenomena. Simultaneously, the ability to shape single-electron wavefunctions opens new possibilities in microscopy and spectroscopy. These developments are primarily driven by innovations in electron microscopy and its intersection with laser science, where laser-driven electron modulation substantially influences quantum electron interactions with light and matter. In this Perspective, we review these developments, highlighting the current challenges and future opportunities. We explore the role of the free electron as a quantum resource, complementing conventional two-level systems and harmonic oscillators. In the coming years, free electrons may offer new modalities for reading and writing quantum information on ultrafast timescales, performing quantum-state tomography, and ultrafast quantum gates on the atomic scale.

Nat. Phys. (2025)

Matter waves and particle beams, Quantum optics

Nature Reviews Physics

Principles for demonstrating condensed phase optical refrigeration

Review Paper | Materials for optics | 2025-01-21 19:00 EST

Zhuoming Zhang, Yang Ding, Peter J. Pauzauskie, Mansoor Sheik-Bahae, Denis V. Seletskiy, Masaru Kuno

Optical refrigeration, or condensed phase laser cooling, uses lasers to remove thermal energy from solids through anti-Stokes photoluminescence. This non-contact, vibration-free, optically addressable cooling technique opens up many application possibilities, ranging from high-resolution space-based imaging to the stabilization of ultraprecise frequency combs. The field has seen rapid progress in the past 25 years, from the first cooling of a rare-earth-doped glass by 0.3 K in 1995 to reaching cryogenic temperatures around 90 K in ytterbium-doped fluoride crystals in 2018. Attention has now shifted to semiconductors with higher cooling power densities and predicted cooling floors as low as 10 K. This has stimulated a race to demonstrate the optical refrigeration of a semiconductor. It is therefore timely to systematize the necessary and sufficient experimental minimum criteria for reporting optical refrigeration results to elevate the reliability and reproducibility of current and future optical refrigeration claims. In this Expert Recommendation, we propose four principles and provide guidelines for verifying and reporting new cooling results: optical cooling metrics, demonstrations of explicit heating versus cooling, thermodynamic consistency and reliable temperature measurements. We further propose that these principles serve as a guide for reviewing literature claims in the field.

Nat Rev Phys (2025)

Materials for optics, Semiconductors

Quantum computing for nonlinear differential equations and turbulence

Review Paper | Computational science | 2025-01-21 19:00 EST

Felix Tennie, Sylvain Laizet, Seth Lloyd, Luca Magri

Many problems in classical physics and engineering, such as turbulence, are governed by nonlinear differential equations, which typically require high-performance computing to be solved. Over the past decade, however, the growth of classical computing power has slowed because the miniaturization of chips is approaching the atomic scale. This development calls for a new computing paradigm: quantum computing is a prime candidate. In this Perspective, we offer a view on the challenges that need to be overcome in order to use quantum computing to simulate nonlinear dynamics. We discuss progress in the development of both quantum algorithms for nonlinear equations and quantum hardware. We propose synergies between quantum algorithms for nonlinear equations and quantum hardware concepts that could bear fruit in the near to mid-term future for the simulation of nonlinear systems and turbulence.

Nat Rev Phys (2025)

Computational science, Computer science

Physical Review Letters

Krylov Subspace Methods for Quantum Dynamics with Time-Dependent Generators

Research article | Quantum chaos | 2025-01-22 05:00 EST

Kazutaka Takahashi and Adolfo del Campo

Krylov subspace methods in quantum dynamics identify the minimal subspace in which a process unfolds. To date, their use is restricted to time evolutions governed by time-independent generators. We introduce a generalization valid for driven quantum systems governed by a time-dependent Hamiltonian that maps the evolution to a diffusion problem in a one-dimensional lattice with nearest-neighbor hopping probabilities that are inhomogeneous and time dependent. This representation is used to establish a novel class of fundamental limits to the quantum speed of evolution and operator growth. We also discuss generalizations of the algorithm, adapted to discretized time evolutions and periodic Hamiltonians, with applications to many-body systems.

Phys. Rev. Lett. 134, 030401 (2025)

Quantum chaos, Quantum circuits, Quantum formalism, Quantum information theory, Quantum phase transitions, 1-dimensional spin chains, Floquet systems, Nonequilibrium systems, Quantum many-body systems

Optimizing Quantum Measurements by Partitioning Multisets of Observables

Research article | Quantum algorithms & computation | 2025-01-22 05:00 EST

O. Veltheim and E. Keski-Vakkuri

Quantum tomography approaches typically consider a set of observables that we wish to measure, designing a measurement scheme that measures each of the observables and then repeats the measurements as many times as necessary. We show that instead of considering only the simple set of observables, one should consider a multiset of the observables taking into account the required repetitions, to minimize the number of measurements. This leads to a graph theoretic multicoloring problem. We show that the multiset method offers at most quadratic improvement but it is achievable. Furthermore, despite the NP-hard optimal coloring problem, the multiset approach with greedy coloring algorithms already offers asymptotically quadratic improvement in test cases.

Phys. Rev. Lett. 134, 030801 (2025)

Quantum algorithms & computation, Quantum communication, protocols & technology, Quantum measurements, Quantum tomography, Quantum verification

Optimal Reconstruction of the Hellings and Downs Correlation

Research article | Gravitational wave detection | 2025-01-22 05:00 EST

Bruce Allen and Joseph D. Romano

A theoretical analysis places limits on the precision for inter-pulsar correlations contained in the Hellings and Downs curve.

Phys. Rev. Lett. 134, 031401 (2025)

Gravitational wave detection, Gravitational waves, Neutron stars & pulsars, Data analysis, Gravitational wave detectors

Complete Next-to-Leading Order QCD Corrections to \(ZZ\) Production in Gluon Fusion

Research article | Quantum chromodynamics | 2025-01-22 05:00 EST

Bakul Agarwal, Stephen Jones, Matthias Kerner, and Andreas von Manteuffel

We calculate the complete next-to-leading order (NLO) QCD corrections to loop-induced \(gg\rightarrow ZZ\) production including full top-quark mass effects. The two-loop virtual corrections are obtained by combining analytic results for the massless, Higgs-mediated, and one-loop factorizable contributions with numerically computed amplitudes containing the top-quark mass. We show that the choice of subtraction scheme for the virtual contribution impacts the precision with which the virtual contribution must be evaluated in order to obtain sufficiently precise phenomenological predictions. For direct production through a massive top-quark loop, we observe that the relative NLO corrections are large. The direct massive and Higgs-mediated contributions individually increase relative to the massless production at high diboson invariant mass, but interfere destructively with each other. At the Large Hadron Collider, the NLO corrections to the gluon channel give a sizable contribution to the \(pp\rightarrow ZZ+X\) cross section at \({\mathrm{N}}^{3}\mathrm{LO}\).

Phys. Rev. Lett. 134, 031901 (2025)

Quantum chromodynamics, Higgs bosons, W & Z bosons

Lattice Light Shift Evaluations in a Dual-Ensemble Yb Optical Lattice Clock

Research article | Atomic & molecular processes in external fields | 2025-01-22 05:00 EST

Tobias Bothwell, Benjamin D. Hunt, Jacob L. Siegel, Youssef S. Hassan, Tanner Grogan, Takumi Kobayashi, Kurt Gibble, Sergey G. Porsev, Marianna S. Safronova, Roger C. Brown, Kyle Beloy, and Andrew D. Ludlow

In state-of-the-art optical lattice clocks, beyond-electric-dipole polarizability terms lead to a breakdown of magic wavelength trapping. In this Letter, we report a novel approach to evaluate lattice light shifts, specifically addressing recent discrepancies in the atomic multipolarizability term between experimental techniques and theoretical calculations. We combine imaging and multi-ensemble techniques to evaluate lattice light shift atomic coefficients, leveraging comparisons in a dual-ensemble lattice clock to rapidly evaluate differential frequency shifts. Further, we demonstrate application of a running wave field to probe both the multipolarizability and hyperpolarizability coefficients, establishing a new technique for future lattice light shift evaluations.

Phys. Rev. Lett. 134, 033201 (2025)

Atomic & molecular processes in external fields, Atomic & molecular structure, Atomic, optical & lattice clocks, Electronic structure of atoms & molecules

Multistable Kuramoto Splay States in a Crystal of Mode-Locked Laser Pulses

Research article | Frequency combs & self-phase locking | 2025-01-22 05:00 EST

T. G. Seidel, A. Bartolo, A. Garnache, M. Giudici, M. Marconi, S. V. Gurevich, and J. Javaloyes

We demonstrate the existence of coexisting frequency combs in a harmonically mode-locked laser that we link to the splay phases of the Kuramoto model with short range interactions. These splay states are multistable and the laser may wander between them under the influence of stochastic forces. Consequently, the many pulses circulating in the cavity are not necessarily coherent with each other. As these partially disordered states for the phase of the field still feature regular intensity pulses, we term them as incoherent crystals of optical pulses. We provide evidence that the notion of coherence should be interpreted by comparing the duration of the measurement time with the Kramers' escape time of each splay state. Our theoretical results are confirmed experimentally by performing high resolution spectral measurements via a heterodyne technique of a passively mode-locked vertical external-cavity surface-emitting laser.

Phys. Rev. Lett. 134, 033801 (2025)

Frequency combs & self-phase locking, Laser dynamics, Optical coherence, III-V semiconductors, VCSELs, Fokker-Planck equation, Kuramoto model, Langevin equation, XY model

Observation of Copropagating Chiral Zero Modes in Magnetic Photonic Crystals

Research article | Photonic crystals | 2025-01-22 05:00 EST

Zhongfu Li, Shaojie Ma, Shuwei Li, Oubo You, Yachao Liu, Qingdong Yang, Yuanjiang Xiang, Peiheng Zhou, and Shuang Zhang

Topological singularities, such as Weyl points (WPs) and Dirac points, can give rise to unidirectional propagation channels known as chiral zero modes (CZMs) when subject to a magnetic field. CZMs, as distinct zeroth Landau levels (bulk modes) with high degeneracy, are responsible for intriguing phenomena like the chiral anomaly in quantum systems. The propagation direction of each CZM is determined by both the applied magnetic field and the topological charge of the singularity point. While counterpropagating CZMs have been observed in 2D and 3D systems, the realization of copropagating CZMs has remained elusive. Here, we present the first experimental observation of copropagating CZMs in magnetic photonic crystals hosting a single pair of ideal Weyl points. By manipulating the crystal's structural configuration and applying a uniform bias magnetic field, we spatially alter the locations of the WPs, creating pseudo-magnetic fields of opposite directions for different WPs. This arrangement results in a pair of CZMs that possess the same group velocity and copropagate. Our work opens up new possibilities for the topological manipulation of wave propagation and may lead to advancements in optical waveguides, switches, and various other applications.

Phys. Rev. Lett. 134, 033802 (2025)

Photonic crystals, Photonics, Optical materials & elements

Realization of Topology-Controlled Photonic Cavities in a Valley Photonic Crystal

Research article | Optical microcavities | 2025-01-22 05:00 EST

Bei Yan, Baoliang Liao, Fulong Shi, Xiang Xi, Yuan Cao, Kexin Xiang, Yan Meng, Linyun Yang, Zhenxiao Zhu, Jingming Chen, Xiao-Dong Chen, Gui-Geng Liu, Baile Zhang, and Zhen Gao

We report the experimental realization of a new type of topology-controlled photonic cavities in valley photonic crystals by adopting judiciously oriented mirrors to localize the valley-polarized edge states along their propagation path. By using microwave frequency- and time-domain measurements, we directly observe the strong confinement of electromagnetic energy at the mirror surface due to the extended time delay required for the valley index flipping. Moreover, we experimentally demonstrate that both the degree of energy localization and quality factors of the topology-controlled photonic cavities are determined by the valley-flipping time which is controlled by the topology of the mirror. These results extend and complement the current design paradigm of topological photonic cavities.

Phys. Rev. Lett. 134, 033803 (2025)

Optical microcavities, Photonic crystals, Topological effects in photonic systems

Giant Tunneling Magnetoresistance Based on Spin-Valley-Mismatched Ferromagnetic Metals

Research article | Electrical properties | 2025-01-22 05:00 EST

Kun Yan, Li Cheng, Yizhi Hu, Junjie Gao, Xiaolong Zou, and Xiaobin Chen

Half metals, which are amenable to perfect spin filtering, can be utilized for high-magnetoresistive devices. However, available half metals are very limited. Here, we demonstrate that materials with intrinsic spin-valley-mismatched (SVM) states can be used to block charge transport, resembling half metals and leading to giant tunneling magnetoresistance. As an example, by using first-principles transport calculations, we show that ferromagnetic \(1T\text{- }{\mathrm{VSe}}_{2}\), \(1T\text{- }{\mathrm{VS}}_{2}\), and \(2H\text{- }{\mathrm{VS}}_{2}\) are such spin-valley-mismatched metals, and giant magnetoresistance of more than 99% can be realized in spin-valve van der Waals (vdW) junctions using these metals as electrodes. Owing to the intrinsic mismatch of spin states, the central-layer materials for the vdW junctions can be arbitrary nonmagnetic materials, in principle. Our research provides clear physical insights into the mechanism for high magnetoresistance and opens new avenues for the search and design of high-magnetoresistance devices.

Phys. Rev. Lett. 134, 036302 (2025)

Electrical properties, Magnetoresistance, Transition metal dichalcogenides, Band structure methods, Density functional theory, First-principles calculations, Green's function methods

Design of Intrinsic Transparent Conductors from a Synergetic Effect of Symmetry and Spatial-Distribution Forbidden Transitions

Research article | Electrical properties | 2025-01-22 05:00 EST

Gui Wang, Ying Ning Du, Pu Huang, Zheng Fang Qian, Peng Zhang, and Su-Huai Wei

Intrinsic transparent conductors (ITCs) correspond to a unique class of TCs that do not need intentional doping. This character can provide ITCs significant advantages by avoiding severe ''doping bottlenecks'' and dopant scattering usually encountered in conventional transparent conducting oxides (TCOs). However, the realization of ITCs generally requires the minimization of photon absorption and reflection in metallic conductors, which is difficult due to the gapless nature of their band structures. Here, based on first-principles calculations, we illustrate a feasible strategy to design optical transparency in metallic conductors by a synergetic effect of symmetry and spatial-distribution forbidden transitions between their energy bands around the Fermi level. The validity of this design strategy is demonstrated in a zero-dimensional electride, \({\mathrm{K}}_{4}{\mathrm{Al}}_{3}{({\mathrm{SiO}}_{4})}_{3}\), which exhibits both electrical conductivity and optical transparency in the ultraviolet spectrum. More interestingly, we find that this transmittance range can be tuned to the visible spectrum region by chemical substitutions in \({\mathrm{K}}_{4}{\mathrm{Al}}_{3}{({\mathrm{SiO}}_{4})}_{3}\) with the elements that have either larger electronegativity or smaller atomic radius. By examining dozens of possible cation substitutions via high-throughput calculations, we identify several promising candidates that have the potential as ITCs.

Phys. Rev. Lett. 134, 036401 (2025)

Electrical properties, Optoelectronics, Transparent conducting oxides, Band structure methods, Density functional theory

Dynamical Theory of Angle-Resolved Electron Energy Loss and Gain Spectroscopies of Phonons and Magnons in Transmission Electron Microscopy Including Multiple Scattering Effects

Research article | Lattice dynamics | 2025-01-22 05:00 EST

José Ángel Castellanos-Reyes, Paul M. Zeiger, and Ján Rusz

We present a method for computing angle-resolved electron energy loss and gain spectroscopies for phonon and magnon excitations in transmission electron microscopy. Fractional scattering intensities are derived from the temperature-dependent time autocorrelation of the auxiliary electron beam wave function. This method captures both single and multiple scattering processes, as well as dynamical diffraction effects, while remaining computationally efficient and easy to parallelize.

Phys. Rev. Lett. 134, 036402 (2025)

Lattice dynamics, Magnons, Phonons, Spin dynamics, Temperature, Electron energy loss spectroscopy, Low-energy electron diffraction

Energy Relaxation and Dynamics in the Correlated Metal \({\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}\) via Terahertz Two-Dimensional Coherent Spectroscopy

Research article | Lifetimes & widths | 2025-01-22 05:00 EST

David Barbalas, Ralph Romero, III, Dipanjan Chaudhuri, Fahad Mahmood, Hari P. Nair, Nathaniel J. Schreiber, Darrell G. Schlom, K. M. Shen, and N. P. Armitage

Energy relaxation rates in Sr2RuO4 probed with THz 2D coherent spectroscopy are strongly subdominant compared to the previously measured momentum relaxation rates.

Phys. Rev. Lett. 134, 036501 (2025)

Lifetimes & widths, Third order nonlinear optical processes, Strongly correlated systems, Two-dimensional coherent spectroscopy

Single-Electron Quantization of Dark Current in Quanta Image Sensors

Research article | Cosmic ray & astroparticle detectors | 2025-01-22 05:00 EST

Joanna Krynski, Daniel McGrath, Alexandre Le Roch, Sarah Holloway, Lucrezia Migliorin, Cédric Virmontois, and Vincent Goiffon

A CMOS-based image sensor with very low noise levels allows observation of the quantization of dark current generation rate of stray electron/hole pairs in unilluminated photodetectors.

Phys. Rev. Lett. 134, 037001 (2025)

Cosmic ray & astroparticle detectors, Optical, UV, & IR astronomy, Optoelectronics, Quantum metrology, Solid-state detectors, Imaging & optical processing, Noise measurements, Optical techniques, Particle detectors, Photoelectron techniques, Single-photon detectors

Criticality in the Luria-Delbr"uck Model with an Arbitrary Mutation Rate

Research article | Cell division | 2025-01-22 05:00 EST

Deng Pan, Jie Lin, and Ariel Amir

The Luria-Delbr"uck model is a classic model of population dynamics with random mutations, that has been used historically to prove that random mutations drive evolution. In typical scenarios, the relevant mutation rate is exceedingly small, and mutants are counted only at the final time point. Here, inspired by recent experiments on DNA repair, we study a mathematical model that is formally equivalent to the Luria-Delbr"uck setup, with the repair rate \(p\) playing the role of mutation rate, albeit taking on large values, of order unity per cell division. We find that although at large times the fraction of repaired cells approaches one, the variance of the number of repaired cells undergoes a phase transition: when \(p>1/2\) the variance decreases with time, but, intriguingly, for \(p<1/2\) even though the fraction of repaired cells approaches 1, the variance in the number of repaired cells increases with time. Analyzing DNA-repair experiments, we find that in order to explain the data the model should also take into account the probability of a successful repair process once it is initiated. Taken together, our work shows how the study of variability can lead to surprising phase transitions as well as provide biological insights into the process of DNA repair.

Phys. Rev. Lett. 134, 038401 (2025)

Cell division, Evolutionary & population dynamics, Gene repair, Mutation, Processes in cells, tissues & organoids

Physical Review X

Dissipative Protection of a GKP Qubit in a High-Impedance Superconducting Circuit Driven by a Microwave Frequency Comb

Research article | Open quantum systems & decoherence | 2025-01-22 05:00 EST

L.-A. Sellem, A. Sarlette, Z. Leghtas, M. Mirrahimi, P. Rouchon, and P. Campagne-Ibarcq

Bosonic qubits are promising platforms for quantum error correction. A new approach to detecting errors ensures precise control of the extracted information.

Phys. Rev. X 15, 011011 (2025)

Open quantum systems & decoherence, Quantum circuits, Quantum error correction, Quantum harmonic oscillator

Review of Modern Physics

Macroscopic stochastic thermodynamics

Research article | Dynamical phase transitions | 2025-01-22 05:00 EST

Gianmaria Falasco and Massimiliano Esposito

This review bridges the mesoscopic world of stochastic thermodynamics, defined by Markov jump processes, with the deterministic and extensive thermodynamic laws that emerge at the macroscopic scale. Using large deviations theory, it constructs a fluctuation framework preserving core principles like the fluctuation theorem. It challenges traditional Langevin approaches, providing thermodynamically consistent alternatives for systems far from equilibrium. From chemical reaction networks to electronic circuits and Potts models, this work elucidates the dynamics of rare fluctuations, attractor transitions, and entropy production principles, offering a robust theoretical foundation for understanding nonequilibrium phenomena across disciplines.

Rev. Mod. Phys. 97, 015002 (2025)

Dynamical phase transitions, Fluctuation theorems, Nonequilibrium & irreversible thermodynamics, Nonequilibrium statistical mechanics, Stochastic thermodynamics, Nonequilibrium systems

arXiv

Band Structure and Pairing Nature of La\(_3\)Ni\(_2\)O\(_7\) Thin Film at Ambient Pressure

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Zhi-Yan Shao, Yu-Bo Liu, Min Liu, Fan Yang

Recently, evidences of superconductivity with onset temperature \(T_c\) above the McMillan limit (\(\approx 40\) K) have been detected in the La\(_3\)Ni\(_2\)O\(_7\) ultrathin film grown on the LaSrAlO substrate at ambient pressure. This progress makes it possible to investigate the pairing mechanism in the bilayer nickelates through adopting various experimental tools. Here we perform a first-principle density-functional-theory (DFT) based calculation for the band structure of this nickelate superconductor. The obtained band structure is different from that of the pressurized bulk La\(_3\)Ni\(_2\)O\(_7\) mainly in that the bonding-\(d_{z^2}\) band is pushed far (\(\approx\) 0.16 eV) below the Fermi level. Taking the low-energy Ni-\((3d_{z^2},3d_{x^2-y^2})\) orbitals placed on the pseudo-tetragonal lattice structure, we construct a 2D bilayer eight-band tight-binding model which well captures the main features of the DFT band structure. Then considering the multi-orbital Hubbard interaction, we adopt the random-phase approximation approach to investigate the pairing symmetry. The obtained spin susceptibility is maximized at the momentum \(Q = (0, 0.86\pi)\) in the folded Brillouin zone, induced by Fermi-surface nesting, leading to interlayer antiferromagnetic spin fluctuation in the diagonal double-stripe pattern similar with that reported for the bulk La\(_3\)Ni\(_2\)O\(_7\). The leading and subleading pairing symmetries are the \(s^{\pm}\) and approximate \(d_{xy}\), which are nearly degenerate. Our results appeal for experimental verifications.

arXiv:2501.10409 (2025)

Superconductivity (cond-mat.supr-con)

4.1 pages, 4 figures with Appendix

Effective longitudinal wave through a random distribution of poroelastic spheres in a poroelastic matrix

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Dossou Gnadjro, Amah Séna d'Almeida

A random distribution of poroelastic spheres in a poroelastic medium obeying Biot's theory is considered. The scattering coefficients of the fast and the slow waves are computed in the low frequency limit using the sealed pore boundary conditions. Analytical expressions of the effective wavenumbers of the coherent longitudinal waves (fast and slow) are deduced the Rayleigh limit using a generalization of the Linton-Martin (LM) formula to poroelastic medium up to the order two in concentration. Some effective quantities (mass density, bulk modulus) of the heterogeneous media are estimated.

arXiv:2501.10411 (2025)

Soft Condensed Matter (cond-mat.soft)

X-ray diffraction characterization of suspended structures for MEMS applications

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

P. Goudeau (SP2MI, LMP (Poitiers)), N. Tamura (LBNL), B. Lavelle (CEMES), S. Rigo (ENIT), T. Masri (ENIT), A. Bosseboeuf (IEF), T. Sarnet (IEF, CNRS), J.-A. Petit (ENIT), J.-M. Desmarres (CNES)

Mechanical stress control is becoming one of the major challenges for the future of micro and nanotechnologies. Micro scanning X-ray diffraction is one of the promising techniques that allows stress characterization in such complex structures at sub micron scales. Two types of MEMS structure have been studied: a bilayer cantilever composed of a gold film deposited on poly-silicon and a boron doped silicon bridge. X-ray diffraction results are discussed in view of numerical simulation experiments.

arXiv:2501.10424 (2025)

Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Classical Physics (physics.class-ph)

Thin Films Stresses And Mechanical Properties, Mar 2005, San Francisco CA, United States

Realization of tilted Dirac-like microwave cone in superconducting circuit lattices

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Amir Youssefi, Ahmad Motavassal, Shingo Kono, Seyed Akbar Jafari, Tobias J. Kippenberg

Dirac-like band crossings are paradigms in condensed matter systems to emulate high-energy physics phenomena. They are associated with two aspects: gap and tilting. The ability to design sign-changing gap gives rise to band topology, whereas the tilting of band crossings which is a gateway for large gravity-like effects remains uncharted. In this work, we introduce an experimental platform to realize tilted Dirac-like microwave cone in large-scale superconducting circuit lattices. The direction and magnitude of the tilt can be controlled by engineering the axially preferred second neighbor coupling. We demonstrate three lattices with 731-site LC resonator featuring tilt values of up to 59% of relative difference in the opposite-direction group velocities. This is obtained by reconstructing the density of states (DOS) of measured microwave resonance frequencies. Harnessing the tilt of Dirac-like band crossings lays the foundation for weaving the fabric of an emergent solid-state spacetime.

arXiv:2501.10434 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), General Relativity and Quantum Cosmology (gr-qc), Quantum Physics (quant-ph)

Enhancing Cell Characterization via Hydrodynamic Compression in Suspended Microchannel Resonators

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Alberto Martin-Perez, Daniel Ramos

Microfluidics offer remarkable flexibility for in-flow analyte characterization and can even measure the mechanical properties of biological cells through the application of hydrodynamic forces. In this work, we present a new approach to enhance the performance of nanomechanical resonators featuring integrated microfluidic channels when they are used as cell sensors by means of applying hydrostatic compressions. For this purpose, we have studied analytically how this kind of compressions affects either the mechanical properties of the resonator as well as the analytes. We found that, depending on factors such as device geometry and material composition, the mass limit of detection of the resonator can be reduced while the buoyant mass of the particles is increased when a hydrostatic compression is applied, improving the performance of the sensor. Furthermore, we demonstrate that applying these hydrostatic compressions induces shifts in mass distributions among cell lines with similar physical properties, which not only potentially enhances the ability to differentiate between these lines, but also opens the door to measure the cell's compressibility, a biophysical parameter of interest with practical diagnostic applications.

arXiv:2501.10439 (2025)

Soft Condensed Matter (cond-mat.soft), Other Condensed Matter (cond-mat.other), Biological Physics (physics.bio-ph)

Pilot study of electrochemical reduction of selected nucleotides and double-stranded DNA at pristine micro-/ultrananocrystalline boron-doped diamond electrodes at very negative potentials

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Michal Augustín, Vlastimil Vyskočil, Ondrej Szabó, Kateřina Aubrechtová Dragounová, Rene Pfeifer, Frank-Michael Matysik, Jiří Barek, Marián Marton, Alexander Kromka

