CMP Journal 2025-09-29
Statistics
Nature Materials: 2
Physical Review Letters: 3
arXiv: 75
Nature Materials
Mechanically liberating polarization bubbles in van der Waals ferroelectrics
Original Paper | Ferroelectrics and multiferroics | 2025-09-28 20:00 EDT
Xingan Jiang, Tingjun Wang, Yixuan Zhang, Zunyi Deng, Xiangping Zhang, Ruixue Zhu, Jiaqian Kang, Xiangdong Yang, Xue Chen, Xiaolei Wang, Peng Gao, Houbing Huang, Xidong Duan, Sang-Wook Cheong, Xueyun Wang, Weiyou Yang, Jiawang Hong
Ferroelectric topological textures have sparked intensive interest, due to their exciting applications in a new era of non-volatile and ultrahigh-density information storage. However, these textures remain largely dependent on the given heterostructures with engineered neighbouring layers to balance the competing energies. Here we report high-density polarization bubbles in van der Waals ferroelectric crystals CuInP2S6, without the need for a spatially confined heterostructure. From piezoresponse force microscopy, it is observed that the formation and distribution of bubble domains exist in the inherent coexistence of polar phases. Crucially, the phase ratio can be facilely tailored by external stimuli such as mechanical force, enabling the labyrinth domains to be manipulated into high-density isolated bubbles through a mechanism involving polar phase competition and flexoelectricity, as revealed through density functional theory and phase-field modelling. Our findings not only provide insights into the creation of topological structures in a controlled manner but also demonstrate potential memory applications based on bubble domains in van der Waals ferroelectrics.
Ferroelectrics and multiferroics, Topological matter
Large linear high-frequency strain by interlocked monoclinic polar nanoregions
Original Paper | Condensed-matter physics | 2025-09-28 20:00 EDT
Yue-Yu-Shan Cheng, Xiaoming Shi, Liang Shu, Qingyu He, Yizhe Li, Jin Luo, Sixu Wang, Yi-Xuan Liu, Lisha Liu, Lizhong Wang, Ziqi Yang, Wei Li, Xin Zhang, Liyu Wei, Yongqi Dong, Sarah J. Haigh, David A. Hall, Minlin Zhong, Zhenlin Luo, Qian Li, Houbing Huang, Shujun Zhang, Jing-Feng Li
Ferroelectric films with large and linear strains are crucial for precision microactuator applications, especially at high frequencies. However, existing strategies that rely on frequency- and temperature-dependent dynamics have had limited success in enhancing strain response under such conditions. Here, through promoted local strain fluctuation, we achieve an interlocked polar configuration in spin-coated epitaxial (K,Na)NbO3-based ferroelectric films. The films demonstrate high-frequency strains exceeding 1.1% with high linearity and stability even when measured at 105 Hz. The presence of interlocked monoclinic and tetragonal polar nanoregions boosts piezoelectric response by promoting polarization dynamics across a broad frequency range. Additionally, the interplay between two distinct polarization switching mechanisms, arising from different symmetries and boundary conditions, mutually compensates, contributing to the observed overall linearity. This approach presents a promising yet facile strategy for achieving ferroelectric films with reliable, large and linear strain across a wide high-frequency range.
Condensed-matter physics, Materials for devices
Physical Review Letters
Characterizing the Multipartite Entanglement Structure of Non-Gaussian Continuous-Variable States with a Single Evolution Operator
Article | Quantum Information, Science, and Technology | 2025-09-29 06:00 EDT
Mingsheng Tian, Xiaoting Gao, Boxuan Jing, Fengxiao Sun, Matteo Fadel, Manuel Gessner, and Qiongyi He
Multipartite entanglement is an essential resource for quantum information tasks, but characterizing entanglement structures in continuous-variable systems remains challenging, especially in multimode non-Gaussian scenarios. In this Letter, we introduce an efficient method for detecting multipartite…
Phys. Rev. Lett. 135, 140201 (2025)
Quantum Information, Science, and Technology
Precision Measurement of Net-Proton-Number Fluctuations in $\mathrm{Au}+\mathrm{Au}$ Collisions at RHIC
Article | Nuclear Physics | 2025-09-29 06:00 EDT
B. E. Aboona et al. (STAR Collaboration)
Experiments at the Relativistic Heavy Ion Collider give the first hints of a critical point in the hot quark-gluon "soup" that is thought to have pervaded the infant Universe.
