CMP Journal 2025-03-05
Statistics
Nature: 26
Nature Materials: 2
Nature Physics: 1
arXiv: 58
Nature
Superconductivity and quantized anomalous Hall effect in rhombohedral graphene
Original Paper | Quantum Hall | 2025-03-04 19:00 EST
Youngjoon Choi, Ysun Choi, Marco Valentini, Caitlin L. Patterson, Ludwig F. W. Holleis, Owen I. Sheekey, Hari Stoyanov, Xiang Cheng, Takashi Taniguchi, Kenji Watanabe, Andrea F. Young
Inducing superconducting correlations in chiral edge states is predicted to generate topologically protected zero energy modes with exotic quantum statistics1,2,3,4,5,6. Experimental efforts so far have focused on engineering interfaces between superconducting materials–typically amorphous metals–and semiconducting quantum Hall7,8,9,10,11 or quantum anomalous Hall12,13 systems. However, the strong interfacial disorder inherent in this approach can prevent the formation of isolated topological modes14,15,16,17. An appealing alternative is to use low-density flat band materials in which the ground state can be tuned between intrinsic superconducting and quantum anomalous Hall states using only the electric field effect. However, quantized transport and superconductivity have not been simultaneously achieved. Here we show that rhombohedral tetralayer graphene aligned to a hexagonal boron nitride substrate hosts a quantized anomalous Hall state at superlattice filling ν = -1 as well as a superconducting state at ν ≈ -3.5 at zero magnetic field. Gate voltage can also be used to actuate non-volatile switching of the chirality in the quantum anomalous Hall state18, allowing, in principle, arbitrarily reconfigurable networks of topological edge modes in locally gated devices. Thermodynamic compressibility measurements further show a topologically ordered fractional Chern insulator at ν = 2/3 (ref. 19)–also stable at zero magnetic field–enabling proximity coupling between superconductivity and fractionally charged edge modes. Finally, we show that, as in rhombohedral bi- and trilayers20,21,22, integrating a transition metal dichalcogenide layer to the heterostructure nucleates a new superconducting pocket20,21,22,23,24, while leaving the topology of the ν = -1 quantum anomalous Hall state intact. Our results pave the way for a new generation of hybrid interfaces between superconductors and topological edge states in the low disorder limit.
Quantum Hall, Superconducting properties and materials, Topological matter
Aspirin prevents metastasis by limiting platelet TXA2 suppression of T cell immunity
Original Paper | Adaptive immunity | 2025-03-04 19:00 EST
Jie Yang, Yumi Yamashita-Kanemaru, Benjamin I. Morris, Annalisa Contursi, Daniel Trajkovski, Jingru Xu, Ilinca Patrascan, Jayme Benson, Alexander C. Evans, Alberto G. Conti, Aws Al-Deka, Layla Dahmani, Adnan Avdic-Belltheus, Baojie Zhang, Hanneke Okkenhaug, Sarah K. Whiteside, Charlotte J. Imianowski, Alexander J. Wesolowski, Louise V. Webb, Simone Puccio, Stefania Tacconelli, Annalisa Bruno, Sara Di Berardino, Alessandra De Michele, Heidi C. E. Welch, I-Shing Yu, Shu-Wha Lin, Suman Mitra, Enrico Lugli, Louise van der Weyden, Klaus Okkenhaug, Kourosh Saeb-Parsy, Paola Patrignani, David J. Adams, Rahul Roychoudhuri
Metastasis is the spread of cancer cells from primary tumours to distant organs and is the cause of 90% of cancer deaths globally1,2. Metastasizing cancer cells are uniquely vulnerable to immune attack, as they are initially deprived of the immunosuppressive microenvironment found within established tumours3. There is interest in therapeutically exploiting this immune vulnerability to prevent recurrence in patients with early cancer at risk of metastasis. Here we show that inhibitors of cyclooxygenase 1 (COX-1), including aspirin, enhance immunity to cancer metastasis by releasing T cells from suppression by platelet-derived thromboxane A2 (TXA2). TXA2 acts on T cells to trigger an immunosuppressive pathway that is dependent on the guanine exchange factor ARHGEF1, suppressing T cell receptor-driven kinase signalling, proliferation and effector functions. T cell-specific conditional deletion of Arhgef1 in mice increases T cell activation at the metastatic site, provoking immune-mediated rejection of lung and liver metastases. Consequently, restricting the availability of TXA2 using aspirin, selective COX-1 inhibitors or platelet-specific deletion of COX-1 reduces the rate of metastasis in a manner that is dependent on T cell-intrinsic expression of ARHGEF1 and signalling by TXA2 in vivo. These findings reveal a novel immunosuppressive pathway that limits T cell immunity to cancer metastasis, providing mechanistic insights into the anti-metastatic activity of aspirin and paving the way for more effective anti-metastatic immunotherapies.
Adaptive immunity, Immunotherapy, Tumour immunology
Homogeneous ZnSeTeS quantum dots for efficient and stable pure-blue LEDs
Original Paper | Lasers, LEDs and light sources | 2025-03-04 19:00 EST
Qianqian Wu, Fan Cao, Wenke Yu, Sheng Wang, Wenjun Hou, Zizhe Lu, Weiran Cao, Jiaqi Zhang, Xiaoyu Zhang, Yingguo Yang, Guohua Jia, Jianhua Zhang, Xuyong Yang
The electroluminescence performance of heavy-metal-free blue quantum dot (QD) light-emitting diodes (QLEDs) is much lower than that of state-of-the-art cadmium-based counterparts. Ecofriendly ZnSeTe QDs are an ideal alternative to cadmium-based blue QDs1,2, but face issues with colour impurity and inferior stability caused by the aggregated tellurium (Ten≥2) that dominates compositional inhomogeneity3,4. Here we developed an isoelectronic control strategy using congeneric sulfur coordinated with triphenyl phosphite (TPP-S) to construct homogeneous ZnSeTeS QDs with pure-blue emissions and near-unity photoluminescence quantum yield. TPP with low electron-donating capability promotes the reactivity balance among anionic precursors, favouring the growth of QDs with uniform composition. The acceptor-like S with high electronegativity weakens the hole localization of the Te atoms by interfering with their surrounding carriers, thereby suppressing the formation of Ten≥2 isoelectronic centres. Furthermore, the congeneric S increases the configurational entropy of the QDs and eliminates the stacking faults and oxygen defects, leading to improved structural stability and reduced non-radiative carrier density. Consequently, the resulting pure-blue QLEDs based on core-shell ZnSeTeS/ZnSe/ZnS QDs emitting at 460 nm show a high external quantum efficiency of 24.7%, a narrow linewidth of 17 nm, and long operational half-lifetime (T50) close to 30,000 hours at 100 cd cm-2, rivalling state-of-the-art cadmium-based blue QLEDs.
Lasers, LEDs and light sources, Quantum dots
Real-time inference for binary neutron star mergers using machine learning
Original Paper | General relativity and gravity | 2025-03-04 19:00 EST
Maximilian Dax, Stephen R. Green, Jonathan Gair, Nihar Gupte, Michael Pürrer, Vivien Raymond, Jonas Wildberger, Jakob H. Macke, Alessandra Buonanno, Bernhard Schölkopf
Mergers of binary neutron stars emit signals in both the gravitational-wave (GW) and electromagnetic spectra. Famously, the 2017 multi-messenger observation of GW170817 (refs. 1,2) led to scientific discoveries across cosmology3, nuclear physics4,5,6 and gravity7. Central to these results were the sky localization and distance obtained from the GW data, which, in the case of GW170817, helped to identify the associated electromagnetic transient, AT 2017gfo (ref. 8), 11 h after the GW signal. Fast analysis of GW data is critical for directing time-sensitive electromagnetic observations. However, owing to challenges arising from the length and complexity of signals, it is often necessary to make approximations that sacrifice accuracy. Here we present a machine-learning framework that performs complete binary neutron star inference in just 1 s without making any such approximations. Our approach enhances multi-messenger observations by providing: (1) accurate localization even before the merger; (2) improved localization precision by around 30% compared to approximate low-latency methods; and (3) detailed information on luminosity distance, inclination and masses, which can be used to prioritize expensive telescope time. Additionally, the flexibility and reduced cost of our method open new opportunities for equation-of-state studies. Finally, we demonstrate that our method scales to long signals, up to an hour in length, thus serving as a blueprint for data analysis for next-generation ground- and space-based detectors.
General relativity and gravity, Mathematics and computing, Nuclear astrophysics, Stars, Transient astrophysical phenomena
TIR1-produced cAMP as a second messenger in transcriptional auxin signalling
Original Paper | Auxin | 2025-03-04 19:00 EST
Huihuang Chen, Linlin Qi, Minxia Zou, Mengting Lu, Mateusz Kwiatkowski, Yuanrong Pei, Krzysztof Jaworski, Jiří Friml
The phytohormone auxin (Aux) is a principal endogenous developmental signal in plants. It mediates transcriptional reprogramming by a well-established canonical signalling mechanism. TIR1/AFB auxin receptors are F-box subunits of an ubiquitin ligase complex; after auxin perception, they associate with Aux/IAA transcriptional repressors and ubiquitinate them for degradation, thus enabling the activation of auxin response factor (ARF) transcription factors1,2,3. Here we revise this paradigm by showing that without TIR1 adenylate cyclase (AC) activity4, auxin-induced degradation of Aux/IAAs is not sufficient to mediate the transcriptional auxin response. Abolishing the TIR1 AC activity does not affect auxin-induced degradation of Aux/IAAs but renders TIR1 non-functional in mediating transcriptional reprogramming and auxin-regulated development, including shoot, root, root hair growth and lateral root formation. Transgenic plants show that local cAMP production in the vicinity of the Aux/IAA-ARF complex by unrelated AC enzymes bypasses the need for auxin perception and is sufficient to induce ARF-mediated transcription. These discoveries revise the canonical model of auxin signalling and establish TIR1/AFB-produced cAMP as a second messenger essential for transcriptional reprograming.
Auxin, Plant signalling
Systematic bone tool production at 1.5 million years ago
Original Paper | Archaeology | 2025-03-04 19:00 EST
Ignacio de la Torre, Luc Doyon, Alfonso Benito-Calvo, Rafael Mora, Ipyana Mwakyoma, Jackson K. Njau, Renata F. Peters, Angeliki Theodoropoulou, Francesco d’Errico
Recent evidence indicates that the emergence of stone tool technology occurred before the appearance of the genus Homo1 and may potentially be traced back deep into the primate evolutionary line2. Conversely, osseous technologies are apparently exclusive of later hominins from approximately 2 million years ago (Ma)3,4, whereas the earliest systematic production of bone tools is currently restricted to European Acheulean sites 400-250 thousand years ago5,6. Here we document an assemblage of bone tools shaped by knapping found within a single stratigraphic horizon at Olduvai Gorge dated to 1.5 Ma. Large mammal limb bone fragments, mostly from hippopotamus and elephant, were shaped to produce various tools, including massive elongated implements. Before our discovery, bone artefact production in pre-Middle Stone Age African contexts was widely considered as episodic, expedient and unrepresentative of early Homo toolkits. However, our results demonstrate that at the transition between the Oldowan and the early Acheulean, East African hominins developed an original cultural innovation that entailed a transfer and adaptation of knapping skills from stone to bone. By producing technologically and morphologically standardized bone tools, early Acheulean toolmakers unravelled technological repertoires that were previously thought to have appeared routinely more than 1 million years later.
Archaeology
Evolutionary fingerprints of epithelial-to-mesenchymal transition
Original Paper | Cancer genetics | 2025-03-04 19:00 EST
Luigi Perelli, Li Zhang, Sarah Mangiameli, Francesca Giannese, Krishnan K. Mahadevan, Fuduan Peng, Francesca Citron, Hania Khan, Courtney Le, Enrico Gurreri, Federica Carbone, Andrew J. C. Russell, Melinda Soeung, Truong Nguyen Anh Lam, Sebastian Lundgren, Sujay Marisetty, Cihui Zhu, Desiree Catania, Alaa M. T. Mohamed, Ningping Feng, Jithesh Jose Augustine, Alessandro Sgambato, Giampaolo Tortora, Giulio F. Draetta, Giovanni Tonon, Andrew Futreal, Virginia Giuliani, Alessandro Carugo, Andrea Viale, Michael P. Kim, Timothy P. Heffernan, Linghua Wang, Raghu Kalluri, Davide Cittaro, Fei Chen, Giannicola Genovese
Mesenchymal plasticity has been extensively described in advanced epithelial cancers; however, its functional role in malignant progression is controversial1,2,3,4,5. The function of epithelial-to-mesenchymal transition (EMT) and cell plasticity in tumour heterogeneity and clonal evolution is poorly understood. Here we clarify the contribution of EMT to malignant progression in pancreatic cancer. We used somatic mosaic genome engineering technologies to trace and ablate malignant mesenchymal lineages along the EMT continuum. The experimental evidence clarifies the essential contribution of mesenchymal lineages to pancreatic cancer evolution. Spatial genomic analysis, single-cell transcriptomic and epigenomic profiling of EMT clarifies its contribution to the emergence of genomic instability, including events of chromothripsis. Genetic ablation of mesenchymal lineages robustly abolished these mutational processes and evolutionary patterns, as confirmed by cross-species analysis of pancreatic and other human solid tumours. Mechanistically, we identified that malignant cells with mesenchymal features display increased chromatin accessibility, particularly in the pericentromeric and centromeric regions, in turn resulting in delayed mitosis and catastrophic cell division. Thus, EMT favours the emergence of genomic-unstable, highly fit tumour cells, which strongly supports the concept of cell-state-restricted patterns of evolution, whereby cancer cell speciation is propagated to progeny within restricted functional compartments. Restraining the evolutionary routes through ablation of clones capable of mesenchymal plasticity, and extinction of the derived lineages, halts the malignant potential of one of the most aggressive forms of human cancer.
Cancer genetics, Cancer models, Gastrointestinal cancer
Fingerprinting the recovery of Antarctic ozone
Original Paper | Atmospheric chemistry | 2025-03-04 19:00 EST
Peidong Wang, Susan Solomon, Benjamin D. Santer, Douglas E. Kinnison, Qiang Fu, Kane A. Stone, Jun Zhang, Gloria L. Manney, Luis F. Millán
The Antarctic ozone ‘hole’ was discovered in 1985 (ref. 1) and man-made ozone-depleting substances (ODSs) are its primary cause2. Following reductions of ODSs under the Montreal Protocol3, signs of ozone recovery have been reported, based largely on observations and broad yet compelling model-data comparisons4. Although such approaches are highly valuable, they do not provide rigorous statistical detection of the temporal and spatial structure of Antarctic ozone recovery in the presence of internal climate variability. Here we apply pattern-based detection and attribution methods as used in climate-change studies5,6,7,8,9,10,11 to separate anthropogenically forced ozone responses from internal variability, relying on trend pattern information as a function of month and height. The analysis uses satellite observations together with single-model and multi-model ensemble simulations to identify and quantify the month-height Antarctic ozone recovery ‘fingerprint’12. We demonstrate that the data and simulations show compelling agreement in the fingerprint pattern of the ozone response to decreasing ODSs since 2005. We also show that ODS forcing has enhanced ozone internal variability during the austral spring, influencing detection of forced responses and their time of emergence. Our results provide robust statistical and physical evidence that actions taken under the Montreal Protocol to reduce ODSs are indeed resulting in the beginning of Antarctic ozone recovery, defined as increases in ozone consistent with expected month-height patterns.