Pristine polycrystalline boron-doped diamond electrodes (BDDEs) -- microcrystalline (B-MCDE) and ultrananocrystalline (B-UNCDE) were applied for the electrochemical reduction of several selected purine nucleotides -- Guanosine 5'-monophosphate (GMP), 2'-Deoxyguanosine 5'-monophosphate (dGMP), Adenosine 5'-monophosphate (AMP), Adenosine 5'-diphosphate (ADP), Adenosine 5'-triphosphate (ATP), and pyrimidine nucleotides -- Cytidine 5'-monophosphate (CMP), Thymidine 5'-monophosphate (TMP), as well as low-molecular-weight double-stranded DNA (dsDNA) at very negative potentials via linear sweep voltammetry (LSV). Three different types of electrode surfaces were employed -- "H-terminated" B-MCDE (H-B-MCDE) and "O-terminated" B-MCDE/B-UNCDE (O-B-MCDE/O-B-UNCDE). It was found that electrochemical reduction of all tested analytes (except GMP) is possible at H-B-MCDE. On the other hand, electrochemical reduction of all selected analytes (except dsDNA) is possible at O-B-MCDE/O-B-UNCDE. Ambient oxygen and preadsorption step in the manner of incubation of the corresponding sensor in the analyte solution for 30 s had a profound effect on the repeatability of the results and, in the case of H-B-MCDE, also on the magnitude of voltammetric signals and the possibility of electrochemical reduction of dGMP. The use of the proposed sensors and their main advantages and disadvantages for the voltammetric determination of the tested analytes (demonstrated via electrochemical reduction of AMP) in the presence of hydrogen evolution reaction (HER) is also discussed.

arXiv:2501.10469 (2025)

Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)

Evaluating Gaussianity of heterogeneous fractional Brownian motion

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Michał Balcerek, Adrian Pacheco-Pozo, Agnieszka Wyłomańska, Diego Krapf

Heterogeneous diffusion processes are prevalent in various fields, including the motion of proteins in living cells, the migratory movement of birds and mammals, and finance. These processes are often characterized by time-varying dynamics, where interactions with the environment evolve, and the system undergoes fluctuations in diffusivity. Moreover, in many complex systems anomalous diffusion is observed, where the mean square displacement (MSD) exhibits non-linear scaling with time. Among the models used to describe this phenomenon, fractional Brownian motion (FBM) is a widely applied stochastic process, particularly for systems exhibiting long-range temporal correlations. Although FBM is characterized by Gaussian increments, heterogeneous processes with FBM-like characteristics may deviate from Gaussianity. In this article, we study the non-Gaussian behavior of switching fractional Brownian motion (SFBM), a model in which the diffusivity of the FBM process varies while temporal correlations are maintained. To characterize non-Gaussianity, we evaluate the kurtosis, a common tool used to quantify deviations from the normal distribution. We derive exact expressions for the kurtosis of the considered heterogeneous anomalous diffusion process and investigate how it can identify non-Gaussian behavior. We also compare the kurtosis results with those obtained using the Hellinger distance, a classical measure of divergence between probability density functions. Through both analytical and numerical methods, we demonstrate the potential of kurtosis as a metric for detecting non-Gaussianity in heterogeneous anomalous diffusion processes.

arXiv:2501.10472 (2025)

Statistical Mechanics (cond-mat.stat-mech), Probability (math.PR)

21 pages, 7 figures

Rubidium intercalation in epitaxial monolayer graphene

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Letizia Ferbel, Stefano Veronesi, Tevfik Onur Mentes, Lars Buß, Antonio Rossi, Neeraj Mishra, Camilla Coletti, Jan Ingo Flege, Andrea Locatelli, Stefan Heun

Alkali metal intercalation of graphene layers has been of particular interest due to potential applications in electronics, energy storage, and catalysis. Rubidium (Rb) is one of the largest alkali metals and the one less investigated as intercalant. Here, we report a systematic investigation, with a multi-technique approach, of the phase formation of Rb under epitaxial monolayer graphene on SiC(0001). We explore a wide phase space with two control parameters: the Rb density (i.e., deposition time) and sample temperature (i.e., room- and low-temperature). We reveal the emergence of \((2 \times 2)\) and \((\sqrt{3} \times \sqrt{3})\)R30° structures formed by a single alkali metal layer intercalated between monolayer graphene and the interfacial C-rich reconstructed surface, also known as buffer layer. Rb intercalation also results in a strong n-type doping of the graphene layer. Progressively annealing to high temperatures, we first reveal diffusion of Rb atoms which results in the enlargement of intercalated areas. As desorption sets in, intercalated regions progressively shrink and fragment. Eventually, at approximately 600°C the initial surface is retrieved, indicating the reversibility of the intercalation process.

arXiv:2501.10477 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Driving a Quantum Phase Transition at Arbitrary Rate: Exact solution of the Transverse-Field Ising model

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

András Grabarits, Federico Balducci, Adolfo del Campo

We study the crossing of the quantum phase transition in the transverse-field Ising model after modulating the magnetic field at an arbitrary rate, exploring the critical dynamics from the slow to the sudden quench regime. We do so by analyzing the defect density, the complete kink number distribution, and its cumulants upon completion of a linearized quench. Our analysis relies on the diagonalization of the model using the standard Jordan-Wigner and Fourier transformations, along with the exact solution of the time evolution in each mode in terms of parabolic cylinder functions. The free-fermion nature of the problem dictates that the kink number distribution is associated with independent and distinguishable Bernoulli variables, each with a success probability \(p_k\). We employ a combination of convergent and asymptotic series expansions to characterize \(p_k\) without restrictions on the driving rate. When the latter is approximated by the Landau-Zener formula, the kink density is described by the Kibble-Zurek mechanism, and higher-order cumulants follow a universal power-law behavior, as recently predicted theoretically and verified in the laboratory. By contrast, for moderate and sudden driving protocols, the cumulants exhibit a nonuniversal behavior that is not monotonic on the driving rate and changes qualitatively with the cumulant order. The kink number statistics remain sub-Poissonian for any driving rate, as revealed by an analysis of the cumulant rations that vary nonmonotonically from the sudden to the slow-driving regime. Thanks to the determination of \(p_k\) for an arbitrary rate, our study provides a complete analytical understanding of kink number statistics from the slow driving regime to the sudden quench limit.

arXiv:2501.10478 (2025)

Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)

8 figures, 20 pages

Non-contact quantitative measurement of thermal Hall angle and transverse thermal conductivity by lock-in thermography

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Takumi Imamura, Takamasa Hirai, Koichi Oyanagi, Ryo Iguchi, Kenta Takamori, Satoru Kobayashi, Ken-ichi Uchida

We propose and demonstrate a non-contact quantitative measurement method for the thermal Hall effect (THE) based on magnetic-field-modulated lock-in thermography. This method enables visualization of THE-induced temperature change and quantitative estimation of the thermal Hall angle \(\theta_{\rm THE}\) by applying periodic magnetic fields to a sample and obtaining the first harmonic response of thermal images. By combining this method with LIT-based measurement techniques for the longitudinal thermal conductivity \(\kappa_{xx}\), we also quantify the transverse thermal conductivity \(\kappa_{xy}\). We validate our measurement methods by estimating \(\theta_{\rm THE}\), \(\kappa_{xx}\), and \(\kappa_{xy}\) in a ferromagnetic Heusler alloy Co\(_2\)MnGa slab showing large THE.

arXiv:2501.10485 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)

18 pages, 6 figures

Frozonium: Freezing Anharmonicity in Floquet Superconducting Circuits

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Keiran Lewellen, Rohit Mukherjee, Haoyu Guo, Saswata Roy, Valla Fatemi, Debanjan Chowdhury

Floquet engineering is a powerful method that can be used to modify the properties of interacting many-body Hamiltonians via the application of periodic time-dependent drives. Here we consider the physics of an inductively shunted superconducting Josephson junction in the presence of Floquet drives in the fluxonium regime and beyond, which we dub the frozonium artificial atom. We find that in the vicinity of special ratios of the drive amplitude and frequency, the many-body dynamics can be tuned to that of an effectively linear bosonic oscillator, with additional nonlinear corrections that are suppressed in higher powers of the drive frequency. By analyzing the inverse participation ratios between the time-evolved frozonium wavefunctions and the eigenbasis of a linear oscillator, we demonstrate the ability to achieve a novel dynamical control using a combination of numerical exact diagonalization and Floquet-Magnus expansion. We discuss the physics of resonances between quasi-energy states induced by the drive, and ways to mitigate their effects. We also highlight the enhanced protection of frozonium against external sources of noise present in experimental setups. This work lays the foundation for future applications in quantum memory and bosonic quantum control using superconducting circuits.

arXiv:2501.10503 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)

14 pages, 9 figures

Quantitative Theory for Critical Conditions of Like-Charge Attraction Between Polarizable Spheres

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Yanyu Duan, Zecheng Gan

Despite extensive experimental and theoretical efforts, a concise quantitative theory to predict the occurrence of like-charge attraction (LCA) between polarizable spheres remains elusive. In this work, we first derive a novel three-point image formula, based on a key observation that connects the classical Neumann's image principle with the incomplete beta function. This approach naturally yields simple yet precise critical conditions for LCA, with a relative discrepancy of less than \(1\%\) compared to numerical simulations, validated across diverse parameter settings. The obtained critical conditions may provide physical insights into various processes potentially involving LCA, such as self-assembly, crystallization, and phase separation across different length scales. Additionally, the new image formula is directly applicable to enhance the efficiency of polarizable force field calculations involving polarizable spheres.

arXiv:2501.10516 (2025)

Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)

21 pages, 4 figures

Thermalization in Quantum Fluids of Light: A Convection-Diffusion Equation

New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-22 20:00 EST

Vladislav Yu. Shishkov, Ivan V. Panyukov, Evgeny S. Andrianov, Anton V. Zasedatelev

We develop a microscopic theory for the dynamics of quantum fluids of light, deriving an effective kinetic equation in momentum space that takes the form of the convection-diffusion equation. In the particular case of two-dimensional systems with parabolic dispersion, it reduces to the Bateman--Burgers equation. The hydrodynamic analogy unifies nonlinear wave phenomena, such as shock wave formation and turbulence, with non-equilibrium Bose--Einstein condensation of photons and polaritons in optical cavities. We introduce the Reynolds number \((\textit{Re})\) and demonstrate that the condensation threshold corresponds exactly to a critical Reynolds number of unity \((\textit{Re}=1)\), beyond which \((\textit{Re} > 1)\) a shock-like front emerges in the momentum space, characterized by the Bose--Einstein distribution for the particle density in states with high momentum.

arXiv:2501.10537 (2025)

Quantum Gases (cond-mat.quant-gas)

Amorphous silicon structures generated using a moment tensor potential and the activation relaxation technique nouveau

New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-22 20:00 EST

Karim Zongo, Hao Sun, Claudiane Ouellet-Plamondon, Normand Mousseau, Laurent Karim Béland

Preparing realistic atom-scale models of amorphous silicon (a-Si) is a decades-old condensed matter physics challenge. Herein, we combine the Activation Relaxation Technique nouveau (ARTn) to a Moment Tensor Potential (MTP) to generate seven a-Si models containing between 216 and 4096 atoms. A thorough analysis of their short-range and medium-range structural properties is performed, alongside assessments of excess energy and mechanical properties. The seven ARTn-MTP models are compared with available experimental data and other high quality a-Si models present in the literature. The seven ARTn-MTP a-Si models are in excellent agreement with available experimental data. Notably, several of our models, including the 216-atom, 512-atom, and 1000-atom a-Si models, exhibit low coordination defects without any traces of crystalline grains. Historically overlooked in previous research, our study underlines the need to assess the validity of the continuous random-network hypothesis for the description of perfect amorphous model by characterizing local crystalline environment and to explore the crystallisation process of a-Si through modelling.

arXiv:2501.10549 (2025)

Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci)

Polymer-based solid-state electrolytes for lithium sulfur batteries

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Praveen Balaji T, Soumyadip Choudhury, Ernesto E. Marinero

Lithium-sulfur (Li-S) batteries offer substantial theoretical energy density gains over Li-ion bat-teries, a crucial factor for transportation electrification. In addition, sulfur is an earth-abundant, inexpensive material obtainable from multiple resources; thus, Li-S batteries are envisioned to provide environmentally sustainable solutions to the growing demand for energy storage. A crit-ical roadblock to the realization of commercial Li-S batteries is the formation of polysulfides and their secondary reactions with liquid organic electrolytes, resulting in low coulombic efficiency for charging and fast self-discharge rates. The realization of solid-state electrolytes for Li-S bat-teries provides potential pathways to address the safety concerns of liquid electrolytes and inhib-it the formation of polysulfides and/or prevent their diffusion into the anode electrode. However, current solid-state electrolytes are limited by low ionic conductivity, inadequate electrode inter-facial compatibility, and restricted electrochemical windows. This review discusses the status of polymer-based electrolytes for Li-S batteries, and outlines current methods for their fabrication, their transport characteristics and ongoing research aimed at overcoming material properties hindering the development of all-solid-state Li-S batteries.

arXiv:2501.10567 (2025)

Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)

32 pages, 7 figures

Properties of two level systems in current-carrying superconductors

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

T. Liu, A. V. Andreev, B. Z. Spivak

At low temperatures, the physical properties of disordered solids are dominated by two-level systems (TLS). We show that in disordered superconductors, at sufficiently low frequencies \(\omega\), the coupling of TLS to external ac electric fields increases dramatically in the presence of a dc supercurrent. This giant enhancement manifests in all ac linear and nonlinear phenomena. In particular, it leads to a parametric enhancement of the real part of the ac conductivity and, consequently, of the equilibrium current fluctuations. If the distribution of TLS relaxation times is broad, the conductivity is inversely proportional to \(\omega\), and the spectrum of the equilibrium current fluctuations takes the form of 1/f noise.

arXiv:2501.10619 (2025)

Superconductivity (cond-mat.supr-con)

Effects of particle elongation on dense granular flows down a rough inclined plane

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Jixiong Liu, Lu Jing, Thomas Pähtz, Yifei Cui, Gordon G. D. Zhou, Xudong Fu

Granular materials in nature are nearly always non-spherical, but particle shape effects in granular flow remain largely elusive. This study uses discrete element method simulations to investigate how elongated particle shapes affect the mobility of dense granular flows down a rough incline. For a range of systematically varied particle length-to-diameter aspect ratios (AR), we run simulations with various flow thicknesses \(h\) and slope angles \(\theta\) to extract the well-known \(h_\textrm{stop}(\theta)\) curves (below which the flow ceases) and the \(Fr\)-\(h/h_\textrm{stop}\) relations following Pouliquen's approach, where \(Fr=u/\sqrt{gh}\) is the Froude number, \(u\) is the mean flow velocity, and \(g\) is the gravitational acceleration. The slope \(\beta\) of the \(Fr\)-\(h/h_\textrm{stop}\) relations shows an intriguing S-shaped dependence on AR, with two plateaus at small and large AR, respectively, transitioning with a sharp increase. We understand this S-shaped dependence by examining statistics of particle orientation, alignment, and hindered rotation. We find that the rotation ability of weakly elongated particles (\(\textrm{AR}\lesssim1.3\)) remains similar to spheres, leading to the first plateau in the \(\beta\)-AR relation, whereas the effects of particle orientation saturates beyond \(\textrm{AR}\approx2.0\), explaining the second plateau. An empirical sigmoidal function is proposed to capture this non-linear dependence. The findings are expected to enhance our understanding of how particle shape affects the flow of granular materials from both the flow- and particle-scale perspectives.

arXiv:2501.10626 (2025)

Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)

Physical Review E 110 (4), 044902 (2024)

Unified Flow Rule of Undeveloped and Fully Developed Dense Granular Flows Down Rough Inclines

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Yanbin Wu, Thomas Pähtz, Zixiao Guo, Lu Jing, Zhao Duan, Zhiguo He

We report on chute measurements of the free-surface velocity \(v\) in dense flows of spheres and diverse sands and spheres-sand mixtures down rough inclines. These and previous measurements are inconsistent with standard flow rules, in which the Froude number \(v/\sqrt{gh}\) scales linearly with \(h/h_s\) or \((\tan\theta/\mu_r)^2h/h_s\), where \(\mu_r\) is the dynamic friction coefficient, \(h\) the flow thickness, and \(h_s(\theta)\) its smallest value that permits a steady, uniform dense flow state at a given inclination angle \(\theta\). This is because the characteristic length \(L\) a flow needs to fully develop can exceed the chute or travel length \(l\) and because neither rule is universal for fully developed flows across granular materials. We use a dimensional analysis motivated by a recent unification of sediment transport to derive a flow rule that solves both problems in accordance with our and previous measurements: \(v=v_\infty[1-\exp(-l/L)]^{1/2}\), with \(v_\infty\propto\mu_r^{3/2}\left[(\tan\theta-\mu_r)h\right]^{4/3}\) and \(L\propto\mu_r^3\left[(\tan\theta-\mu_r)h\right]^{5/3}h\).

arXiv:2501.10631 (2025)

Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn), Geophysics (physics.geo-ph)

Physical Review Letters 134 (2), 028201 (2025)

Spin-Degenerate Bulk Bands and Topological Surface States of RuO2

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

T. Osumi, K. Yamauchi, S. Souma, P. Shubhankar, A. Honma, K. Nakayama, K. Ozawa, M. Kitamura, K. Horiba, H. Kumigashira, C. Bigi, F. Bertran, T. Oguchi, T. Takahashi, Y. Maeno, T. Sato

Altermagnets are a novel platform to realize exotic electromagnetic properties distinct from those of conventional ferromagnets and antiferromagnets. We report results of micro-focused angle-resolved photoemission spectroscopy (ARPES) on RuO2, of which altermagnetic nature has been under fierce debate. We have elucidated the band structure of the (100), (110) and (101) surfaces of a bulk single crystal. We found that, irrespective of the surface orientation, the experimental band structures obtained by ARPES commonly show a semi-quantitative agreement with the bulk-band calculation for the nonmagnetic phase, but display a severe disagreement with that for the antiferromagnetic phase. Moreover, spin-resolved ARPES signifies a negligible spin polarization for the bulk bands. These results suggest the absence of antiferromagnetism and altermagnetic spin splitting. Furthermore, we identified a flat surface band and a dispersive one near the Fermi level at the (100)/(110) and (101) surfaces, respectively, both of which are attributed to the topological surface states associated with the bulk Dirac nodal lines. The present ARPES results suggest that the crystal-orientation-dependent topological surface/interface states need to be taken into account to properly capture the transport and catalytic characteristics of RuO2.

arXiv:2501.10649 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

29 pages, 9 figures

Magnetic switching of phonon angular momentum in a ferrimagnetic insulator

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Fangliang Wu, Jing Zhou, Song Bao, Liangyue Li, Jinsheng Wen, Yuan Wan, Qi Zhang

Phonons, which carry circular atomic motions, offer a new route for mediating angular momentum in solids. However, controlling phonon angular momentum without altering the material's structure or composition remains challenging. Here, we demonstrate the non-volatile switching of angular momentum-carrying phonons by leveraging intrinsic ferrimagnetism in an insulator. We find a pair of chiral phonons with giant energy splitting reaching 20% of the phonon frequency, due to spontaneously broken time-reversal symmetry. With a moderate magnetic field, the phonon angular momentum of the two chiral phonon branches can be switched along with the magnetization. Notably, near the critical temperature, the effective phonon magnetic moment is enhanced, reaching 2.62 Bohr magneton, exceeding the moment of a magnon. A microscopic model based on phonon-magnon coupling accounts for the observations. Furthermore, we identify two types of phononic domains with opposite phonon Zeeman splitting and propose the existence of topologically protected phononic edge modes at domain boundaries. These results demonstrate effective manipulation of chiral phonons with magnetism, and pave the way for engineering chiral phononic domains on the micrometer scale.

arXiv:2501.10650 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Role of Random Interaction Connection in the Order Transition of Active Matter Based on the Vicsek Model

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Ruizhi Jin, Kejun Dong

Randomness plays a key role in the order transition of active matter but has not yet been explicitly considered in pairwise interaction connection. In this letter, we introduce the perception rate P into the Vicsek model as the probability of the interaction connections and model the connections as superposition states. We show that with increasing P, the polar order number undergoes an order transition and then saturation. The order transition is a first-order phase transition with band formation, and the effect of P is different from density. The change of the order number is linked with the interaction structure. The order transition, order saturation, and phase separation correspond to different critical changes in the local interaction number. The global interaction structure is further analyzed as a network. The decrease of P is comparable to random edge removal, under which the network experiences modal transitions near the critical points of the order number, and the network exhibits surprising robustness. Our results suggest that random interaction can be a new important factor in active matter models, with potential applications in robotic swarms and social activities.

arXiv:2501.10669 (2025)

Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn)

8 pages, 5 figures

Multilayered MXenes for future two-dimensional nonvolatile magnetic memories

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

P. Kumar, Y. Miura, Y. Kotani, A. Sumiyoshiya, T. Nakamura, Gaurav K. Shukla, S. Isogami

MXenes have attracted considerable attention in recent years due to their two-dimensional (2D) layered structure with various functionalities similar to the existing graphene and transition metal dichalcogenides. Aiming to open a new application field for MXenes in the realm of electronic devices such as ultrahigh-integrated magnetic memory, we have developed a spin-orbit torque (SOT) bilayer structure consisting of bare MXene of Cr2N: substrate//Cr2N/[Co/Pt]3/MgO using magnetron sputtering technique. We demonstrate the field-free current-induced magnetization switching (CIMS) in the Hall-cross configuration with the critical current density of ~30 MA/cm2. An attempt to replace the Cr2N layer by the Pt layer leads to the absence of field-free CIMS. As the SOT efficiency increases with increasing the Cr2N thickness, the first-principles calculation predicts the pronounced orbital-Hall conductivity in the out-of-plane component, compared to the spin-Hall conductivity in the Cr2N. X-ray magnetic circular dichroism reveals the out-of-plane uncompensated magnetic moment of Cr in the Cr2N layer at the interface, by contacting with Co in the [Co/Pt]3 ferromagnetic layer. The interfacial spin-filtering-like effect against the out-of-plane polarized spin owing to the uncompensated magnetic moment of Cr might be a possible cause for the field-free CIMS. These results show a significant milestone in the advanced 2D-spintronics, promising low-power and ultrahigh-integration.

arXiv:2501.10678 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)

Variations of saturation vapor pressure and evaporation rate with cohesive energy of liquids

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Xuefeng Xu

Cohesion energy is an important property of liquid, and thus should affect the saturation vapor pressure and the evaporation rate of the liquids. Here, an analytical expression that relates the saturation vapor pressure of a liquid with its cohesive energy was first deduced, and the relationship of the evaporation rate of sessile liquid droplet to the liquid cohesive energy was then obtained.

arXiv:2501.10683 (2025)

Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)

Centenary progress from the Nernst theorem to the Nernst statement

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Xiaohang Chen, Shanhe Su, Yinghui Zhou, Jincan Chen

It is found from textbooks that there are the different versions of the schematic diagram related to the Nernst equation, and consequently, it leads to some discussion related to the Nernst equation and the discovery of other meaningful schematic diagrams never appearing in literature. It is also found that through the introduction of a new function, the schematic diagram of the Nernst equation in the isothermal process of any thermodynamic system can be generated in a unified way and that the Nernst equation can be re-obtained from the experimental data of low-temperature chemical reactions without any artificial additional assumptions. The results obtained here show clearly that the centenary progress from the Nernst theorem to the Nernst statement is completed.

arXiv:2501.10701 (2025)

Statistical Mechanics (cond-mat.stat-mech), Popular Physics (physics.pop-ph)

Microwave-driven synthesis and modification of nanocarbons and hybrids in liquid and solid phases

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Nagaraj Nandihalli

Over the past 20 years, nanocarbons have become more significant as nanostructured fillers in composites and, more recently, as functional elements in a brand-new class of hybrid materials. Microwave-assisted synthesis and processing is a burgeoning subject matter in materials research with significant strides in the realm of nanocarbon during the last decade. The review examines recent approaches to producing various nanocarbons using microwaves as energy sources, the characterization of such materials for various applications, and their results. The underlying factors supporting the increased performance of such materials or their composites are analyzed and reaction mechanisms are presented wherever necessary. In particular, the recently developed and verified approaches to produce porous carbon materials, CNTs and fibers, carbon nanospheres, carbon dots, CQDs, reduced graphene oxide, nanocarbon hybrid materials, and the purification and modification of CNTs are discussed. The reduction of graphene oxide and the preparation of graphene derivative hybrids using solid-state and liquid-state routes such as polyopl, mixed solvents, ionic liquids, and microwave-assisted hydrothermal/solvothermal methods are analyzed in detail. In addition, the principles of microwave heating in liquid and solid states, the use of metals particles as arcing agents or catalysts, and carbonaceous materials as internal or external susceptors during synthesis and modifications are presented in detail.

arXiv:2501.10706 (2025)

Materials Science (cond-mat.mtrl-sci)

Journal of Energy Storage 2025, 111, 115315

Optimal control for preparing fractional quantum Hall states in optical lattices

New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-22 20:00 EST

Ling-Na Wu, Xikun Li, Nathan Goldman, Botao Wang

Preparing fractional quantum Hall (FQH) states represents a key challenge for quantum simulators. While small Laughlin-type states have been realized by manipulating two atoms or two photons, scaling up these settings to larger ensembles stands as an impractical task using existing methods and protocols. In this work, we propose to use optimal-control methods to substantially accelerate the preparation of small Laughlin-type states, and demonstrate that the resulting protocols are also well suited to realize larger FQH states under realistic preparation times. Our schemes are specifically built on the recent optical-lattice experiment [Leonard et al., Nature (2023)], and consist in optimizing very few control parameters: the tunneling amplitudes and linear gradients along the two directions of the lattice. We demonstrate the robustness of our optimal-control schemes against control errors and disorder, and discuss their advantages over existing preparation methods. Our work paves the way to the efficient realization of strongly-correlated topological states in quantum-engineered systems.

arXiv:2501.10720 (2025)

Quantum Gases (cond-mat.quant-gas), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)

Density of States Calculation of CeO\(_2\) Based on VASP

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Ruyi Hou

In this study, the Density of States (DOS) of CeO\(_2\) was analyzed in detail using the Density Functional Theory (DFT) method based on VASP software. As an important functional material, CeO\(_2\) finds wide applications in catalysis, optics, and electronic devices. Through structural optimization, self-consistent electronic calculations, and non-self-consistent calculations, we thoroughly investigated the crystal structure and electronic energy level distribution of CeO\(_2\). The lattice parameter optimization results from the structural calculations indicated a stable crystal structure for CeO\(_2\). Self-consistent electronic calculations revealed a bandgap of approximately 2.403 eV, with the valence band maximum primarily contributed by O 2p orbitals and the conduction band minimum mainly originating from Ce 4f orbitals. Non-self-consistent calculations further demonstrated the total DOS and partial DOS of CeO\(_2\), confirming the significant roles of Ce 4f and O 2p states in its electronic conduction and optical properties. These results not only provide theoretical support for the applications of CeO\(_2\) in catalysis and electronic materials but also deepen our understanding of its fundamental electronic structural characteristics, offering guidance for the design and development of novel CeO\(_2\)-based materials.

arXiv:2501.10724 (2025)

Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)

6 pages, 3 figures

Unraveling screening mechanisms in Kondo impurities using an NRG-MPS-based method

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Lidia Stocker, Oded Zilberberg

The Kondo effect is a hallmark of strongly-correlated systems, where an impurity's local degrees of freedom are screened by conduction electrons, forming a many-body singlet. With increasing degrees of freedom in the impurity, theoretical studies face significant challenges in accurately identifying and characterizing the underlying mechanisms that screen the impurity. In this work, we introduce a straightforward yet powerful methodology for identifying the formation of Kondo singlets and their screening mechanisms, by utilizing the numerical renormalization group (NRG) combined with the matrix product states (MPS) technique. We demonstrate the effectiveness of our method on the single and two-level Anderson impurity models (AIM). Furthermore, we discuss potential generalizations of the method to multichannel and multiorbital Kondo impurities. Harnessing advanced tensor network techniques, our approach extends to complex impurity systems, offering a robust and versatile framework for studying Kondo physics.