Phys. Rev. Lett. 135, 142301 (2025)
Nuclear Physics
Spin Transport Revealed by Spin Quantum Geometry
Article | Condensed Matter and Materials | 2025-09-29 06:00 EDT
Longjun Xiang, Hao Jin, and Jian Wang
We present the framework of spin quantum geometry, which is fundamentally linked to the spin degree of freedom of Bloch electrons and incorporates both the spin quantum geometric tensor (QGT) and the recently introduced Zeeman QGT, to elucidate spin transport. We show that the spin and Zeeman QGTs, …
Phys. Rev. Lett. 135, 146303 (2025)
Condensed Matter and Materials
arXiv
From Phenomenology to a Nonlinear Model of Dynamic Snap-Through of an Elastica
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Chiraprabha Bhattacharyya, Ramsharan Rangarajan
Rotating the clamped ends of a buckled elastica induces a snap-through instability. Predicting the limit point and determining the equilibria at the start and end of the snap are routine computations in the quasi-static setting. The instability itself, however, is dynamic, and quite violently so. We propose an energy-preserving nonlinear single degree of freedom model for this dynamic phenomenon in the case of a symmetrically deforming elastica. The model hinges on a surprising observation relating elastica profiles during the free dynamic snap with a specific sequence of geometrically-constrained elastic energy minimizing configurations. We corroborate this phenomenological observation over a significant range of arch depths through experiments and finite element simulations. The resulting model does not rely on modal expansions, explicit slowness assumptions, or linearization of the arch’s kinematics. Instead, the model is effective because its solutions approximate the action integral well. The model provides distinctive computational benefits and new insights into the snap-through phenomenon. Our study is motivated by an application harnessing snap-through instabilities in submerged ribbons for underwater propulsion. We briefly describe its novel working principle and discuss its relationship to the problem studied.
Soft Condensed Matter (cond-mat.soft)
27 pages, 14 figures
Interpretable Spectral Features Predict Conductivity in Self-Driving Doped Conjugated Polymer Labs
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Ankush Kumar Mishra, Jacob P. Mauthe, Nicholas Luke, Aram Amassian, Baskar Ganapathysubramanian
Self-driving labs (SDLs) promise faster materials discovery by coupling automation with machine learning, but a central challenge is predicting costly, slow-to-measure properties from inexpensive, automatable readouts. We address this for doped conjugated polymers by learning interpretable spectral fingerprints from optical spectroscopy to predict electrical conductivity. Optical spectra are fast, non-destructive, and sensitive to aggregation and charge generation; we automate their featurization by combining a genetic algorithm (GA) with area-under-the-curve (AUC) computations over adaptively selected spectral windows. These data-driven spectral features, together with processing parameters, are used to train a quantitative structure-property relationship (QSPR) linking optical response and processing to conductivity. To improve accuracy and interpretability in the small-data regime, we add domain-knowledge-based feature expansions and apply SHAP-guided selection to retain a compact, physically meaningful feature set. The pipeline is evaluated under a leak-free train/test protocol, and GA is repeated to assess feature stability. The data-driven model matches the performance of a baseline built from expert-curated descriptors while reducing experimental effort (about 33%) by limiting direct conductivity measurements. Combining data-driven and expert features yields a hybrid QSPR with superior predictive performance, highlighting productive human-ML collaboration. The learned features recover known descriptors in pBTTT (0-0/0-1 vibronic intensity ratio) and reveal a tail-state region correlated with polymer bleaching during successful doping. This approach delivers interpretable, noise-robust, small-data-friendly features that convert rapid measurements into reliable predictions of costly properties and readily extends to other spectral modalities (e.g., XANES, Raman, FTIR).
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft), Machine Learning (cs.LG)
31 Pages, 19 Figures
Least-Dissipation Interfaces in Fully Miscible Fluids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Gyeong Min Choi, Heon Sang Lee
Sharp interfaces in miscible fluids have long been observed, yet classical theory associates them only with phase coexistence and non-convex free energies. We present a minimal variational frame work where adding a Fermi-Dirac (FD) free energy to a convex bulk contribution preserves miscibility, while the convex term drops out in the gradient balance, leaving the FD part to set a logistic profile by the principle of least dissipation. After formation, the FD interface propagates diffusively and later broadens by ripening, giving a unified view of interfacial dynamics in miscible fluids.