Atmospheric chemistry
Sensory input, sex and function shape hypothalamic cell type development
Original Paper | Cell type diversity | 2025-03-04 19:00 EST
Harris S. Kaplan, Brandon L. Logeman, Kai Zhang, Tate A. Yawitz, Celine Santiago, Noor Sohail, Mustafa Talay, Changwoo Seo, Serhiy Naumenko, Shannan J. Ho Sui, David D. Ginty, Bing Ren, Catherine Dulac
Mammalian behaviour and physiology undergo major changes in early life. Young animals rely on conspecifics to meet their needs and start showing nutritional independence and sex-specific social interactions at weaning and puberty, respectively. How neuronal populations regulating homeostatic functions and social behaviours develop during these transitions remains unclear. We used paired transcriptomic and chromatin accessibility profiling to examine the developmental trajectories of neuronal populations in the hypothalamic preoptic region, where cell types with key roles in physiological and behavioural control have been identified1,2,3,4,5,6. These data show a marked diversity of developmental trajectories shaped by the sex of the animal, and the location and behavioural or physiological function of the corresponding cell types. We identify key stages of preoptic development, including early diversification, perinatal emergence of sex differences, postnatal maturation and refinement of signalling networks, and nonlinear transcriptional changes accelerating at the time of weaning and puberty. We assessed preoptic development in various sensory mutants and find a major role for vomeronasal sensing in the timing of preoptic cell type maturation. These results provide new insights into the development of neurons controlling homeostatic functions and social behaviours and lay ground for examining the dynamics of these functions in early life.
Cell type diversity, Social behaviour
Prohormone cleavage prediction uncovers a non-incretin anti-obesity peptide
Original Paper | Metabolism | 2025-03-04 19:00 EST
Laetitia Coassolo, Niels B. Danneskiold-Samsøe, Quennie Nguyen, Amanda Wiggenhorn, Meng Zhao, David Cheng-Hao Wang, David Toomer, Jameel Lone, Yichao Wei, Aayan Patel, Irene Liparulo, Deniz Kavi, Lianna W. Wat, Saranya Chidambaranathan Reghupaty, Julie Jae Kim, Tina Asemi, Ewa Bielczyk-Maczynska, Veronica L. Li, Maria Dolores Moya-Garzon, Nicole A. J. Krentz, Andreas Stahl, Danny Hung-Chieh Chou, Liqun Luo, Katrin J. Svensson
Peptide hormones, a class of pharmacologically active molecules, have a critical role in regulating energy homeostasis. Prohormone convertase 1/3 (also known as PCSK1/3) represents a key enzymatic mechanism in peptide processing, as exemplified with the therapeutic target glucagon-like peptide 1 (GLP-1)1,2. However, the full spectrum of peptides generated by PCSK1 and their functional roles remain largely unknown. Here we use computational drug discovery to systematically map more than 2,600 previously uncharacterized human proteolytic peptide fragments cleaved by prohormone convertases, enabling the identification of novel bioactive peptides. Using this approach, we identified a 12-mer peptide, BRINP2-related peptide (BRP). When administered pharmacologically, BRP reduces food intake and exhibits anti-obesity effects in mice and pigs without inducing nausea or aversion. Mechanistically, BRP administration triggers central FOS activation and acts independently of leptin, GLP-1 receptor and melanocortin 4 receptor. Together, these data introduce a method to identify new bioactive peptides and establish pharmacologically that BRP may be useful for therapeutic modulation of body weight.
Metabolism, Obesity
10,000-h-stable intermittent alkaline seawater electrolysis
Original Paper | Electrocatalysis | 2025-03-04 19:00 EST
Qihao Sha, Shiyuan Wang, Li Yan, Yisui Feng, Zhuang Zhang, Shihang Li, Xinlong Guo, Tianshui Li, Hui Li, Zhongbin Zhuang, Daojin Zhou, Bin Liu, Xiaoming Sun
Seawater electrolysis powered by renewable electricity provides an attractive strategy for producing green hydrogen1,2,3,4,5. However, direct seawater electrolysis faces many challenges, primarily arising from corrosion and competing reactions at the anode caused by the abundance of halide ions (Cl-, Br-) in seawater6. Previous studies3,6,7,8,9,10,11,12,13,14 on seawater electrolysis have mainly focused on the anode development, because the cathode operates at reducing potentials, which is not subject to electrode dissolution or chloride corrosion reactions during seawater electrolysis11,15. However, renewable energy sources are intermittent, variable and random, which cause frequent start-shutdown operations if renewable electricity is used to drive seawater electrolysis. Here we first unveil dynamic evolution and degradation of seawater splitting cathode in intermittent electrolysis and, accordingly, propose construction of a catalyst’s passivation layer to maintain the hydrogen evolution performance during operation. An in situ-formed phosphate passivation layer on the surface of NiCoP-Cr2O3 cathode can effectively protect metal active sites against oxidation during frequent discharge processes and repel halide ion adsorption on the cathode during shutdown conditions. We demonstrate that electrodes optimized using this design strategy can withstand fluctuating operation at 0.5 A cm-2 for 10,000 h in alkaline seawater, with a voltage increase rate of only 0.5% khr-1. The newly discovered challenge and our proposed strategy herein offer new insights to facilitate the development of practical seawater splitting technologies powered by renewable electricity.
Electrocatalysis
Cell-autonomous innate immunity by proteasome-derived defence peptides
Original Paper | Antimicrobial responses | 2025-03-04 19:00 EST
Karin Goldberg, Arseniy Lobov, Paola Antonello, Merav D. Shmueli, Idan Yakir, Tal Weizman, Adi Ulman, Daoud Sheban, Einav Laser, Matthias P. Kramer, Ronen Shteinvil, Guoyun Chen, Angham Ibraheem, Vera Sysoeva, Vered Fishbain-Yoskovitz, Gayatree Mohapatra, Anat Abramov, Sandy Shimshi, Kseniia Ogneva, Madhurima Nandy, Sivan Amidror, Hadar Bootz-Maoz, Shanny H. Kuo, Nili Dezorella, Assaf Kacen, Aaron Javitt, Gee W. Lau, Nissan Yissachar, Zvi Hayouka, Yifat Merbl
For decades, antigen presentation on major histocompatibility complex class I for T cell-mediated immunity has been considered the primary function of proteasome-derived peptides1,2. However, whether the products of proteasomal degradation play additional parts in mounting immune responses remains unknown. Antimicrobial peptides serve as a first line of defence against invading pathogens before the adaptive immune system responds. Although the protective function of antimicrobial peptides across numerous tissues is well established, the cellular mechanisms underlying their generation are not fully understood. Here we uncover a role for proteasomes in the constitutive and bacterial-induced generation of defence peptides that impede bacterial growth both in vitro and in vivo by disrupting bacterial membranes. In silico prediction of proteome-wide proteasomal cleavage identified hundreds of thousands of potential proteasome-derived defence peptides with cationic properties that may be generated en route to degradation to act as a first line of defence. Furthermore, bacterial infection induces changes in proteasome composition and function, including PSME3 recruitment and increased tryptic-like cleavage, enhancing antimicrobial activity. Beyond providing mechanistic insights into the role of proteasomes in cell-autonomous innate immunity, our study suggests that proteasome-cleaved peptides may have previously overlooked functions downstream of degradation. From a translational standpoint, identifying proteasome-derived defence peptides could provide an untapped source of natural antibiotics for biotechnological applications and therapeutic interventions in infectious diseases and immunocompromised conditions.
Antimicrobial responses, Antimicrobials, Proteasome
A mixed-precision memristor and SRAM compute-in-memory AI processor
Original Paper | Electrical and electronic engineering | 2025-03-04 19:00 EST
Win-San Khwa, Tai-Hao Wen, Hung-Hsi Hsu, Wei-Hsing Huang, Yu-Chen Chang, Ting-Chien Chiu, Zhao-En Ke, Yu-Hsiang Chin, Hua-Jin Wen, Wei-Ting Hsu, Chung-Chuan Lo, Ren-Shuo Liu, Chih-Cheng Hsieh, Kea-Tiong Tang, Mon-Shu Ho, Ashwin Sanjay Lele, Shih-Hsin Teng, Chung-Cheng Chou, Yu-Der Chih, Tsung-Yung Jonathan Chang, Meng-Fan Chang
Artificial intelligence (AI) edge devices1,2,3,4,5,6,7,8,9,10,11,12 demand high-precision energy-efficient computations, large on-chip model storage, rapid wakeup-to-response time and cost-effective foundry-ready solutions. Floating point (FP) computation provides precision exceeding that of integer (INT) formats at the cost of higher power and storage overhead. Multi-level-cell (MLC) memristor compute-in-memory (CIM)13,14,15 provides compact non-volatile storage and energy-efficient computation but is prone to accuracy loss owing to process variation. Digital static random-access memory (SRAM)-CIM16,17,18,19,20,21,22 enables lossless computation; however, storage is low as a result of large bit-cell area and model loading is required during inference. Thus, conventional approaches using homogeneous CIM architectures and computation formats impose a trade-off between efficiency, storage, wakeup latency and inference accuracy. Here we present a mixed-precision heterogeneous CIM AI edge processor, which supports the layer-granular/kernel-granular partitioning of network layers among on-chip CIM architectures (that is, memristor-CIM, SRAM-CIM and tiny-digital units) and computation number formats (INT and FP) based on sensitivity to error. This layer-granular/kernel-granular flexibility allows simultaneous optimization within the two-dimensional design space at the hardware level. The proposed hardware achieved high energy efficiency (40.91 TFLOPS W-1 for ResNet-20 with CIFAR-100 and 28.63 TFLOPS W-1 for MobileNet-v2 with ImageNet), low accuracy degradation (<0.45% for ResNet-20 with CIFAR-100 and for MobilNet-v2 with ImageNet) and rapid wakeup-to-response time (373.52 μs).
Electrical and electronic engineering, Electronic devices
Structure of mitochondrial pyruvate carrier and its inhibition mechanism
Original Paper | Cryoelectron microscopy | 2025-03-04 19:00 EST
Zheng He, Jianxiu Zhang, Yan Xu, Eve J. Fine, Carl-Mikael Suomivuori, Ron O. Dror, Liang Feng
The mitochondrial pyruvate carrier (MPC) governs the entry of pyruvate–a central metabolite that bridges cytosolic glycolysis with mitochondrial oxidative phosphorylation–into the mitochondrial matrix1,2,3,4,5. It thus serves as a pivotal metabolic gatekeeper and has fundamental roles in cellular metabolism. Moreover, MPC is a key target for drugs aimed at managing diabetes, non-alcoholic steatohepatitis and neurodegenerative diseases4,5,6. However, despite MPC’s critical roles in both physiology and medicine, the molecular mechanisms underlying its transport function and how it is inhibited by drugs have remained largely unclear. Here our structural findings on human MPC define the architecture of this vital transporter, delineate its substrate-binding site and translocation pathway, and reveal its major conformational states. Furthermore, we explain the binding and inhibition mechanisms of MPC inhibitors. Our findings provide the molecular basis for understanding MPC’s function and pave the way for the development of more-effective therapeutic reagents that target MPC.
Cryoelectron microscopy, Permeation and transport, Transporters
Vulnerability of amphibians to global warming
Original Paper | Animal physiology | 2025-03-04 19:00 EST
Patrice Pottier, Michael R. Kearney, Nicholas C. Wu, Alex R. Gunderson, Julie E. Rej, A. Nayelli Rivera-Villanueva, Pietro Pollo, Samantha Burke, Szymon M. Drobniak, Shinichi Nakagawa
Amphibians are the most threatened vertebrates, yet their resilience to rising temperatures remains poorly understood1,2. This is primarily because knowledge of thermal tolerance is taxonomically and geographically biased3, compromising global climate vulnerability assessments. Here we used a phylogenetically informed data-imputation approach to predict the heat tolerance of 60% of amphibian species and assessed their vulnerability to daily temperature variations in thermal refugia. We found that 104 out of 5,203 species (2%) are currently exposed to overheating events in shaded terrestrial conditions. Despite accounting for heat-tolerance plasticity, a 4 °C global temperature increase would create a step change in impact severity, pushing 7.5% of species beyond their physiological limits. In the Southern Hemisphere, tropical species encounter disproportionally more overheating events, while non-tropical species are more susceptible in the Northern Hemisphere. These findings challenge evidence for a general latitudinal gradient in overheating risk4,5,6 and underscore the importance of considering climatic variability in vulnerability assessments. We provide conservative estimates assuming access to cool shaded microenvironments. Thus, the impacts of global warming will probably exceed our projections. Our microclimate-explicit analyses demonstrate that vegetation and water bodies are critical in buffering amphibians during heat waves. Immediate action is needed to preserve and manage these microhabitat features.
Animal physiology, Biogeography, Climate-change ecology, Ecophysiology, Evolutionary ecology
A subcortical switchboard for perseverative, exploratory and disengaged states
Original Paper | Neural circuits | 2025-03-04 19:00 EST
Mehran Ahmadlou, Maryam Yasamin Shirazi, Pan Zhang, Isaac L. M. Rogers, Julia Dziubek, Margaret Young, Sonja B. Hofer
To survive in dynamic environments with uncertain resources, animals must adapt their behaviour flexibly, choosing strategies such as persevering with a current choice, exploring alternatives or disengaging altogether. Previous studies have mainly investigated how forebrain regions represent choice costs and values as well as optimal strategies during such decisions1,2,3,4,5. However, the neural mechanisms by which the brain implements alternative behavioural strategies such as persevering, exploring or disengaging remain poorly understood. Here we identify a neural hub that is critical for flexible switching between behavioural strategies, the median raphe nucleus (MRN). Using cell-type-specific optogenetic manipulations, fibre photometry and circuit tracing in mice performing diverse instinctive and learnt behaviours, we found that the main cell types of the MRN–GABAergic (γ-aminobutyric acid-expressing), glutamatergic (VGluT2+) and serotonergic neurons–have complementary functions and regulate perseverance, exploration and disengagement, respectively. Suppression of MRN GABAergic neurons–for instance, through inhibitory input from lateral hypothalamus, which conveys strong positive valence to the MRN–leads to perseverative behaviour. By contrast, activation of MRN VGluT2+ neurons drives exploration. Activity of serotonergic MRN neurons is necessary for general task engagement. Input from the lateral habenula that conveys negative valence suppresses serotonergic MRN neurons, leading to disengagement. These findings establish the MRN as a central behavioural switchboard that is uniquely positioned to flexibly control behavioural strategies. These circuits thus may also have an important role in the aetiology of major mental pathologies such as depressive or obsessive-compulsive disorders.
Neural circuits, Neuroscience
A cryptic pocket in CB1 drives peripheral and functional selectivity
Original Paper | Receptor pharmacology | 2025-03-04 19:00 EST
Vipin Ashok Rangari, Evan S. O’Brien, Alexander S. Powers, Richard A. Slivicki, Zachariah Bertels, Kevin Appourchaux, Deniz Aydin, Nokomis Ramos-Gonzalez, Juliet Mwirigi, Li Lin, Elizaveta Mangutov, Briana L. Sobecks, Yaseen Awad-Agbaria, Manoj B. Uphade, Jhoan Aguilar, Teja Nikhil Peddada, Yuki Shiimura, Xi-Ping Huang, Jakayla Folarin-Hines, Maria Payne, Anirudh Kalathil, Balazs R. Varga, Brian K. Kobilka, Amynah A. Pradhan, Michael D. Cameron, Kaavya Krishna Kumar, Ron O. Dror, Robert W. Gereau IV, Susruta Majumdar
The current opioid overdose epidemic highlights the urgent need to develop safer and more effective treatments for chronic pain1. Cannabinoid receptor type 1 (CB1) is a promising non-opioid target for pain relief, but its clinical use has been limited by centrally mediated psychoactivity and tolerance. We overcame both issues by designing peripherally restricted CB1 agonists that minimize arrestin recruitment. We achieved these goals by computationally designing positively charged derivatives of the potent CB1 agonist MDMB-Fubinaca2. We designed these ligands to occupy a cryptic pocket identified through molecular dynamics simulations–an extended binding pocket that opens rarely and leads to the conserved signalling residue D2.50 (ref. 3). We used structure determination, pharmacological assays and molecular dynamics simulations to verify the binding modes of these ligands and to determine the molecular mechanism by which they achieve this dampening of arrestin recruitment. Our lead ligand, VIP36, is highly peripherally restricted and demonstrates notable efficacy in three mouse pain models, with 100-fold dose separation between analgesic efficacy and centrally mediated side effects. VIP36 exerts analgesic efficacy through peripheral CB1 receptors and shows limited analgesic tolerance. These results show how targeting a cryptic pocket in a G-protein-coupled receptor can lead to enhanced peripheral selectivity, biased signalling, desired in vivo pharmacology and reduced adverse effects. This has substantial implications for chronic pain treatment but could also revolutionize the design of drugs targeting other G-protein-coupled receptors.