arXiv:2501.10746 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

9 pages, 4 figures, comments are welcome

Theory of spin magnetization driven by chiral phonons

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Dapeng Yao, Shuichi Murakami

We construct a general theory of spin magnetization driven by chiral phonons under an adiabatic process, in which atoms rotate around their equilibrium positions with a low phonon frequency. Here the spin magnetization originates from the modulated electronic states with spin-orbital coupling by atomic rotations. Under the adiabatic approximation, the time-dependent spin magnetization can be calculated by a Berry-phase method. In this paper, we focus on its time average, which is evaluated by assuming that the phonon displacement is small. As a result, the time average of the spin magnetization is concisely formulated in the form of the Berry curvature defined in the phonon-displacement space as an intrinsic property of atomic rotations. Our formula for spin magnetization reflects the chiral nature of phonons, and is convenient for \(ab\) \(initio\) calculations.

arXiv:2501.10766 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

9 pages, 3 figures

Nanoscale defects and heterogeneous cavitation in water

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Marin Šako, Fabio Staniscia, Roland R. Netz, Emanuel Schneck, Matej Kanduč

Cavitation, the formation of vapor bubbles in metastable liquids, is highly sensitive to nanoscale surface defects. Using molecular dynamics simulations and classical nucleation theory, we show that pure water confined within defect-free walls can withstand extreme negative pressures, far beyond those observed experimentally. Hydrophobic surfaces trigger heterogeneous cavitation and lower the cavitation pressure magnitude, but not to experimental levels. Notably, a single nanoscopic surface defect capable of hosting a vapor bubble drastically reduces the tensile strength of water. We find that defects as small as 1-2 nm can act as effective cavitation nuclei, a scale smaller than predicted by simple mechanical stability arguments. This discrepancy arises from stochastic fluctuations of the vapor bubble, which can overcome the kinetic free-energy barrier for cavitation. Our findings show that cavitation is predominantly determined by the largest surface defect rather than the overall defect density, emphasizing the importance of eliminating the largest surface imperfections to enhance stability against cavitation.

arXiv:2501.10776 (2025)

Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph), Fluid Dynamics (physics.flu-dyn)

10 pages, 7 figures

Boundary curvature-dependent dynamical trapping of undulating worms

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Sohum Kapadia, Arshad Kudrolli

We investigate the behavior of {} in polygonal chambers and show that the worms align with the boundaries as they move forward and get dynamically trapped at concave corners over prolonged periods of time before escaping. We develop a kinematic model to calculate and describe the evolution of the worm's mean body orientation angle relative to the boundary. Performing simulations with a minimal active elastic dumbbell model, we then show that both the boundary aligning and corner trapping behavior of the worm are captured by steric interactions with the boundaries. The dimensionless ratio of the strength of forward motion and diffusion caused by the worm's undulatory and peristaltic strokes is shown to determine the boundary alignment dynamics and trapping time scales of the worm. The simulations show that that the body angle with the boundary while entering the concave corner is important to the trapping time distributions with shallow angles leading to faster escapes. Our study demonstrates that directed motion and limited angular diffusion can give rise to aggregation which can mimic shelter seeking behavior in slender undulating limbless worms even when thigmotaxis or contact seeking behavior is absent.

arXiv:2501.10783 (2025)

Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)

this http URL contains supplementary information

Materials design criteria for ultra-high thermoelectric power factors in metals

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Patrizio Graziosi, Kim-Isabelle Mehnert, Rajeev Dutt, Jan-Willem G. Bos, Neophytos Neophytou

Metals have high electronic conductivities, but very low Seebeck coefficients, which traditionally make them unsuitable for thermoelectric materials. Recent studies, however, showed that metals can deliver ultra-high thermoelectric power factors (PFs) under certain conditions. In this work, we theoretically examine the electronic structure and electronic transport specifications which allow for such high PFs. Using Boltzmann transport (BTE) simulations and a multi-band electronic structure model, we show that metals with: i) high degree of transport asymmetry between their bands, ii) strong inter-band scattering, and iii) a large degree of band overlap, can provide ultra-high power factors. We show that each of these characteristics adds to the steepness of the transport distribution function of the BTE, which allows for an increase of the Seebeck coefficient to sizable values, simultaneously with an increase in the electrical conductivity. This work generalizes the concept that transport asymmetry (i.e., mixture of energy regions of high and low contributions to the electrical conductivity), through a combination of different band masses, scattering strengths, or energy filtering scenarios, etc., can indeed result in very high thermoelectric power factors, even in the absence of a material bandgap. Under certain conditions, transport asymmetry can over-compensate any performance degradation to the PF due to bipolar conduction and the naturally low Seebeck coefficients that otherwise exist in this class of materials.

arXiv:2501.10790 (2025)

Materials Science (cond-mat.mtrl-sci)

paper and supporting information, 50 pages

PRX Energy 3, 043009, 2024

Tuning magnetism in graphene nanoribbons via strain and adatoms

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Pablo Moles, Hernán Santos, Francisco Domínguez-Adame, Leonor Chico

We investigate the impact of strain and adsorbed H adatoms on the magnetic properties of zigzag graphene nanoribbons (ZGNRs) using a combination of tight-binding and density functional theory methods for both, ferromagnetic (FM) and antiferromagnetic edge configurations (AFM). Our study reveals that longitudinal strain induces a significant enhancement in the edge magnetic moment, that we attribute to strain-driven modifications in the band structure. In addition, we describe H~adatoms within the tight-binding approach by employing both an unrelaxed vacancy model and the Anderson impurity model. By comparing to density functional theory results, we corroborate that the Anderson impurity model is best suited to describe H adsorption. We then focus on the metallic FM edge configuration of the ZGNRs to better exploit the tuning of its properties. We find that the magnetic configuration of H~adatoms is strongly influenced by the edges, with an AFM coupling between edges and the H~adatom. In fact, the magnetic spatial pattern of the H adatom differs to that found in graphene due to this edge coupling. Importantly, we find robust discrete plateaus of integer magnetic moment as strain is varied in the defected ZGNRs, that we relate to changes in the band structure, namely, a half-metallic character or the opening of a gap. This behavior can be of interest for magnetic applications of carbon-based nanostructures

arXiv:2501.10801 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Surface impedance measurements in superconductors in dc magnetic fields: challenges and relevance to particle physics experiments

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Andrea Alimenti, Nicola Pompeo, Kostiantyn Torokhtii, Enrico Silva

Particle physics and radio-frequency (RF) superconductivity have driven each other on since the 1970s. The unique properties of superconductors (SC) have been the enabling keys for the realization of accelerators with always increased performances thanks to the realization of all-superconducting cavities. The use of increasingly pure superconducting coatings for accelerating cavities, with lower and lower RF losses, determined such high-quality factors that the need to operate at low temperatures (below the superconducting transition temperature Tc) was well paid for. Recently, with respect to the path followed by the high frequency superconductivity, a new field opened since SCs are being considered for GHz operation in high dc magnetic fields, and measurements (and optimization) of totally different quantities are needed. The possibility of successfully using SCs in high magnetic fields for these purposes is far from obvious and it depends on the outcome of accurate measurements of usually overlooked quantities.

arXiv:2501.10804 (2025)

Superconductivity (cond-mat.supr-con), High Energy Physics - Experiment (hep-ex)

19 pages, 5 figures, published in: IEEE Instrumentation & Measurement Magazine

IEEE Instrumentation & Measurement Magazine, vol. 24, no. 9, pp. 12-20, December 2021

Experimental models for cohesive granular materials: a review

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Ram Sudhir Sharma, Alban Sauret

Granular materials are involved in most industrial and environmental processes, as well as many civil engineering applications. Although significant advances have been made in understanding the statics and dynamics of cohesionless grains over the past decades, most granular systems we encounter often display some adhesive forces between grains. The presence of cohesion has effects at distances substantially larger than the closest neighbors and consequently can greatly modify their overall behavior. While considerable progress has been made in understanding and describing cohesive granular systems through idealized numerical simulations, controlled experiments corroborating and expanding the wide range of behavior remain challenging to perform. In recent years, various experimental approaches have been developed to control inter-particle adhesion that now pave the way to further our understanding of cohesive granular flows. This article reviews different approaches for making particles sticky, controlling their relative stickiness, and thereby studying their granular and bulk mechanics. Some recent experimental studies relying on model cohesive grains are synthesized, and opportunities and perspectives in this field are discussed.

arXiv:2501.10830 (2025)

Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn), Geophysics (physics.geo-ph)

Ordered InAs quantum dots on pre-patterned GaAs (0 0 1) by local oxidation nanolithography

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

J. Martín-Sánchez, Y. González, L. González, M. Tello, R. García, D. Granados, J.M. García, F. Briones

Ordered InAs quantum dot (QD) arrays have been obtained on pre-patterned GaAs (0 0 1) substrates by atomic force microscopy (AFM) local oxidation nanolithography. Prior to InAs molecular beam epitaxy (MBE) deposition, an ordered square array of nanoholes is formed at the GaAs pre-patterned surface following in situ etching with atomic hydrogen. A low substrate temperature is maintained during the whole process in order to avoid pattern smoothing. Our results show that the density and dimensions of the nanoholes on the GaAs surface determine InAs QD size, nucleation site and InAs dose necessary for their formation. As a function of the geometrical parameters of the nanohole array, we can obtain either ordered 2D arrays of separated QD, closely packed QD or localized areas for QD formation.

arXiv:2501.10849 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)

J. Crystal Growth 284, 313-318 (2005)

Stokes flow in the electronic fluid with odd viscosity

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Yonatan Messica, Alex Levchenko, Dmitri B. Gutman

We investigate the Stokes flow around a slowly moving sphere in a fluid with odd viscosity, focusing on a system of electrons in a Weyl semimetal with a single axis of asymmetry arising from broken time-reversal symmetry. We analyze the flow around the sphere, compute the Hall force acting perpendicular to its direction of motion, and study the implications for the Hall resistivity of Weyl semimetals in the hydrodynamic regime.

arXiv:2501.10890 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn)

5+2 pages, 1 figure. Comments welcome!

Is p-Type Doping in SeO2 Feasible?

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Zewen Xiao

The significance of p-type transparent oxide semiconductors (TOS) in the semiconductor industry is paramount, driving advancements in optoelectronic technologies for transparent electronic devices with unique properties. The recent discovery of p-type behavior in SeO2 has stirred both interest and confusion in the scientific community. In this Letter, we employ density functional theory calculations to unveil the intrinsic insulating characteristics of SeO2, highlighting substantial challenges in carrier doping. Our electronic structure analyses indicate that the Se 5s2 states are energetically positioned too low to effectively interact with the O 2p orbitals, resulting in a valence band maximum (VBM) primarily dominated by the O 2p orbitals. The deep and localized nature of the VBM in SeO2 limits its potential as a high-mobility p-type TOS. Defect calculations demonstrate that all intrinsic defects in SeO2 exhibit deep transition levels within the bandgap. The Fermi level consistently resides in the mid-gap region, regardless of synthesis conditions. Furthermore, deep intrinsic acceptors and donors exhibit negative formation energies in the n-type and p-type regions, respectively, facilitating their spontaneous formation and impeding external doping efforts. Thus, the reported p-type conductivity in SeO2 samples is unlikely intrinsic and is more plausibly attributed to reduced elemental Se, a well-known p-type semiconductor.

arXiv:2501.10912 (2025)

Materials Science (cond-mat.mtrl-sci)

Unveiling an in-plane Hall effect in rutile RuO\(_2\) films

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Meng Wang, Jianbing Zhang, Di Tian, Pu Yu, Fumitaka Kagawa

The in-plane-magnetic-field-induced Hall effect (IPHE) observed in Weyl semimetals and PT-symmetric antiferromagnets has attracted increasing attention, as it breaks the stereotype that the Hall effect is induced by an out-of-plane magnetic field or magnetization. To date, the IPHE has been discussed mainly for materials with low-symmetry crystal/magnetic point groups. Here, we show that even if symmetry forbids an inherent IPHE that arises from any mechanism, an apparent IPHE can be generated by selecting a low-symmetry crystalline plane for measurement. For rutile RuO\(_2\), although its high symmetry forbids an inherent IPHE, films grown along the low-symmetry (1 1 1) and (1 0 1) orientations are found to exhibit a distinct IPHE. The in-plane Hall coefficients are quantitatively reproduced by referring to the out-of-plane Hall coefficients measured for the high-symmetry (1 0 0) and (0 0 1) planes, indicating that the observed IPHE is caused by a superposition of inequivalent out-of-plane Hall effects. Similar behaviour is also observed for paramagnetic rutile systems, indicating the ubiquity of the apparent IPHE in electronic and spintronic devices with low-symmetry crystalline planes.

arXiv:2501.10931 (2025)

Materials Science (cond-mat.mtrl-sci)

4 figures

The anomalous density of states and quasi-localized vibration through homogeneous thermalization of an inhomogeneous elastic system

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Cunyuan Jiang

Amorphous solids are dynamically inhomogeneous due to in lack of translational symmetry and hence exhibit vibrational properties different from crystalline solids with anomalous low frequency vibrational density of states (VDOS) and related low temperature thermal properties. However, an interpretation of their origin from basic physical laws is still needed compared with rapidly progressed particle level investigations. In this work, we start with the quasi-equilibrium condition, which requires elastic potential energy to be homogeneously distributed even in an inhomogeneous elastic solid over long time observation. Analytical result shows that the anomalous low frequency VDOS behavior \(D(\omega) \propto \omega^4\) can be obtained when the quasi-equilibrium condition is satisfied on an inhomogeneous elastic system. Under high frequency after a crossover depending on the length scale of inhomogeneity, the power law of VDOS is changed to square \(D(\omega) \propto \omega^2\) which is Debye's law for crystalline solids. These features agree with recent particle level investigations. Our work suggest that the universal low frequency anomaly of amorphous solids can be considered as a result of homogeneous thermalization.

arXiv:2501.10947 (2025)

Soft Condensed Matter (cond-mat.soft)

Interactive Multiscale Modeling to Bridge Atomic Properties and Electrochemical Performance in Li-CO\(_2\) Battery Design

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Mohammed Lemaalem, Selva Chandrasekaran Selvaraj, Ilias Papailias, Naveen K. Dandu, Arash Namaeighasemi, Larry A. Curtiss, Amin Salehi-Khojin, Anh T. Ngo

Li-CO\(_2\) batteries show promise as energy storage solutions, offering high theoretical energy density and CO\(_2\) fixation. Their performance relies on the formation and decomposition of Li\(_2\)CO\(_3\)/C during discharge and charge cycles, respectively. We used a multiscale modeling framework that integrates Density Functional Theory (DFT), Ab-Initio Molecular Dynamics (AIMD), classical Molecular Dynamics (MD), and Finite Element Analysis (FEA) to investigate atomic and cell-level properties. The Li-CO\(_2\) battery consists of a lithium metal anode, an ionic liquid electrolyte, and a carbon cloth porous cathode with a Sb\(_{0.67}\)Bi\(_{1.33}\)Te\(_3\) catalyst. DFT and AIMD determined the electrical conductivities of Sb\(_{0.67}\)Bi\(_{1.33}\)Te\(_3\) and Li\(_2\)CO\(_3\) using the Kubo-Greenwood formalism and studied the CO\(_2\) reduction mechanism on the cathode catalyst. MD simulations calculated the CO\(_2\) diffusion coefficient, Li\(^+\) transference number, ionic conductivity, and Li\(^+\) solvation structure. The FEA model, incorporating results from atomistic simulations, reproduced experimental voltage-capacity profiles at 1 mA/cm\(^2\) and revealed spatio-temporal variations in Li\(_2\)CO\(_3\)/C deposition, porosity, and CO\(_2\) concentration dependence on discharge rates in the cathode. Accordingly, Li\(_2\)CO\(_3\) can form toroidal and thin film deposits, leading to dispersed and local porosity changes at 0.1 mA/cm\(^2\) and 1 mA/cm\(^2\), respectively. The capacity decreases exponentially from 81,570 mAh/g at 0.1 mA/cm\(^2\) to 6,200 mAh/g at 1 mA/cm\(^2\), due to pore clogging that limits CO\(_2\) transport to the cathode interior. Therefore, the performance of Li-CO\(_2\) batteries can be significantly improved by enhancing CO\(_2\) transport, regulating Li\(_2\)CO\(_3\) deposition, and optimizing cathode architecture.

arXiv:2501.10954 (2025)

Materials Science (cond-mat.mtrl-sci)

38 pages (main paper), 5 figures, graphical abstract, and supporting information file

Pseudo-Ising superconductivity induced by \(p\)-wave magnetism

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Zi-Ting Sun, Xilin Feng, Ying-Ming Xie, Benjamin T. Zhou, Jin-Xin Hu, K. T. Law

Unconventional magnetic orders usually interplay with superconductivity in intriguing ways. In this work, we propose that a conventional superconductor in proximity to a compensated \(p\)-wave magnet exhibits behaviors analogous to those of Ising superconductivity found in transition-metal dichalcogenides, which we refer to as pseudo-Ising superconductivity. The pseudo-Ising superconductivity is characterized by several distinctive features: (i) it stays much more robust under strong \(p\)-wave magnetism than usual ferromagnetism or \(d\)-wave altermagnetism, thanks to the apparent time-reversal symmetry in \(p\)-wave spin splitting; (ii) in the low-temperature regime, a second-order superconducting phase transition occurs at a significantly enhanced in-plane upper critical magnetic field \(B_{c2}\); (iii) the supercurrent-carrying state establishes non-vanishing out-of-plane spin magnetization, which is forbidden by symmetry in Rahsba and Ising superconductors. We further propose a spin-orbit-free scheme to realize Majorana zero modes by placing superconducting quantum wires on a \(p\)-wave magnet. Our work establishes a new form of unconventional superconductivity generated by \(p\)-wave magnetism.

arXiv:2501.10960 (2025)

Superconductivity (cond-mat.supr-con)

6 pages, 4 figures

The stochastic porous medium equation in one dimension

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Maximilien Bernard, Andrei A. Fedorenko, Pierre Le Doussal, Alberto Rosso

We study the porous medium equation (PME) in one space dimension in presence of additive non-conservative white noise, and interpreted as a stochastic growth equation for the height field of an interface. We predict the values of the two growth exponents \(\alpha\) and \(\beta\) using the functional RG. Extensive numerical simulations show agreement with the predicted values for these exponents, however they also show anomalous scaling with an additional "local" exponent \(\alpha_{\rm loc}\), as well as multiscaling originating from broad distributions of local height differences. The stationary measure of the stochastic PME is found to be well described by a random walk model, related to a Bessel process. This model allows for several predictions about the multiscaling properties.

arXiv:2501.10975 (2025)

Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mathematical Physics (math-ph), Probability (math.PR)

Dissipative quantum phase transitions in electrically driven lasers

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Lei-Lei Nian, Yi-Cheng Wang, Jin-Yi Wang, Long Xiong, Jing-Tao Lü

Embedding quantum dot circuits into microwave cavities has emerged as a novel platform for controlling photon emission statistics by electrical means. With such a model, we reveal previously undefined quantum phase transitions in electrically driven lasing regimes by breaking the photon gain-loss balance condition. For one-photon interaction, the scaling theory indicates that the system undergoes a continuous phase transition from thermal to coherent photon emissions, consistent with conventional laser physics. Going beyond this, a hidden discontinuous quantum phase transition from superbunched to coherent states in two-photon processes, accompanied by the bistability within a mean-field theory, is predicted. Our prediction, along with its extension to multiphoton processes, represents a key step towards accessing lasing phase transitions.

arXiv:2501.10997 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Odd-parity topological superconductivity in kagome metal RbV\(_3\)Sb\(_5\)

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Xilin Feng, Zi-Ting Sun, Ben-Chuan Lin, K. T. Law

Kagome superconductors AV\(_3\)Sb\(_5\) (A=K, Rb, Cs) have sparked considerable interest due to the presence of several intertwined symmetry-breaking phases within a single material. Recently, hysteresis and reentrant superconductivity were observed experimentally through magnetoresistance measurements in RbV\(_{3}\)Sb\(_{5}\), providing strong evidence of a spontaneous time-reversal symmetry breaking superconducting state. The unconventional magnetic responses, combined with crystalline symmetry, impose strong constraints on the possible pairing symmetries of the superconducting state. In this work, we propose that RbV\(_3\)Sb\(_5\) is an odd-parity superconductor characterized by spin-polarized Cooper pairs. The hysteresis in magnetoresistance and the reentrant superconductivity can both be explained by the formation and evolution of superconducting domains composed of non-unitary pairing. Considering the nodal properties of the kagome superconductor RbV\(_{3}\)Sb\(_{5}\), it is topological and characterized by Majorana zero modes at its boundary, which can be detected through tunneling experiments.

arXiv:2501.10998 (2025)

Superconductivity (cond-mat.supr-con)

Thermal conductivity of 3C-SiC from configuration space sampling

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Paweł T. Jochym, Jan Łażewski

Cubic silicon carbide phonon thermal conductivity has been calculated using anharmonic phonon analysis. The atomic interaction model was built using displacement-force data obtained with the High Efficiency Configuration Space Sampling (HECSS) technique and density functional theory calculated forces. In the new version of HECSS we replaced the Markov chain scheme of Metropolis-Hastings Monte-Carlo with weighting of the final sampling according to the target distribution. This increased the efficiency of the method and allowed to use -- with appropriate weight -- all generated and ab-initio evaluated samples. The quality of the proposed method is confirmed by the accuracy with which the experimental results taken from the literature were reproduced.

arXiv:2501.11008 (2025)

Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Statistical Mechanics (cond-mat.stat-mech)

Submission to SciPost Physics

Learning the Electrostatic Response of the Electron Density through a Symmetry-Adapted Vector Field Model

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Mariana Rossi, Kevin Rossi, Alan M. Lewis, Mathieu Salanne, Andrea Grisafi

A current challenge in atomistic machine learning is that of efficiently predicting the response of the electron density under electric fields. We address this challenge with symmetry-adapted kernel functions that are specifically derived to account for the rotational symmetry of a three-dimensional vector field. We demonstrate the equivariance of the method on a set of rotated water molecules and show its high efficiency with respect to number of training configurations and features for liquid water and naphthalene crystals. We conclude showcasing applications for relaxed configurations of gold nanoparticles, reproducing the scaling law of the electronic polarizability with size, up to systems with more than 2000 atoms. By deriving a natural extension to equivariant learning models of the electron density, our method provides an accurate and inexpensive strategy to predict the electrostatic response of molecules and materials.

arXiv:2501.11019 (2025)

Materials Science (cond-mat.mtrl-sci)

5 pages, 3 figures

On the correlation between entanglement and the negative sign problem

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Ping Xu, Yang Shen, Yuan-Yao He, Mingpu Qin

In this work, we study the correlation between entanglement and the negative sign problem in quantum Monte Carlo for the simulation of low-dimensional strongly correlated quantum many body systems. Entanglement entropy characterizes the difficulty of many-body simulation with tensor network state related methods, while the average sign measures the difficulty in many-body simulation for a variety of quantum Monte Carlo methods. Although there exist cases where one type of method works better than the other, it is desirable to find the possible correlation between entanglement and average sign for general hard strongly correlated systems regarding computational complexity. We take the doped two-dimensional Hubbard model as an example and numerically calculate the doping evolution of both the entanglement in the ground state with Density Matrix Renormalization Group and the average sign in the Auxiliary Field Quantum Monte Carlo simulation at low temperature. The results show that they are indeed correlated. The entanglement entropy (average sign) shows a peak (dip) around 20% doping, indicating that it is the difficult region for both methods. The vicinity of 20% doping is also the most intriguing region in both the Hubbard model and cuprate high-Tc superconductors where competing states with close energy intertwine with each other. Recognizing the correlation between entanglement and average sign provides new insight into our understanding of the difficulty in the simulation of strongly correlated quantum many-body systems.

arXiv:2501.11022 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)

5 pages, 2 figures

A large anomalous Hall effect and Weyl nodes in bulk FeNi\(_3\): a density functional theory study

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Shivani Thakur, Santu Baidya

In this work, we report the study of electronic structure, magnetism, and the existence of Weyl nodes in a pristine bulk FeNi\(_{3}\), a member of Fe-Ni inver alloy compounds, known as good metal catalysts with high activity and stability for water splitting for a very long time. Our observation of Weyl points in the bulk FeNi\(_{3}\) may lead to a new technology to design highly efficient topological catalysts. While the previous literature mainly focused on the thermal and catalytic properties of FeNi\(_{3}\) we report the interplay of Fe \(d\)-Ni \(d\) hybridization and spin-orbit coupling give rise to the ferromagnetic Weyl nodes in the bulk FeNi\(_{3}\). Our study shows that the ground state of the bulk FeNi\(_{3}\) is a Weyl metal with a large number of Weyl nodes at the Fermi energy away from high-symmetry \(k\)-points. Furthermore, we predict a large intrinsic anomalous Hall conductivity of about \(10000~S/m\) at the ground state. In addition, we show the existence of Weyl nodes along the high symmetry \(k\)-points \(~0.2eV\) above and \(~0.05eV\) below self-consistent Fermi level that may be achieved either by the electron or hole doping, or by external perturbation. In this article, FeNi\(_{3}\) has been studied to explore this scenario using first-principles density functional theory and subsequent Wannier90-based tight-binding method. Furthermore, we report the existence of two types of Weyl cones, type-I and type-II, \(~0.2eV\) above the Fermi level. Our report provides a realistic material to further explore the intrinsic properties related to Weyl cones, and the spintronic applications.

arXiv:2501.11025 (2025)

Materials Science (cond-mat.mtrl-sci)

5 pages, 5 figures

Revealing the role played by \(\alpha\)- and \(\beta\)-relaxation in hydrostatically compressed metallic glasses

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Jie Shen, Antoine Cornet, Alberto Ronca, Eloi Pineda, Fan Yang, Jean-Luc Garden, Gael Moiroux, Gavin Vaughan, Marco di Michiel, Gaston Garbarino, Fabian Westermeier, Celine Goujon, Murielle Legendre, Jiliang Liu, Daniele Cangialosi, Beatrice Ruta

Any property of metallic glasses is controlled by the microscopic ongoing relaxation processes. While the response of these processes to temperature is well documented, little is known on their pressure dependence, owning to non-trivial experimental challenges. By combining fast differential scanning calorimetry, X-ray diffraction and high-pressure technologies, we identify the origin of a recently discovered pressure-induced rejuvenation in metallic glasses from the different pressure response of the \(\alpha\)- and \(\beta\)-relaxation in a series of hydrostatically compressed Vit4 glasses. While the localized \(\beta\)-relaxation promotes rejuvenation and is associated to a constant looser atomic packing independent of the applied pressure, the collective \(\alpha\)-relaxation triggers density driven ordering processes promoting the stability. The latter parameter however cannot be solely described by the degree of equilibration reached during the compression, which instead determines the crossover between the two regimes allowing to rescale the corresponding activation energies of the two processes on a master curve.

arXiv:2501.11026 (2025)

Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft)

Frustrated magnetism in antiferromagnetic nonsymmorphic square-net lattice: NdSbSe

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Prabuddha Kant Mishra, Priyanka Nehla, Rishabh Shukla, Rie Umetsu, Ashok Kumar Ganguli