Receptor pharmacology, Structure-based drug design
Fine-scale patterns of SARS-CoV-2 spread from identical pathogen sequences
Original Paper | Ecological epidemiology | 2025-03-04 19:00 EST
Cécile Tran-Kiem, Miguel I. Paredes, Amanda C. Perofsky, Lauren A. Frisbie, Hong Xie, Kevin Kong, Amelia Weixler, Alexander L. Greninger, Pavitra Roychoudhury, JohnAric M. Peterson, Andrew Delgado, Holly Halstead, Drew MacKellar, Philip Dykema, Luis Gamboa, Chris D. Frazar, Erica Ryke, Jeremy Stone, David Reinhart, Lea Starita, Allison Thibodeau, Cory Yun, Frank Aragona, Allison Black, Cécile Viboud, Trevor Bedford
Pathogen genomics can provide insights into underlying infectious disease transmission patterns1,2, but new methods are needed to handle modern large-scale pathogen genome datasets and realize this full potential3,4,5. In particular, genetically proximal viruses should be highly informative about transmission events as genetic proximity indicates epidemiological linkage. Here we use pairs of identical sequences to characterize fine-scale transmission patterns using 114,298 SARS-CoV-2 genomes collected through Washington State (USA) genomic sentinel surveillance with associated age and residence location information between March 2021 and December 2022. This corresponds to 59,660 sequences with another identical sequence in the dataset. We find that the location of pairs of identical sequences is highly consistent with expectations from mobility and social contact data. Outliers in the relationship between genetic and mobility data can be explained by SARS-CoV-2 transmission between postcodes with male prisons, consistent with transmission between prison facilities. We find that transmission patterns between age groups vary across spatial scales. Finally, we use the timing of sequence collection to understand the age groups driving transmission. Overall, this study improves our ability to use large pathogen genome datasets to understand the determinants of infectious disease spread.
Ecological epidemiology, Infectious diseases
Impact of Amazonian deforestation on precipitation reverses between seasons
Original Paper | Forestry | 2025-03-04 19:00 EST
Yingzuo Qin, Dashan Wang, Alan D. Ziegler, Bojie Fu, Zhenzhong Zeng
Tropical deforestation was found to cause large reductions in precipitation using a range of observation-based datasets1. However, the limitations of satellite-based space-for-time statistical analysis have hindered understanding of the roles of reshaped mesoscale atmospheric circulation and regional precipitation recycling at different scales. These effects are considered nonlocal effects, which are distinct from the local effects governed by deforestation-induced reductions in evapotranspiration (ET). Here we show reversed precipitation responses to Amazon deforestation across wet and dry seasons. During the wet season, deforested grids experienced a noteworthy increase in precipitation (0.96 mm month-1 per percentage point forest loss), primarily attributed to enhanced mesoscale atmospheric circulation (that is, nonlocal effect). These nonlocal increases weaken with distance from deforested grids, leading to significant precipitation reductions in buffers beyond 60 km. Conversely, during the dry season, precipitation decreases in deforested grids and throughout all analysis buffers, with local effects from reduced ET dominating. Our findings highlight the intricate balance between local effects and nonlocal effects in driving deforestation-precipitation responses across different seasons and scales and emphasize the urgent need to address the rapid and extensive loss of forest in the Amazon region.
Forestry, Hydrology, Tropical ecology, Water resources
Genome duplication in a long-term multicellularity evolution experiment
Original Paper | Experimental evolution | 2025-03-04 19:00 EST
Kai Tong, Sayantan Datta, Vivian Cheng, Daniella J. Haas, Saranya Gourisetti, Harley L. Yopp, Thomas C. Day, Dung T. Lac, Ahmad S. Khalil, Peter L. Conlin, G. Ozan Bozdag, William C. Ratcliff
Whole-genome duplication (WGD) is widespread across eukaryotes and can promote adaptive evolution1,2,3,4. However, given the instability of newly formed polyploid genomes5,6,7, understanding how WGDs arise in a population, persist, and underpin adaptations remains a challenge. Here, using our ongoing Multicellularity Long Term Evolution Experiment (MuLTEE)8, we show that diploid snowflake yeast (Saccharomyces cerevisiae) under selection for larger multicellular size rapidly evolve to be tetraploid. From their origin within the first 50 days of the experiment, tetraploids persisted for the next 950 days (nearly 5,000 generations, the current leading edge of our experiment) in 10 replicate populations, despite being genomically unstable. Using synthetic reconstruction, biophysical modelling and counter-selection, we found that tetraploidy evolved because it confers immediate fitness benefits under this selection, by producing larger, longer cells that yield larger clusters. The same selective benefit also maintained tetraploidy over long evolutionary timescales, inhibiting the reversion to diploidy that is typically seen in laboratory evolution experiments. Once established, tetraploidy facilitated novel genetic routes for adaptation, having a key role in the evolution of macroscopic multicellular size via the origin of evolutionarily conserved aneuploidy. These results provide unique empirical insights into the evolutionary dynamics and impacts of WGD, showing how it can initially arise due to its immediate adaptive benefits, be maintained by selection and fuel long-term innovations by creating additional dimensions of heritable genetic variation.
Experimental evolution, Polyploidy
Clonal dynamics and somatic evolution of haematopoiesis in mouse
Original Paper | Ageing | 2025-03-04 19:00 EST
Chiraag D. Kapadia, Nicholas Williams, Kevin J. Dawson, Caroline Watson, Matthew J. Yousefzadeh, Duy Le, Kudzai Nyamondo, Sreeya Kodavali, Alex Cagan, Sarah Waldvogel, Xiaoyan Zhang, Josephine De La Fuente, Daniel Leongamornlert, Emily Mitchell, Marcus A. Florez, Krzysztof Sosnowski, Rogelio Aguilar, Alejandra Martell, Anna Guzman, David Harrison, Laura J. Niedernhofer, Katherine Y. King, Peter J. Campbell, Jamie Blundell, Margaret A. Goodell, Jyoti Nangalia
Haematopoietic stem cells maintain blood production throughout life1. Although extensively characterized using the laboratory mouse, little is known about clonal selection and population dynamics of the haematopoietic stem cell pool during murine ageing. We isolated stem cells and progenitors from young and old mice, identifying 221,890 somatic mutations genome-wide in 1,845 single-cell-derived colonies. Mouse stem cells and progenitors accrue approximately 45 somatic mutations per year, a rate only approximately threefold greater than human progenitors despite the vastly different organismal sizes and lifespans. Phylogenetic patterns show that stem and multipotent progenitor cell pools are established during embryogenesis, after which they independently self-renew in parallel over life, evenly contributing to differentiated progenitors and peripheral blood. The stem cell pool grows steadily over the mouse lifespan to about 70,000 cells, self-renewing about every 6 weeks. Aged mice did not display the profound loss of clonal diversity characteristic of human haematopoietic ageing. However, targeted sequencing showed small, expanded clones in the context of murine ageing, which were larger and more numerous following haematological perturbations, exhibiting a selection landscape similar to humans. Our data illustrate both conserved features of population dynamics of blood and distinct patterns of age-associated somatic evolution in the short-lived mouse.
Ageing, Evolutionary genetics, Haematopoietic stem cells, Mutation, Phylogenetics
Canopy functional trait variation across Earth’s tropical forests
Original Paper | Ecosystem ecology | 2025-03-04 19:00 EST
Jesús Aguirre-Gutiérrez, Sami W. Rifai, Xiongjie Deng, Hans ter Steege, Eleanor Thomson, Jose Javier Corral-Rivas, Aretha Franklin Guimaraes, Sandra Muller, Joice Klipel, Sophie Fauset, Angelica F. Resende, Göran Wallin, Carlos A. Joly, Katharine Abernethy, Stephen Adu-Bredu, Celice Alexandre Silva, Edmar Almeida de Oliveira, Danilo R. A. Almeida, Esteban Alvarez-Davila, Gregory P. Asner, Timothy R. Baker, Maíra Benchimol, Lisa Patrick Bentley, Erika Berenguer, Lilian Blanc, Damien Bonal, Kauane Bordin, Robson Borges de Lima, Sabine Both, Jaime Cabezas Duarte, Domingos Cardoso, Haroldo C. de Lima, Larissa Cavalheiro, Lucas A. Cernusak, Nayane Cristina C. dos Santos Prestes, Antonio Carlos da Silva Zanzini, Ricardo José da Silva, Robson dos Santos Alves da Silva, Mariana de Andrade Iguatemy, Tony César De Sousa Oliveira, Benjamin Dechant, Géraldine Derroire, Kyle G. Dexter, Domingos J. Rodrigues, Mário Espírito-Santo, Letícia Fernandes Silva, Tomas Ferreira Domingues, Joice Ferreira, Marcelo Fragomeni Simon, Cécile A. J. Girardin, Bruno Hérault, Kathryn J. Jeffery, Sreejith Kalpuzha Ashtamoorthy, Arunkumar Kavidapadinjattathil Sivadasan, Bente Klitgaard, William F. Laurance, Maurício Lima Dan, William E. Magnusson, Eduardo Malta Campos-Filho, Rubens Manoel dos Santos, Angelo Gilberto Manzatto, Marcos Silveira, Ben Hur Marimon-Junior, Roberta E. Martin, Daniel Luis Mascia Vieira, Thiago Metzker, William Milliken, Peter Moonlight, Marina Maria Moraes de Seixas, Paulo S. Morandi, Robert Muscarella, María Guadalupe Nava-Miranda, Brigitte Nyirambangutse, Jhonathan Oliveira Silva, Imma Oliveras Menor, Pablo José Francisco Pena Rodrigues, Cinthia Pereira de Oliveira, Lucas Pereira Zanzini, Carlos A. Peres, Vignesh Punjayil, Carlos A. Quesada, Maxime Réjou-Méchain, Terhi Riutta, Gonzalo Rivas-Torres, Clarissa Rosa, Norma Salinas, Rodrigo Scarton Bergamin, Beatriz Schwantes Marimon, Alexander Shenkin, Priscyla Maria Silva Rodrigues, Axa Emanuelle Simões Figueiredo, Queila Souza Garcia, Tereza Spósito, Danielle Storck-Tonon, Martin J. P. Sullivan, Martin Svátek, Wagner Tadeu Vieira Santiago, Yit Arn Teh, Prasad Theruvil Parambil Sivan, Marcelo Trindade Nascimento, Elmar Veenendaal, Irie Casimir Zo-Bi, Marie Ruth Dago, Soulemane Traoré, Marco Patacca, Vincyane Badouard, Samuel de Padua Chaves e Carvalho, Lee J. T. White, Huanyuan Zhang-Zheng, Etienne Zibera, Joeri Alexander Zwerts, David F. R. P. Burslem, Miles Silman, Jérôme Chave, Brian J. Enquist, Jos Barlow, Oliver L. Phillips, David A. Coomes, Yadvinder Malhi
Tropical forest canopies are the biosphere’s most concentrated atmospheric interface for carbon, water and energy1,2. However, in most Earth System Models, the diverse and heterogeneous tropical forest biome is represented as a largely uniform ecosystem with either a singular or a small number of fixed canopy ecophysiological properties3. This situation arises, in part, from a lack of understanding about how and why the functional properties of tropical forest canopies vary geographically4. Here, by combining field-collected data from more than 1,800 vegetation plots and tree traits with satellite remote-sensing, terrain, climate and soil data, we predict variation across 13 morphological, structural and chemical functional traits of trees, and use this to compute and map the functional diversity of tropical forests. Our findings reveal that the tropical Americas, Africa and Asia tend to occupy different portions of the total functional trait space available across tropical forests. Tropical American forests are predicted to have 40% greater functional richness than tropical African and Asian forests. Meanwhile, African forests have the highest functional divergence–32% and 7% higher than that of tropical American and Asian forests, respectively. An uncertainty analysis highlights priority regions for further data collection, which would refine and improve these maps. Our predictions represent a ground-based and remotely enabled global analysis of how and why the functional traits of tropical forest canopies vary across space.
Ecosystem ecology, Forest ecology, Plant ecology
Chanoclavine synthase operates by an NADPH-independent superoxide mechanism
Original Paper | Biophysics | 2025-03-04 19:00 EST
Chun-Chi Chen, Zhi-Pu Yu, Ziwei Liu, Yongpeng Yao, Peter-Leon Hagedoorn, Rob Alexander Schmitz, Lujia Yang, Lu Yu, Aokun Liu, Xiang Sheng, Hao Su, Yaqing Ma, Te Wang, Jian-Wen Huang, Lilan Zhang, Juzhang Yan, Jinping Bao, Chengsen Cui, Xian Li, Panpan Shen, Wuyuan Zhang, Jian Min, Chang-Yun Wang, Rey-Ting Guo, Shu-Shan Gao
More than ten ergot alkaloids comprising both natural and semi-synthetic products are used to treat various diseases1,2. The central C ring forms the core pharmacophore for ergot alkaloids, giving them structural similarity to neurotransmitters, thus enabling their modulation of neurotransmitter receptors3. The haem catalase chanoclavine synthase (EasC) catalyses the construction of this ring through complex radical oxidative cyclization4. Unlike canonical catalases, which catalyse H2O2 disproportionation5,6, EasC and its homologues represent a broader class of catalases that catalyse O2-dependent radical reactions4,7. We have elucidated the structure of EasC by cryo-electron microscopy, revealing a nicotinamide adenine dinucleotide phosphate (reduced) (NADPH)-binding pocket and a haem pocket common to all haem catalases, with a unique homodimeric architecture that is, to our knowledge, previously unobserved. The substrate prechanoclavine unprecedentedly binds in the NADPH-binding pocket, instead of the previously suspected haem-binding pocket, and two pockets were connected by a slender tunnel. Contrary to the established mechanisms, EasC uses superoxide rather than the more generally used transient haem iron-oxygen complexes (such as compounds I, II and III)8,9, to mediate substrate transformation through superoxide-mediated cooperative catalysis of the two distant pockets. We propose that this reactive oxygen species mechanism could be widespread in metalloenzyme-catalysed reactions.
Biophysics, Biotechnology, Electron microscopy
Emerging supersolidity in photonic-crystal polariton condensates
Original Paper | Polaritons | 2025-03-04 19:00 EST
Dimitrios Trypogeorgos, Antonio Gianfrate, Manuele Landini, Davide Nigro, Dario Gerace, Iacopo Carusotto, Fabrizio Riminucci, Kirk W. Baldwin, Loren N. Pfeiffer, Giovanni I. Martone, Milena De Giorgi, Dario Ballarini, Daniele Sanvitto
A supersolid is a counter-intuitive phase of matter in which its constituent particles are arranged into a crystalline structure, yet they are free to flow without friction. This requires the particles to share a global macroscopic phase while being able to reduce their total energy by spontaneous, spatial self-organization. The existence of the supersolid phase of matter was speculated more than 50 years ago1,2,3,4. However, only recently has there been convincing experimental evidence, mainly using ultracold atomic Bose-Einstein condensates (BECs) coupled to electromagnetic fields. There, various guises of the supersolid were created using atoms coupled to high-finesse cavities5,6, with large magnetic dipole moments7,8,9,10,11,12,13, and spin-orbit-coupled, two-component systems showing stripe phases14,15,16. Here we provide experimental evidence of a new implementation of the supersolid phase in a driven-dissipative, non-equilibrium context based on exciton-polaritons condensed in a topologically non-trivial, bound state in the continuum (BiC) with exceptionally low losses, realized in a photonic-crystal waveguide. We measure the density modulation of the polaritonic state indicating the breaking of translational symmetry with a precision of several parts in a thousand. Direct access to the phase of the wavefunction allows us to also measure the local coherence of the supersolid. We demonstrate the potential of our synthetic photonic material to host phonon dynamics and a multimode excitation spectrum.
Polaritons, Ultracold gases
Evolution of temperature preference in flies of the genus Drosophila
Original Paper | Neural circuits | 2025-03-04 19:00 EST
Matthew Capek, Oscar M. Arenas, Michael H. Alpert, Emanuela E. Zaharieva, Iván D. Méndez-González, José Miguel Simões, Hamin Gil, Aldair Acosta, Yuqing Su, Alessia Para, Marco Gallio
The preference for a particular thermal range is a key determinant of the distribution of animal species. However, we know little on how temperature preference behaviour evolves during the colonization of new environments. Here we show that at least two distinct neurobiological mechanisms drive the evolution of temperature preference in flies of the genus Drosophila. Fly species from mild climates (D. melanogaster and D. persimilis) avoid both innocuous and noxious heat, and we show that the thermal activation threshold of the molecular heat receptor Gr28b.d precisely matches species-specific thresholds of behavioural heat avoidance. We find that desert-dwelling D. mojavensis are instead actively attracted to innocuous heat. Notably, heat attraction is also mediated by Gr28b.d (and by the antennal neurons that express it) and matches its threshold of heat activation. Rather, the switch in valence from heat aversion to attraction correlates with specific changes in thermosensory input to the lateral horn, the main target of central thermosensory pathways and a region of the fly brain implicated in the processing of innate valence1,2,3,4,5. Together, our results demonstrate that, in Drosophila, the adaptation to different thermal niches involves changes in thermal preference behaviour, and that this can be accomplished using distinct neurobiological solutions, ranging from shifts in the activation threshold of peripheral thermosensory receptor proteins to a substantial change in the way temperature valence is processed in the brain.
Neural circuits, Sensory processing
Solanum pan-genetics reveals paralogues as contingencies in crop engineering
Original Paper | Agricultural genetics | 2025-03-04 19:00 EST
Matthias Benoit, Katharine M. Jenike, James W. Satterlee, Srividya Ramakrishnan, Iacopo Gentile, Anat Hendelman, Michael J. Passalacqua, Hamsini Suresh, Hagai Shohat, Gina M. Robitaille, Blaine Fitzgerald, Michael Alonge, Xingang Wang, Ryan Santos, Jia He, Shujun Ou, Hezi Golan, Yumi Green, Kerry Swartwood, Nicholas G. Karavolias, Gina P. Sierra, Andres Orejuela, Federico Roda, Sara Goodwin, W. Richard McCombie, Elizabeth B. Kizito, Edeline Gagnon, Sandra Knapp, Tiina E. Särkinen, Amy Frary, Jesse Gillis, Joyce Van Eck, Michael C. Schatz, Zachary B. Lippman
Pan-genomics and genome-editing technologies are revolutionizing breeding of global crops1,2. A transformative opportunity lies in exchanging genotype-to-phenotype knowledge between major crops (that is, those cultivated globally) and indigenous crops (that is, those locally cultivated within a circumscribed area)3,4,5 to enhance our food system. However, species-specific genetic variants and their interactions with desirable natural or engineered mutations pose barriers to achieving predictable phenotypic effects, even between related crops6,7. Here, by establishing a pan-genome of the crop-rich genus Solanum8 and integrating functional genomics and pan-genetics, we show that gene duplication and subsequent paralogue diversification are major obstacles to genotype-to-phenotype predictability. Despite broad conservation of gene macrosynteny among chromosome-scale references for 22 species, including 13 indigenous crops, thousands of gene duplications, particularly within key domestication gene families, exhibited dynamic trajectories in sequence, expression and function. By augmenting our pan-genome with African eggplant cultivars9 and applying quantitative genetics and genome editing, we dissected an intricate history of paralogue evolution affecting fruit size. The loss of a redundant paralogue of the classical fruit size regulator CLAVATA3 (CLV3)10,11 was compensated by a lineage-specific tandem duplication. Subsequent pseudogenization of the derived copy, followed by a large cultivar-specific deletion, created a single fused CLV3 allele that modulates fruit organ number alongside an enzymatic gene controlling the same trait. Our findings demonstrate that paralogue diversifications over short timescales are underexplored contingencies in trait evolvability. Exposing and navigating these contingencies is crucial for translating genotype-to-phenotype relationships across species.
Agricultural genetics, Evolutionary genetics, Genome informatics, Plant domestication
Nature Materials
Surfactant-induced hole concentration enhancement for highly efficient perovskite light-emitting diodes
Original Paper | Electronic devices | 2025-03-04 19:00 EST
Jiajun Qin, Jia Zhang, Xianjie Liu, Yu Wang, Heyong Wang, Utkarsh Singh, Yanyan Wang, Haoliang Wang, Tianxiang Hu, Yiqiang Zhan, Yipeng Tang, Bin Hu, Constantin Bach, Carsten Deibel, Wei-Xin Ni, Sergei I. Simak, Igor A. Abrikosov, Mats Fahlman, Feng Gao
It is widely acknowledged that constructing small injection barriers for balanced electron and hole injections is essential for light-emitting diodes (LEDs). However, in highly efficient LEDs based on metal halide perovskites, a seemingly large hole injection barrier is usually observed. Here we rationalize this high efficiency through a surfactant-induced effect where the hole concentration at the perovskite surface is enhanced to enable sufficient bimolecular recombination pathways with injected electrons. This effect originates from the additive engineering and is verified by a series of optical and electrical measurements. In addition, surfactant additives that induce an increased hole concentration also significantly improve the luminescence yield, an important parameter for the efficient operation of perovskite LEDs. Our results not only provide rational design rules to fabricate high-efficiency perovskite LEDs but also present new insights to benefit the design of other perovskite optoelectronic devices.
Electronic devices, Inorganic LEDs, Organic LEDs
Rapid growth of inch-sized lanthanide oxychloride single crystals
Original Paper | Electronic devices | 2025-03-04 19:00 EST
Zhuofeng Shi, Wei Guo, Saiyu Bu, Lingmiao Ma, Zhaoning Hu, Yaqi Zhu, Haotian Wu, Xiaohui Chen, Xiaodong Zhang, Kostya S. Novoselov, Boyang Mao, Ning Kang, Li Lin
The layered lanthanide oxychloride (LnOCl) family, featuring a low equivalent oxide thickness, high breakdown field and magnetic ordering properties, holds great promise for next-generation van der Waals devices. However, the exploitation of LnOCl materials has been hindered by a lack of reliable methods for growing their single-crystalline phases. Here we achieved the growth of inch-sized bulk LnOCl single crystals and single-crystalline thin films with thickness down to the monolayer in a few hours. The monolayer LnOCl exhibits ultralow equivalent oxide thicknesses, for instance, LaOCl and SmOCl have values of 0.25 and 0.34, respectively. Furthermore, using LnOCl as a dielectric in graphene devices, we demonstrate wafer-scale enhancement of carrier mobility and a well-developed quantum Hall effect. The induced strong magnetic proximity effect by SmOCl and DyOCl enables efficient interfacial charge transfer with magnetic exchange coupling This work provides a general strategy for synthesizing large-sized single-crystalline layered materials, enriching the library of ultralow-equivalent-oxide-thickness dielectric materials, and two-dimensional magnetic materials with induced strong magnetic proximity effect.
Electronic devices, Two-dimensional materials
Nature Physics
Bias in physics peer recognition does not explain gaps in perceived peer recognition
Original Paper | Applied physics | 2025-03-04 19:00 EST
Meagan Sundstrom, N. G. Holmes
Gaining recognition as a physics person by peers is an important contributor to undergraduate students’ physics identity and their success in physics courses. Previous research has separately demonstrated that women perceive less recognition from peers than men in their physics courses (perceived peer recognition) and that women receive fewer nominations from their peers for being strong in their physics course than men (received peer recognition). The relation between perceived and received peer recognition for men and women, however, is not well understood. Here we test three plausible models for this relation and find that, for students receiving the same amount of recognition from peers as measured from private nominations on a survey, women report significantly lower perceived peer recognition than men. We did this by conducting a quantitative study of over 1,700 students enrolled in introductory physics courses at eight institutions in the United States. We directly compare student gender, perceived peer recognition and received peer recognition, controlling for race and ethnicity, academic year and major, and course-level variability. These findings offer important implications for testable instructional interventions.
Applied physics, Physics
arXiv
A General Neural Network Potential for Energetic Materials with C, H, N, and O elements
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Mingjie Wen, Jiahe Han, Wenjuan Li, Xiaoya Chang, Qingzhao Chu, Dongping Chen
The discovery and optimization of high-energy materials (HEMs) are constrained by the prohibitive computational expense and prolonged development cycles inherent in conventional approaches. In this work, we develop a general neural network potential (NNP) that efficiently predicts the structural, mechanical, and decomposition properties of HEMs composed of C, H, N, and O. Our framework leverages pre-trained NNP models, fine-tuned using transfer learning on energy and force data derived from density functional theory (DFT) calculations. This strategy enables rapid adaptation across 20 different HEM systems while maintaining DFT-level accuracy, significantly reducing computational costs. A key aspect of this work is the ability of NNP model to capture the chemical activity space of HEMs, accurately describe the key atomic interactions and reaction mechanisms during thermal decomposition. The general NNP model has been applied in molecular dynamics (MD) simulations and validated with experimental data for various HEM structures. Results show that the NNP model accurately predicts the structural, mechanical, and decomposition properties of HEMs by effectively describing their chemical activity space. Compared to traditional force fields, it offers superior DFT-level accuracy and generalization across both microscopic and macroscopic properties, reducing the computational and experimental costs. This work provides an efficient strategy for the design and development of HEMs and proposes a promising framework for integrating DFT, machine learning, and experimental methods in materials research. (To facilitate further research and practical applications, we open-source our NNP model on GitHub: this https URL.)
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
41 pages,16 figures
Unveiling temperature and phase boundaries in laser-driven shocked and released copper: insights from ultra-fast X-ray Absorption Spectroscopy up to 300 GPa
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Sofia Balugani, Jean-Alexis Hernandez, Fabien Brieuc, James Boust, Philipp Hesselbach, Nicolas Sévelin-Radiguet, Vanina Recoules, Olivier Mathon, Daniel E. Eakins, Hugo Doyle, Alessandra Ravasio, Raffaella Torchio
Cu is an ubiquitous material used in industry for its great thermal and electrical properties. Studying the high-pressure high temperature properties of copper (Cu) is relevant for nuclear fusion research as projectiles and flyers used in hypervelocity impacts are generally made of copper, where it is used also in the design of the nuclear fusion targets. Recently, a solid (fcc)-solid (bcc) phase transition has been detected in shock compressed Cu with X-Ray Diffraction. Here, we present a study on shock compressed copper up to 300 GPa and 7100 K probed by single pulse (100 ps FWHM) X-ray Absorption Spectroscopy (XAS). Based on the analysis of the XAS spectra, we provide structural identification and bulk temperature measurements along the Hugoniot up to the melting. The collection of XAS spectra under release conditions, i.e. at later times than the breakout time of the shock wave, helped constraining the experimental fcc-bcc and solid-liquid phase boundaries. In particular, we report the first bulk temperature measurement in shock compressed copper on the melting plateau located between 237(40) GPa and 5750(1130) K and 261 (27) GPa and 6240 (1155) K and on liquid copper at 300 GPa and 7100 K.
Materials Science (cond-mat.mtrl-sci), Plasma Physics (physics.plasm-ph)
Spectroscopic classification of non-ergodic populations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-05 20:00 EST
Nicolas Underwood, Fabien Paillusson
Non-ergodicity impacts statistical inference in a diverse range of disciplines inside and outside of physics. However the concept of ergodicity is used inconsistently, and may refer to several nonequivalent notions. To help address this, we first identify and clarify the relationship between three major interpretations of ergodicity. We then introduce a method of spectral analysis of non-ergodicity which may be performed using data alone, and so may be applied in both numerical and empirical contexts. This may be used to identify, quantify, and classify non-ergodic populations within an ergodic decomposition. This is demonstrated with an application to the Kob-Andersen kinetically constrained lattice glass model.
Statistical Mechanics (cond-mat.stat-mech)
6 pages, 3 figures
Nonreciprocity of hydrodynamic electron transport in noncentrosymmetric conductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-05 20:00 EST
E. Kirkinis, L. Bonds, A. Levchenko, A. V. Andreev
We show that the nonreciprocity of hydrodynamic electron transport in noncentrosymmetric conductors with broken time-reversal symmetry (TRS) is significantly enhanced compared to the disorder-dominated regime. This enhancement is caused by the linear dependence of the viscosity of the electron liquid on the flow velocity, which is allowed in the absence of TRS and Galilean invariance. The resulting nonlinear flows do not possess dynamical similarity and are characterized by two dimensionless parameters: the Reynolds number and the nonreciprocity number. The latter is linear in velocity but independent of system size. We determine the nonlinear conductance of a Hall bar and show that the nonreciprocal correction to the current can be of comparable magnitude to its reciprocal counterpart.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
5 pages, 2 figures
Enforced Gaplessness from States with Exponentially Decaying Correlations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
Rahul Sahay, Curt von Keyserlingk, Ruben Verresen, Carolyn Zhang
It is well known that an exponentially localized Hamiltonian must be gapless if its ground state has algebraic correlations. We show that even certain exponentially decaying correlations can imply gaplessness. This is exemplified by the deformed toric code $\propto \exp(\beta \sum_{\ell} Z_{\ell}) |\mathsf{TC}\rangle$, where $|\mathsf{TC}\rangle$ is a fixed-point toric code wavefunction. Although it has a confined regime for $\beta > \beta_c$, recent work has drawn attention to its perimeter law loop correlations. Here, we show that these unusual loop correlations – namely, perimeter law coexisting with a 1-form symmetry whose disorder operator has long-range order – imply that any local parent Hamiltonian must either be gapless or have a degeneracy scaling with system size. Moreover, we construct a variational low-energy state for arbitrary local frustration-free Hamiltonians, upper bounding the finite-size gap by $O(1/L^3)$ on periodic boundary conditions. Strikingly, these variational states look like loop waves – non-quasiparticle analogs of spin waves – generated from the ground state by non-local loop operators. Our findings have implications for identifying the subset of Hilbert space to which gapped ground states belong, and the techniques have wide applicability. For instance, a corollary of our first result is that Glauber dynamics for the ordered phase of the two-dimensional classical Ising model on the torus must have a gapless Markov transition matrix, with our second result bounding its gap.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
17 pages main text (w/ 3 figures) + 17 pages supplemental (w/ 2 figures)
Superconducting qubit based on a single molecule: the carbon nanotube gatemon
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-05 20:00 EST
H. Riechert, S. Annabi, A. Peugeot, H. Duprez, M. Hantute, K. Watanabe, T. Taniguchi, E. Arrighi, J. Griesmar, J.-D. Pillet, L. Bretheau
Gate-tunable transmon qubits are based on quantum conductors used as weak links within hybrid Josephson junctions. These gatemons have been implemented in just a handful of systems, all relying on extended conductors, namely epitaxial semiconductors or exfoliated graphene. Here we present the coherent control of a gatemon based on a single molecule, a one-dimensional carbon nanotube, which is integrated into a circuit quantum electrodynamics architecture. The measured qubit spectrum can be tuned with a gate voltage and reflects the quantum dot behaviour of the nanotube. Our ultraclean integration, using a hexagonal boron nitride substrate, results in record coherence times of 200ns for such a qubit. Furthermore, we investigate its decoherence mechanisms, thus revealing a strong gate dependence and identifying charge noise as a limiting factor. On top of positioning carbon nanotubes as contenders for future quantum technologies, our work paves the way for studying microscopic fermionic processes in low-dimensional quantum conductors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
13 pages, 11 figures
Statistical mechanics of a cold tracer in a hot bath
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-05 20:00 EST
Amer Al-Hiyasat, Sunghan Ro, Julien Tailleur
We study the dynamics of a zero-temperature particle interacting linearly with a bath of hot Brownian particles. Starting with the most general model of a linearly-coupled bath, we eliminate the bath degrees of freedom exactly to map the tracer dynamics onto a generalized Langevin equation, allowing for an arbitrary external potential on the tracer. We apply this result to determine the fate of a tracer connected by springs to $N$ identical bath particles or inserted within a harmonic chain of hot particles. In the former “fully-connected” case, we find the tracer to transition between an effective equilibrium regime at large $N$ and an FDT-violating regime at finite $N$, while in the latter “loop” model the tracer never satisfies an FDT. We then study the fully-connected model perturbatively for large but finite $N$, demonstrating signatures of irreversibility such as ratchet currents, non-Boltzmann statistics, and positive entropy production. Finally, we specialize to harmonic external potentials on the tracer, allowing us to exactly solve the dynamics of both the tracer and the bath for an arbitrary linear model. We apply our findings to show that a cold tracer in a hot lattice suppresses the fluctuations of the lattice in a long-ranged manner, and we generalize this result to linear elastic field theories.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
18 pages, 1 figure
At extreme strain rates, pure metals thermally harden while alloys thermally soften
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Ian Dowding, Christopher A. Schuh
When materials are deformed at extreme strain rates, greater than $10^6 \text{ s}^{-1}$, a counterintuitive mechanical response is seen where the strength and hardness of pure metals increases with increasing temperature. The anti-thermal hardening is due to defects in the material becoming pinned by phonons in the crystal lattice. However, here, using optically driven microballistic impact testing to measure the dynamic strength and hardness, we show that when the composition is systematically varied away from high purity, the mechanical response of metals transitions from ballistic transport of dislocations back to thermally activated pinning of dislocations, even at the highest strain rates. This boundary from “hotter-is-stronger” to “hotter-is-softer” is observed and mapped for nickel, titanium, and gold. The ability to tune between deformation mechanisms with very different temperature dependencies speaks to new directions for alloy design in extreme conditions.