Spintronics has emerged as a field of vast applicability, and layered magnetic materials have served as a ground for advancement in this direction. Here, we report the synthesis and detailed magnetic and specific heat studies on NdSbSe, (a ZrSiS-based structure) magnetic topological material. The temperature-dependent magnetization shows the presence of competing magnetic interactions (\(T_N<T<150\) K) in addition to a long-range antiferromagnetic (AFM) ordering below 4.2~K. In the AFM state, the isothermal magnetization confirms spin reorientation to the critical magnetic field of 40 kOe. Frequency-dependent ac-susceptibility measurements have probed the nonequilibrium dynamics of frustrated magnetic moments (near 150 K). The \(\lambda\)-like peak at 3.8~K observed in the specific heat shifts to a lower temperature with applied magnetic fields and validates the AFM order. In addition, the specific heat does not exhibit any sign corresponding to the short-range magnetic order near 150 K (spin-glass-like memory effect). In addition, the derived parameters from specific heat suggest the presence of a strong electronic correlation in NdSbSe, resulting in a Kondo-like signature in temperature-dependent resistivity data.

arXiv:2501.11038 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

10 pages, 7 figures

Shot-noise-driven macroscopic vibrations and displacement transduction in quantum tunnel junctions

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Prasanta Kumbhakar, Anusha Shanmugam, Akhileshwar Mishra, Ravi Pant, J L Reno, S Addamane, Madhu Thalakulam

Inherent randomness and the resulting stochastic behavior of fundamental particles manifested as quantum noise put a lower bound on measurement imprecision in the quantum measurement process. In addition, the quantum noise imparts decoherence and dephasing to the system being measured, referred to as the measurement back-action. While the microscopic effects of back-action have been observed, macroscopic evidence is a rarity. Here we report a macroscopic display of the back-action of an ultra-sensitive quantum point contact (QPC) electrical amplifier whose transport is defined by the quantum tunneling of electrons. The QPC amplifier, realized on GaAs-AlGaAs heterostructures, coupled to a planar superconducting resonator, operates at a frequency of 2.155 GHz in the shot-noise-limited regime. The shot-noise excitation of the mechanical modes and the resulting piezoelectric polarization enhancing the shot-noise at the mode frequencies form a positive feedback loop between the electrical and mechanical degrees of freedom. While the excitation of the vibrational modes is a display of the macroscopic effects of measurement back-action, the amplitudes of the noise peaks allow us to calibrate the displacement sensitivity of the QPC-resonator systems, which is in the order of 35 fm/SQRT(Hz) range, making it an excellent sensor for ultra-sensitive and fast strain or displacement detection.

arXiv:2501.11056 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

20 pages, includes supplementary informations

Refining Au/Sb alloyed ohmic contacts in undoped Si/SiGe strained quantum wells

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

LuckyDonald L Kynshi, Umang Soni, Chithra H Sharma, Shengqiang Zhou and, Madhu Thalakulam

Shallow undoped Si/SiGe quantum wells are the leading platforms for hosting quantum processors based on spin-qubits. The ohmic contacts to the electron gas in these systems are accomplished by ion-implantation technique since the conventional Au/Sb alloyed contacts present a rough surface consisting of sharp islands and pits. These sharp protrusions cause electrical discharge across the gate-dielectric between the ohmic contacts and the accumulation-gates causing device break-down. A clear understanding of the surface morphology, elemental, compositional and electrical characterization of the alloyed region would enable one to engineer a smoother post alloyed surface. In this work, we find that the rough surface morphology is a cumulative effect of the Au/Si eutectic reaction and the threading dislocations inherent in the heterostructure. The structural, elemental, and chemical-state analysis show that the inverted pyramidal pits are resulting from the enhanced Au/Si eutectic reaction at the threading dislocations stemming from the heterostructure interface, while, the sharp protrusions causing accumulation gate-leakage are gold-rich precipitations. The protrusions are removed using an aqua regia treatment prior to the deposition of the gate-oxide and gate electrode. Exploiting a Hall bar device, we analyse the mobility and carrier concentration of the undoped Si/SiGe consisting of Au/Sb alloyed contacts down to 1.5 K. The measured mobility ~10^5 cm^2/Vs and carrier concentration of ~10^11/cm2are comparable to the reported values on similar high-mobility heterostructures confirming the efficacy of our modified Au/Sb alloy technique in accomplishing high-efficiency contacts to undoped Si/SiGe heterostructures.

arXiv:2501.11059 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)

28 pages including supplementary information

Superlubric-Locked Transition of Twist Grain Boundaries in 3D Crystals

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Jin Wang, Erio Tosatti

Properties of twist grain boundaries (TGB), long known structurally but not tribologically, are simulated under sliding and load, with Au(111) our test case. The load-free TGB moiré is smooth and superlubric at incommensurate twists. Strikingly, load provokes a first-order structural transformation, where the highest energy moiré nodes are removed -- an Aubry-type transition for which we provide a Landau theory and a twist-load phase diagram. Upon frictional sliding, the transformation causes a superlubric-locked transition, with a huge friction jump, and irreversible plastic flow. The predicted phenomena are robust, also recovered in a Lennard-Jones lattice TGB, and not exclusive to gold or to metals.

arXiv:2501.11061 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)

6 pages, 5 figures

On the Topological Features of the Helical Phase Transition in MnSi

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

S.M. Stishov, A.E. Petrova, A. M. Belemuk

Many decades of study have revealed very unusual properties of the helical phase transition in MnSi. This situation is briefly described and illustrated in the present note. As one will be able to see, one peculiarity is that the phase transition point in MnSi is accompanied by extremes of different thermodynamic and kinetic quantities on the high temperature side of the transition, which look similar to a property of 2D systems. The whole situation can be tentatively described as a phase transformation of the helical phase of MnSi to the paramagnetic state, which occurs in two steps, first as a first order phase transition and then following a breakdown of topological objects such as spin vortices.

arXiv:2501.11078 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

5 pages, 8 figures

Ultrahigh interfacial thermal conductance for cooling gallium oxide electronics using cubic boron arsenide

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Wenjiang Zhou, Nianjie Liang, Wei Xiao, Zhaofei Tong, Fei Tian, Bai Song

Gallium oxide (Ga\(_2\)O\(_3\)) has attracted significant interest for its unique potential especially in power electronics. However, its low and anisotropic thermal conductivity poses a major challenge for heat dissipation. Here, we explore an effective cooling strategy centering on the heterogeneous integration of \(\beta\)-Ga\(_2\)O\(_3\) devices with cubic boron arsenide (cBAs), an emerging material with an ultrahigh thermal conductivity \(\kappa\) of ~1300 Wm\(^{-1}\)K\(^{-1}\). Machine-learned potentials for representative \(\beta\)-Ga\(_2\)O\(_3\)/cBAs interfaces are trained, enabling accurate and efficient calculation of the interfacial thermal conductance \(G\) via nonequilibrium molecular dynamics. At 300 K, remarkable \(G\) values of 749$\(33 MWm\)^{-2}\(K\){-1}$ and 824$\(35 MWm\)^{-2}\(K\){-1}$ are predicted for Ga-As and O-B bonding across the interface, respectively, which are primarily attributed to the well-matched phonon density of states considering the similar Debye temperatures of \(\beta\)-Ga\(_2\)O\(_3\) and cBAs. Moreover, finite-element simulations directly show a notable device temperature reduction when comparing cBAs with other substrates. The simultaneously ultrahigh \(\kappa\) and \(G\) highlight cBAs as an ideal substrate for Ga\(_2\)O\(_3\) electronics.

arXiv:2501.11082 (2025)

Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)

Advancing Atom Probe Tomography of SrTiO\(_3\): Measurement Methodology and Impurity Detection Limits

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

J. E. Rybak, J. Arlt, B. Gault, C. A. Volkert

Strontium titanate (STO) possesses promising properties for applications in thermoelectricity, catalysis, fuel cells, and more, but its performance is highly dependent on stoichiometry and impurity levels. While atom probe tomography (APT) can provide detailed three-dimensional atomic-scale chemical information, STO specimens have been challenging to analyze due to premature specimen fracture. In this study, we show that by applying a thin metal coating to atom probe tips, STO specimens can be analyzed with nearly 100% success. Using this approach, we investigate both undoped STO and 1 at% Nb-doped STO, achieving sufficient sensitivity to detect Nb concentrations as low as 0.7 at%. This work establishes a reliable APT method for high-resolution chemical analysis of STO at the nanoscale.

arXiv:2501.11089 (2025)

Materials Science (cond-mat.mtrl-sci)

33 pages, 8 figures + 7 pages supplementary material

Grain boundary interstitial segregation in substitutional binary alloys

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Zuoyong Zhang, Chuang Deng

Grain boundary (GB) segregation is a powerful approach for optimizing the thermal and mechanical properties of metal alloys. In this study, we report significant GB interstitial segregation in a representative substitutional binary alloy system (Al-Ni) through atomistic simulations, challenging prevailing assumptions in the literature. Our findings show that Ni atoms preferentially segregate to interstitial sites within numerous kite-like GB structures in the Al bicrystals. An intriguing interplanar interstitial segregation pattern was also observed and analyzed. Additionally, interstitial segregation can induce unexpected GB transitions, such as kite transitions and nano-faceting, due to the existence of small interstitial sites. Building upon these observations, we developed a robust method to systematically identify the interstitial candidate sites for accommodating solutes at GBs. This approach combines site detection with structural filtering to produce distributions of interstitial sites that closely match atomistic simulation results. Applied to nanocrystalline alloys, this method enabled the calculation of interstitial segregation energies, significantly improving GB segregation predictions for the Al-Ni system. Furthermore, machine learning models using smooth overlap of atomic positions descriptors successfully predicted per-site interstitial segregation energy. This study highlights the critical role of GB interstitial segregation in advancing our understanding of solute behavior and provides valuable insights for designing next-generation alloys.

arXiv:2501.11101 (2025)

Materials Science (cond-mat.mtrl-sci)

34 pages and 11 figures for the main manuscript, 10 pages and 11 figures for supplemental

One-dimensional confined Rashba states in a two-dimensional Si\(_{2}\)Bi\(_{2}\) induced by vacancy line defects

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Arif Lukmantoro, Edi Suprayoga, Moh. Adhib Ulil Absor

Advanced defect engineering techniques have enabled the creation of unique quantum phases from pristine materials. One-dimensional (1D) atomic defects in low-dimensional systems are particularly intriguing due to their distinct quantum properties, such as 1D Rashba states that allow for the generation of nondissipative spin currents, making them ideal for spintronic devices. Using density-functional calculations and model-based symmetry analysis, we report the emergence of 1D Rashba states in a two-dimensional Si\(_{2}\)Bi\(_{2}\) monolayer (ML) with vacancy line defects (VLDs). We show that introducing VLDs in the Si\(_{2}\)Bi\(_{2}\) ML induces 1D confined defect states near the Fermi level, which are strongly localized along the extended defect line. Notably, we observed 1D Rashba spin-split bands in these defect states with significant spin splitting originating mainly from the strong \(p-p\) coupling orbitals between Si and Bi atoms near the defect sites. These spin-split defect states exhibit perfectly collinear spin polarization in momentum \(\vec{k}\)-space, which is oriented perpendicularly to the VLD orientation. Moreover, using \(\vec{k}\cdot\vec{p}\) perturbation theory supplemented with symmetry analysis, we show that the 1D Rashba states with collinear spin polarization are enforced by the lowering of symmetry of the VLDs into the \(C_{s}\) point group, which retains the \(M_{xz}\) mirror symmetry along with the 1D nature of the VLDs. The observed 1D Rashba states in this system protect carriers against spin decoherence and support an exceptionally long spin lifetime, which could be promising for developing highly efficient spintronic devices.

arXiv:2501.11108 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

6 Figures

Almost Strong Zero Modes at Finite Temperature

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Niklas Tausendpfund, Aditi Mitra, Matteo Rizzi

Interacting fermionic chains exhibit extended regions of topological degeneracy of their ground states as a result of the presence of Majorana or parafermionic zero modes localized at the edges. In the opposite limit of infinite temperature, the corresponding non-integrable spin chains, obtained via generalized Jordan-Wigner mapping, are known to host so-called Almost Strong Zero Modes, which are long-lived with respect to any bulk excitations. Here, we study the fairly unexplored territory that bridges these two extreme cases of zero and infinite temperature. We blend two established techniques for states, the Lanczos series expansion and a tensor network ansatz, uplifting them to the level of operator algebra. This allows us to efficiently simulate large system sizes for arbitrarily long timescales and to extract the temperature-dependent decay rates. We observe that for the Kitaev-Hubbard model, the decay rate of the edge mode depends exponentially on the inverse temperature \(\beta\), and on an effective energy scale \(\Delta_{\rm eff}\) that is greater than the thermodynamic gap of the system \(\Delta\).

arXiv:2501.11121 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)

22 pages

Computational statistics of segregation and dislocation activities of hydrogen charged free surfaces and grain boundaries

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Matthew J. Melfi, S. Mohadeseh Taheri-Mousavi

Revealing statistics of H-defect interactions provides insights into significant ductility loss due to the particular strain partitioning in H-charged structural alloys. Experimental investigation of these interactions is extremely difficult, labor-intensive, and costly. Here, we used MD and GCMC simulations and studied H-diffusion deformation at polycrystalline scale with atomic resolution efficiently. To study H-free surface interactions, large pillars including all possible angles and planes of free surfaces were modeled. To study H-grain boundary interactions, several polycrystalline models containing comparable statistics of low and high angle grain boundaries were examined. We studied the statistics of H-segregation tendencies based on free surface angles and grain boundary types. Dislocation activities were also classified for these various types and total density and strength were compared and analyzed compared to H-free samples. In the free surface model, it was observed that H was evenly distributed along the model's surface. Although the dislocation density was reduced compared to H-free samples, localized bands of dislocations were produced. Additionally in the polycrystalline samples, it was concluded that H tends to segregate along grain boundaries with misorientation angles less than or equal to 25 degrees. However, specific misorientation angle interactions -- namely \(>45\) degrees -- led to increased dislocation density in H-charged samples compared to their H-free counterparts.

arXiv:2501.11134 (2025)

Materials Science (cond-mat.mtrl-sci)

27 pages total, 15 pages of text, 137 references, 8 figures

Quantum Criticality of Type-I and Critically Tilted Dirac Semimetals

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Huanzhi Hu, Frank Krüger

We investigate the universality of an Ising symmetry breaking phase transition of tilted two-dimensional Dirac fermions, in the type-I phase as well as at the Lifshitz transition between a type-I and a type-II semimetal, where the Fermi surface changes from point-like to one with electron and hole pockets that touch at the overtilted Dirac cones. We compute the Landau damping of long-wavelength order parameter fluctuations by tilted Dirac fermions and use the resulting IR propagator as input for a renormalisation-group analysis of the resulting Gross-Neveu-Yukawa field theory. We first demonstrate that the criticality of tilted type-I fermions is controlled by a line of fixed points along which the poles of the renormalised Green function correspond to an untilted Dirac spectrum with varying anisotropy of Fermi velocities. At the phase transition the Lorentz invariance is restored, resulting in the same critical exponents as for conventional Dirac systems. The multicritical point is given by the endpoint of the fixed-point line. It can be approached along any path in parameter space that avoids the fixed point line of the critical type-I semimetal. We show that the critical exponents at the Lifshitz point are different and that Lorentz invariance is broken.

arXiv:2501.11143 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

For an issue of Physics C dedicated to Jan Zaanen

Surface Reconstructions in Thin-Films of Magnetic Topological Insulator MnBi\(_2\)Te\(_4\)

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Shahid Sattar, Daniel Hedman, C. M. Canali

Understanding the nature of surface states and their exchange gaps in magnetic topological insulator MnBi\(_2\)Te\(_4\) (MBT) thin films is crucial for achieving robust topological Chern and Axion insulating phases where the Quantum Anomalous Hall Effect and the Topological Magneto-electric Effect can be realized. Here, we focus on the rather unexplored issue of how surface reconstructions, which are likely to occur in experiments, influence these properties. Using first-principles calculations together with molecular dynamics simulations accelerated by machine learning force field, we demonstrate that interstitial-2H and peripheral-2H type atomic reconstructions are responsible for modifying the exchange gap and surface characteristics of MBT thin films, with important implications for the topological indices and the nature of quasi one-dimensional side-wall edge states dominating quantum transport. in Angle-Resolved Photoemission Spectroscopy (ARPES) measurements. Our analysis provides a theoretical framework to elucidate the nature and effect of reconstructions in MBT thin films, with predictions for the experimental realization of different topological phases.

arXiv:2501.11176 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

6 pages, 5 figures

Spontaneous spatial sorting by cell shape in growing colonies of rod-like bacteria

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Mateusz Ratman, Jimmy Gonzalez Nuñez, Daniel A. Beller

Mechanical interactions among cells in a growing microbial colony can significantly influence the colony's spatial genetic structure and, thus, evolutionary outcomes such as the fates of rare mutations. Here, we computationally investigate how this spatial genetic structure changes as a result of heritable phenotypic variations in cell shape. By modeling rod-like bacterial cells as lengthening and dividing circo-rectangles in a 2D Brownian dynamics framework, we simulate the growth of a colony containing two populations with different aspect ratios. Compared to monodisperse colonies, such bidisperse colonies exhibit diminished intermixing between sub-populations when the less elongated cells are too short to nematically order, instead forming large clusters. We find that the cells with longer aspect ratio gradually segregate to the colony periphery. We present evidence that this demixing is related to nematic order in the bulk and to active nematic mixing dynamics near the periphery. These findings are qualitatively robust across different growth rate protocols and initial conditions. Because the periphery is often an advantageous position when nutrients are limited, our results suggest a possible evolutionary selective pressure of mechanical origin that favors large cell aspect ratio.

arXiv:2501.11177 (2025)

Soft Condensed Matter (cond-mat.soft), Populations and Evolution (q-bio.PE)

17 pages, 9 figures

Bulk-edge correspondence in circular-symmetric models

New Submission | Other Condensed Matter (cond-mat.other) | 2025-01-22 20:00 EST

Klaus Ziegler

We propose a systematic analysis of the eigenfunctions of two-band systems in two dimensions with a circular edge. Our approach is based on an analytic continuation of the wavenumber, which yields a mapping from the bulk modes to the edge modes. Phase relations of the eigenfunctions are described by their mapping onto a three-dimensional field of unit vectors. This mapping is studied in detail for a two-band Laplacian model and a Dirac model. The direction of the unit vector identifies the phase relation of the eigenfunctions and enables us to distinguish between the upper band, the lower band and the edge spectrum. Bulk and edge modes are spectrally separated, which results in two transitions from delocalized bulk modes to localized edge modes. These transitions are accompanied by transitions of the phase relations.

arXiv:2501.11186 (2025)

Other Condensed Matter (cond-mat.other), Mathematical Physics (math-ph), Quantum Physics (quant-ph)

12 pages, 5 figures

Advances in modeling complex materials: The rise of neuroevolution potentials

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Penghua Ying, Cheng Qian, Rui Zhao, Yanzhou Wang, Feng Ding, Shunda Chen, Zheyong Fan

Interatomic potentials are essential for driving molecular dynamics (MD) simulations, directly impacting the reliability of predictions regarding the physical and chemical properties of materials. In recent years, machine-learned potentials (MLPs), trained against first-principles calculations, have become a new paradigm in materials modeling as they provide a desirable balance between accuracy and computational cost. The neuroevolution potential (NEP) approach, implemented in the open-source GPUMD software, has emerged as a promising machine-learned potential, exhibiting impressive accuracy and exceptional computational efficiency. This review provides a comprehensive discussion on the methodological and practical aspects of the NEP approach, along with a detailed comparison with other representative state-of-the-art MLP approaches in terms of training accuracy, property prediction, and computational efficiency. We also demonstrate the application of the NEP approach to perform accurate and efficient MD simulations, addressing complex challenges that traditional force fields typically can not tackle. Key examples include structural properties of liquid and amorphous materials, chemical order in complex alloy systems, phase transitions, surface reconstruction, material growth, primary radiation damage, fracture in two-dimensional materials, nanoscale tribology, and mechanical behavior of compositionally complex alloys under various mechanical loadings. This review concludes with a summary and perspectives on future extensions to further advance this rapidly evolving field.

arXiv:2501.11191 (2025)

Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)

43 pages, 28 figures

Control of ferroelectric domain wall dynamics by point defects: Insights from ab initio based simulations

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Sheng-Han Teng, Aris Dimou, Benjamin Udofia, Majid Ghasemi, Markus Stricker, Anna Grünebohm

The control of ferroelectric domain walls and their dynamics on the nanoscale becomes increasingly important for advanced nanoelectronics and novel computing schemes. One common approach to tackle this challenge is the pinning of walls by point defects. The fundamental understanding on how different defects influence the wall dynamics is, however, incomplete. In particular, the important class of defect dipoles in acceptor-doped ferroelectrics is currently underrepresented in theoretical work. In this study, we combine molecular dynamics simulations based on an -derived effective Hamiltonian and methods from materials informatics, and analyze the impact of these defects on the motion of 180\(^{\circ}\) domain walls in tetragonal BaTiO\(_3\). We show how these defects can act as local pinning centers and restoring forces on the domain structure. Furthermore, we reveal how walls can flow around sparse defects by nucleation and growth of dipole clusters, and how pinning, roughening and bending of walls depend on the defect distribution. Surprisingly, the interaction between acceptor dopants and walls is short-ranged. We show that the limiting factor for the nucleation processes underlying wall motion is the defect-free area in front of the wall.

arXiv:2501.11193 (2025)

Materials Science (cond-mat.mtrl-sci)

Metallicity and Anomalous Hall Effect in Epitaxially-Strained, Atomically-thin RuO2 Films

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Seung Gyo Jeong, Seungjun Lee, Bonnie Lin, Zhifei Yang, In Hyeok Choi, Jin Young Oh, Sehwan Song, Seung wook Lee, Sreejith Nair, Rashmi Choudhary, Juhi Parikh, Sungkyun Park, Woo Seok Choi, Jong Seok Lee, James M. LeBeau, Tony Low, Bharat Jalan

The anomalous Hall effect (AHE), a hallmark of time-reversal symmetry breaking, has been reported in rutile RuO2, a debated metallic altermagnetic candidate. Previously, AHE in RuO2 was observed only in strain-relaxed thick films under extremely high magnetic fields (~50 T). Yet, in ultrathin strained films with distinctive anisotropic electronic structures, there are no reports, likely due to disorder and defects suppressing metallicity thus hindering its detection. Here, we demonstrate that ultrathin, fully-strained 2 nm TiO2/t nm RuO2/TiO2 (110) heterostructures, grown by hybrid molecular beam epitaxy, retain metallicity and exhibit a sizeable AHE at a significantly lower magnetic field (< 9 T). Density functional theory calculations reveal that epitaxial strain stabilizes a non-compensated magnetic ground state and reconfigures magnetic ordering in RuO2 (110) thin films. These findings establish ultrathin RuO2 as a platform for strain-engineered magnetism and underscore the transformative potential of epitaxial design in advancing spintronic technologies.

arXiv:2501.11204 (2025)

Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)

23 pages

CNN-based TEM image denoising from first principles

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Jinwoong Chae, Sungwook Hong, Sungkyu Kim, Sungroh Yoon, Gunn Kim

Transmission electron microscope (TEM) images are often corrupted by noise, hindering their interpretation. To address this issue, we propose a deep learning-based approach using simulated images. Using density functional theory calculations with a set of pseudo-atomic orbital basis sets, we generate highly accurate ground truth images. We introduce four types of noise into these simulations to create realistic training datasets. Each type of noise is then used to train a separate convolutional neural network (CNN) model. Our results show that these CNNs are effective in reducing noise, even when applied to images with different noise levels than those used during training. However, we observe limitations in some cases, particularly in preserving the integrity of circular shapes and avoiding visible artifacts between image patches. To overcome these challenges, we propose alternative training strategies and future research directions. This study provides a valuable framework for training deep learning models for TEM image denoising.

arXiv:2501.11225 (2025)

Materials Science (cond-mat.mtrl-sci), Computer Vision and Pattern Recognition (cs.CV), Image and Video Processing (eess.IV)

10 pages and 4 figures

Nonlinear Hall effect driven by spin-charge-coupled motive force

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Kohei Hattori, Hikaru Watanabe, Ryotaro Arita

Parity-time-reversal symmetric (\(\mathcal{PT}\)-symmetric) magnets have garnered much attention due to their spin-charge coupled dynamics enriched by the parity-symmetry breaking. By real-time simulations, we study how localized spin dynamics can affect the nonlinear Hall effect in \(\mathcal{PT}\)-symmetric magnets. To identify the leading-order term, we derive analytical expressions for the second-order optical response and classify the contributions by considering their transformation properties under \(\mathcal{PT}\) symmetry. Notably, our results reveal that the sizable contribution is attributed to the mixed dipole effect, which is analogous to the Berry curvature dipole term.

arXiv:2501.11234 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)

33 page, 8 figures, 4 tables. arXiv admin note: text overlap with arXiv:2311.12212

Electronic States and Mechanical Behaviors of Phosphorus Carbide Nanotubes -- Structural and Quantum Phase Transitions in a Quasi-one-dimensional Material

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Shivam Sharma, Chenhaoyue Wang, Hsuan Ming Yu, Amartya S. Banerjee

Quasi-one-dimensional (1D) materials can manifest exotic electronic properties in manners that are distinct from the bulk phase or other low-dimensional systems. Helical symmetries in such materials -- e.g., nanotubes with intrinsic or applied twist -- can simultaneously lead to strong electronic correlation and anomalous transport behavior. However, these materials remain underexplored, in part due to computational challenges. Using specialized symmetry-adapted first-principles calculations, we show that mono-layer \(P_2C_3\) -- identified in a previous letter to possess double Kagome bands'' -- exhibits a number of striking properties when rolled up into phosphorous carbide nanotubes ($P_2C_3$NTs). Both armchair and zigzag $P_2C_3$NTs are stable at room temperature and display a degenerate combination of Dirac points and electronic flat bands at the Fermi level. Notably, these flat bands are highly resilient to elastic deformations. Large strains can transform the nanotube structure from honeycomb-kagome tobrick-wall'', and trigger multiple quantum phase transitions. Edge states in \(P_2C_3\)NTs, spin-degeneracy lifting induced by vacancies and dopants, and strain-tunable magnetism are also discussed.

arXiv:2501.11239 (2025)

Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)

Keywords: chiral nanomaterial, flat bands, strong correlation, quantum phase transition

High-throughput calculations of two-dimensional auxetic \(M_4X_8\) with magnetism, electrocatalysis, and alkali metal battery applications

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Haidi Wang, Wei Lin, Weiduo Zhu, Zhao Chen, Zhongjun Li, Xiaofeng Liu

Two-dimensional (2D) materials with multifunctional properties, such as negative Poisson's ratio (NPR), magnetism, catalysis, and energy storage capabilities, are of significant interest for advanced applications in flexible electronics, spintronics, catalysis, and lithium-ion batteries. However, the discovery of such materials, particularly in low-dimensional forms, remains a challenge. In this study, we perform high-throughput density-functional theory (DFT) calculations to explore a new class of 2D V-shaped monolayers with remarkable physicochemical properties. Among 18 stable \(M_4X_8\) (M = transition metal; X = halogen) compounds, we identify 9 auxetic monolayers, with standing out for its exceptionally high NPR of -0.798. Notably, 4 of these materials exhibit half semiconductor properties, while 5 others are bipolar magnetic semiconductors, offering a unique combination of electronic and magnetic behavior. Additionally, these materials demonstrate promising catalytic activity for hydrogen and oxygen evolution reactions (HER/OER) and show potential as anodes for rechargeable metal-ion batteries, particularly in alkali-ion systems. This work not only expands the family of 2D NPR materials but also introduces new candidates with multifunctional capabilities for a wide range of applications in nanoelectronics, catalysis, and energy storage.

arXiv:2501.11242 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)

Microscopic evidence of charge- and spin-density waves in La\(_3\)Ni\(_2\)O\(_{7-\delta}\) revealed by \(^{139}\)La-NQR

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

J. Luo, J. Feng, G. Wang, N. N. Wang, J. Dou, A. F. Fang, J. Yang, J. G. Cheng, Guo-qing Zheng, R. Zhou

The recent discovery of superconductivity in La\(_3\)Ni\(_2\)O\(_{7-\delta}\) with a transition temperature \(T_c\) close to 80 K at high pressures has attracted significant attention, due particularly to a possible density wave (DW) transition occurring near the superconducting dome. Identifying the type of DW order is crucial for understanding the origin of superconductivity in this system. However, owing to the presence of La\(_4\)Ni\(_3\)O\(_{10}\) and other intergrowth phases in La\(_3\)Ni\(_2\)O\(_{7-\delta}\) samples, extracting the intrinsic information from the La\(_3\)Ni\(_2\)O\(_7\) phase is challenging. In this study, we employed \(^{139}\)La nuclear quadrupole resonance (NQR) measurements to eliminate the influence of other structural phases in the sample and obtain microscopic insights into the DW transition in La\(_3\)Ni\(_2\)O\(_{7-\delta}\). Below the DW transition temperature \(T_{\rm DW} \sim\) 153K, we observe a distinct splitting in the \(\pm\) 5/2 \(\leftrightarrow\) \(\pm\) 7/2 transition of the NQR resonance peak at the La(2) site, while only a line broadening is seen in the \(\pm\) 3/2 \(\leftrightarrow\) \(\pm\) 5/2 transition peak. Through further analysis of the spectra, we show that the line splitting is due to the unidirectional charge modulation. A magnetic line broadening is also observed below \(T_{\rm DW}\), accompanied by a large enhancement of the spin-lattice relaxation rate, indicating the formation of magnetic ordered moments in the DW state. Our results suggest the formation of charge- and spin-density wave order in La\(_3\)Ni\(_2\)O\(_{7-\delta}\) simultaneously, thereby offering critical insights into the electronic correlations in Ni-based superconductors.

arXiv:2501.11248 (2025)

Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)

13 pages, 4 figures

The origin of anomalous non-linear microwave absorption in Josephson junction qubits: mysterious nature of two level systems or their dynamic interaction?