Materials Science (cond-mat.mtrl-sci)
Stabilization of three-body resonances to bound states in a continuum
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-03-05 20:00 EST
Three-body resonances are ubiquitous in few-body physics and are characterized by a finite lifetime before decaying into continuum states of their composing subsystems. In this work we present a theoretical study on the possibility to stabilize three-body resonances to so-called bound states in a continuum: resonances with vanishing width that do not decay. Within a simple two-channel approach we unveil the underlying mechanism and suggest that the lifetime can be varied by a continuous tuning of system parameters. The validity of our theory is illustrated in two rather different examples, a mass-imbalanced system in one dimension and a system of three identical bosons in three dimensions, relevant to Efimov physics. Crucially, for the latter we find that one of the tunable parameters to achieve a three-body bound state in a continuum is an external magnetic field, a common tunable variable in cold-atom experiments. Due to the fundamental nature of our theory, it is expected to hold in other few-body systems, possibly opening new avenues for basic studies of otherwise unstable systems, and elevating few-body systems to interesting candidates for quantum technology.
Quantum Gases (cond-mat.quant-gas)
Metastability and Ostwald Step Rule in the Crystallisation of Diamond and Graphite from Molten Carbon
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Davide Donadio, Margaret L. Berrens, Wanyu Zhao, Shunda Chen, Tianshu Li
The crystallisation of carbon from the melt under extreme conditions is highly relevant to earth and planetary science, materials manufacturing, and nuclear fusion research. The thermodynamic conditions near the graphite-diamond-liquid (GDL) triple point are especially of interest for geological and technological applications, but high-pressure flash heating experiments aiming to resolve this region of the phase diagram of carbon exhibit large discrepancies. Experimental challenges are often related to the persistence of metastable crystalline or glassy phases, superheated crystals, or supercooled liquids. A deeper understanding of the crystallisation kinetics of diamond and graphite is crucial for effectively interpreting the outcomes of these experiments. Here, we reveal the microscopic mechanisms of diamond and graphite nucleation from liquid carbon through molecular simulations with first-principles machine learning potentials. Our simulations accurately reproduce the experimental phase diagram of carbon in the region around the GDL triple point and show that liquid carbon crystallises spontaneously upon cooling at constant pressure. Surprisingly, metastable graphite crystallises in the domain of diamond thermodynamic stability at pressures above the triple point. Furthermore, whereas diamond crystallises through a classical nucleation pathway, graphite follows a two-step process in which low-density fluctuations forego ordering. Calculations of the nucleation rates of the two competing phases confirm this result and reveal a manifestation of Ostwald’s step rule where the strong metastability of graphite hinders the transformation to the stable diamond phase. Our results provide a new key to interpreting melting and recrystallisation experiments and shed light on nucleation kinetics in polymorphic materials with deep metastable states.
Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
21 pages, 4 figures
Tunable Non-Equilibrium Magic and Minimum Twist Angles in AA-Stacked Twisted Multilayer Graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
We report the discovery of a series of non-equilibrium magic angles at which isolated topological flat quasienergy bands form in AA-stacked twisted multilayer graphene under circularly polarized light. These non-equilibrium magic angles can be traced back to specific static twist angles where the bandwidth reaches a minimum \textit{without} the formation of isolated flat bands. We refer to these as minimum twist angles, in contrast to the magic angles observed in twisted bilayer graphene. We show that an applied displacement field can further flatten the optically induced topological flat bands accompanied by larger non-equilibrium magic angles. The discovery of these electrically tunable topological flat quasienergy bands is expected to open up a new avenue of exploring exotic Floquet-driven phenomena in AA-stacked twisted multilayer graphene.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
4 pages, 4 figures, plus Supplemental Material
Sliding-induced topological transitions in bilayer biphenylene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-05 20:00 EST
L. L. Lage, S. Bravo, O. Arroyo-Gascón, Leonor Chico, A. Latgé
Sliding-induced topological transitions in biphenylene bilayers are investigated, considering various stacking configurations which are analyzed from a symmetry perspective and described in detail,highlighting the intricate patterns of type-II Dirac cone crossings. Topological changes in the Fermi surface are assessed via the Euler characteristic, linking each transition to its corresponding symmetry, which can be experimentally tested by conductance measurements. Moreover, the ability to tune these topological properties by sliding the layers provides a simpler and more effective way to observe such phenomena.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Hunting for Room Temperature Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-05 20:00 EST
Room temperature superconductivity, as one of the famous jewels on the crown of physics, has attracted continuous attention and unremitting efforts from numerous scientists. In recent years, more and more reports on room temperature superconductivity evoke many anticipations, but results remain controversial. Here, we introduce the characteristics of superconducting phenomena and propose 10 feasible paths to achieve room-temperature superconductivity in the future. This is an Editorial of The Innovation Materials in Feb. 2025.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 1 figure and limited 5 references. Citation: Luo H. (2025). Hunting for room temperature superconductors. The Innovation Materials 3:100119
The Innovation Materials 3,100119 (2025)
Phase diagram of a coupled trimer system at half filling using the Hubbard model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
Sourabh Saha, Hosho Katsura, Manoranjan Kumar
Flat band systems have recently attracted significant attention due to their instability under small perturbations, which can lead to the stabilization of many exotic quantum phases. We study a trimer ladder which shows a middle flat band in the absence of onsite Coulomb interaction. We investigate the quantum phases of the Hubbard model on this geometry using exact diagonalization (ED), density matrix renormalization group (DMRG), and perturbation theory. We construct a quantum phase diagram in the plane of the next-nearest-neighbor hopping parameter $t_2$ and onsite Coulomb interaction $U$, revealing five distinct quantum phases. At low $U$ and moderate to high magnitude of $t_2$, the system exhibits metallic behavior, while at large $U$ and small magnitude of $t_2$, it transitions to a ferrimagnetic insulator phase, similar to those observed in certain trimer materials. In the small $t_2$ limit, the Fermi energy is in the flat band, leading to localization of the electrons within the trimer. At low $U$ and small magnitude of $t_2$, the flat band mechanism favors insulating ferrimagnetism, whereas at large $U$, ferrimagnetic states emerge from singlet dimer formation between neighboring sites of a trimer and an isolated corner spin, which connect ferromagnetically. The insulating cell spin density wave phase displays an up-up-down-down spin configuration due to competing nearest neighbor hopping, $t_1$. Interestingly, in moderate $U$ and $|t_2|>0.3$, the ground state behaves like metallic Tomonaga-Luttinger liquid.
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 11 figures
Light Control of Triplet Pairing in Correlated Electrons with Mixed-Sign Interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
Zecheng Shen, Chendi Xie, Wei-Chih Chen, Yao Wang
Spin-triplet superconductivity is a key platform for topological quantum computing, yet its experimental realization and control in solid-state materials remain a significant challenge. For this purpose, we propose an ultrafast optical strategy to manipulate spin-triplet superconductivity by leveraging $p$-wave pairing instabilities in the extended Hubbard model, a framework applicable to transition-metal oxides. Utilizing Floquet engineering, we demonstrate that transient flipping of the effective spin-exchange interaction can enhance $p$-wave pairing correlations under linearly polarized optical pulses. Furthermore, we reveal that this emergent spin-triplet pairing in strongly correlated systems can be selectively switched by an orthogonal optical pulse. This work provides a new pathway for stabilizing and controlling spin-triplet superconductivity in correlated materials.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 5 figures
Exploring the world of rhamnolipids: A critical review of their production, interfacial properties, and potential application
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-05 20:00 EST
Eduardo Guzman, Francisco Ortega, Ramon G. Rubio
Rhamnolipids are very promising sugar-based biosurfactants, generally produced by bacteria, with a wide range of properties that can be exploited at an industrial and technological level, e.g. in cosmetics, food science, or oil recovery, to provide benefits for human health and the environment. This has led to intensive research into optimizing their production to increase yields and minimize costs, which is challenging because biotechnological methods for rhamnolipid production result in complex product mixtures and require the introduction of complex separation strategies to ensure the purity of the rhamnolipid obtained. This is an important issue for the introduction of rhamnolipids to the market due to the differences that exist between the properties of the different congeners. This review attempts to provide an overview of the interfacial properties, potential applications, and recent advances in understanding the molecular mechanisms that govern the adsorption to interfaces and assembly in solution of rhamnolipids. In addition, the review also discusses some general aspects related to the production and purification methods of rhamnolipids, highlighting the need for further research to fully exploit their potential. It is hoped that this review will contribute to the growing body of knowledge about rhamnolipids and stimulate further research in this field.
Soft Condensed Matter (cond-mat.soft)
Published in Current Opinion in Colloid and Interface Science 69 (2024) 101780
Current Opinion in Colloid and Interface Science 69 (2024) 101780
Polymerization of environmentally stable 1D-NF chain with high-energy density
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Guo Chen, Ling Lin, Chengfeng Zhang, Jie Zhang, Xianlong Wang
Based on first-principles calculations and ab initio molecular dynamics methods, the energies density, suitable precursor, and synthesis conditions of Cmca-type NF compound with 1D chain feature are investigated. We find that if using Al as reducing agent, it possesses an gravimetric energy density of 13.55 kJ/g higher than that of cg-N (9.70 kJ/g), since it has both polymerized nitrogen and strong oxidizing F atoms. The cis N2F2 molecules is a suitable precursor, and they can polymerize to cis NF chains above 90 GPa. Furthermore, the phase diagram of Cmca-type NF compound is established at conditions of 0-3000 K and 0-200 GPa. Importantly, NF chains polymerized under high temperature and pressure can be quenched to ambient conditions.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
High-energy-density material, First-principles calculation, Ab initio molecular dynamics, NF compound
Giant moment increase by ultrafast laser light
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Sangeeta Sharma, Deepika Gill, Jyoti Krishna, Eddie Harris-Lee, John Kay Dewhurst, Sam Shallcross
It is now well established that a few femtosecond laser pulse will induce an ultrafast loss of moment in a magnetic material. Here we show that the opposite effect can also occur: an ultrafast increase in moment. Employing both tight-binding and state-of-the-art time dependent density functional theory we find that laser light tuned to the majority spin conduction band in the 2d magnets CrI$_3$ and CrSBr generates an ultrafast giant moment increase, of up to 33% in the case of CrI$_3$ (2~$\mu_B$). Underpinning this is spin-orbit induced valence band spin texture that, in combination with a strong field light pulse, facilitates an optical spin flip transition involving both intra- and inter-band excitation. Our findings, that establish a general mechanism by which ultrafast light pulses may enhance as well as decrease the magnetic moment, point towards rich possibilities for light control over magnetic matter at femtosecond times.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Optics (physics.optics), Quantum Physics (quant-ph)
Electronic structures of crystalline and amorphous GeSe and GeSbTe compounds using machine learning empirical pseudopotentials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Sungmo Kang, Rokyeon Kim, Seungwu Han, Young-Woo Son
The newly developed machine learning (ML) empirical pseudopotential (EP) method overcomes the poor transferability of the traditional EP method with the help of ML techniques while preserving its formal simplicity and computational efficiency. We apply the new method to binary and ternary systems such as GeSe and Ge-Sb-Te (GST) compounds, well-known materials for non-volatile phase-change memory and related technologies. Using a training set of {\it ab initio} electronic energy bands and rotation-covariant descriptors for various GeSe and GST compounds, we generate transferable EPs for Ge, Se, Sb, and Te. We demonstrate that the new ML model accurately reproduces the energy bands and wavefunctions of structures outside the training set, closely matching first-principles calculations. This accuracy is achieved with significantly lower computational costs due to the elimination of self-consistency iterations and the reduced size of the plane-wave basis set. Notably, the method maintains accuracy even for diverse local atomic environments, such as amorphous phases or larger systems not explicitly included in the training set.
Materials Science (cond-mat.mtrl-sci)
9 pages, 6 figures and 3 tables
Wyckoff Transformer: Generation of Symmetric Crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Nikita Kazeev, Wei Nong, Ignat Romanov, Ruiming Zhu, Andrey Ustyuzhanin, Shuya Yamazaki, Kedar Hippalgaonkar
Symmetry rules that atoms obey when they bond together to form an ordered crystal play a fundamental role in determining their physical, chemical, and electronic properties such as electrical and thermal conductivity, optical and polarization behavior, and mechanical strength. Almost all known crystalline materials have internal symmetry. Consistently generating stable crystal structures is still an open challenge, specifically because such symmetry rules are not accounted for. To address this issue, we propose WyFormer, a generative model for materials conditioned on space group symmetry. We use Wyckoff positions as the basis for an elegant, compressed, and discrete structure representation. To model the distribution, we develop a permutation-invariant autoregressive model based on the Transformer and an absence of positional encoding. WyFormer has a unique and powerful synergy of attributes, proven by extensive experimentation: best-in-class symmetry-conditioned generation, physics-motivated inductive bias, competitive stability of the generated structures, competitive material property prediction quality, and unparalleled inference speed.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Computational Physics (physics.comp-ph)
this https URL
Measurement-Induced Crossover of Quantum Jump Statistics in Postselection-Free Many-Body Dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-05 20:00 EST
Kazuki Yamamoto, Ryusuke Hamazaki
We reveal a nontrivial crossover of subsystem fluctuations of quantum jumps in continuously monitored many-body systems, which have a trivial maximally mixed state as a steady-state density matrix. While the fluctuations exhibit the standard volume law $\propto L$ following Poissonian statistics for sufficiently weak measurement strength, anomalous yet universal scaling law $\propto L^\alpha :(\alpha\sim 2.7)$ indicating super-Poissonian statistics appears for strong measurement strength. This drastically affects the precision of estimating the rate of quantum jumps: for strong (weak) measurement, the estimation uncertainty is enhanced (suppressed) as the system size increases. We demonstrate that the anomalous scaling of the subsystem fluctuation originates from an integrated many-body autocorrelation function and that the transient dynamics contributes to the scaling law rather than the Liouvillian gap. The measurement-induced crossover is accessed only from the postselection-free information obtained from the time and the position of quantum jumps and can be tested in ultracold atom experiments.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
7 + 5 pages, 4 + 7 figures
Structural and Dynamical Behaviors of Fast Ionic Conducting Potassium nido-(Carba)borates
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Mads B. Amdisen, Hui Wu, Mikael S. Andersson, Mirjana Dimitrievska, Wei Zhou, Torben R. Jensen, Craig M. Brown, Juscelino B. Leão, Terrence J. Udovic
Solid-state batteries are one of the most recent iterations of electrochemical energy storage, and the technology can potentially provide safer and more-energy-dense batteries. The metal closo- and nido-(carba)borates show promise as versatile solid electrolytes and have been shown to have some of the highest ionic conductivities as well as wide electrochemical stability windows. In the present study, we investigate the four potassium nido-(carba)borates KB${11}$H${14}$, K-7-CB${10}$H${13}$, K-7,8-C$2$B$9$H${12}$, and K-7,9-C$2$B$9$H${12}$, and a total of eight new crystal structures were solved. All four compounds transition from a low-temperature, ordered phase to a high-temperature, disordered phase with the space group Fm-3m. In the high-temperature polymorphs, the anions are disordered and undergo rapid reorientational dynamics, which is confirmed by quasielastic neutron scattering experiments. Reorientational activation energies of 0.151(2) eV, 0.146(32) eV, and 0.143(3) eV were determined for K-7-CB${10}$H${13}$, K-7,8-C$_2$B$9$H${12}$, and K-7,9-C$_2$B$9$H${12}$, respectively. Additionally, such rotationally fluid anions are concomitant with fast potassium-ion conductivity. The highest ionic conductivity is observed for K-7,8-C$_2$B$9$H${12}$ with 1.7$\times$10$^{-2}$ Scm$^{-1}$ at 500 K and an activation energy of 0.28 eV in the disordered state. The differences in phase transition temperatures, reorientational dynamics, and ionic conductivities between the potassium nido-(carba)borates illustrate a strong correlation between the K$^+$ cationic mobility and the local cation-anion interactions, anion dynamics, and the specific positions of the carbon-atoms in the nido-(carba)borate anion cages.
Materials Science (cond-mat.mtrl-sci)
64 pages, 22 figures
Spiral folding of a flexible chain of chiral active particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-05 20:00 EST
We investigate a flexible polymer chain made up of chiral active Brownian particles in two dimensions using computer simulations. In the presence of chiral active Brownian forces, the radius of gyration of the chain reduces significantly. We further identify the formation of spirals using the tangent-tangent correlation to characterize the internal structure of the chain. The polymer chain forms a pair of spirals with opposite spiral turns on both ends of the polymer. We compute the number of turns of both spirals, and find that the total number of turns increases with angular frequency as well as P{é}clet number. However, the spirals become weak and the number of turns decreases at a very high P{é}clet number. We draw a phase diagram using the turn number. The end-to-end correlation displays oscillatory behavior, which signifies the rotational dynamics of the chain. We quantify the rotation frequency from the end-to-end vector, which follows a power law behavior with exponent $3/2$. We also provide a scaling relation between the radius of gyration and the chain length, and the exponent decreases significantly in the presence of chiral active forces.
Soft Condensed Matter (cond-mat.soft)
10 pages
Spin valve effect in junctions with a single ferromagnet
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Fengrui Yao, Volodymyr Multian, Kenji Watanabe, Takashi Taniguchi, Ignacio Gutierrez Lezama, Alberto F. Morpurgo
Spin valves are essential components in spintronic memory devices, whose conductance is modulated by controlling spin-polarized electron tunneling through the alignment of the magnetization in ferromagnetic elements. Whereas conventional spin valves unavoidably require at least two ferromagnetic elements, here we demonstrate a van der Waals spin valve based on a tunnel junction that comprises only one such ferromagnetic layer. Our devices combine a Fe3GeTe2 electrode acting as spin injector together with a paramagnetic tunnel barrier, formed by a CrBr3 multilayer operated above its Curie temperature. We show that these devices exhibit a conductance modulation with values comparable to that of conventional spin valves. A quantitative analysis of the magnetoconductance that accounts for the field-induced magnetization of CrBr3, and that includes the effect of exchange interaction, confirms that the spin valve effect originates from the paramagnetic response of the barrier, in the absence of spontaneous magnetization in CrBr3.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Theory of Photocurrent and High-Harmonic Generation with Chiral Fermions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Yuya Ominato, Masahito Mochizuki
We theoretically discover possible dc-current induction and high-harmonic generation from photodriven chiral fermions in B20-type semimetals irradiated with circularly polarized light as nonlinear optical responses with several unconventional properties. First, we find multiple sign changes of the induced bulk dc photocurrent as a function of light parameters, which is ascribed to the nature of asymmetric photon-dressed bands in chiral systems. Moreover, we observe a parity-dependent directivity of high-harmonic generation where the odd- and even-order harmonics have intensities only in directions perpendicular and parallel to the polarization plane, respectively, which can be understood from dynamical symmetry of the present photodriven chiral systems.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
6 pages, 4 figures
Spin injection and detection in all-van der Waals 2D devices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-05 20:00 EST
Jan Bärenfänger, Kenji Watanabe, Takashi Taniguchi, Jonathan Eroms, Dieter Weiss, Mariusz Ciorga
In this work we report efficient out-of-plane spin injection and detection in an all-van der Waals based heterostructure using only exfoliated 2D materials. We demonstrate spin injection by measuring spin-valve and Hanle signals in non-local transport in a stack of Fe$_3$GeTe$_2$ (FGT), hexagonal boron nitride (hBN) and graphene layers. FGT flakes form the spin aligning electrodes necessary to inject and detect spins in the graphene channel. The hBN tunnel barrier provides a high-quality interface between the ferromagnetic electrodes and graphene, eliminating the conductivity mismatch problem, thus ensuring efficient spin injection and detection with spin injection efficiencies of up to $P=40$,%. Our results demonstrate that FGT/hBN/graphene heterostructures form a promising platform for realizing 2D van der Waals spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Main text: 8 pages, 6 figures; Supplemental: 9 pages, 12 figures
Enhanced Charge Transport in A-site Ordered Perovskite Derivatives A2A’Bi2I9 (A = Cs; A’= Ag, Cu): A First-Principles Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Shuhan Li (1,2), Siyu Song (1,2), Peng Lv (3), Shihao Wang (1,2), Jiawang Hong (4), Gang Tang (1,2), ((1) Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing, China, (2) Beijing Institute of Technology, Zhuhai Beijing Institute of Technology (BIT) Zhuhai, <a href=”http://P.R.China“ rel=”external noopener nofollow” class=”link-external link-http”>this http URL</a>, (3) Key Laboratory for High Efficiency Energy Conversion Science and Technology of Henan Province, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, School of Physics and Electronics, Henan University, Kaifeng, China, (4) School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China)
Recent experiments have synthesized Cs2AgBi2I9 by partially substituting Cs+ with Ag+ at the A-site of Cs3Bi2I9, resulting in enhanced charge transport properties compared to Cs3Bi2I9. However, the atomic-scale mechanisms behind this enhancement remain unclear. In this work, we investigate the carrier transport mechanisms in Cs2A’Bi2I9 (A’ = Ag, Cu) using first-principles calculations and Boltzmann transport calculations. Our results reveal that A-site ordered Cs2A’Bi2I9 exhibits carrier mobilities that are 3-4 times higher than those of Cs3Bi2I9 within the 100-500 K temperature range. We identify polar phonon scattering as the dominant mechanism limiting mobility. Furthermore, the enhanced out-of-plane carrier mobility in Cs2A’Bi2I9, particularly between 100 and 200K, leads to reduced mobility anisotropy. These improvements are mainly due to the shorter A’-I bond lengths and increased Ag+/Cu+ s-I p orbital coupling. Notably, substitution with Cu+ results in a further reduction in the band gap and enhanced hole mobility compared to Ag+ substitution in Cs3Bi2I9. Further analysis reveals that the significant increase in carrier mobility in Cs2A’Bi2I9 can be largely explained by the smaller carrier effective masses (m\ast) and weaker Fröhlich coupling strengths ({\alpha}), resulting in a lower polar mass {\alpha}(m\ast/me), compared to Cs3Bi2I9. Our study provides valuable insights into the transport properties of Bi-based perovskite derivatives, paving the way for their future applications in optoelectronic devices.
Materials Science (cond-mat.mtrl-sci)
THz-Driven Coherent Phonon Fingerprints of Hidden Symmetry Breaking in 2D Layered Hybrid Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Joanna M. Urban (1), Michael S. Spencer (1), Maximilian Frenzel (1), Gaëlle Trippé- Allard (2), Marie Cherasse (1 and 3), Charlotte Berrezueta Palacios (4), Olga Minakova (1), Eduardo Bedê Barros (5 and 6), Luca Perfetti (3), Stephanie Reich (4), Martin Wolf (1), Emmanuelle Deleporte (2), Sebastian F. Maehrlein (1, 7 and 8) ((1) Fritz Haber Institute of the Max Planck Society, Berlin, Germany, (2) Lumière, Matière et Interfaces (LuMIn) Laboratory, Université Paris-Saclay, ENS Paris-Saclay, CentraleSupélec, CNRS, Gif-sur-Yvette, France, (3) Laboratoire des Solides Irradiés, CEA/DRF/lRAMIS, École Polytechnique, CNRS, Institut Polytechnique de Paris, Palaiseau, France, (4) Department of Physics, Freie Universität Berlin, Berlin, Germany (5) Department of Physics, Universidade Federal do Ceara, Fortaleza, Ceara, Brazil (6) Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany (7) Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Dresden, Germany (8) Technische Universität Dresden, Institute of Applied Physics, Dresden, Germany)
Metal-halide perovskites (MHPs) emerged as a family of novel semiconductors with outstanding optoelectronic properties for applications in photovoltaics and light emission. Recently, they also attract interest as promising candidates for spintronics. In materials lacking inversion symmetry, spin-orbit coupling (SOC) leads to the Rashba-Dresselhaus effect, offering a pathway for spin current control. Therefore, inversion symmetry breaking in MHPs, which are characterized by strong SOC, has crucial implications. Yet, in complex low-dimensional hybrid organic-inorganic perovskites (HOIPs), the presence of and structural contributions to inversion symmetry breaking remain elusive. Here, employing intense THz fields, we coherently drive lattice dynamics carrying spectroscopic fingerprints of inversion symmetry breaking in Ruddlesden-Popper (PEA)$2$(MA)${n-1}$PbnI${3n+1}$ perovskites, which are globally assigned to a centrosymmetric space group. We demonstrate coherent control by THz pulses over specific phonons, which we assign to either purely inorganic or highly anharmonic hybrid cage-ligand vibrations. By developing a general polarization analysis for THz-driven phonons, we pinpoint linear and nonlinear driving mechanisms. From this, we identify simultaneous IR- and Raman-activity of inorganic cage modes below 1.5 THz, indicating mode-selective inversion symmetry breaking. By exploring the driving pathways of these coherent phonons, we lay the groundwork for simultaneous ultrafast control of optoelectronic and spintronic properties in 2D HOIPs.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Optics (physics.optics)
54 pages, 24 figures
Twist deformation of physical trefoil knots
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-05 20:00 EST
Taiki Goto, Shunsuke Nomura, Tomohiko G. Sano
Knots across various length scales, from micro to macro-scales, such as polymers, DNA, shoelaces, and surgery, serving their unique mechanical properties. The shape of ideal knots has been extensively studied in the context of knot theory, while that of physical knots has been discussed very recently. The complex interplay of elasticity and geometry, such as bending, twisting, and contact, needs to be disentangled to predict their deformation. Still, the unified understanding of the deformation of physical knots is insufficient. Here, we focus on the trefoil knot, a closed knot with a nontrivial topology, and study the relationship between the shapes of the trefoil knot and applied physical twists, combining experiments and simulations. As we twist the elastomeric rod, the knot becomes either tightened or loosened, preserving the original three-fold symmetry, and then buckles and exhibits symmetry breaking at critical angles. The curvature profiles computed through the X-ray tomography analysis also exhibit similar symmetry breaking. The transition would be triggered by the mechanical instability, where the imposed twist energy is converted into the bending energy. The phase transition observed here is analogous to the classical buckling phenomena of elastic rings known as the Michell instability. We find that the twist buckling instability of the trefoil knot results from the interplay of bending, twisting, and contact properties of the rod. In other words, the buckling of the knot is predictable based on the elasticity and geometry of rods, which would be useful in avoiding or even utilizing their buckling in practical engineering applications such as surgery and the shipping industry.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
7 pages, 4 figures
Systematic Mapping of Altermagnetic Magnons by Resonant Inelastic X-Ray Circular Dichroism
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
Nikolaos Biniskos, Manuel dos Santos Dias, Stefano Agrestini, David Sviták, Ke-Jin Zhou, Jiří Pospíšil, Petr Čermák
Altermagnets, a unique class of magnetic materials that combines features of both ferromagnets and antiferromagnets, have garnered attention for their potential in spintronics and magnonics. While the electronic properties of altermagnets have been well studied, characterizing their magnon excitations is essential for fully understanding their behavior and enabling practical device applications. In this work, we introduce a measurement protocol combining resonant inelastic X-ray scattering (RIXS) with circular polarization and azimuthal scanning to probe the chiral nature of the altermagnetic split magnon modes in CrSb. This approach circumvents the challenges posed by domain averaging in macroscopic samples, allowing for precise measurements of the polarization and energy of the magnons in individual antiferromagnetic domains. Our findings demonstrate a pronounced circular dichroism in the magnon peaks, with an azimuthal dependence that directly confirms the theoretical predictions. By establishing a reliable and accessible method for probing altermagnetic magnons, this work opens new avenues for fundamental studies of these collective excitations and for developing next-generation magnonic device applications.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
18 pages, 3 figures. Comments are welcome
Comparison of various UHMWPE formulations from contemporary total knee replacements before and after accelerated aging
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Petr Fulin, Veronika Gajdosova, Ivana Sloufova, Jiri Hodan, David Pokorny, Miroslav Slouf
We have collected 21 different formulations of ultrahigh molecular weight polyethylene (UHMWPE), which have been employed as liners in contemporary total knee replacements (TKR). The UHMWPE liners were bought from the most important manufacturers on the orthopedic market in the Czech Republic as of 2020. The collected liners represented a broad range of both traditional and modern UHMWPE formulations, which differed by the level of crosslinking, type of thermal treatment, sterilization and/or stabilization. All obtained UHMWPE’s were characterized by multiple methods immediately after purchase and after the accelerated aging in H2O2. The experimental results (oxidative degradation, structure changes, and micromechanical properties) were correlated with manufacture’s data (crosslinking, thermal treatment, sterilization, and stabilization). The investigated UHMWPE liners exhibited significant differences in their properties, namely in their resistance to long term oxidative degradation. The stiffness-related mechanical properties showed a strong correlation with the overall crystallinity. The crystallinity depended mostly on the oxidative degradation of the UHMWPE liners, while the thermal treatment played a minor role. The highest resistance to oxidation and wear, which promises the best in vivo performance, was found for the crosslinked UHMWPE formulations with biocompatible stabilizers (such as alpha-tocopherol, which is the key component of vitamin E).