New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-22 20:00 EST

Alexander L. burin

Quantum two-level systems (TLSs) commonly found at low temperature in amorphous and disordered materials are responsible for decoherence in superconducting Josephson junction qubits particularly because they absorb energy of coherent qubit oscillations in the microwave frequency range. In planar Josephson resonators with oxide interfaces this absorption is characterized by an anomalously weak loss tangent dependence on the field in the non-linear regime that conflicts with the theoretical expectations and the observations in amorphous dielectrics. It was recently suggested that this anomalous absorption is due to TLS dynamic interactions. Here we show that such interactions cannot lead to the observed loss-tangent field dependence and suggest the alternative explanation assuming that TLS dipole moments \(p\) are distributed according to the specific power law \(P(p) \propto 1/p^{3-\eta}\) (\(0\leq \eta <1\)). This assumption, indeed, results in the observed loss tangent behavior. The hypothesis of a power law distribution is supported both by the recent measurements of individual TLS dipole moments and the theoretical model of TLS formation due to the long-range dipole-dipole interaction, thus connecting the anomalous absorption with the possible solution of the long-standing problem of the nature of TLSs.

arXiv:2501.11259 (2025)

Disordered Systems and Neural Networks (cond-mat.dis-nn)

31 pages, 5 figures, comments are welcome

Spin-phonon coupling and thermal Hall effect in Kitaev spin liquid

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Taekoo Oh, Naoto Nagaosa

Kitaev spin liquid (KSL), consisting of the bond direction-dependent spin interactions in the honeycomb lattice, attracts huge attention because of its exact solvability and prospect for applications to quantum computing. An important feature of KSL is the half-quantized thermal Hall conductivity (HQTHC) under the magnetic field perpendicular to the lattice, but HQTHC stands only at low temperatures. Here, in the temperature range beyond the HQTHC regime, we theoretically propose the extrinsic phonon contribution to thermal Hall Effect in KSL via the skew-scattering of chiral phonons by the scalar spin chirality, which was previously studied in Mott insulators. We show the emergence of the scalar spin chirality of fluctuating spins, estimate the emergent field strength and its symmetric form applied to the chiral phonons, and obtain the associated thermal Hall conductivity, which is semi-quantitatively consistent with the existing experiments. This work provides a basic understanding of the role of spin-phonon interactions in strongly correlated systems.

arXiv:2501.11272 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

22 pages, 4 figures, 1 TOC figure

A Machine-Learning Bond-Order Potential for Exploring the Configuration Space of Carbon

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Ikuma Kohata, Kaoru Hisama, Keigo Otsuka, Shigeo Maruyama

Construction of transferable machine-learning interatomic potentials with a minimal number of parameters is important for their general applicability. Here, we present a machine-learning interatomic potential with the functional form of the bond-order potential for comprehensive exploration over the configuration space of carbon. The physics-based design of this potential enables robust and accurate description over a wide range of the potential energy surface with a small number of parameters. We demonstrate the versatility of this potential through validations across various tasks, including phonon dispersion calculations, global structure searches for clusters, phase diagram calculations, and enthalpy-volume mappings of local minima structures. We expect that this potential can contribute to the discovery of novel carbon materials.

arXiv:2501.11297 (2025)

Materials Science (cond-mat.mtrl-sci)

17 pages, 12 figures

Overdamped van der Waals Josephson junctions by area engineering

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Annu Anns Sunny, H Choubey, A Khola, S Narayanan, R Bharadwaj, P Gireesan, Madhu Thalakulam

Van der Waals (vW) Josephson junctions (JJs) realized by stacking materials such as few-layered NbSe2, offers a new landscape to realize superconducting quantum devices with superior properties owing to its crystalline nature and defect-free junctions. For quantum technology, overdamped JJs are highly sought-after, whose realization demands precise control of junction capacitance by engineering the junction area using microfabrication techniques. NbSe2 is highly reactive and susceptible to damage during microfabrication processes. In this manuscript, we demonstrate both underdamped and overdamped NbSe2-NbSe2 JJs by controlling the junction area. We devise a minimally invasive microfabrication procedure, post-junction formation, to precisely control the junction area. The McCumber parameter characterizing the damping is extracted from the electrical transport measurements down to 130 mK. The results show that our sample fabrication recipe has preserved the material qualities and paved the way for the realization of scalable JJ devices on NbSe2 and similar systems.

arXiv:2501.11300 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

13 pages including supplementary information

Power-efficiency trade-off for finite-time quantum harmonic Otto heat engine via phase-space approach

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Hyun-Myung Chun, Jong-Min Park

Thermodynamic constraints impose a trade-off between power and efficiency in heat engines, preventing the simultaneous achievement of high power and high efficiency. For classical microscopic engines, explicit inequalities have been discovered, demonstrating the inherent inevitability of this power-efficiency trade-off. However, extensions of these results to quantum engines have so far been limited to cases of slow operation. In this study, we derive a power-efficiency trade-off relation for a paradigmatic quantum engine operating within a finite time, specifically the Otto cycle of a quantum harmonic oscillator. By utilizing a phase-space approach based on quasi-probability representations, we establish a universal trade-off relation applicable to arbitrary time-dependent protocols during the adiabatic processes. Our results reveal that the power of the quantum engine vanishes as the efficiency approaches the quantum mechanical efficiency bound, which is stricter than the Carnot bound. Furthermore, we identify the conditions under which the upper bound is attained, which indicate maximum power is achieved when the generation of quantum coherence is reduced, and the difference in time durations of the isochoric processes increases. These findings are validated through numerical calculations, which confirm their applicability across various types of protocols for heat engine cycles.

arXiv:2501.11317 (2025)

Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)

7 pages, 3 figures

Direct ab initio calculation of magnons in altermagnets: method, spin-space symmetry aspects, and application to MnTe

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

L. M. Sandratskii, K. Carva, V. M. Silkin

We suggest the method for direct ab initio calculation of magnons in complex collinear magnets. The method is based on the density-functional-theory calculation under two different constraints: one constraint governs the change of the magnetization with respect to the ground state, and the other is the symmetry constraint responsible for the value of the magnon wave vector. The performance of the method is demonstrated by the application to an altermagnet MnTe. An important role in both the formulation and the application of the method play the aspects of generalized symmetry described by the spin-space groups. The symmetry analysis connects in one coherent picture the following three parts of the consideration: (i) the generalized translational symmetry of the magnons as a crucial condition for their efficient ab-initio calculation, (ii) altermagnetic spin-splitting of the electron states in the ground magnetic state, and (iii) chirality splitting of the magnon excitations. It is demonstrated that both the spin splitting of the electron states and the chirality splitting of the magnons have identical patterns in the corresponding wave vector spaces. Since the altermagnetism of MnTe is the consequence of the presence of the Te atoms, an adequate attention is devoted to the symmetry analysis and calculation results for the Te moments induced in the magnon states. The knowledge of the symmetry properties of the Te moments allows to accelerate the numerical convergence of the magnon states and serves as a test for the accuracy of the calculations. To expose the connection between electron band structures of the magnon states of the system and the chirality properties of these states we investigate the transformation of the electron structure in the transition from the collinear ground state to a noncollinear magnon state.

arXiv:2501.11327 (2025)

Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)

Active chemo-mechanical solitons

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Lev Truskinovsky, Giuseppe Zurlo

In many biological systems localized mechanical information is transmitted by mechanically neutral chemical signals. Typical examples include contraction waves in acto-myosin cortex at cellular scale and peristaltic waves at tissue level. In such systems, chemical activity is transformed into mechanical deformation by distributed motor-type mechanisms represented by continuum degrees of freedom. To elucidate the underlying principles of chemo-mechanical coupling, we present in this Letter the simplest example. It involves directional motion of a localized solitary wave in a distributed mechanical system guided by a purely chemical cue. Our main result is that mechanical signals can be driven by chemical activity in a highly efficient manner.

arXiv:2501.11368 (2025)

Soft Condensed Matter (cond-mat.soft)

Effect of Te doping in GeSe parent thick film by experimental in situ temperature-dependent structural investigation

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

P. Armand (ICGM, UM), R. Escalier (ICGM, UM), G. Silly (ICGM, UM), J. Lizion (ICGM, UM), A. Piarristeguy (ICGM, UM)

As-deposited and unencapsulated GeSe\(_{1-x}\)Te\(_x\) (\(x = 0, 0.25\)) 3-\(\mu\)m-thick amorphous films on Si(001) were obtained via the co-evaporation technique to study the effect of selenium (Se) substitution for tellurium (Te) on the GeSe parent structure in the function of the heating temperature. In situ, grazing-incidence X-ray scattering (XRS), and fluorescence X-ray Absorption Near Edge Structure (XANES) data were collected in isochronal annealing conditions under nitrogen flow. The results show that the onset temperature of crystallization \(T_c\) and the crystallized phase symmetry are susceptible to the Te 25 at. % doping. Furthermore, Ge and Se K-edge XANES analyses reveal significant alterations in the local atomic environments surrounding Ge and Se atoms during the transition from the amorphous to the crystalline state. These modifications are accompanied by an observable increase in local structural disorder upon substitution with Te atoms.

arXiv:2501.11373 (2025)

Materials Science (cond-mat.mtrl-sci)

Materials Research Bulletin, 2025, 185, pp.113280

A simple magnetic field stabilization technique for atomic Bose-Einstein condensate experiments

New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-22 20:00 EST

S Tiengo (IOGS), R Eid (IOGS), M Apfel (IOGS), G Brulin (IOGS), T Bourdel (IOGS)

We demonstrate a simple magnetic field stabilization technique in a Bose-Einstein condensate experiment. Our technique is based on the precise measurement of the current fluctuations in the main magnetic field coils and amounts to their compensation using an auxiliary coil. It has the advantage of simplicity as compensation is done using a low inductance coil that can be straightforwardly driven at the relevant frequencies (1 kHz). The performances of the different components (power supply, current transducer, electronics...) are precisely characterized. In addition, for optimal stability the ambient magnetic field is also measured and compensated. The magnetic field stability around 57 G is measured by Ramsey spectroscopy of magnetic field sensitive radiofrequency transition between two spin states of potassium 39 and the shot-to-shot fluctuations are reduced to 64(7) \(\mu\)G rms, i.e. at the 1 x 10 -6 level. In the context of our experiment, this result opens interesting prospects for the study of three-body interactions in Bose-Einstein condensate potassium spin mixtures.

arXiv:2501.11375 (2025)

Quantum Gases (cond-mat.quant-gas)

Optical control of the crystal structure in the bilayer nickelate superconductor La\(_3\)Ni\(_2\)O\(_7\) via nonlinear phononics

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Shu Kamiyama, Tatsuya Kaneko, Kazuhiko Kuroki, Masayuki Ochi

Superconductivity in the bilayer nickelate La\(_3\)Ni\(_2\)O\(_7\) occurs when the interlayer Ni-O-Ni bond angle becomes straight under pressure, suggesting a strong relationship between the crystal structure and the emergence of superconductivity. In this study, we theoretically propose a way to control the crystal structure of La\(_3\)Ni\(_2\)O\(_7\) toward the tetragonal symmetry via light irradiation instead of pressure using the idea of nonlinear phononics. Here, resonant optical excitation of an infrared-active (IR) lattice vibration induces a nonlinear Raman-mode displacement through the anharmonic phonon-phonon coupling. We calculate the light-induced phonon dynamics on the anharmonic lattice potential determined by first-principles calculation. We find that the interlayer Ni-O-Ni bond angle gets slightly closer to straight when an appropriate IR mode is selectively excited. Our study suggests that light irradiation can be a promising way for structural control of La\(_3\)Ni\(_2\)O\(_7\).

arXiv:2501.11377 (2025)

Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)

12 pages, 10 figures

Band representations in Strongly Correlated Settings: The Kitaev Honeycomb Model

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Axel Fünfhaus, Mikel García-Díez, M. G. Vergniory, Thilo Kopp, Stephen M. Winter, Roser Valentí

In the study of quantum spin liquids, the Kitaev model plays a pivotal role due to the fact that its ground state is exactly known as well as the fact that it may be realized in strongly frustrated materials such as \({\alpha}\)-RuCl\({}_3\). While topological insulators and superconductors can be investigated by means of topological band theory -- in particular the topological quantum chemistry (TQC) formalism -- the Kitaev model evades such a treatment, as it is not possible to set up a proper single-particle Green's function for it. We instead associate spin operators with ``orbitals'' that give rise to a band structure. It is thereby possible to analyze the corresponding excitation spectrum engendered by these localized excitations by means of TQC. Special attention is given to the low-energy topological edge mode spectrum. Our work sheds light on the question how the TQC formalism may be generalized to strongly correlated and topologically ordered systems like the Kitaev model.

arXiv:2501.11396 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

Probing Coherences and Itinerant Magnetism in a Dipolar Lattice Gas

New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-22 20:00 EST

Thomas Lauprêtre, Ana Maria Rey, Laurent Vernac, Bruno Laburthe-Tolra

We report on the study of itinerant magnetism of lattice-trapped magnetic atoms, driven by magnetic dipole-dipole interactions, in the low-entropy and close-to-unit filling regime. We have used advanced dynamical decoupling techniques to efficiently suppress the sensitivity to magnetic field fluctuations. We have thus measured the spin coherence of an itinerant spin 3 Bose dipolar gas throughout a quantum phase transition from a superfluid phase to a Mott insulating phase. In the superfluid phase, a metastable ferromagnetic behavior is observed below a dynamical instability which occurs at lattice depths below the phase transition. In the insulating phase, the thermalization towards a paramagnetic state is driven by an interplay between intersite and superexchange interactions.

arXiv:2501.11402 (2025)

Quantum Gases (cond-mat.quant-gas)

12 pages, 7 figures

Influence of coupling symmetries and noise on the critical dynamics of synchronizing oscillator lattices

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Ricardo Gutierrez, Rodolfo Cuerno

Recent work has shown that the synchronization process in lattices of self-sustained (phase and limit-cycle) oscillators displays universal scale-invariant behavior previously studied in the physics of surface kinetic roughening. The type of dynamic scaling ansatz which is verified depends on the randomness that occurs in the system, whether it is columnar disorder (quenched noise given by the random assignment of natural frequencies), leading to anomalous scaling, or else time-dependent noise, inducing the more standard Family-Vicsek dynamic scaling ansatz, as in equilibrium critical dynamics. The specific universality class also depends on the coupling function: for a sine function (as in the celebrated Kuramoto model) the critical behavior is that of the Edwards-Wilkinson equation for the corresponding type of randomness, with Gaussian fluctuations around the average growth. In all the other cases investigated, Tracy-Widom fluctuations ensue, associated with the celebrated Kardar-Parisi-Zhang equation for rough interfaces. Two questions remain to be addressed in order to complete the picture, however: 1) Is the atypical scaling displayed by the sine coupling preserved if other coupling functions satisfying the same (odd) symmetry are employed (as suggested by continuum approximations and symmetry arguments)? and 2) how does the competition between both types of randomness (which are expected to coexist in experimental settings) affect the nonequilibrium behavior? We address the latter question by numerically characterizing the crossover between thermal-noise and columnar-disorder criticality, and the former by providing evidence confirming that it is the symmetry of the coupling function that sets apart the sine coupling, among other odd-symmetric couplings, due to the absence of Kardar-Parisi-Zhang fluctuations.

arXiv:2501.11432 (2025)

Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO)

Submitted to Physica D (2025). 16 pages, 9 figures

Stability and Nucleation of Dipole Strings in Uniaxial Chiral Magnets

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Vladyslav M. Kuchkin, Nikolai S. Kiselev, Andreas Haller, Štefan Liščák, Andreas Michels, Thomas L. Schmidt

We report on the stability of the magnetic dipole string (DS), a three-dimensional magnetic texture formed by two coupled Bloch points with opposite topological charges, separated by an equilibrium distance. Previous studies demonstrated the stability of such configurations through geometric confinement or coupling with local perturbations in the magnetization field, such as skyrmion strings or dislocations in helical modulations. Here, we show that, in uniaxial chiral magnets, an isolated DS remains stable in an unperturbed vacuum, thus representing a true three-dimensional soliton. The phase diagram illustrates the stability of the DS embedded in the conical or helical phases across a broad range of material parameters and external magnetic fields. Using the geodesic nudged elastic band method applied to a regularized micromagnetic model, we demonstrate that isolated DSs are protected from collapse by an energy barrier. Stochastic spin-lattice simulations demonstrate that DSs can spontaneously nucleate during in-field annealing. This work aims to stimulate the experimental observation of DSs and further exploration of uniaxial chiral magnets.

arXiv:2501.11439 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

11 pages, 3 figures

Stochastic bubble dynamics in phase-separated scalar active matter

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Mingqi Yan, Erwin Frey, Marcus Müller, Stefan Klumpp

In ABP systems, phase separation is accompanied by the emergence of vapor bubbles within liquid domains. Using large-scale particle-based simulations, we study the stochastic dynamics of these bubbles and find that most nucleate, grow, and dissolve within liquid domains. We show that their area dynamics can be described by a Langevin equation with a constant negative drift and noise proportional to the perimeter, fully characterizing bubble area and lifetime statistics. Additionally, we develop a lattice gas model that captures the morphological properties, including the decrease in bubble asphericity with increasing area. These findings provide new insights into phase separation in active matter and highlight limitations in current continuum theories.

arXiv:2501.11442 (2025)

Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)

6 pages, 4 figures

Nitrogen-Vacancy Centers in Epitaxial Laterally Overgrown Diamond: Towards Up-scaling of Color Center-based Quantum Technologies

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Nimba Oshnik, Sebastian Westrich, Nina Burmeister, Oliver Roman Opaluch, Lahcene Mehmel, Riadh Issaoui, Alexandre Tallaire, Ovidiu Brinza, Jocelyn Achard, Elke Neu

Providing high-quality, single-crystal diamond (SCD) with a large area is desirable for up-scaling quantum technology applications that rely on color centers in diamond. Growth methods aiming to increase the area of SCD are an active research area. Native color centers offer a sensitive probe for local crystal quality in such novel materials e.g., via their reaction to stress. In this work, we investigate individual native nitrogen-vacancy (NV) centers in SCD layers manufactured via laterally overgrowing hole arrays in a heteroepitaxially grown large-scale substrate. Heteroepitaxy has become a common tool for growing large SCDs; however, achieving the high crystal quality needed for quantum applications remains a challenge. In the overgrown layer, we identify NV centers with spin-decoherence times in the order of hundreds of microseconds, comparable to high-purity homoepitaxial SCD. We quantify the effective crystal strain in different regions of the overgrown layer, indicating a low stress overall and a stress reduction in the diamond layer above the holes.

arXiv:2501.11481 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)

8 pages, 4 figures. For openly availabel data supporting the manuscript see this https URL

Influence of the pretreatment anneal on Co germanide Schottky contacts

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

L. Lajaunie, M.L. David, F. Pailloux, C. Tromas, E. Simoen, C. Claeys, J.F. Barbot

A thin cobalt layer is deposited by electron beam evaporation onto a germanium substrate after an in situ cleaning annealing at 400 or 700 C. The effect of these pretreatments on the Co/Ge Schottky barrier properties and on the germanide formation is investigated by using different techniques. A strong influence of the pre-treatment is observed. The pre-treatment at 700 C removes the native oxide but enhances the diffusion of contaminants. After post-metal deposition annealing, the sample pre-treated at 700 C shows a double layer structure due to interdiffusion, whereas some large isolated islands are present in the sample pre-treated at 400 C.

arXiv:2501.11492 (2025)

Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)

Materials Science in Semiconductor Processing 11 2008 300 304

Laser-driven resonant soft-X-ray scattering for probing picosecond dynamics of nanometre-scale order

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Leonid Lunin, Martin Borchert, Niklas Schneider, Konstanze Korell, Michael Schneider, Dieter Engel, Stefan Eisebitt, Bastian Pfau, Daniel Schick

X-ray scattering has been an indispensable tool in advancing our understanding of matter, from the first evidence of the crystal lattice to recent discoveries of nuclei's fastest dynamics. In addition to the lattice, ultrafast resonant elastic scattering of soft X-rays provides a sensitive probe of charge, spin, and orbital order with unparalleled nanometre spatial and femto- to picosecond temporal resolution. However, the full potential of this technique remains largely unexploited due to its high demand on the X-ray source. Only a selected number of instruments at large-scale facilities can deliver the required short-pulsed and wavelength-tunable radiation, rendering laboratory-scale experiments elusive so far. Here, we demonstrate time-resolved X-ray scattering with spectroscopic contrast at a laboratory-based instrument using the soft-X-ray radiation emitted from a laser-driven plasma source. Specifically, we investigate the photo-induced response of magnetic domains emerging in a ferrimagnetic heterostructure with 9\(\,\)ps temporal resolution. The achieved sensitivity allows for tracking the reorganisation of the domain network on pico- to nanosecond time scales in great detail. This instrumental development and experimental demonstration break new ground for studying material dynamics in a wide range of laterally ordered systems in a flexible laboratory environment.

arXiv:2501.11506 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Geometrical Responses of Generalized Landau Levels: Structure Factor and the Quantized Hall Viscosity

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Carolina Paiva, Jie Wang, Tomoki Ozawa, Bruno Mera

We present a new geometric characterization of generalized Landau levels (GLLs). The GLLs are a generalization of Landau levels to non-uniform Berry curvature, and are mathematically defined in terms of a holomorphic curve -- an ideal Kähler band -- and its associated unitary Frenet-Serret moving frame. Here, we find that GLLs are harmonic maps from the Brillouin zone to the complex projective space and they are critical points of the Dirichlet energy functional, as well as the static structure factor up to fourth order. We also find that filled GLLs exhibit quantized Hall viscosity, similar to the ordinary Landau levels. These results establish GLLs as a versatile generalization of Landau levels.

arXiv:2501.11519 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph)

5 pages

SANS evidence for the dispersion of nanoparticles in W-1Y\(_2\)O\(_3\) and W-1La\(_2\)O\(_3\) processed by hot isostatic pressing

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

A. Munoz, J. Martinez, M.A. Monge, B. Savoini, R. Pareja, A. Radulescu

The development of dispersion of nanoparticles in the W-1%Y\(_2\)O\(_3\) and W-1%La\(_2\)O\(_3\) (wt%) alloys processed by hot isostatic pressing has been investigated using small angle neutron scattering. The mode values of these centers are found at 10 and 40 nm in W-1%Y\(_2\)O\(_3\), and 15 and 80 nm in W-1%La\(_2\)O\(_3\). The scanning electron microscopy analyses showed the presence of small second phase particles. The contribution of the pore space to the scattering curves has been analyzed using the results obtained for pure W processed following the same procedure used for the alloys, and the porosity measurements of the samples.

arXiv:2501.11521 (2025)

Materials Science (cond-mat.mtrl-sci)

4 pages, 4 figures, 2 tables, research article

Inter. Journal of Refractory Metals and Hard Materials, Volume 33, 2012, Pages 6 9

Nanostructured thin films of indium oxide nanocrystals confined in alumina matrixes

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

A. Bouifoulen, M. Edely, N. Errien, A. Kassiba, A. Outzourhit, M. Makowska-Janusik, N. Gautier, L. Lajaunie, A. Oueriagli

Nanocrystals of indium oxide (In\(_2\)O\(_3\)) with sizes below 10 nm were prepared in alumina matrixes by using a co-pulverization method. The used substrates such as borosilicate glasses or (100) silicon as well as the substrate temperatures during the deposition process were modified and their effects characterized on the structural and physical properties of alumina-In\(_2\)O\(_3\) films. Complementary investigation methods including X-ray diffraction, optical transmittance in the range 250-1100 nm and transmission electron microscopy were used to analyze the nanostructured films. The crystalline order, morphology and optical responses were monitored as function of the deposition parameters and the post-synthesis annealing. The optimal conditions were found and allow realizing suitable nanostructured films with a major crystalline order of cubic phase for the In\(_2\)O\(_3\) nanocrystals. The optical properties of the films were analyzed and the key parameters such as direct and indirect band gaps were evaluated as function of the synthesis conditions and the crystalline quality of the films.

arXiv:2501.11527 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Thin Solid Films Volume 519, Issue 7, 31 January 2011, Pages 2141 2145

Navigating the Complexities of Multiple Redox State Interactions in Aqueous Systems

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Shishir Mundra, Mohit Pundir, Barbara Lothenbach, David S. Kammer, Ueli M. Angst