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Tunable Thermal Conductivity and Mechanical Properties of Metastable Silicon by Phase Engineering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Yubing Du, Guoshuai Du, Zhixi Zhu, Jiaohui Yan, Jiayin Li, Tiansong Zhang, Lina Yang, Ke Jin, Yabin Chen
The extensive applications of cubic silicon in flexible transistors and infrared detectors are much hindered by its intrinsic properties. Metastable silicon phases, such as Si-III, IV and XII prepared using extreme pressure method, provide a unique “genetic bank” with diverse structures and exotic characteristics, however, exploration on their inherent physical properties remains immature. Herein, we demonstrate the phase engineering strategy to modulate the thermal conductivity and mechanical properties of metastable silicon. The thermal conductivity obtained via Raman optothermal approach presents the broad tunability across various Si-I, III, XII and IV phases. The hardness and Young’s modulus of Si-IV are remarkably greater than those of Si-III/XII mixture, confirmed by nanoindentation technique. Moreover, it was found that the pressure-induced structural defects can substantially degrade the thermal and mechanical properties of silicon. This systematic investigation can offer feasible route to design novel semiconductors and further advance their desirable applications in advanced nanodevices and mechanical transducers.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 5 figures
Controlling the microscopic quantum pathways for ultrafast charge transfer in van der Waals heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-05 20:00 EST
Niklas Hofmann, Johannes Gradl, Leonard Weigl, Stiven Forti, Camilla Coletti, Isabella Gierz
Efficient charge separation in van der Waals (vdW) heterostructures is crucial for optimizing light-harvesting and detection applications. However, precise control over the microscopic pathways governing ultrafast charge transfer remains an open challenge. These pathways are intrinsically linked to charge transfer states with strongly delocalized wave functions that appear at various momenta in the Brillouin zone. Here, we use time- and angle-resolved photoemission spectroscopy (trARPES) to investigate the possibility of steering carriers through specific charge transfer states in a prototypical WS2-graphene heterostructure. By selectively exciting electron-hole pairs at the K-point and close to the Q-point of WS2 with different pump photon energies, we find that charge separation is faster at higher excitation energies. We attribute this to distinct tunneling mechanisms dictated by the momentum where the initial excitation takes place. Our findings introduce a novel strategy for controlling charge transfer dynamics in vdW heterostructures, paving the way for more efficient optoelectronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
11 pages, 5 figures, 2 tables
Interaction induced Anderson transition in a kicked one dimensional Bose gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-03-05 20:00 EST
Hazel Olsen, Pierre Devillard, Gianni Aupetit-Diallo, Patrizia Vignolo, Mathias Albert
We investigate the Lieb-Liniger model of one-dimensional bosons subjected to periodic kicks. In both the non-interacting and strongly interacting limits, the system undergoes dynamical localization, leading to energy saturation at long times. However, for finite interactions, we reveal an interaction-driven transition from an insulating to a metallic phase at a critical kicking strength, provided the number of particles is three or more. Using the Bethe Ansatz solution of the Lieb-Liniger gas, we establish a formal correspondence between its dynamical evolution and an Anderson model in $N$ spatial dimensions, where $N$ is the number of particles. This theoretical prediction is supported by extensive numerical simulations for three particles, complemented by finite-time scaling analysis, demonstrating that this transition belongs to the orthogonal Anderson universality class.
Quantum Gases (cond-mat.quant-gas)
6 pages, 3 figures
Dual Optical Hyperbolicity of PdCoO$_2$ and PdCrO$_2$ Delafossite Single Crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Salvatore Macis, Annalisa DArco, Eugenio Del Re, Lorenzo Mosesso, Maria Chiara Paolozzi, Vincenzo Stagno, Alexander McLeod, Yu Tao, Pahuni Jain, Yi Zhang, Fred Tutt, Marco Centini, Maria Cristina Larciprete, Chris Leighton, Stefano Lupi
Hyperbolic materials exhibit a very peculiar optical anisotropy with simultaneously different signs of the dielectric tensor components. This anisotropy allows the propagation of exotic surface-wave excitations like hyperbolic phonons and plasmon polaritons. While hyperbolic materials hold promise for applications in subwavelength photonics and enhanced light-matter interactions, their natural occurrence is limited to few materials, often accompanied by significant dielectric losses and limited hyperbolic spectral bandwidth. Focusing on PdCoO$_2$ and PdCrO$_2$ delafossite transition-metal oxides, in this paper we demonstrate their unique dual hyperbolic regimes: one localized around a phonon absorption in the mid-infrared spectral region, and the other extending into the visible range. Both hyperbolic regimes show exceptional properties including low dissipation and high hyperbolic quality factors. These results pave the way for innovative applications of delafossite layered metals in subwavelength photonics, imaging, and sensing.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Symmetrical bipolar electrobending deformation in acceptor-doped piezoceramics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Yi Cheng, Shuo Tian, Bin Li, Yejing Dai
Since 2022, large apparent strains (>1%) with highly asymmetrical strain-electric field (S-E) curves have been reported in various thin piezoceramic materials, attributed to a bidirectional electric-field-induced bending (electrobending) deformation, which consistently produces convex bending along the negative electric field direction. In this study, we report a novel unidirectional electrobending behavior in acceptor-doped K0.5Na0.5NbO3 ceramics, where convex bending always occurs along the pre-poling direction regardless of the direction of the applied electric field. This unique deformation is related to the reorientation of the defect dipoles in one surface layer during the pre-poling process, resulting in an asymmetrical distribution of defect dipoles in the two surface layers. The synergistic interaction between ferroelectric domains and defect dipoles in the surface layers induces this unidirectional electrobending, as evidenced by a butterfly-like symmetrical bipolar S-E curve with a giant apparent strain of 3.2%. These findings provide new insights into defect engineering strategies for developing advanced piezoelectric materials with large electroinduced displacements.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Visualizing the breakdown of the quantum anomalous Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-05 20:00 EST
George M. Ferguson, Run Xiao, Anthony R. Richardella, Austin Kaczmarek, Nitin Samarth, Katja C. Nowack
The creation of topologically non-trivial matter across electronic, mechanical, cold-atom, and photonic platforms is advancing rapidly, yet understanding the breakdown of topological protection remains a major challenge. In this work, we use magnetic imaging combined with global electrical transport measurements to visualize the current-induced breakdown of the quantum anomalous Hall effect (QAHE) in a magnetically doped topological insulator. We find that dissipation emerges at localized hot spots near electrical contacts, where an abrupt change in Hall angle leads to significant distortions of the current density. Using the local magnetization as a proxy for electron temperature, we directly observe that the electrons are driven out of equilibrium with the lattice at the hot spots and throughout the device in the breakdown regime. By characterizing energy relaxation processes in our device, we show that the breakdown of quantization is governed entirely by electron heating, and that a vanishing thermal relaxation strength at millikelvin temperatures limits the robustness of the QAHE. Our findings provide a framework for diagnosing energy relaxation in topological materials and will guide realizing robust topological protection in magnetic topological insulators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Amorphous to Crystalline Transformation: How Cluster Aggregation Drives the Multistep Nucleation of ZIF-8
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Sambhu Radhakrishnan, Flip de Jong, Estelle Becquevort, Olivier Deschaume, C. Vinod Chandran, Yovan de Coene, Carmen Bartic, Mark Van der Auweraer, Wim Thielemans, Christine Kirschhock, Monique A. van der Veen, Thierry Verbiest, Eric Breynaert, Stijn Van Cleuvenbergen
Nucleation, the pivotal first step of crystallization, governs essential characteristics of crystallization products, including size distribution, morphology, and polymorphism. While understanding this process is paramount to the design of chemical, pharmaceutical and industrial production processes, major knowledge gaps remain, especially with respect to the crystallization of porous solids. Also for nanocrystalline ZIF-8, one of the most widely studied metal-organic frameworks, questions regarding the species involved in the nucleation pathway and their structural and chemical transformations remain unanswered. By combining harmonic light scattering, inherently sensitive to structural changes, with NMR spectroscopy, which reveals molecular exchanges between particles and solution, we were able to capture the crystallization mechanism of ZIF-8 in unprecedented detail. This dual approach provides concurrent structural and chemical insights, revealing key processes not previously observed in ZIF crystallization. Upon mixing small charged prenucleation clusters (PNCs) are formed, exhibiting an excess of ligands and net positive charge. We show that nucleation is initiated by aggregation of PNCs, through the release of ligands and associated protons to the liquid. This leads to the formation of charge neutral amorphous precursor particles (APPs) which incorporate neutral monomers from solution, and crystallize ZIF-8. Our work highlights chemical dynamics as a vital, yet often overlooked, dimension in the multi-stage structural evolution of MOFs. By establishing the critical role of PNCs in the nucleation of ZIF-8, new pathways open up for controlling crystallization of metal-organic frameworks through targeted chemical interactions with these species.
Materials Science (cond-mat.mtrl-sci)
Quantum Phases for Finite-Temperature Gases of Bosonic Polar Molecules Shielded by Dual Microwaves
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-03-05 20:00 EST
Wei Zhang, Kun Chen, Su Yi, Tao Shi
We investigate the finite-temperature phase diagram of polar molecules shielded by dual microwave fields using the path integral Monte Carlo method combined with the worm algorithm. We determine the critical temperature $T_c$ for Bose-Einstein condensations (BECs) and identify two distinct phases below $T_c$: the expanding gas (EG) phase and the self-bound gas (SBG) phase. We further analyze the temperature and interaction-strength dependence of the condensate and superfluid fractions. Notably, in contrast to dilute atomic BECs, the SBG phase displays a low condensate fraction and a high superfluid fraction, resembling the behavior of strongly correlated $^4$He superfluids. These significant many-body correlations arise from the interplay between long-range dipole-dipole interactions and the short-range shielding potential. Furthermore, we demonstrate that the aspect ratio of the gas provides a characteristic geometric signature to accurately determine the EG-to-SBG transition, robust against external trapping potentials. Our findings provide unbiased and numerically exact results to guide upcoming experiments with polar molecules.
Quantum Gases (cond-mat.quant-gas)
Identifying two-dimensional topological phase transition by entanglement spectrum : A fermion Monte Carlo study
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
Weilun Jiang, Xiaofan Luo, Bin-Bin Mao, Zheng Yan
Among many types of quantum entanglement properties, the entanglement spectrum provides more abundant information than other observables. Exact diagonalization and density matrix renormalization group method could handle the system in one-dimension properly, while in higher dimension, it exceeds the capacity of the algorithms. To expand the ability of existing numerical methods, we takes a different approach via quantum Monte Carlo algorithm. By exploiting particle number and spin symmetry, we realize an efficient algorithms to solve the entanglement spectrum in the interacting fermionic system. Taking two-dimensional interacting Su-Schrieffer-Heeger as example, we verify the existence of topological phase transition under different types of many-body interactions. The calculated particle number distribution and wave-function of entanglement Hamiltonian indicate that the two belong distinct types of topological phase transitions.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
6 pages, 4 figures
Four regimes of primary radiation damage in tungsten
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Jesper Byggmästar, Ville-Markus Yli-Suutala, Aslak Fellman, Jan Åström, Jan Westerholm, Fredric Granberg
We observe for the first time in silico the transition to a linear regime in the primary damage production in tungsten. As the critical plasma-facing material in fusion reactors, radiation damage in tungsten has been studied extensively in experiments and simulations. Irradiation experiments routinely produce recoils in the MeV range while full atomistic modelling has been limited to a few hundred keV. Here we bridge these scales with extremely large-scale and accurate machine-learning-driven molecular dynamics simulations with recoil energies up to 2 MeV in systems up to one billion atoms. We reveal four regimes of primary damage as a function of damage energy, with a transition to a high-energy regime that deviates from all previous models. Curiously, the start of the high-energy regime coincides with the highest possible recoil energy to tungsten atoms from fusion-emitted neutrons (300 keV).
Materials Science (cond-mat.mtrl-sci)
Flat band driven itinerant magnetism in the Co-pnictides (La,Ca)Co$_2$(As,P)$_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
D. Subires, M. García-Díez, A. Kar, C.-Y. Lim, Victoria M. Li, V. Yannello, Dina Carbone, P. Gargiani, T. Yilmaz, J. Dai, M. Tallarida, E. Vescovo, M. Shatruk, Maia G. Vergniory, S. Blanco-Canosa
Flat bands can induce strong electron correlation effects that help stabilize both magnetic and superconducting states. Here, we carry out angle-resolved photoemission spectroscopy and density functional theory calculations to study the electronic structure of the Co-pnictides CaCo$_2$As$_2$ and LaCo$_2$P$_2$. We find that, while the $k_z$ Fermi topology of ferromagnetic LaCo$_2$P$_2$ is markedly 2-dimensional, antiferromagnetic CaCo$2$As$2$ develops a 3D Fermi surface described by a $zig-zag$-like band dispersion perpendicular to the Co-As plane. Furthermore, the magnetism is driven by the electronic correlations of the flat bands with $d{xy}$ and $d{z^2}$ orbital character at the Fermi level. Our results link the electronic dimensionality and the magnetic order, and emphasize the critical role of the As-As and P-P bond strength along the $c$-direction to understand the electronic band structure and the rich phase diagram of transition metal pnictides.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
New investigation of the electronic and structural properties of (Mg,Ti)-doped and co-doped ZnO structures: A DFT and DFT+U study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Sidi Ahmedbowba, Fehmi Khadri, Walid Ouerghui, Said Ridene
This study investigates the novelty of the crystalline and electronic structure of (Mg,Ti)-doped ZnO and the co-doped Zn1-x-yMgxTiyO structures using Gaussian and plane-wave basis sets, as implemented in the CP2K code. The goal of incorporating low concentration of Mg and Ti into ZnO is to influence its electronic properties without significantly altering its geometrical and crystalline structure. Within the framework of density functional theory (DFT), we analyze various doped and co-doped configurations. Our results show that Ti-doped ZnO exhibits an indirect band gap, while Mg doping preserves the direct semiconductor behavior of ZnO structure, with an increase in band gap energy. Additionally, the co-doped Zn1-x-yMgxTiyO system, at varying concentrations of Ti and Mg, displays minimal lattice deformation. These findings suggest that this material could be a promising candidate for transparent electronic devices, highlighting the importance of understanding the electronic structure of ZnO to optimize its physical properties.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Micro/nanoscale spacers for enhanced thermophotovoltaic and thermionic energy conversion: a comprehensive review
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Nicolas A Loubet, Katie Bezdjian, Esther Lopez, Alejandro Datas
Thermionics and thermophotovoltaics are solid-state technologies that convert high-temperature heat into electricity by utilizing fundamental particles, electrons in thermionics and photons in thermophotovoltaics, as energy carriers. Both systems have the potential to achieve high efficiency and power density, contingent on the optimization of radiative/electronic energy fluxes. A critical factor in enhancing energy flux in these devices is the introduction of microscale (thermionics) or nanoscale (thermophotovoltaics) gaps between the hot thermal emitter and the cooler receiver. In thermionic converters, microscale gaps mitigate space charge effects that create energy barriers to electron flow. For thermophotovoltaic systems, nanoscale gaps facilitate photon tunneling, significantly boosting photon flux towards the thermophotovoltaic cell. Forming these small-scale gaps often necessitates intermediate materials or spacers between the emitter and receiver. Over the past few decades, various spacer designs have been proposed and studied, demonstrating their effectiveness in enhancing energy transfer and conversion. However, challenges remain regarding their reliability and scalability. This article provides a comprehensive overview of spacer technologies for thermionics and thermophotovoltaics and summarizes recent advancements, current capabilities, and persistent challenges.