Numerous aqueous systems host elements in multiple redox states, with wide ranging implications such as their influence on the formation/dissolution of minerals, water toxicity, and nutrient cycling. To uncover governing mechanisms and complex chemical interactions in aqueous systems, reactive-transport models have increasingly gained importance. However, their predictive capabilities remain limited because existing approaches struggle to accurately account for the full complexities of redox reactions. Here, we develop a reactive-transport framework that leverages recent advancements in thermodynamic modelling, speciation chemistry, and redox kinetics. Distinct from traditional models, we uniquely treat redox kinetics along with transport as transient phenomena, decoupled from Gibbs free energy minimisation. Ensuring ion concentrations are governed by non-equilibrium rate laws, this approach allows predicting the tempo-spatial distribution of speciation and precipitation of species across oxidation states. We illustrate the versatility of our framework through two case studies: manganese speciation in natural waters and the fate of dissolved iron in aqueous/porous media. Our framework significantly enhances the modelling of a diverse range of redox-sensitive environments.

arXiv:2501.11536 (2025)

Materials Science (cond-mat.mtrl-sci)

Green's Function Approach to Josephson Dot Dynamics and Application to Quantum Mpemba Effects

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Kateryna Zatsarynna, Andrea Nava, Reinhold Egger, Alex Zazunov

We develop a Green's function approach for the nonequilibrium dynamics of multi-level quantum dots coupled to multiple fermionic reservoirs in the presence of a bosonic environment. Our theory is simpler than the Keldysh approach and goes beyond scattering state constructions. In concrete terms, we study Josephson junctions containing a quantum dot and coupled to an electromagnetic environment. In the dot region, spin-orbit interactions, a Zeeman field, and in principle also Coulomb interactions can be included. We then study quantum Mpemba effects, assuming that the average phase difference across the Josephson junction is subject to a rapid quench. For a short singlechannel junction, we show that both types of quantum Mpemba effects allowed in open quantum systems are possible. We also study an intermediate-length junction, where spin-orbit interactions and a Zeeman field are included. Again quantum Mpemba effects are predicted.

arXiv:2501.11609 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)

21 pages, 8 figures

The \((2+\delta)\)-dimensional theory of the electromechanics of lipid membranes: III. Constitutive models

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Yannick A. D. Omar, Zachary G. Lipel, Kranthi K. Mandadapu

This article concludes a three-part series developing a self-consistent theoretical framework of the electromechanics of lipid membranes at the continuum scale. Owing to their small thickness, lipid membranes are commonly modeled as two-dimensional surfaces. However, this approach breaks down when considering their electromechanical behavior as it requires accounting for their thickness. To address this, we developed a dimension reduction procedure in part 1 to derive effective surface theories explicitly capturing the thickness of lipid membranes. We applied this method to dimensionally reduce Gauss' law and the electromechanical balance laws and referred to the resulting theory as \((2+\delta)\)-dimensional, where \(\delta\) indicates the membrane thickness. However, the \((2+\delta)\)-dimensional balance laws derived in part 2 are general, and specific material models are required to specialize them to lipid membranes. In this work, we devise appropriate three-dimensional constitutive models that capture the in-plane fluid and out-of-plane elastic behavior of lipid membranes. The viscous behavior is recovered by a three-dimensional Newtonian fluid model, leading to the same viscous stresses as strictly two-dimensional models. The elastic resistance to bending is recovered by imposing a free energy penalty on local volume changes. While this gives rise to the characteristic bending resistance of lipid membranes, it differs in its higher-order curvature terms from the Canham-Helfrich-Evans theory. Furthermore, motivated by the small mid-surface stretch of lipid membranes, we introduce reactive stresses that enforce mid-surface incompressibility, resulting in an effective surface tension. Finally, we use the constitutive and reactive stresses to derive the equations of motion describing the electromechanics of lipid membranes.

arXiv:2501.11612 (2025)

Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)

Dynamics of local photoconductivity in GaAs and InP investigated by THz SNOM

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Tinkara Troha, Arvind Singh, Petr Kužel, Hynek Němec

Terahertz scanning near-field optical microscope (THz-SNOM) is employed to measure ultrafast evolution of THz conductivity spectra after photoexcitation of GaAs and InP wafers using ultrashort laser pulses. Unlike in GaAs, the THz photoconductivity decay in InP is controlled mainly by the diffusion of electrons away from the photoexcited area, and also by the drift due to band-bending at the surface of the semiconductor. We propose and discuss several general strategies of the analysis of signals measured using THz-SNOM, and we estimate the accuracy of the obtained near-field photoconductivity spectra.

arXiv:2501.11615 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Relaxation times under pulsed ponderomotive forces and the Central Limit Theorem

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Juan-Luis Domenech-Garret

We study the relaxation time of a plasma which is perturbed by means of a time-dependent pulsed force. This time pulse is modelled using a Gaussian superposition. During such a pulse two forces are considered: An inhomogeneous oscillating electric force and the corresponding ponderomotive force. The evolution of such an ensemble is driven by the Boltzmann Equation, and the perturbed population is described by a power-law distribution function. In this work, as a new feature, instead the usual techniques the transient between both distributions is analysed using the Central Limit Theorem. This technique, together with the ad hoc solved equation of motion of the charges under this particular system of pulsed forces, allows to find the corresponding expressions relating the time pulse with the relaxation times and the dynamic conditions. Furthermore, numerical estimates are also presented. As a result, we show a persistence effect of excitation at high frequencies, when the initial excitation pulse has already ended. The concatenation of such successive pulses could be of interest, for example, in experimental applications with pulsed lasers.

arXiv:2501.11625 (2025)

Statistical Mechanics (cond-mat.stat-mech)

17 pages, 8 figures

Andreev spin relaxation time in a shadow-evaporated InAs weak link

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Haoran Lu, David F. Bofill, Zhenhai Sun, Thomas Kanne, Jesper Nygård, Morten Kjaergaard, Valla Fatemi

Andreev spin qubits are a new qubit platform that merges superconductivity with semiconductor physics. The mechanisms dominating observed energy relaxation remain unidentified. We report here on three steps taken to address these questions in an InAs nanowire weak link. First, we designed a microwave readout circuit tuned to be directly sensitive to the spin-dependent inductance of the weak link so that higher orbital states are not necessary for readout -- this resulted in larger windows in parameter space in which the spin state properties can be probed. Second, we implemented a successful gap-engineering strategy to mitigate quasiparticle poisoning. Third, the weak link was fabricated by shadow evaporation, which has been shown to improve atomic-scale disorder. We show how our design allows characterization of the spin stability and coherence over the full range of magnetic flux and gate voltage of an odd parity bias point. The spin relaxation and dephasing rates are comparable with the best devices previously reported, suggestive that surface atomic-scale disorder and QP poisoning are not linked to spin relaxation in InAs nanowires. Our design strategies are transferrable to novel materials platforms for Andreev qubits such as germanium and carbon.

arXiv:2501.11627 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)

Mapping the Configuration Space of Half-Heusler Compounds via Subspace Identification for Thermoelectric Materials Discovery

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Angela Pak, Kamil Ciesielski, Maria Wróblewska, Eric S. Toberer, Elif Ertekin

Half-Heuslers are a promising family for thermoelectric (TE) applications, yet only a small fraction of their potential chemistries has been experimentally explored. In this work, we introduce a distinct computational high-throughput screening approach designed to identify underexplored yet promising material subspaces, and apply it to half-Heusler thermoelectrics. We analyze 1,126 half-Heuslers satisfying the $``$18 valence electron rule \(''\), including 332 predicted to be semiconductors, using electronic structure calculations, semi-empirical transport models, and thermoelectric quality factor \(\beta\). Unlike conventional filtering workflows, our approach employs statistical analysis of candidate material groups to uncover trends in their collective behavior, providing robust insights and minimizing reliance on uncertain predictions for individual compounds. Our findings link \(n\)-type performance to ultra-high mobility at conduction band edges and \(p\)-type performance to high band degeneracy. Statistical correlations reveal elemental subspaces associated with high \(\beta\). We identify two primary (Y- and Zr-containing) and two secondary (Au- and Ir-containing) subspaces that reinforce key physical design principles, making them promising candidates for further exploration. These recommendations align with previous experimental results on yttrium pnictides. Inspired by these insights, we synthesize and characterize rare-earth gold stannides (REAuSn), finding Sc\(_{0.5}\)Lu\(_{0.5}\)AuSn to exhibit low thermal conductivity (0.9-2.3 Wm\(^{-1}\)K\(^{-1}\) at 650 K). This work demonstrates alternative strategies for high throughput screening when using approximate but unbiased models, and offers predictive tools and design strategies for optimizing half-Heusler chemistries for TE performance.

arXiv:2501.11644 (2025)

Materials Science (cond-mat.mtrl-sci)

Imaging signatures of edge currents in a magnetic topological insulator

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

G. M. Ferguson, Run Xiao, Anthony R. Richardella, Austin Kaczmarek, Nitin Samarth, Katja C. Nowack

Magnetic topological insulators (MTIs) host topologically protected edge states, but the role that these edge states play in electronic transport remains unclear. Using scanning superconducting quantum interference device (SQUID) microscopy, we performed local measurements of the current distribution in a quantum anomalous Hall (QAH) insulator at large bias currents, where the quantization of the conductivity tensor breaks down. We find that bulk currents in the channel interior coexist with edge currents at the sample boundary. While the position of the edge current changes with the reversal of the magnetic field, it does not depend on the current direction. To understand our observations, we introduce a model which includes contributions from both the sample magnetization and currents driven by chemical potential gradients. To parameterize our model, we use local measurements of the chemical potential induced changes in the sample magnetization. Our model reveals that the observed edge currents can be understood as changes in the magnetization generated by the electrochemical potential distribution in the sample under bias. Our work underscores the complexity of electronic transport in MTIs and highlights both the value and challenges of using magnetic imaging to disentangle various contributions to the electronic transport signatures.

arXiv:2501.11666 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)

Quantum confining excitons with electrostatic moir'e superlattice

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Liuxin Gu, Lifu Zhang, Sam Felsenfeld, Rundong Ma, Suji Park, Houk Jang, Takashi Taniguchi, Kenji Watanabe, You Zhou

Quantum confining excitons has been a persistent challenge in the pursuit of strong exciton interactions and quantum light generation. Unlike electrons, which can be readily controlled via electric fields, imposing strong nanoscale potentials on excitons to enable quantum confinement has proven challenging. In this study, we utilize piezoresponse force microscopy to image the domain structures of twisted hexagonal boron nitride (hBN), revealing evidence of strong in-plane electric fields at the domain boundaries. By placing a monolayer MoSe2 only one to two nanometers away from the twisted hBN interface, we observe energy splitting of neutral excitons and Fermi polarons by several millielectronvolts at the moiré domain boundaries. By directly correlating local structural and optical properties, we attribute such observations to excitons confined in a nanoscale one-dimensional electrostatic potential created by the strong in-plane electric fields at the moiré domain boundaries. Intriguingly, this 1D quantum confinement results in pronounced polarization anisotropy in the excitons' reflection and emission, persistent to temperatures as high as ~80 Kelvins. These findings open new avenues for exploring and controlling strongly interacting excitons for classical and quantum optoelectronics.

arXiv:2501.11713 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)

23 pages, 11 figures

Atomistic Modeling of Martensitic Phase Transition in Hexamethylbenzene

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Zarif Fahim, Pedro A. Santos-Florez, Qiang Zhu

Materials exhibiting a martensitic phase transition are essential for applications in shape memory alloys, actuators and sensors. Hexamethylbenzene (HMB) has long been considered as a classical example of ferroelastic organic crystals since Mnyukh's pioneering work in 1970s. However, the atomistic mechanism underlying this phase transition has never been clarified. In this work, we present a direct molecular dynamics simulation to investigate the phase transition mechanism in HMB. For the first time, we report a simulation results that can accurately reproduce both the transition temperature and hysteresis loop observed in previous experimental studies. By analyzing the MD trajectories, the potential energy surface, we identified that a low-barrier atomic sliding mode along the close-packed (11\(\overline{1}\)) plane of the low-temperature phase is the key to trigger the phase transition at the critical temperature window. This is further confirmed by the observed continuous softening of shear modulus around the transition window. Our results demonstrate that the integration of various atomistic modeling techniques can provide invaluable insight into the martensitic phase transition mechanisms in organic crystals and guide the development of new organic martensites.

arXiv:2501.11719 (2025)

Materials Science (cond-mat.mtrl-sci)

9 pages, 9 figures

Nanopillar-Driven Antibacterial Surfaces: Elucidating Bactericidal Mechanisms and Engineering Nanostructures for Enhanced Efficacy

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Akash Singh, Yi Zhang, Qing Cao, Yumeng Li

Insects like dragonflies and cicadas possess nanoprotusions on their wings that rupture bacterial membranes upon contact, inspiring synthetic antibacterial surfaces mimicking this phenomenon. Designing such biomimetic surfaces requires understanding the mechanical interaction between nanopillars and bacterial membranes. However, the small scales of these interactions pose challenges. Molecular Dynamics simulations offer precise and efficient modeling at these scales. This study presents a coarse-grained membrane model to explore the mechanical responses of gram-positive and gram-negative bacterial membranes to nanopillar arrays. By varying bacterial shapes (spherical and cylindrical), membrane bending rigidity, and loading rates, we identified two distinct failure mechanisms. Low bending rigidity, typical of gram-negative bacteria, leads to tearing near nanopillar tips, contrary to prior assumptions. High bending rigidity, characteristic of gram-positive bacteria, results in puncturing at contact points. Gram-positive bacteria are more resistant, requiring a threefold increase in loading rate for effective piercing. Nanopillar height and spacing also critically impact bactericidal efficacy: greater heights enhance activity beyond a critical threshold, while increased spacing reduces efficacy. This simplified coarse-grained model, representing bacterial membranes with high fidelity, enables cost-effective, full-scale simulations over extended periods. Our findings provide essential insights for optimizing nanopillared surface designs, advancing antibacterial technology through tailored height and spacing configurations.

arXiv:2501.11727 (2025)

Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Biological Physics (physics.bio-ph), Computational Physics (physics.comp-ph)

Double-tough ceramics: Optimization-supported multiscale computational design

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Jian Zhang, Francesco Aiello, Mauro Salazar, Diletta Giuntini

To overcome the brittleness limitation of ceramics, various toughening mechanisms have been proposed. Some of the most remarkable, especially for oxides, include the tetragonal-to-monoclinic phase transformation leading to crack shielding in zirconia, and bioinspired brick-and-mortar microstructures fostering crack deflection. It has, however, proven challenging to incorporate both these mechanisms into a single all-ceramic material. In this work, we propose a computational methodology for the design of a material that combines these two toughening strategies, using a multiscale modeling approach that captures both their individual contributions and the overall fracture performance. This is achieved by developing an all-ceramic composite with a brick-and-mortar microstructure, in which the nanocrystalline mortar is transformation-toughened. Key factors influencing phase transformation, such as grain boundary properties, grain orientations, and kinetic coefficients, are analyzed, and the resulting transformation stress-strain behavior is incorporated into the microscale mortar constitutive model. We demonstrate that the synergistic effect of the two toughening mechanisms is achievable, and that it is an extremely effective strategy to boost fracture performance. The influence of brick size, mortar thickness, and properties of the constituent materials is then systematically investigated. Finally, a gradient-free optimization algorithm is employed to identify optimal geometric and material parameters, revealing that longer, thinner bricks with minimal mortar thickness provide the best fracture resistance. Optimal combinations of material properties are identified for given brick sizes and mortar thicknesses.

arXiv:2501.11728 (2025)

Materials Science (cond-mat.mtrl-sci)

Quantum-Geometric Spin- and Charge Josephson Diode Effects

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Niklas L. Schulz, Danilo Nikolić, Matthias Eschrig

We present a general mechanism for large charge and spin Josephson diode effects in strongly spin-polarized superconductor-ferromagnet hybrid structures with a noncoplanar spin texture, formulated in terms of quantum-geometric phases. We present necessary conditions for this effect to occur, and show numerical results for disordered materials, relevant for applications. We calculate Josephson diode efficiencies for both charge- and spin-diodes and show that a spin-diode efficiency of 100% can be reached. Finally, we present a SQUID device that can switch between nearly pure spin-up and spin-down equal-spin supercurrents across the ferromagnet by reversing the flux. These findings establish functionalities that are absent for coplanar spin textures.

arXiv:2501.11751 (2025)

Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

5 pages, 4 figures

Strain induced topological phase transitions in split and line graphs of bipartite lattices featuring flat bands

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Shivam Sharma, Amartya S. Banerjee

In recent years, materials with topological flat bands have attracted significant attention due to their association with extraordinary transport properties and strongly correlated electrons. This includes phenomena such as high-temperature superconductivity, magnetism, Wigner crystallization, and Mott-insulating behavior. Among these systems, two-dimensional (2D) materials are particularly compelling as they can host electronic states with unique band structures, such as dispersionless states alongside linearly dispersive Dirac cones. In this work, we use tight-binding models to comprehensively investigate a class of 2D lattices that generically support flat bands, and focus on the effects of strain on their electronic and topological properties. The studied lattices are constructed within a unifying graph-theoretic framework, whereupon split-graph and line-graph operations on bipartite square and hexagonal lattices are employed to generate new structures. In the absence of strain, the introduction of spin-orbit coupling (SOC) induces a bulk excitation gap, which transforms flat bands into quasi-flat bands with topologically nontrivial characteristics. By tuning system parameters and external strain, we observe the emergence of directional flat bands, and tilted and semi-Dirac cones. Remarkably, all lattices studied show phase transitions among trivial insulating, semimetallic, and topological phases. Our results highlight the potential of strain engineering as a versatile tool for manipulating electronic and topological phases in a wide variety of 2D materials.

arXiv:2501.11783 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)

Keywords: Flat bands, strongly correlated electrons, topological phase transitions, graph theory, 2D materials

Self-aligned multilayered nitrogen vacancy diamond nanoparticles for high spatial resolution magnetometry of microelectronic currents

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Yash Gokhale, Brandon S Coventry, Tsani Rogers, Maya Lines, Anna Vena, Jack Phillips, Tianxiang Zhu, Ilhan Bok, Dariana J. Troche, Mitchell Glodowski, Adam Vareberg, Suyash Bhatt, Alireza Ashtiani, Kevin W. Eliceiri, Aviad Hai

Nitrogen Vacancy diamond nanoparticles (NVNPs) are increasingly integrated with methods for optical detection of magnetic resonance (ODMR), providing new opportunities in magnetic characterization that span the visualization of magnetic fields in microelectronic circuits, environmental sensing and biology. However, only a small number of studies utilize aggregates of NVNPs for surface-wide magnetometry being that spin orientations in aggregate NVNPs are inherently misaligned, precluding their use for proper magnetic field detection compared with expensive monocrystalline diamonds. A postprocessing method for layering NVNPs with aligned NV center orientations can potentially facilitate superior NV magnetometry by allowing sensitive detection combined with simplified probe preparation. We present a novel technology for creating densely stacked monolayers of NVNP with inherent interlayer alignment for sensitive measurement of local magnetic field perturbations in microelectronic traces. We establish spatial characteristics of deposited aggregates and demonstrate their ability to capture magnetic dipoles from conducting microwires via ODMR. Our approach forms a novel accessible protocol that can be used for broad applications in micromagnetometry.

arXiv:2501.11796 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Instrumentation and Detectors (physics.ins-det)

Influence of conjugated structure for tunable molecular plasmons in peropyrene and its derivatives

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Haoran Liu, Nan Gao, Yurui Fang

Advances in research have sparked an increasing curiosity in understanding the plasmonic excitation properties of molecular-scale systems. Polycyclic aromatic hydrocarbons, as the fundamental building blocks of graphene, have been documented to possess plasmonic properties through experimental observations, making them prime candidates for investigation. By doping different elements, the conjugated structure of the molecule can be altered. In this study, the plasmonic excitation properties influenced by conjugated structures in peropyrene and its derivatives are investigated through first-principles calculations that combine the plasmonicity index, generalized plasmonicity index and transition contribution maps. For molecular plasmonic excitation, the conjugated structure can influence the oscillation modes of valence electrons, which is pivotal in yielding distinct field enhancement characteristics. Furthermore, charge doping can lead to a certain degree of alteration in the conjugated structures, and the doping of elements will result in varying degrees of such alteration, thereby initiating different trends in the evolution of plasmonic resonance. This further enhances the tunability of molecular plasmonic resonance. The results provide novel insights into the development and utilization of molecular plasmonic devices in practical applications.

arXiv:2501.11802 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)

19 pages, 6 figures

Room-temperature quantum emission from \(\mathrm{Cu_{Zn}}\)-\(\mathrm{V_{S}}\) defects in ZnS:Cu colloidal nanocrystals

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Yossef E. Panfil, Sarah M. Thompson, Gary Chen, Jonah Ng, Cherie R. Kagan, Lee C. Bassett

We report room-temperature observations of \(\mathrm{Cu_{Zn}}\)-\(\mathrm{V_{S}}\) quantum emitters in individual ZnS:Cu nanocrystals (NCs). Using time-gated imaging, we isolate the distinct, $\(3-\)$s-long, red photoluminescence (PL) emission of \(\mathrm{Cu_{Zn}}\)-\(\mathrm{V_{S}}\) defects, enabling their precise identification and statistical characterization. The emitters exhibit distinct blinking and photon antibunching, consistent with individual NCs containing two to four \(\mathrm{Cu_{Zn}}\)-\(\mathrm{V_{S}}\) defects. The quantum emitters' PL spectra show a pronounced blue shift compared to NC dispersions, likely due to photochemical and charging effects. Emission polarization measurements of quantum emitters are consistent with a \(\sigma\)-character optical dipole transition and the symmetry of the \(\mathrm{Cu_{Zn}}\)-\(\mathrm{V_{S}}\) defect. These observations motivate further investigation of \(\mathrm{Cu_{Zn}}\)-\(\mathrm{V_{S}}\) defects in ZnS NCs for use in quantum technologies.

arXiv:2501.11812 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)

29 pages, 17 figures

Repulsive thermal van der Waals interaction in multi-species asymmetric electrolytes driven by external electric fields

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Guangle Du, David S. Dean, Bing Miao, Rudolf Podgornik

It is well established that the long-range component of the thermal van der Waals interaction between two semi-infinite dielectrics becomes short-range when an electrolyte is present between them, this is the well known phenomenon of screening. In Phys. Rev. Lett, 133, 238002 (2024) it was shown that for a binary symmetric electrolyte, an electric field parallel to the dielectric boundaries disrupts screening and a long-range thermal repulsive interaction appears. At large applied fields this long-range repulsive interaction can be explained by the fact that the cations and anions have differing average drifts moving in opposite directions, leading to the correlation of charge density fluctuations between the two species to decouple. Here we extend these results to binary electrolytes which are asymmetric as well as electrolytes with more than two ionic species.

arXiv:2501.11838 (2025)

Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)

23 pages, 1 figure

The critical role of entropy in glass transition kinetics

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Lijian Song, Meng Gao, Juntao Huo, Li-Min Wang, Yuanzheng Yue, Jun-Qiang Wang

Glass transition is a reversible transition that occurs in most amorphous materials. However, the nature of glass transition remains far from being clarified. A key to understand the glass transition is to clarify what determines the glass transition temperature (Tg) and liquid fragility (m). Here the glass transition thermodynamics for 150 different glass-forming systems are studied statistically. It is found that the activation characters in the energy landscape are crucial to precisely portray the glass transition and, in particular, both the activation free energy (G) and the activation entropy (S) play critical roles. Gdetermines Tg, Tg=G/290+25.5, while Sdetermines m, m=S/Rln10+15 with R is gas constant. Based on the Boltzmann definition of entropy, the fragility is an indication of the number of the degeneracy of the evolution paths. This explains why the nano-confined, low-dimension or high-pressured glasses exhibit stronger characteristics, which has been a puzzling phenomenon for a long time.

arXiv:2501.11857 (2025)

Materials Science (cond-mat.mtrl-sci)

Development of an uncertainty-aware equation of state for gold

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Lin H. Yang, James A. Gaffney

This study introduces a framework that employs Gaussian Processes (GPs) to develop high-fidelity equation of state (EOS) tables, essential for modeling material properties across varying temperatures and pressures. GPs offer a robust predictive modeling approach and are especially adept at handling uncertainties systematically. By integrating Error-in-Variables (EIV) into the GP model, we adeptly navigate uncertainties in both input parameters (like temperature and density) and output variables (including pressure and other thermodynamic properties). Our methodology is demonstrated using first-principles density functional theory (DFT) data for gold, observing its properties over maximum density compression (up to 100 g/cc) and extreme temperatures within the warm dense matter region (reaching 300 eV). Furthermore, we assess the resilience of our uncertainty propagation within the resultant EOS tables under various conditions, including data scarcity and the intrinsic noise of experiments and simulations.

arXiv:2501.11878 (2025)

Materials Science (cond-mat.mtrl-sci)

3D structure and stability prediction of DNA with multi-way junctions in ionic solutions

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Xunxun Wang, Ya-Zhou Shi

Understanding the three-dimensional (3D) structure and stability of DNA is fundamental for its biological function and the design of novel drugs. In this study, we introduce an improved coarse-grained (CG) model, incorporating a more refined electrostatic energy term, the replica-exchange Monte Carlo algorithm, and the weighted histogram analysis method. The enhanced model predicts the 3D structures and stability of DNA with multi-way junctions (three-way and four-way) in various ionic environments, going beyond traditional single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). Our model demonstrates remarkable accuracy in predicting the structures of DNAs with multi-way junctions from sequences and offers reliable estimates of their thermal stability across a range of sequences and lengths, with both monovalent and divalent salts. Notably, our analysis of the thermally unfolding pathways reveals that the stability of DNA with multi-way junctions is strongly influenced by the relative stabilities of their unfolded intermediate states, providing key insights into DNA structure-function relationships.

arXiv:2501.11891 (2025)

Soft Condensed Matter (cond-mat.soft)

30 pages, 7 figures, 1 table

Hybridization induced quantum phase transition in bilayer Hubbard model

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Xun Liu, Mi Jiang

Inspired by the recent experimental report on the pressure induced superconductor-insulator transition in cuprate superconductors as well as the superconductivity of the Ruddlesden-Popper-phase La\(_3\)Ni\(_2\)O\(_7\) under high pressure, we systematically investigated the single-orbital bilayer Hubbard model in the regime of large interlayer hybridization to mimic the pressure effects. We map out the phase diagram of interlayer hybridization versus density in the regime of intermediate to strong hybridization. In particular, we found that the sufficiently strong hybridization can destroy the \(s^{\pm}\)-wave pairing and induces its transition to correlated metallic, pseudogap, and Fermi liquid phases depending on the doping regime. The phase diagram hosted by the bilayer model implies its role as the versatile platform to explore the pressure effects on the two-dimensional to three-dimensional crossover physics of Hubbard-type models.

arXiv:2501.11907 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), Superconductivity (cond-mat.supr-con)

9 pages, 8 figures

Evidence of pseudogap and absence of spin magnetism in the time-reversal-symmetry-breaking state of Ba\(_{1-x}\)K\(_x\)Fe\(_2\)As\(_2\)

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Florian Bärtl, Nadia Stegani, Federico Caglieris, Ilya Shipulin, Yongwei Li, Quanxin Hu, Yu Zheng, Chi-Ming Yim, Sven Luther, Jochen Wosnitza, Rajib Sarkar, Hans-Henning Klauss, Julien Garaud, Egor Babaev, Hannes Kühne, Vadim Grinenko

Muon-spin-rotation (\(\mu\)SR) experiments and the observation of a spontaneous Nernst effect indicate time-reversal symmetry breaking (BTRS) at \(T_{\rm c}^{\rm Z2}\) above the superconducting transition temperature \(T_{\rm c}\) in Ba\(_{1-x}\)K\(_x\)Fe\(_2\)As\(_2\), with \(x\approx0.8\). Further studies have pointed out that BTRS is caused by the formation of a new state of matter associated with the condensation of pairs of electron pairs. Despite exhibiting multiple unconventional effects that warrant further investigation, the electronic spectral properties of this electron quadrupling state remain largely unexplored. Here, we present detailed \(^{75}\)As nuclear magnetic resonance (NMR) measurements of Ba\(_{1-x}\)K\(_x\)Fe\(_2\)As\(_2\), with \(x = 0.77\), which has \(T_{\rm c}^{\rm Z2}\) > \(T_{\rm c}\) according to measurements of the spontaneous Nernst effect. The NMR data obtained in this work provide the first direct electronic spectral characteristics of the electron quadrupling state by indicating that it evolves from a pseudogap that sets in at \(T^\ast\) well above \(T_{\rm c}^{\rm Z2}\). This pseudogap behavior is consistent with \(\mu\)SR Knight-shift, specific-heat, and transport data indicating the formation of a bound state of electrons. According to a theory of electron quadrupling condensates, such bound-state formations should precede the onset of BTRS correlations between pairs of electron pairs. The second important insight from NMR data is the absence of spin-related magnetism. The temperature dependence of the spin-lattice relaxation rate \(1/T_1T\) and the evolution of the NMR linewidth prove the absence of a magnetic transition at \(T_{\rm c}^{\rm Z2}\) and rule out even a proximity to some magnetic instability. This indicates that the spontaneous magnetic fields detected in this compound are not caused by spin magnetism but are associated with persistent real-space currents.

arXiv:2501.11936 (2025)

Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)

22 pages, 18 figures

Freezing in flat monolayers of soft spherocylinders

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Jaydeep Mandal, Henricus H. Wensink, Prabal K. Maiti

Lamellar or smectic phases often have an intricate intralamellar structure that remains scarcely understood from a microscopic viewpoint. In this work, we use molecular dynamics simulations to study the effect of volume exclusion and electrostatic repulsion on the phase transitions of a flat membrane of soft spherocylinders. With increasing rod packing, we identify nematic and solid phases and find that the nematic-crystal phase transition happens at a uniform packing fraction (\(\eta_c \approx 0.82\)), independent of the spherocylinder aspect ratio. This value is considerably higher than the well-known critical freezing transition of a hard disk fluid (\(\eta_c \approx 0.7\)) to which one could naively map a system of near-parallel rods with co-planar mass centers. We attribute this difference to a non-vanishing residual orientational entropy per rod. Our findings are corroborated by a simple theory based on a simple microscopic density functional theory of freezing of a two-dimensional rod fluid. Introduction of electrostatic interactions between the rods reduces the lateral compressibility of the monolayer fluid but keeps the positional order unhindered, which in turn maintains the packing fraction at the nematic-crystal transition. The strength of the orientational fluctuations of the individual rods in our membranes exhibits a density scaling that differs from 3D bulk smectics. Our findings contribute to a qualitative understanding of liquid crystal phase stability in strong planar confinement and engage with recent experimental explorations involving nanorods on 2D substrates.

arXiv:2501.11952 (2025)

Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)

10 pages, 9 figures

Metamaterials that learn to change shape

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Yao Du, Jonas Veenstra, Ryan van Mastrigt, Corentin Coulais

Learning to change shape is a fundamental strategy of adaptation and evolution of living organisms, from bacteria and cells to tissues and animals. Human-made materials can also exhibit advanced shape morphing capabilities, but lack the ability to learn. Here, we build metamaterials that can learn complex shape-changing responses using a contrastive learning scheme. By being shown examples of the target shape changes, our metamaterials are able to learn those shape changes by progressively updating internal learning degrees of freedom -- the local stiffnesses. Unlike traditional materials that are designed once and for all, our metamaterials have the ability to forget and learn new shape changes in sequence, to learn multiple shape changes that break reciprocity, and to learn multistable shape changes, which in turn allows them to perform reflex gripping actions and locomotion. Our findings establish metamaterials as an exciting platform for physical learning, which in turn opens avenues for the use of physical learning to design adaptive materials and robots.

arXiv:2501.11958 (2025)

Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)

12 pages, 5 figures

Hybrid Gauge Approach for Accurate Real-Time TDDFT Simulations with Numerical Atomic Orbitals

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Haotian Zhao, Lixin He

Ultrafast real-time dynamics are critical for understanding a broad range of physical processes. Real-time time-dependent density functional theory (rt-TDDFT) has emerged as a powerful computational tool for simulating these dynamics, offering insight into untrafast processes and light-matter interactions. In periodic systems, the velocity gauge is essential because it preserves the system's periodicity under an external electric field. Numerical atomic orbitals (NAOs) are widely employed in rt-TDDFT codes due to their efficiency and localized nature. However, directly applying the velocity gauge within the NAO basis set neglects the position-dependent phase variations within atomic orbitals induced by the vector potential, leading to significant computational errors-particularly in current calculations. To resolve this issue, we develop a hybrid gauge that incorporates both the electric field and the vector potential, preserving the essential phase information in atomic orbitals and thereby eliminating these errors. Our benchmark results demonstrate that the hybrid gauge fully resolves the issues encountered with the velocity gauge in NAO-based calculations, providing accurate and reliable results. This algorithm offers a robust framework for future studies on ultrafast dynamics in periodic systems using NAO bases.

arXiv:2501.11961 (2025)

Materials Science (cond-mat.mtrl-sci)

Exploiting the presence of chiral spin states in molecular nanomagnets

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Aman Ullah, Ziqi Hu, Alejandro Gaita-Ariño

In a three-spin-center system, antiferromagnetic exchange interactions give rise to two ground-state doublets, each state within the doublet exhibiting distinct spin-spectrum chirality. This chirality becomes significant when external perturbations are introduced. We explored, from a theoretical perspective, the presence of spin-chirality in Lanthanide complexes that feature two magnetic centers. The applied electric-potential, couples to the system electric dipole moment (\(\mu\)), modifying the spin-orbit interaction (\(\hat{L}.\hat{S}\)). This modification is formally expressed through the Dzyaloshinskii-Moriya interaction (DMI), whose role is to selectively activate one spin state in the doublet pair, as confirmed by computing the scalar spin-chirality (\(\chi\)). To validate the presence of chiral spin states, we performed spin-dynamics simulations using the Liouville-von Neumann equation within the density matrix formalism. The initial state was prepared as a superposition \(1/\sqrt{2}(\rho_{01}+\rho_{10})\), and its time evolution revealed that each state in the doublet acquires a distinct phase, indicating their residence in separate phase spaces. This also demonstrated that the fidelity of the initial prepared state remains stable over an extended period.

arXiv:2501.11964 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)

A method based on a dual frequency resonator to estimate physical parameters of superconductors from surface impedance measurements in a magnetic field

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Nicola Pompeo, Kostiantyn Torokhtii, Andrea Alimenti, Enrico Silva

High frequency applications of superconductors in a dc magnetic field rely on the estimate of the characteristic crossover frequency \(\nu_c\) between low and high losses. Customarily, high sensitivity resonant techniques, intrinsically operating at discrete frequencies, are used to estimate \(\nu_c\). We exploit here a method based on a dual frequency resonator. We show that single-frequency evaluations of \(\nu_c\) lead to heavy underestimations of the superconductor surface resistance. We describe a combined analytical and experimental approach that gives more accurate estimates for \(\nu_c\), and additionally allows to test the underlying physical model.

arXiv:2501.11966 (2025)

Superconductivity (cond-mat.supr-con)

13 pages, 9 figures, published on Measurement

Measurement, Volume 184, 2021, 109937, ISSN 0263-2241

Ferromagnetic resonance in Y3AlFe4O12 garnets

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

D. Popadiuk, V. Borynskyi, A. Kravets, Y. Shlapa, S. Solopan, A. Belous, A. Tovstolytkin, V. Korenivski

Spin dynamics in Al-substituted yttrium iron garnets is investigated using broadband ferromagnetic resonance measurements in the temperature range T=200-360 K. Using the measured data, the resonance field and linewidth as well as their temperature dependence are determined, with implications for the uniformity and overall quality of the samples prepared via different chemical fabrication routes. These key parameters governing the spin dynamics in the material are important for its applications in high-speed spintronic and magnonic devices.

arXiv:2501.11969 (2025)

Materials Science (cond-mat.mtrl-sci)

8 pages, 3 figures

Basic aspects of ferroelectricity induced by noncollinear alignment of spins

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

I. V. Solovyev

Basic principles of ferroelectric activity induced by the noncollinear spins are reviewed. There is a fundamental reason why the inversion symmetry can be broken by magnetic order. Such situation occurs when the magnetic order simultaneously involves ferromagnetic (\(F\)) and antiferromagnetic (\(A\)) patterns, transforming under the spatial inversion \(\mathcal{I}\) and time reversal \(\mathcal{T}\) as \(\mathcal{I}F=F\) and \(\mathcal{IT}A=A\). The incompatibility of these two conditions breaks the inversion symmetry, imposing a constraint on possible dependencies of polarization on directions of spins, which can include only antisymmetric coupling and single-ion anisotropy in the from \(\vec{P} = \vec{\boldsymbol{\mathcal{P}}}_{12} [ \boldsymbol{e}_{1} \times \boldsymbol{e}_{2} ] + \boldsymbol{e}_{1} \vec{\mathbb{\Pi}} \boldsymbol{e}_{1} - \boldsymbol{e}_{2} \vec{\mathbb{\Pi}} \boldsymbol{e}_{2}\). \(\vec{\boldsymbol{\mathcal{P}}}_{12}\) can be evaluated in the framework of superexchange theory, resulting in \(\vec{\boldsymbol{\mathcal{P}}}_{12} \sim \vec{\boldsymbol{r}}_{12}^{\phantom{0}}\), where \(\vec{\boldsymbol{r}}_{12}^{\phantom{0}}\) is the part of the position operator produced by the spin-orbit coupling. \(\vec{\boldsymbol{r}}_{12}\) remains invariant under \(\mathcal{I}\), explaining why noncollinear spins can induce \(\vec{P}\) even in the centrosymmetric case. The properties of \(\vec{\boldsymbol{r}}_{12}\) are rationalized from the viewpoint of symmetry of the Kramers states. The Katsura-Nagaosa-Balatsky rule \(\vec{P} \propto \vec{\epsilon}_{21} \times [\boldsymbol{e}_{1} \times \boldsymbol{e}_{2}]\) (\(\vec{\epsilon}_{21}\) being the bond direction) is justified only for relatively high symmetry. The single-ion anisotropy vanishes for the spin 1/2 or if magnetic ions are located in the inversion centers. The properties of known multiferroics are reconsidered from the viewpoint of these principles.

arXiv:2501.11970 (2025)

Materials Science (cond-mat.mtrl-sci)

20 pages, 12 figures

Advanced Spectroscopic Analyses on a:C-H Materials: Revisiting the EELS Characterization and its Coupling with multi-wavelength Raman Spectroscopy

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

L. Lajaunie, C. Pardanaud, C. Martin, P. Puech, C. Hu, M. J. Biggs, R. Arenal

Hydrogenated amorphous carbon thin films (a:C-H) are very promising materials for numerous applications. The growing of relevance of a:C-H is mainly due to the long-term stability of their outstanding properties. For improving their performances, a full understanding of their local chemistry is highly required. Fifteen years ago, electron energy-loss spectroscopy (EELS), developed in a transmission electron microscope (TEM), was the technique of choice to extract such kind of quantitative information on these materials. Other optical techniques, as Raman spectroscopy, are now clearly favored by the scientific community. However, they still lack of the spatial resolution offered by TEM-EELS. In addition, nowadays, the complexity of the physics phenomena behind EELS is better known. Here, a:C-H thin films have been isothermally annealed and the evolution of their physical and chemical parameters have been monitored at the local and macroscopic scales. In particular, chemical in-depth inhomogeneities and their origins are highlighted. Furthermore, a novel procedure to extract properly and reliably quantitative chemical information from EEL spectra is presented. Finally, the pertinence of empirical models used by the Raman community is discussed. These works demonstrate the pertinence of the combination of local and macroscopic analyses for a proper study of such complex materials.

arXiv:2501.11973 (2025)

Materials Science (cond-mat.mtrl-sci)

Carbon Volume 112, February 2017, Pages 149-161 Volume 112, February 2017, Pages 149-161

Unusual magnetic order, field induced melting and role of spin-lattice coupling in 2D Van der Waals materials: a case study of CrSiTe3

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Smita Gohil, Saswata Halder, Karthik K Iyer, Shankar Ghosh, A. Thamizhavel, Kalobaran Maiti

Two-dimensional (2D) Van der Waals compounds exhibit interesting electronic and magnetic properties due to complex intra-layer and inter-layer interactions, which are of immense importance in realizing exotic physics as well as advanced technology. Various experimental and theoretical studies led to significantly different ground state properties often contrasting each other. Here, we studied a novel 2D material, CrSiTe3 employing magnetic, specific heat and Raman measurements. Experimental results reveal evidence of incipient antiferromagnetism below 1 kOe concomitant to ferromagnetic order at 33 K. Antiferromagnetic and ferromagnetic interactions coexists at low field in the temperature regime, 15 - 33 K. Low field data reveal an additional magnetic order below 15 K, which melts on application of external magnetic field and remain dark in the heat capacity data. Raman spectra exhibit anomalies at the magnetic transitions; an evidence of strong spin-lattice coupling. Below 15 K, Eg modes exhibit hardening while Ag modes become significantly softer suggesting weakening of the inter-layer coupling at low temperatures which might be a reason for the unusual magnetic ground state and field induced melting of the magnetic order. These results reveal evidence of exceptional ground state properties linked to spin-lattice coupling and also suggest a pathway to study complex magnetism in such technologically important materials.

arXiv:2501.12019 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

6 figures

Multiterminal Josephson junctions with tunable topological properties

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Panch Ram, Detlef Beckmann, Romain Danneau, Wolfgang Belzig

Since the discovery of the Andreev reflection process at normal-metal/superconductor junctions and the corresponding Andreev bound states in superconductor/normal-metal/superconductor junctions, various multiterminal Josephson junctions have been studied to explore many exotic phases of quantum matter, where the formation of Andreev bound states in the normal region account for dissipationless supercurrent and play a central role in determining exotic properties. Recently, an intriguing aspect of the multiterminal Josephson junctions has been proposed to study the topological properties, wherein the Andreev bound states acquire topological characteristics upon tuning the phase differences of superconducting terminals. In this work, we investigate topologically non-trivial phases in four-terminal Josephson junctions based on square and graphene lattices. Additionally, we apply a gating potential that smoothly drives the Andreev bound states from a topologically non-trivial state to a trivial state. Furthermore, we observe that the gating potential in our setup produces the similar physics of the topological Andreev bound states of the double (single) quantum-dot multiterminal Josephson junctions when the gating potential is small (large) compared to the superconducting gap.

arXiv:2501.12024 (2025)

Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

9 pages, 5 figures

Low-Cost 3D printed, Biocompatible Ionic Polymer Membranes for Soft Actuators

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Nils Trümpler, Ryo Kanno, Niu David, Anja Huch, Pham Huy Nguyen, Maksims Jurinovs, Gustav Nyström, Sergejs Gaidukovs, Mirko Kovac

Ionic polymer actuators, in essence, consist of ion exchange polymers sandwiched between layers of electrodes. They have recently gained recognition as promising candidates for soft actuators due to their lightweight nature, noise-free operation, and low-driving voltages. However, the materials traditionally utilized to develop them are often not human/environmentally friendly. Thus, to address this issue, researchers have been focusing on developing biocompatible versions of this actuator. Despite this, such actuators still face challenges in achieving high performance, in payload capacity, bending capabilities, and response time. In this paper, we present a biocompatible ionic polymer actuator whose membrane is fully 3D printed utilizing a direct ink writing method. The structure of the printed membranes consists of biodegradable ionic fluid encapsulated within layers of activated carbon polymers. From the microscopic observations of its structure, we confirmed that the ionic polymer is well encapsulated. The actuators can achieve a bending performance of up to 124\(^\circ\) (curvature of 0.82 \(\text{cm}^{-1}\)), which, to our knowledge, is the highest curvature attained by any bending ionic polymer actuator to date. It can operate comfortably up to a 2 Hz driving frequency and can achieve blocked forces of up to 0.76 mN. Our results showcase a promising, high-performing biocompatible ionic polymer actuator, whose membrane can be easily manufactured in a single step using a standard FDM 3D printer. This approach paves the way for creating customized designs for functional soft robotic applications, including human-interactive devices, in the near future.

arXiv:2501.12025 (2025)

Soft Condensed Matter (cond-mat.soft), Robotics (cs.RO)

6 pages, 8 figures, Accepted in IEEE International Conference on Soft Robotics 2025 (Robosoft)

Nanoscale functionalization of MoS\(_2\) monolayers with DNA origami

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Shen Zhao, Zhijie Li, Zsófia Meggyesi, Elisabeth Erber, Christoph Sikeler, Kenji Watanabe, Takashi Taniguchi, Anvar S. Baimuratov, Tim Liedl, Alexander Högele, Irina V. Martynenko

The functionalization of two-dimensional (2D) materials with organic molecules is a promising approach for realizing nanoscale optoelectronic devices with tailored functionalities, such as quantum light generation and p-n junctions. However, achieving control over the molecules' precise positioning on the 2D material remains a significant challenge. Here, we overcome the limitations of solution- and vapor deposition methods and use a DNA origami placement technique to spatially arrange various organic molecules on a chip surface at the single-molecule level with high assembly yields. This versatile method allows for precise patterning of transition metal dichalcogenides (TMDs) with organic molecules, including thiols and fluorescent dyes. We successfully integrated MoS\(_2\) monolayers with micron-scale molecule-origami patterns achieving both single photon emission from thiol-induced localized excitons in MoS\(_2\) and photoexcitation energy transfer with patterned fluorescent dyes. Our approach offers a pathway for producing complex, tailored 2D inorganic-organic heterostructures with molecular-level control, opening up new possibilities for advanced materials and device design.

arXiv:2501.12029 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

On the pseudo-doublet ground state of the non-Kramers compound SrTm2O4 and its frustrated antiferromagnetic interactions

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

D. L. Quintero Castro, A. Bhat Kademane, M. Pregelj, R. Toft-Petersen, D. G. Mazzone, G. S. Tucker, C. Salazar Mejia, J. Gronemann, H.-F. Li

Here we present experimental evidence of the pseudo-doublet ground state of the non-Kramers compound SrTm2O4, based on specific heat, magnetic entropy and electron paramagnetic resonance. We demonstrate that the two crystallographic Tm3+ sites give rise to distinct single-ion anisotropies, and by extension, SrTm2O4 hosts two magnetic sublattices. Inelastic neutron scattering reveals low-lying dispersing crystal-field excitations, which we modelled using an effective charge model and mean field random phase approximation. The extracted magnetic exchange interactions are both antiferromagnetic and frustrated for both chains. Interchain magnetic exchange interactions are negligible. The strength of the magnetic exchange interactions in relation to the size of crystal field gaps, together with the frustration and low dimensionality, force the system to remain paramagnetic down to the lowest experimentally reachable temperature despite the pseudo-doublet nature of its ground state.

arXiv:2501.12035 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

Generalized Bond Polarizability model for more accurate atomistic modeling of Raman spectra

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Atanu Paul, Nagaprasad Reddy Samala, Ilya Grinberg

Raman spectroscopy is an important tool for studies of molecules, liquids and solids. While Raman spectra can be obtained theoretically from molecular dynamics (MD) simulations, this requires the calculation of the electronic polarizability along the simulation trajectory. First-principles calculations of electronic polarizability are computationally expensive, motivating the development of atomistic models for the evaluation of the changes in the electronic polarizability with the changes in the atomic coordinates of the system. The bond polarizability model (BPM) is one of the oldest and simplest such atomistic models, but cannot reproduce the effects of angular vibrations, leading to inaccurate modeling of Raman spectra. Here, we demonstrate that the generalization of BPM through inclusion of terms for atom pairs that are traditionally considered to be not involved in bonding dramatically improves the accuracy of polarizability modeling and Raman spectra calculations. The generalized BPM (GBPM) reproduces the ab initio polarizability and Raman spectra for a range of tested molecules (SO2, H2S, H2O, NH3, CH4, CH3OH and CH3CH2OH) with high accuracy and also shows significantly improved agreement with ab initio results for the more complex ferroelectric BaTiO3 systems. For liquid water, the anisotropic Raman spectrum derived from atomistic MD simulations using GBPM evaluation of polarizability shows significantly improved agreement with the experimental spectrum compared to the spectrum derived using BPM. Thus, GBPM can be used for the modeling of Raman spectra using large-scale molecular dynamics and provides a good basis for the further development of atomistic polarizability models.

arXiv:2501.12059 (2025)

Materials Science (cond-mat.mtrl-sci)

Exploring the Limits of Superconductivity in Metal-Stuffed B-C Clathrates via Ionic Lattice Anharmonicity

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Wenbo Zhao, Ying Sun, Jiaxiang Li, Peng Yuan, Toshiaki Iitaka, Xin Zhong, Hefei Li, Yue-Wen Fang, Hanyu Liu, Ion Errea, Yu Xie

Metal-stuffed B-C compounds with sodalite clathrate structure have captured increasing attention due to their predicted exceptional superconductivity above liquid nitrogen temperature at ambient pressure. However, by neglecting the quantum lattice anharmonicity, the existing studies may result in an incomplete understanding of such a lightweight system. Here, using state-of-the-art initiomethods incorporating quantum effects and machine learning potentials, we revisit the properties of a series of \(XY\text{B}_{6}\text{C}_{6}\) clathrates where \(X\) and \(Y\) are metals. Our findings show that ionic quantum and anharmonic effects can harden the \(E_g\) and \(E_u\) vibrational modes, enabling the dynamical stability of 15 materials previously considered unstable in the harmonic approximation, including materials with previously unreported \((XY)^{1+}\) state, which is demonstrated here to be crucial to reach high critical temperatures. Further calculations based on the isotropic Migdal-Eliashberg equation demonstrate that the \(T_c\) values for \(\text{KRbB}_{6}\text{C}_{6}\) and \(\text{RbB}_{3}\text{C}_{3}\) among these stabilized compounds are 87 and 98 K at 0 and 15 GPa, respectively, both being higher than \(T_c\) of 77 K of \(\text{KPbB}_{6}\text{C}_{6}\) at the anharmonic level. These record-high \(T_c\) values, surpassing liquid nitrogen temperatures, emphasize the importance of anharmonic effects in stabilizing B-C clathrates with large electron-phonon coupling strength and advancing the search for high-\(T_c\) superconductivity at (near) ambient pressure.

arXiv:2501.12068 (2025)

Superconductivity (cond-mat.supr-con)

Unveiling the thermal transport mechanism in compressed plastic crystals assisted by deep potential

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Yangjun Qin, Zhicheng Zong, Junwei Che, Tianhao Li, Haisheng Fang, Nuo Yang

The unique properties of plastic crystals highlight their potential for use in solid-state refrigeration. However, their practical applications are limited by thermal hysteresis due to low thermal conductivity. In this study, the effect of compressive strain on the thermal transport properties of plastic crystal [(CH3)4N][FeCl4] was investigated using molecular dynamic simulation with a deep neural network potential. It is found that a 9% strain along [001] direction enhances thermal conductivity sixfold. The underlying mechanisms are analyzed through vibrational density of states, spectral energy densities, and mean square displacements. The enhancement in thermal conductivity is primarily due to increased group velocity and reduced phonon scattering, driven by volume compression within the 0-1 THz. These findings offer theoretical insights for the practical application of plastic crystals in thermal management systems.

arXiv:2501.12078 (2025)

Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)

Momentum-dependent electron-phonon coupling in cuprates by RIXS: the roles of phonon symmetry and electronic structure

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Maryia Zinouyeva, Rolf Heid, Giacomo Merzoni, Riccardo Arpaia, Nikolai Andreev, Marco Biagi, Nicholas B. Brookes, Daniele Di Castro, Alexei Kalaboukhov, Kurt Kummer, Floriana Lombardi, Leonardo Martinelli, Francesco Rosa, Flora Yakhou-Harris, Lucio Braicovich, Marco Moretti Sala, Paolo G. Radaelli, Giacomo Ghiringhelli

The experimental determination of the magnitude and momentum dependence of electron-phonon coupling (EPC) is an outstanding problem in condensed matter physics. Resonant inelastic x-ray scattering (RIXS) has been previously employed to determine the EPC, since the intensity of phonon peaks in RIXS spectra has been directly related to the underlying EPC strength. In order to assess the limits of validity of such a relation, we compare experimental results and theoretical predictions for several high-T\(_c\) superconducting cuprates. Namely, we investigate the intensity of the bond-stretching phonon mode in CaCuO\(_2\), La\(_2\)CuO\(_{4+\delta}\), La\(_{1.84}\)Sr\(_{0.16}\)CuO\(_4\) and YBa\(_2\)Cu\(_3\)O\(_{7-\delta}\) along the high symmetry (\(\zeta\),0), (\(\zeta\),\(\zeta\)) directions and as a function of the azimuthal angle \(\phi\) at fixed modulus of the in-plane momentum \(\mathbf{q_\parallel}\). Using two different theoretical approaches for the description of the RIXS scattering from phonons, we find that the \(\mathbf{q_\parallel}\)-dependence of the RIXS intensity can be largely ascribed to the symmetry of the phonon mode, and that satisfactory prediction of the experimental results cannot be obtained without including realistic details of the electronic structure in the calculations. Regardless of the theoretical model, RIXS provides a reliable momentum dependence of EPC in cuprates and can be used to test advanced theoretical predictions.

arXiv:2501.12089 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

15 pages, 7 figures

A glance to Luttinger liquid and its platforms

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Isabelle Bouchoule, Roberta Citro, Tim Duty, Thierry Giamarchi, Randall G. Hulet, Martin Klanjsek, Edmond Orignac, Bent Weber

The concept of a Tomonaga-Luttinger liquid (TLL) has been established as a fundamental theory for the understanding of one-dimensional quantum systems. Originally formulated as a replacement for Landau's Fermi-liquid theory, which accurately predicts the behaviour of most 3D metals but fails dramatically in 1D, the TLL description applies to a even broader class of 1D systems,including bosons and anyons. After a certain number of theoretical breakthroughs, its descriptive power has now been confirmed experimentally in different experimental platforms. They extend from organic conductors, carbon nanotubes, quantum wires, topological edge states of quantum spin Hall insulators to cold atoms, Josephson junctions, Bose liquids confined within 1D nanocapillaries and spin chains. In the ground state of such systems, quantum fluctuations become correlated on all length scales, but, counter-intuitively, no long-range order exists. In this respect, this review will illustrate the validity of conformal field theory for describing real-world systems, establishing the boundaries for its application and, on the other side will discuss the spectacular demonstration of how the quantum-critical TLL state governs the properties of many-body systems in one dimension.

arXiv:2501.12097 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas)