Materials Science (cond-mat.mtrl-sci)
Melting of devil’s staircases in the long-range Dicke-Ising model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
Jan Alexander Koziol, Anja Langheld, Kai Phillip Schmidt
We present quantum phase diagrams for the antiferromagnetic long-range Ising model with a linear coupling to a single bosonic mode on the square and triangular lattice. For zero coupling, the ground-state magnetization forms a devil’s staircase structure of magnetization plateaux as a function of a longitudinal field. Apart from a paramagnetic superradiant phase with a finite photon density at strong light-matter couplings, the long-range interactions lead to a plethora of intermediate phases that break the translational symmetry and have a finite photon density at the same time. We apply an adaption of the unit-cell-based mean-field calculations, which captures all possible magnetic unit cells up to a chosen extent. Further, we exploit an exact mapping of the non-superradiant phases to an effective Dicke model to calculate upper bounds for phase transitions towards superradiant phases. Finally, to treat quantum fluctuations in a quantitative fashion, we employ a generalized wormhole quantum Monte Carlo algorithm. We discuss how these three methods are used in a cooperative fashion. In the calculated phase diagrams we see several features arising from the long-range interactions: The devil’s staircases of distinct magnetically ordered normal phases and non-trivial magnetically ordered superradiant phases beyond the findings for nearest-neighbor interactions. Examples are a superradiant phase with a three-sublattice magnetic order on the square lattice and the superradiant Wigner crystal with four sites per unit cell on the triangular lattice. We find the transition between normal and superradiant phases with the same (different) magnetic order to be of second order with Dicke universality (first order). Further, between superradiant phases we find first-order phase transitions, besides specially highlighted regimes for which we find indications for second-order behavior.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
19 pages, 5 figures
Topological Phases in Fractals: Local Spin Chern Marker in the Sierpinski carpet Kane-Mele-Rashba Model
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-05 20:00 EST
L. L. Lage, A. B. Félix, S. dos A. Sousa-Júnior, A. Latgé, Tarik P. Cysne
We study the spectral properties and local topology of the Kane-Mele-Rashba model on a Sierpinski Carpet (SC) fractal, constructed from a rectangular flake with an underlying honeycomb arrangement and open boundary conditions. When the system parameters correspond to a topologically trivial phase, the energy spectrum is characterized solely by bulk states that are not significantly modified by the system’s fractality. For parameters corresponding to the quantum spin Hall insulator (QSHI) phase, in addition to bulk states, the energy spectrum exhibits in-gap topological states that are strongly influenced by the fractal geometry. As the fractal generation increases, the in-gap topological states acquire a staircase profile, which translates into sharp peaks in the density of states. We also show that both the QSHI and the trivial phase exhibit a large gap in the valence-projected spin spectrum, allowing the use of the local spin Chern marker (LSCM) to index the local topology of the system. Fractality does not affect this gap, allowing the application of LSCM to higher fractal generations. Our results explore the LSCM versatility, showing its potential to access local topology in complex geometries such as fractal systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Topotactic Growth of Zintl Phase Eu$_5$In$_2$As$_6$ Nanowires with Antiferromagnetic Behavior
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Man Suk Song, Lothar Houben, Nadav Rothem, Ambikesh Gupta, Shai Rabkin, Beena Kalisky, Haim Beidenkopf, Hadas Shtrikman
We demonstrate a topotactic transformation of zincblende InAs(Sb) nanowires into the Zintl phase Eu$_5$In$_2$As$_6$ through a vapor-solid mutual exchange process involving Eu and In in molecular beam epitaxy. This conversion preserves the polyhedral coordination lattice of the parent InAs(Sb) structure while inducing orthorhombic symmetry in the product phase, Eu$_5$In$_2$As$_6$, in which quasi-one-dimensional [InAs$_3$]$^6$^-$ chains with tetrahedral sites align along the <110> direction of the zincblende structure. Local and global magnetic characterization identified two distinct antiferromagnetic phase transitions at approximately 7 K and 16 K in Eu$_5$In$_2$As$_6$ nanowires, potentially classified as altermagnetic phases. The versatility of the topotactic conversion of III-V semiconductor nanowires provides a platform for designing functional Zintl materials with tunable magnetic properties, making them promising candidates for spintronic applications.
Materials Science (cond-mat.mtrl-sci)
32 pages, 22 figures
Selective electron-phonon coupling strength from nonequilibrium optical spectroscopy: The case of MgB$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-05 20:00 EST
S. Mor, F. Boschini, E. Razzoli, M. Zonno, M. Michiardi, G. Levy, N.D. Zhigadlo, P.C. Canfield, G. Cerullo, A. Damascelli, C. Giannetti, S. Dal Conte
The coupling between quasiparticles and bosonic excitations rules the energy transfer pathways in condensed matter systems. The possibility of inferring the strength of specific coupling channels from their characteristic time scales measured in nonequilibrium experiments is still an open question. Here, we investigate MgB$2$, in which conventional superconductivity at temperatures as high as 39 K is mediated by the strong coupling between the conduction electrons and the E${2g}$ phonon mode. By means of broadband time-resolved optical spectroscopy, we show that this selective electron-phonon coupling dictates the nonequilibrium optical response of MgB$2$ at early times (<100 fs) after photoexcitation. Furthermore, based on an effective temperature model analysis, we estimate its contribution to the total electron-boson coupling function extracted from complementary equilibrium spectroscopy approaches, namely optical reflectivity and ARPES. The coupling strength with the E${2g}$ phonon modes is thus estimated to be $\lambda$ ~ 0.56, which is approximately half of the total coupling constant, in agreement with ab-initio calculations from the literature. As a benchmark, broadband time-resolved optical spectroscopy is performed also on the isostructural and non-superconducting compound AlB$_2$, showing that the nonequilibrium optical response relaxes on a slower timescale due to the lack of strongly-coupled phonon modes. Our findings demonstrate the possibility to resolve and quantify selective electron-phonon coupling from nonequilibrium optical spectroscopy.
Superconductivity (cond-mat.supr-con)
Elastic Pseudoturbulence in Polymer Solutions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-05 20:00 EST
Mithun Ravisankar, Roberto Zenit
We study the effects of polymer additives on pseudoturbulence induced by a swarm of bubbles rising in a quiescent fluid. We find that, beyond a critical polymer concentration, the energy spectra of velocity fluctuations in bubble-induced turbulence decay more steeply with respect to the wavenumber $k$. This new scaling is significantly steeper than the classical $k^{-3}$ scaling observed for bubbles in Newtonian fluids; it is independent of the gas volume fraction in the inertial limit and occurs within the length scales between the bubble wake length and the bubble diameter. Furthermore, we provide strong evidence that the presence of polymers enhances the coherence of the flow, highlighting the significant role of polymer additives in modifying the characteristics of pseudoturbulence.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
16 pages, 15 figures
Ground State of $\mathrm{SU}\left(3\right)$ spin model on the checkerboard lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
Junhao Zhang, Jie Hou, Jie Lou, Yan Chen
Geometric frustration in quantum spin systems can lead to exotic ground states. In this study, we investigate the $\mathrm{SU}(3)$ spin model on the checkerboard lattice to explore the effects of frustration arising from its point-connected $(N+1)$-site local structure. We employ density matrix renormalization group (DMRG) and exact diagonalization (ED) techniques to determine the ground state properties. Our results reveal the absence of both 3-sublattice antiferromagnetic order and valence cluster solid order. Instead, we identify ground states with bond stripe patterns sensitive to boundary conditions and system size, comprising staggered singlet arrays and uniform flat stripes. Notably, these stripes are relatively decoupled, and similar patterns can be reconstructed in quasi-one-dimensional ladders. These findings suggest that geometric frustration drives the system toward a mixed phase, combining characteristics of spin-liquid and valence cluster solid states, providing new insights into the behavior of frustrated quantum spin systems.
Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 36 figures
Viscosity of polymer melts using non-affine theory based on vibrational modes
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-05 20:00 EST
Ankit Singh, Vinay Vaibhav, Timothy W. Sirk, Alessio Zaccone
Viscosity, a fundamental transport and rheological property of liquids, quantifies the resistance to relative motion between molecular layers and plays a critical role in understanding material behavior. Conventional methods, such as the Green-Kubo (GK) approach, rely on time integration of correlation functions, which becomes computationally intensive near the glass transition due to slow correlation decay. A recently proposed method based on non-affine lattice dynamics (NALD) and instantaneous normal mode analysis offers a promising alternative for estimating the viscosity. In this study, we apply the NALD approach to compute the viscosity of the Kremer-Grest polymer system over a range of temperatures and compare these results with those from the GK method and non-equilibrium molecular dynamics simulations. Our findings reveal that all vibration modes, including the instantaneous normal modes, contribute to the viscosity. This work presents an efficient framework for calculating viscosity across diverse systems, including near the glass transition where the GK method is no longer applicable. Also, it opens the avenue to understanding the role of different vibrational modes linked with structure, facilitating the design of materials with tunable rheological properties.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
Magnetoelectric Control of Helical Light Emission in a Moiré Chern Magnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-05 20:00 EST
Eric Anderson, Heonjoon Park, Kaijie Yang, Jiaqi Cai, Takashi Taniguchi, Kenji Watanabe, Liang Fu, Ting Cao, Di Xiao, Xiaodong Xu
Magnetoelectric effects and their coupling to light helicity are important for both fundamental science and applications in sensing, communication, and data storage. Traditional approaches require complex device architectures, involving separate spin-injection, ferromagnetic, and optically active layers. Recently, the emergence of 2D semiconductor moiré superlattices with flat Chern bands and strong light-matter interactions has established a simple yet powerful platform for exploring the coupling between photon, electron, and spin degrees of freedom. Here, we report efficient current control of spontaneous ferromagnetism and associated helicity of light emission in moiré MoTe2 bilayer - a system which hosts a rich variety of topological phases, including newly discovered zero-field fractional Chern insulators. We show that the current control is effective over a wide range of doping of the first moiré Chern band, implying the uniformity of the Berry curvature distribution over the flat band. By setting the system into the anomalous Hall metal phase, a current as small as 10nA is sufficient to switch the magnetic order, a substantial improvement over both conventional spin torque architectures and other moiré systems. The realized current control of ferromagnetism leads to continuous tuning of trion photoluminescence helicity from left to right circular via spin/valley Hall torque at zero magnetic field. Our results pave the way for topological opto-spintronics based on semiconductors with synthetic flat Chern bands.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 4 figures, plus supplementary material
Microwave Microscope Studies of Trapped Vortex Dynamics in Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-05 20:00 EST
Chung-Yang Wang, Steven M. Anlage
Trapped vortices in superconductors introduce residual resistance in superconducting radio-frequency (SRF) cavities and disrupt the operation of superconducting quantum and digital electronic circuits. Understanding the detailed dynamics of trapped vortices under oscillating magnetic fields is essential for advancing these technologies. We have developed a near-field magnetic microwave microscope to study the dynamics of a limited number of trapped vortices under the probe when stimulated by a localized rf magnetic field. By measuring the local second-harmonic response ($P_\mathrm{2f}$) at sub-femto-Watt levels, we isolate signals exclusively arising from trapped vortices, excluding contributions from surface defects and Meissner screening currents. Toy models of Niobium superconductor hosting vortex pinning sites are introduced and studied with Time-Dependent Ginzburg-Landau (TDGL) simulations of probe/sample interaction to better understand the measured second-harmonic response. The simulation results demonstrate that the second-harmonic response of trapped vortex motion under a localized rf magnetic field shares key features with the experimental data. This measurement technique provides access to vortex dynamics at the micron scale, such as depinning events and spatially-resolved pinning properties, as demonstrated in measurements on a Niobium film with an antidot flux pinning array.
Superconductivity (cond-mat.supr-con)
Polycrystalline Morphology and Anomalous Hall Effect in RF-Sputtered Co2MnGa Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Carter E. Wade, Sunny Phan, Katherine Coffin, Gabe Paynter, Ty J. Cawein, Kurt G. Eyink, Andrei Kogan, Joseph P. Corbett
The Heusler compound Co2MnGa is a topological semimetal with intriguing electronic and magnetic properties, making it a promising candidate for spintronic applications. This study systematically investigates the effects of substrate temperature and RF sputtering power on the structure, morphology, and anomalous Hall effect (AHE) in Co2MnGa thin films. Using X-ray diffraction line analysis, we identify variations in film orientation and crystallinity, revealing the emergence of high-index textures at specific growth conditions. Atomic force microscopy imaging provide insight into grain morphology and size distributions demonstrating a correlation between deposition parameters and film texture. Hall transport measurements confirm a strong dependence of AHE on growth conditions, exhibiting a non-monotonic relationship with RF power and temperature. Despite significant variations in microstructure, a striking linear relationship between AHE and the zero-field slope of the Hall resistivity is observed, suggesting an underlying universal mechanism. These findings provide a foundation for investigating the complex interplay of CMG thin film conditions and transport for next-generation magnetic and electronic devices.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Critical Dynamics in Short-Range Quadratic Hamiltonians
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-05 20:00 EST
We investigate critical transport and the dynamical exponent through the spreading of an initially localized particle in quadratic Hamiltonians with short-range hopping in lattice dimension $d_l$. We consider critical dynamics that emerges when the Thouless time, i.e., the saturation time of the mean-squared displacement, approaches the typical Heisenberg time. We establish a relation, $z=d_l/d_s$, linking the critical dynamical exponent $z$ to $d_l$ and to the spectral fractal dimension $d_s$. This result has notable implications: it says that superdiffusive transport in $d_l\geq 2$ and diffusive transport in $d_l\geq 3$ cannot be critical in the sense defined above. Our findings clarify previous results on disordered and quasiperiodic models and, through Fibonacci potential models in two and three dimensions, provide non-trivial examples of critical dynamics in systems with $d_l\neq1$ and $d_s\neq1$.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
A Comprehensive Computational Photovoltaic Study of Lead-free Inorganic NaSnCl$_3$-based Perovskite Solar Cell: Effect of Charge Transport Layers and Material Parameters
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Md Tashfiq Bin Kashem, Sadia Anjum Esha
Lead-free all-inorganic halide perovskite solar cells (PSCs) have emerged as a promising alternative to toxic lead-based solar cells and organic solar cells, which have limited stability. This work explores such a PSC with sodium tin chloride (NaSnCl$_3$) as the absorber, due to its significant potential for optoelectronic applications. To investigate this potential, a comprehensive computational analysis of NaSnCl$_3$-based solar cells is performed using the one-dimensional solar cell capacitance simulator (SCAPS -1D). Simulations are performed for device structures with front contact/Indium Tin Oxide (ITO)/electron transport layer (ETL)/NaSnCl$_3$/hole transport layer (HTL)/back contact configuration, where TiO$_2$, SnS$_2$, IGZO, ZnSe, CdS, GaSe, ZnSnN$_2$, WS$_2$, PCBM, STO, and CSTO are utilized as ETLs and CNTS, GO, Mg-CuCrO$_2$, Spiro-OMeTAD, CdTe, GaAs, MoTe$_2$, BaSi$_2$, and P3HT are utilized as HTLs. Based on the obtained power conversion efficiency (PCE), six best ETL-HTL combinations with SnS$_2$, STO, WS$_2$, IGZO, ZnSe and CSTO as ETLs and MoTe$_2$ as HTL are chosen for further analysis. The effects of different material and device parameters, such as thickness and doping density; effective density of states; bulk and interface defects; series and shunt resistance; and operating conditions, such as temperature and light intensity are investigated. Using the optimized material parameters, SnS$_2$ ETL and MoTe$_2$ HTL-based solar cell show the best performance with open circuit voltage, Voc = 1.196V, short circuit current density, Jsc = 35.82 mA/cm$^2$, fill factor, FF = 89.72% and PCE = 38.42%. This detailed study provides valuable insights for the fabrication of high efficiency NaSnCl$_3$-based solar cells.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Steady-state dynamical mean field theory based on influence functional matrix product states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-05 20:00 EST
Mithilesh Nayak, Julian Thoenniss, Michael Sonner, Dmitry A. Abanin, Philipp Werner
We implement the recently developed influence functional matrix product states approach as impurity solver in equilibrium and nonequilibrium dynamical mean field theory (DMFT) calculations of the single-band Hubbard model. The method yields numerically exact descriptions of metallic states without sharp spectral features, at a moderate numerical cost. Systems with narrow quasiparticle or spin-polaron peaks, as well as low-temperature Mott insulators provide more challenges, since these simulations require long time contours or high bond dimensions. A promising field of application is the DMFT simulation of nonequilibrium steady states, which we demonstrate with results for photo-doped Mott systems with long-lived doublon and holon populations.
Strongly Correlated Electrons (cond-mat.str-el)
23 pages, 10 figures
Large-Angle Convergent-Beam Electron Diffraction Patterns via Conditional Generative Adversarial Networks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-05 20:00 EST
Joseph. J Webb, Rudolf A. Römer
We show how generative machine learning can be used for the rapid computation of strongly dynamical electron diffraction directly from crystal structures, specifically in large-angle convergent-beam electron diffraction (LACBED) patterns. We find that a conditional generative adversarial network can learn the connection between the projected potential from a cubic crystal’s unit cell and the corresponding LACBED pattern. Our model can generate diffraction patterns on a GPU many orders of magnitude faster than existing direct simulation methods. Furthermore, our approach can accurately retrieve the projected potential from diffraction patterns, opening a new approach for the inverse problem of determining crystal structure.
Materials Science (cond-mat.mtrl-sci)
9 pages, 7 figures