Brief review of Tomonaga-Luttinger liquid physics and its experimental realizations. Comments and suggestions welcome. (RevTeX 4.2, 21 pages, 6 figures)

Dzyaloshinskii-Moriya interaction chirality reversal with ferromagnetic thickness

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Capucine Gueneau, Fatima Ibrahim, Johanna Fischer, Libor Vojáček, Charles-Élie Fillion, Stefania Pizzini, Laurent Ranno, Isabelle Joumard, Stéphane Auffret, Jérôme Faure-Vincent, Claire Baraduc, Mairbek Chshiev, Hélène Béa

In ultrathin ferromagnetic films sandwiched between two distinct heavy metal layers or between a heavy metal and an oxide layer, the Dzyaloshinskii-Moriya interaction (DMI) is recognized as being of interfacial origin. Its chirality and strength are determined by the properties of the adjacent heavy metals and the degree of oxidation at the interfaces. Here, we demonstrate that the chirality of the DMI can change solely with variations in the thickness of the ferromagnetic layer - an effect that has not been experimentally observed or explained until now. Our experimental observation in the trilayer system Ta/FeCoB/TaOx is supported by ab initio calculations: they reveal that variations in orbital filling and inter-atomic distances at the interface, driven by the number of ferromagnetic atomic layers, lead to an inversion of DMI chirality. This mechanism takes place for ferromagnetic layers with more than three atomic layers, for which the two interfaces start to be decoupled. We hence propose a new degree of freedom to tune DMI chirality and the associated chiral spin textures by tailoring crystal structure e.g. using strain or surface acoustic waves.

arXiv:2501.12098 (2025)

Materials Science (cond-mat.mtrl-sci)

5 figures + supplementary materials

Quantum trajectories and Page-curve entanglement dynamics

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Katha Ganguly, Preethi Gopalakrishnan, Atharva Naik, Bijay Kumar Agarwalla, Manas Kulkarni

We consider time dynamics of entanglement entropy between a filled fermionic system and an empty reservoir. We consider scenarios (i) where the system is subjected to a dephasing mechanism and the reservoir is clean, thereby emulating expansion of effectively interacting fermions in vacuum, and (ii) where both the system and the reservoir are subjected to dephasing and thereby enabling us to address how the entanglement between the part of the effectively interacting system and its complement evolves in time. We consider two different kinds of quantum trajectory approaches, namely stochastic unitary unraveling and quantum state diffusion. For both protocols, we observe and characterize the full Page curve-like dynamics for the entanglement entropy. Depending on the protocol and the setup, we observe very distinct characteristics of the Page curve and the associated Page time and Page value. We also compute the number of fermions leaking to the reservoir and the associated current and shed light on their plausible connections with entanglement entropy. Our findings are expected to hold for a wide variety of generic interacting quantum systems.

arXiv:2501.12110 (2025)

Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)

18 pages, 8 figures (including supplementary material)

Floquet engineering of point-gapped topological superconductors

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Xiang Ji, Hao Geng, Naeem Akhtar, Xiaosen Yang

Non-Hermitian systems exhibit two distinct topological classifications based on their gap structure: line-gap and point-gap topologies. Although point-gap topology is intrinsic to non-Hermitian systems, its systematic construction remains a challenge. Here, we present the Floquet engineering approach for realizing point-gapped topological superconductors. By combining Floquet theory with particle-hole symmetry (PHS), we show that a point gap hosting robust Majorana edge modes emerges at the overlap of Floquet bands with opposite winding numbers. In the thermodynamic limit, even weak non-Hermiticity opens a point gap from a gapless spectrum, driving a topological phase transition and breaking non-Bloch parity-time (\(\mathcal{PT}\)) symmetry. This transition is accompanied by the appearance of the Floquet \(Z_2\) skin effect. Furthermore, the point-gapped topological phase and the non-Bloch \(\mathcal{PT}\) symmetry exhibit size-dependent phenomena driven by the critical skin effect. Our work offers a new pathway for exploring the point-gapped topological phases in non-Hermitian systems.

arXiv:2501.12129 (2025)

Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)

6 pages, 5 figures

Orientation dependent transport in junctions formed by \(d\)-wave altermagnets and \(d\)-wave superconductors

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Wenjun Zhao, Yuri Fukaya, Pablo Burset, Jorge Cayao, Yukio Tanaka, Bo Lu

We investigate de Gennes and Saint-James states and Josephson effect in hybrid junctions based on \(d\)-wave altermagnet and \(d\)-wave superconductor. In a normal metal/altermagnet/\(d\)-wave superconductor junction, we find that the \(d_{x^{2}-y^{2}}\)-altermagnet can generate de Gennes and Saint-James states in a short junction due to the enhanced mismatch between electron and hole wave vectors, resulting in the vanishing zero-biased conductance peak with pronounced resonance spikes in the subgap conductance spectra. By contrast, the de Gennes and Saint-James states are not found for \(d_{xy}\)-altermagnet in the short junction but can be formed in the long junction. Moreover, the well-known features such as V-shape conductance for \(d_{x^2-y^2}\) pairings and zero-biased conductance peak for \(d_{xy}\) pairings are not affected by the strength of \(d_{xy}\)-altermagnetism in the short junction. We also study the Josephson current-phase relation $I( ) $ of \(d\)-wave superconductor/altermagnet/\(d\)-wave superconductor hybrids, where $$ is the macroscopic phase difference between two \(d\)-wave superconductors. In symmetric junctions, we obtain anomalous current phase relation such as a \(0\)-\(\pi\) transition by changing either the orientation or the magnitude of the altermagnetic order parameter and dominant higher Josephson harmonics. Interestingly, we find the first-order Josephson coupling in an asymmetric $ d_{x^{2}-y{2}}\(-superconductor/altermagnet/\)d_{xy}$-superconductor junction when the symmetry of altermagnetic order parameter is neither \(d_{x^{2}-y^{2}}\)- nor $ d_{xy}$-wave. We present the symmetry analysis and conclude that the anomalous orientation-dependent current-phase relations are ascribed to the peculiar feature of the altermagnetic spin-splitting field.

arXiv:2501.12141 (2025)

Superconductivity (cond-mat.supr-con)

10 pages, 5 figures

Exact solution to the hydrodynamic equation of quantum lattice gases with dephasing noise via classical run-and-tumble processes

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Michele Coppola

The average state dynamics of free fermions subject to random projective measurements of local site occupation numbers is governed by a Lindblad equation with dephasing noise. In the continuous limit, the equation of motion for the correlation matrix is mapped to a hydrodynamic equation for the Wigner function, which takes the form of a linear, nonlocal partial differential equation. As a main result, we derive the analytical solution to the hydrodynamic equation using the quasiparticle picture, showing that the Wigner dynamics emerges from stochastic sampling of classical run-and-tumble processes. As an application, we recover the crossover between ballistic and diffusive transport regimes.

arXiv:2501.12155 (2025)

Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas)

9 pages, 3 figures

Coherent spin dynamics of electrons and holes photogenerated with large kinetic energy in lead halide perovskite crystals

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Evgeny A. Zhukov, Dmitri R. Yakovlev, Erik Kirstein, Nataliia E. Kopteva, Oleh Hordiichuk, Maksym V. Kovalenko, Manfred Bayer

The coherent spin dynamics of electrons and holes are studied in a FA0.9Cs0.1PbI2.8Br0.2 perovskite bulk crystal, using time-resolved Kerr ellipticity in a two-color pump-probe scheme. The probe photon energy is tuned to the exciton resonance, while the pump photon energy is detuned from it up to 0.75 eV to higher energies. The spin-oriented electrons and holes photogenerated with significant excess kinetic energy relax into states in vicinity of the band gap, where they undergo Larmor precession in an external magnetic field. At cryogenic temperatures down to 1.6 K, the spin dephasing time reaches the nanosecond range. During energy relaxation, the carrier spin relaxation is inefficient and only happens when the carriers become localized. In experiments with two pump pulses, all-optical control of the amplitudes and phases of the electron and hole spin signals is achieved in the additive regime by varying the intensities of the pump pulses and the time delay between them.

arXiv:2501.12159 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Non-Hermitian wave-packet dynamics and its realization within a non-Hermitian chiral cavity

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Weicen Dong, Qing-Dong Jiang, Matteo Baggioli

Topological wave-packet dynamics provide a powerful framework for studying quantum transport in topological materials. However, extending this approach to non-Hermitian quantum systems presents several important challenges, primarily due to ambiguities in defining the Berry phase and the non-unitary evolution of the wave-packets when \(\mathcal{P}\mathcal{T}\) symmetry is broken. In this work, we adopt the complex Berry phase definition using the bi-orthogonal formalism and derive the semiclassical equations of motion (EOM) for a wave-packet in a non-Hermitian topological system. Interestingly, we find that the complex Berry curvature introduces both an anomalous velocity and an anomalous force into the semiclassical EOM. To validate the derived EOM, we design a non-Hermitian Haldane model featuring non-reciprocal next-nearest-neighbor (NNN) hopping, where the imbalance in the NNN hopping amplitudes gives rise to an emergent `complex chirality'. We reveal that the real and imaginary components of the complex chirality dictate the signs of both the real and imaginary parts of the complex Berry curvature, as well as the direction and dissipation rate of the edge states. Our analytical findings are confirmed by direct numerical simulations of the wave-packet dynamics. Finally, we suggest a potential experimental realization of this complex Haldane model using a non-Hermitian optical chiral cavity, providing a promising platform for testing our theoretical predictions.

arXiv:2501.12163 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)

v1: comments are welcome!

Mesoscopic Collective Dynamics in Liquids and the Dual Model

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-22 20:00 EST

Fabio Peluso

A microscopic vision is presented of a Dual Model of Liquids from a solid picture. Among the novelties of this model is that it provides quantitative expressions of various extensive thermophysical properties. The introduction of the statistical number of excited degrees of freedom (DoF) allows bypassing the problem of other dual models which are sometimes unable to correctly reproduce the expressions for those thermophysical quantities showing deviations due to the activation or deactivation of internal DoF. The interpretation of the relaxation times is given, their Order of Magnitude calculated and the way in which these times are involved in the different phases of the collective dynamics of liquids is discussed. A comparison is provided with results obtained in the frame of another phononic model of liquids, as well as with the predictions for the viscoelastic transition regions and with systems exhibiting kgap. In the last part of the paper, theoretical insights and experiments are suggested as potential directions for future research and development.

arXiv:2501.12180 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)

Journal of Heat Transfer (ASME), Nov 2022, 144(11): 112501

Magnetism in symmetry-enforced nodal-line semimetals

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Andressa R. Medeiros-Silva, Natanael C. Costa, Mariana Malard, Rodrigo G. Pereira, Thereza Paiva

Nodal-line semimetals (NLSMs) harbor a variety of novel physical properties owing to the particularities of the band degeneracies that characterize the spectrum of these materials. In symmetry-enforced NLSMs, band degeneracies, being imposed by symmetries, are robust to arbitrarily strong perturbations that preserve the symmetries. We investigate the effects of electron-electron interactions on a recently proposed vacancy-engineered NLSM known as holey graphene. Using mean-field calculations and quantum Monte Carlo simulation, we show that the Hubbard model on the depleted holey-graphene lattice at half-filling exhibits a transition from a NLSM to an insulating antiferromagnetic phase for an arbitrarily weak repulsive interaction \(U\). In contrast to the semi-metal-insulator transition in the pristine honeycomb lattice, which occurs at a finite critical value of \(U\), in the depleted lattice, the transition at \(U=0\) is associated with a van Hove singularity arising from the crossing of accidental nodal lines enforced by symmetry. We also employ linear spin wave theory (LSWT) to the effective Heisenberg model in the strong-coupling limit and obtain the global antiferromagnetic order parameter \(m_{\rm AFM} \approx 0.146\). The order parameters from both QMC and LSWT agree quantitatively. Our findings indicate that vacancy engineering offers an effective way to tailor the magnetic properties of quantum materials.

arXiv:2501.12187 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

13 pages, 14 figures

Thermodynamics of driven systems with explicitly broken detailed balance

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Markus Hofer, Jan Korbel, Rudolf Hanel, Stefan Thurner

In systems with detailed balance, the stationary distribution and the equilibrium distribution are identical, creating a clear connection between energetic and entropic quantities. Many driven systems violate detailed balance and still pose a challenge for a consistent thermodynamic interpretation. Even steady-state potentials like entropy or free energy are no longer state variables. Here, we use a framework for systems with broken detailed balance, where Boltzmann entropy can be computed while properly taking constraints on state transitions into account. As an illustration, we establish the thermodynamic relations for arbitrarily driven sample space-reducing processes that are non-equilibrium but show steady states. We demonstrate that, despite explicitly broken detailed balance, it remains feasible to define and unambiguously interpret the effective thermodynamic potentials.

arXiv:2501.12192 (2025)

Statistical Mechanics (cond-mat.stat-mech)

6 pages, 1 figure

Symmetry and Critical Dynamics in Supercooled Liquid Crystals: Insights into the Glass Transition

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Szymon Starzonek, Aleš Iglič, Aleksandra Drozd-Rzoska, Sylwester J. Rzoska

This study introduces a modeling approach aimed at elucidating the pivotal role of symmetry in phase transitions, focusing specifically on the isotropic-nematic (I-N) transition characteristic of liquid crystal systems. By leveraging insights from the Ising model and incorporating considerations of topological defects, the transition to the glassy state in rod-like molecular systems in the supercooled state is examined. Through a critical-like analysis of the system's dynamical properties, universality classes directly linked to symmetry are discerned. This paper delves into the role of symmetry in the glass transition, as manifested in the generalized critical relation of configurational entropy \(S_C(T)=S_0(1-T_K/T)^n\), where the critical exponent \(n\) is intricately tied to the system's symmetry. The determined values of the pseudocritical exponent \(n\) exhibit universality across the studied systems and demonstrate excellent agreement with thermodynamic data. Furthermore, the congruence between the dynamic representation, as indicated by the primary relaxation time, and the thermodynamic representation, exemplified by the specific heat capacity, underscores the robustness of the findings. The identification of critical-like behavior and the observation of symmetry breaking during the transition to the glass state suggest its intrinsic thermodynamic nature. This work provides a unified framework for understanding the glass transition, bridging dynamic and thermodynamic perspectives through the lens of symmetry.

arXiv:2501.12201 (2025)

Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn)

Strong phonon-mediated high temperature superconductivity in Li\(_2\)AuH\(_6\) under ambient pressure

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Zhenfeng Ouyang, Bo-Wen Yao, Xiao-Qi Han, Peng-Jie Guo, Ze-Feng Gao, Zhong-Yi Lu

We used our developed AI search engine~(InvDesFlow) to perform extensive investigations regarding ambient stable superconducting hydrides. A cubic structure Li\(_2\)AuH\(_6\) with Au-H octahedral motifs is identified to be a candidate. After performing thermodynamical analysis, we provide a feasible route to experimentally synthesize this material via the known LiAu and LiH compounds under ambient pressure. The further first-principles calculations suggest that Li\(_2\)AuH\(_6\) shows a high superconducting transition temperature (\(T_c\)) \(\sim\) 140 K under ambient pressure. The H-1\(s\) electrons strongly couple with phonon modes of vibrations of Au-H octahedrons as well as vibrations of Li atoms, where the latter is not taken seriously in other previously similar cases. Hence, different from previous claims of searching metallic covalent bonds to find high-\(T_c\) superconductors, we emphasize here the importance of those phonon modes with strong electron-phonon coupling (EPC). And we suggest that one can intercalate atoms into binary or ternary hydrides to introduce more potential phonon modes with strong EPC, which is an effective approach to find high-\(T_c\) superconductors within multicomponent compounds.

arXiv:2501.12222 (2025)

Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI), Computational Physics (physics.comp-ph)

6 pages; 4 figures

Theory of quantum-geometric charge and spin Josephson diode effects in strongly spin-polarized hybrid structures with noncoplanar spin textures

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-22 20:00 EST

Niklas L. Schulz, Danilo Nikolić, Matthias Eschrig

We present a systematic study of the spin-resolved Josephson diode effect (JDE) in strongly spin-polarized ferromagnets (sFM) coupled to singlet superconductors (SC) via ferromagnetic insulating interfaces (FI). All metallic parts are described in the framework of the quasiclassical Usadel Green's function theory applicable to diffusive systems. The interfaces are characterized by an S-matrix obtained for a model potential with exchange vectors pointing in an arbitrary direction with respect to the magnetization in the sFM. Our theory predicts a large charge Josephson diode effect with an efficiency exceeding \(33\%\) and a perfect spin diode effect with \(100\%\) efficiency. To achieve these the following conditions are necessary: (i) a noncoplanar profile of the three magnetization vectors in the system and (ii) different densities of states of spin-\(\uparrow\) and spin-\(\downarrow\) bands in the sFM achieved by a strong spin polarization. The former gives rise to the quantum-geometric phase, \(\Delta\varphi\), that enters the theory in a very similar manner as the superconducting phase difference across the junction, \(\Delta\chi\). We perform a harmonic analysis of the Josephson current in both variables and find symmetries between Fourier coefficients allowing an interpretation in terms of transfer processes of multiple equal-spin Cooper pairs across the two ferromagnetic spin bands. We point out the importance of crossed pair transmission processes. Finally, we study a spin-switching effect of an equal-spin supercurrent by reversing the magnetic flux in a SQUID device incorporating the mentioned junction and propose a way for measuring it.

arXiv:2501.12232 (2025)

Superconductivity (cond-mat.supr-con)

26 pages, 19 figures

Dynamic Metal-Support Interaction Dictates Cu Nanoparticle Sintering on Al\(_2\)O\(_3\) Surfaces

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

Jiayan Xu, Shreeja Das, Amar Deep Pathak, Abhirup Patra, Sharan Shetty, Detlef Hohl, Roberto Car

Nanoparticle sintering remains a critical challenge in heterogeneous catalysis. In this work, we present a unified deep potential (DP) model for Cu nanoparticles on three Al\(_2\)O\(_3\) surfaces (\(\gamma\)-Al\(_2\)O\(_3\)(100), \(\gamma\)-Al\(_2\)O\(_3\)(110), and \(\alpha\)-Al\(_2\)O\(_3\)(0001)). Using DP-accelerated simulations, we reveal striking facet-dependent nanoparticle stability and mobility patterns across the three surfaces. The nanoparticles diffuse several times faster on \(\alpha\)-Al\(_2\)O\(_3\)(0001) than on \(\gamma\)-Al\(_2\)O\(_3\)(100) at 800 K while expected to be more sluggish based on their larger binding energy at 0 K. Diffusion is facilitated by dynamic metal-support interaction (MSI), where the Al atoms switch out of the surface plane to optimize contact with the nanoparticle and relax back to the plane as the nanoparticle moves away. In contrast, the MSI on \(\gamma\)-Al\(_2\)O\(_3\)(100) and on \(\gamma\)-Al\(_2\)O\(_3\)(110) is dominated by more stable and directional Cu-O bonds, consistent with the limited diffusion observed on these surfaces. Our extended long-time MD simulations provide quantitative insights into the sintering processes, showing that the dispersity of nanoparticles (the initial inter-nanoparticle distance) strongly influences coalescence driven by nanoparticle diffusion. We observed that the coalescence of Cu\(_{13}\) nanoparticles on \(\alpha\)-Al\(_2\)O\(_3\)(0001) can occur in a short time (10 ns) at 800 K even with an initial inter-nanoparticle distance increased to 30 Å, while the coalescence on \(\gamma\)-Al\(_2\)O\(_3\)(100) is inhibited significantly by increasing the initial inter-nanoparticle distance from 15 Å to 30 Å. These findings demonstrate that the dynamics of the supporting surface is crucial to understanding the sintering mechanism and offer guidance for designing sinter-resistant catalysts by engineering the support morphology.

arXiv:2501.12283 (2025)

Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)

Reply to comment on "Controlled bond expansion for Density Matrix Renormalization Group ground state search at single-site costs"

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Andreas Gleis, Jheng-Wei Li, Jan von Delft

We reply to McCulloch and Osborne's recent comment on our manuscript (Phys. Rev. Lett. 130, 246402 (2023)) on controlled bond expansion (CBE) for density matrix renormalization group (DMRG) ground state search. We appreciate their suggestion to consider randomized SVD and address their constructive critique on the variational properties of CBE-DMRG. However, we strongly disagree with their proposal to omit the projection to the 2-site tangent space and explain its importance for efficient bond expansion. In particular, in the context of CBE applied to the time-dependent variational principle (TDVP), we show that omitting this projection can lead to avoidable errors. Lastly, we emphasize the complementary roles of 3S mixing and CBE, reiterating our recommendation from Phys. Rev. Lett. 130, 246402 (2023) to combine both methods (CBE+\(\alpha\)). We provide examples to demonstrate the superior efficiency and robustness of CBE+\(\alpha\).

arXiv:2501.12291 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

6 pages (including supplement), 1 figure

Charge-density-wave quantum critical point under pressure in 2\(H\)-TaSe\(_2\)

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-22 20:00 EST

Yuliia Tymoshenko, Amir-Abbas Haghighirad, Rolf Heid, Tom Lacmann, Alsu Ivashko, Adrian Merritt, Xingchen Shen, Michael Merz, Gaston Garbarino, Luigi Paolasini, Alexei Bosak, Florian K. Diekmann, Kai Rossnagel, Stephan Rosenkranz, Ayman H. Said, Frank Weber

Suppressing of an ordered state that competes with superconductivity is one route to enhance superconducting transition temperatures. Whereas the effect of suppressing magnetic states is still not fully understood, materials featuring charge-density waves and superconductivity offer a clearer scenario as both states can be associated with electron-phonon coupling. Metallic transition-metal dichalcogenides are prime examples for such intertwined electron-phonon-driven phases, yet, various compounds do not show the expected interrelation or feature additional mechanisms which makes an unambiguous interpretation difficult. Here, we report high-pressure X-ray diffraction and inelastic X-ray scattering measurements of the prototypical transition-metal dichalcogenide 2\(H\)-TaSe\(_2\) and determine the evolution of the charge-density-wave state and its lattice dynamics up to and beyond its suppression at the critical pressure \(p_c = 19.9(1)\,\rm{GPa}\) and at low temperatures. The high quality of our data allows the full refinement of the commensurate charge-density-wave superstructure at low pressure and we find the quantum critical point of the charge-density-wave to be in close vicinity to the reported maximum superconducting transition temperature \(T_{sc} = 8.2\,\rm{K}\). \(Ab-initio\) calculations corroborate that 2\(H\)-TaSe\(_2\) is a reference example of order-suppressed enhanced superconductivity and can serve as a textbook case to investigate superconductivity near a charge-density-wave quantum critical point.

arXiv:2501.12315 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)

The Rouse ring chain with attractive harmonic potential of spherical symmetry

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-22 20:00 EST

Nail Fatkullin, Carlos Mattea, Kevin Lindt, Siegfried Stapf, Margarita Kruteva

We study the static and dynamic properties of a cyclic Rouse chain modified by the inclusion of an effective, spherically symmetric, attracting potential of entropic nature , is the position vector of ring center of mass, is the position vector of the segment with number n, is the Boltzmann constant multiplied on absolute temperature, is a parameter of the potential, square of which is inverse to strength of the potential. It is shown that very weak potentials with , N is the number Kuhn segments in polymer ring, b is the length of Kuhn segment, lead to dramatic compression of the polymer chain whose radius of inertia becomes much smaller compared to the free size At values of the potential parameter of order , is the concentration of Kuhn segments in the melt, the concentration of the intrinsic segments of the polymer ring becomes of order and the state of the polymer ring can be regarded as globular. The terminal relaxation time of the polymer ring turns out to be of the order of , the mean squared displacement of the center of mass of the macromolecule during this time , which can lead to a pseudo plateau for the time dependence of the mean squared displacements of the polymer segments before entering the normal diffusion mode of motion.

arXiv:2501.12324 (2025)

Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)

Building unconventional magnetic phases on graphene by H atom manipulation: From altermagnets to Lieb ferrimagnets

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

B. Viña-Bausá, M. A. García-Blázquez, S. Chourasia, R. Carrasco, D. Expósito, I. Brihuega, J. J. Palacios

Engineering all fundamental magnetic phases within a single material platform would mark a significant milestone in materials science and spintronics, reducing complexity and costs in device fabrication by eliminating the need for integrating and interfacing different materials. Here, we demonstrate that graphene can host all non-relativistic magnetic phases-namely, diamagnetism, paramagnetism, ferromagnetism, antiferromagnetism, ferrimagnetism, altermagnetism and fully compensated ferrimagnetism -- by using single hydrogen atoms as building blocks. Through precise manipulation of these atoms by scanning tunneling microscopy, we can experimentally create all such magnetic phases. Their different magnetic character is confirmed by density functional theory and mean-field Hubbard calculations. In particular, we show that the new magnetic paradigm known as altermagnetism can be realized, exhibiting directionally spin-split energy bands coexisting with zero net magnetization due to protecting spatial symmetries. It is furthermore possible to create fully compensated ferrimagnets, lacking these symmetries and therefore presenting unrestricted spin splitting of the bands, with a vanishing net magnetization which in this case is protected by Lieb's theorem. These findings put forward H-functionalized graphene as a versatile platform to design, build and study these new emergent magnetic phases at the atomic scale.

arXiv:2501.12329 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

4 figures, 8 supplementary figures

Towards neural reinforcement learning for large deviations in nonequilibrium systems with memory

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-22 20:00 EST

Venkata D. Pamulaparthy, Rosemary J. Harris

We introduce a reinforcement learning method for a class of non-Markov systems; our approach extends the actor-critic framework given by Rose et al. [New J. Phys. 23 013013 (2021)] for obtaining scaled cumulant generating functions characterizing the fluctuations. The actor-critic is implemented using neural networks; a particular innovation in our method is the use of an additional neural policy for processing memory variables. We demonstrate results for current fluctuations in various memory-dependent models with special focus on semi-Markov systems where the dynamics is controlled by nonexponential interevent waiting time distributions.

arXiv:2501.12333 (2025)

Statistical Mechanics (cond-mat.stat-mech)

42 pages, 13 figures

Direct imaging of hydrogen-driven dislocation and strain field evolution in a stainless steel grain

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-22 20:00 EST

David Yang, Mujan Seif, Guanze He, Kay Song, Adrien Morez, Benjamin de Jager, Ross J. Harder, Wonsuk Cha, Edmund Tarleton, Ian K. Robinson, Felix Hofmann

Hydrogen embrittlement (HE) poses a significant challenge to the durability of materials used in hydrogen production and utilization. Disentangling the competing nanoscale mechanisms driving HE often relies on simulations and electron-transparent sample techniques, limiting experimental insights into hydrogen-induced dislocation behavior in bulk materials. This study employs in situ Bragg coherent X-ray diffraction imaging to track three-dimensional dislocation and strain field evolution during hydrogen charging in a bulk grain of austenitic 316 stainless steel. Tracking a single dislocation reveals hydrogen-enhanced mobility and relaxation, consistent with dislocation dynamics simulations. Subsequent observations reveal dislocation unpinning and climb processes, likely driven by osmotic forces. Additionally, nanoscale strain analysis around the dislocation core directly measures hydrogen-induced elastic shielding. These findings experimentally validate theoretical predictions and offer mechanistic insights into hydrogen-driven dislocation behavior, paving the way for the design of HE-resistant materials.

arXiv:2501.12364 (2025)

Materials Science (cond-mat.mtrl-sci)

16 pages, 5 figures