Soft Condensed Matter (cond-mat.soft)
6 pages, 2 figures
Dimer-driven multiple reentrant localization with composite potential
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-09-29 20:00 EDT
Pei-Jie Chang, Dong Ruan, Gui-Lu Long
Recent studies have revealed reentrant localization transitions in quasi-periodic one-dimensional lattices, where the competition between dimerized hopping and staggered disorder plays a central role. Yet the extent to which such reentrant localization persists under more general conditions, such as additional periodic potentials, modified quasi-periodic modulations remains unclear. Here we investigate localization phenomena in a one-dimensional lattice subject to a periodic potential and an additional quasi-periodic modulation. Using both eigenstate-based indicators and experimentally accessible dynamical observables, we identify robust reentrant, or multiple, localization transitions. We show that these transitions are uniquely stabilized by the dimer structure of the unit cell, where the competition between the onsite periodic potential and the quasi-periodic modulation becomes most pronounced. By systematically varying the periodicity parameter $ \alpha$ and the quasi-periodic frequency $ \beta$ , we find that the robust multiple reentrant localization behavior disappears for any deviation from the dimer configuration, confirming its essential role. Our results suggest that the interplay between these competing factors drives the multiple reentrant localization transitions.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
Dynamical Response of Deformable Microchannels under Pressure-Driven Flow of Aqueous Polymer Solutions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Sampad Laha, Siddhartha Mukherjee, Suman Chakraborty
Microfluidic channels are integral to biomedical technology and process engineering, offering versatility in handling fluids with complex properties, often a combination of viscous and elastic attributes. Despite significant advancements in understanding small-scale fluid-structure interactions, however, experimental insights on the flow of complex fluids in deformable microchannels remain limited. Here, we present controlled experiments using polymer solutions as model viscoelastic fluids to examine the effects of polymer concentration on the elasto-mechanical characteristics of slender cylindrical microchannels. The findings indicate significant differences in fluid-structure interactions between dilute and semi-dilute polymer solutions with varying molecular weights. At higher polymer concentrations, these interactions intensify, leading to reduced pressure drops in high-shear regions and increased pressure drops in low-shear areas, linked to local wall deformation. The increased elasticity of higher concentration solutions further enhances local deformation, disrupts flow, and dissipates energy, resulting in a non-linear rise in pressure drop. This behaviour is aggravated by the solutions increased apparent viscosity due to the entangled polymer network. A theoretical model of flow-induced deformation is also developed, accounting for polymer chain extensibility. These insights highlight the importance of polymer constitution in optimizing the flow characteristics, advancing the development of adaptive microfluidic devices in biological and industrial applications for optimal performance.
Soft Condensed Matter (cond-mat.soft)
Non-reciprocal coalescence-breakup dynamics in concentrated emulsions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Ivan Girotto, Andrea Scagliarini, Lei Yi, Roberto Benzi, Chao Sun, Federico Toschi
Dense stabilized emulsions are mixtures of immiscible fluids where the high-volume fraction droplet dispersed phase is stabilized against coalescence by steric interactions. The production of emulsions involves high-shear flows and it is well known that at a critical volume fraction the emulsion loses stability, undergoing an extremely rapid process where the fluid components in the emulsion exchange roles. This process, called catastrophic phase inversion, which resembles in several respects a dynamical phase transition, has remained widely elusive from an experimental and theoretical point of view. In this work, we present state-of-the-art experimental and numerical data to support a dynamical-system framework capable of precisely highlighting the dynamics occurring in the system as it approaches the catastrophic phase inversion. Our study clearly highlights that at high volume fractions, dynamical changes in the emulsion morphology, due to coalescence and breakup of droplets, play a critical role in determining emulsion’s rheology and stability. Additionally, we show that at approaching the critical volume fractions, the dynamics can be simplified as being controlled by the dynamics of a correlation length represented, in our systems, by the size of the largest droplet. This dynamics shares a close connection with non-reciprocal phase transition where two different physical mechanisms, coalescence and breakups, can get out of balance leading to large non-symmetric periodic excursions in phase space. We clarify the phenomenology observed and quantitatively explain the essential aspect of the highly complex dynamics of stabilized emulsions undergoing catastrophic phase inversion.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
29 pages, 11 figures
Capillarity in Stationary Random Granular Media: Distribution-Aware Screening and Quantitative Supercell Sizing
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Christian Tantardini, Fernando Alonso-Marroquin
We develop a quantitative framework to determine the minimal periodic supercell required for representative simulations of capillarity-screened Darcy flow in stationary random, polydisperse granular media. The microstructure is characterized by two-point statistics (covariance and spectral density) that govern finite-size fluctuations. Capillarity is modeled as a screened, modified-Helmholtz problem with phase-dependent transport under periodic boundary conditions; periodic homogenization yields an apparent conductivity, an apparent screening parameter, and a macroscopic capillary decay length. Because screening imparts a spatial low-pass response, we introduce a distribution-aware treatment of polydispersity consisting of a capillarity-weighted volume fraction and a screened analogue of the integral range that preserves variance units and recovers classical descriptors in the appropriate limits. These descriptors lead to two sizing rules: (i) a length criterion on the shortest cell edge controlled by a microstructural correlation length, the macroscopic decay length, and a high quantile of grain size; and (ii) a volume criterion that links the target coefficient of variation to the screened integral range and the phase contrast. The framework couples statistical microstructure information to capillary response and yields reproducible, distribution-aware supercell selection for image-based finite-element or fast-Fourier-transform solvers.
Soft Condensed Matter (cond-mat.soft)
Polymer-based probabilistic bits for thermodynamic computing
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Stephen H. Foulger, Yuriy Bandera, Igor Luzinov, Travis Wanless, Lubomir Kostal, Vojtech Nádazdy, Petr Janovský, Jarmila Vilčáková
Probabilistic bits (p-bits) are stochastic hardware elements whose output probability can be tuned by an input bias, offering a route to energy-efficient architectures that exploit, rather than suppress, fluctuations. Here we report p-bit generation in an organic memristive device, establishing polymers as the first class of soft-matter systems to realize probabilistic hardware. The active element is a dithieno[3,2-b:2’,3’-d]pyrrole (DTP)-backbone polymer with pendant triphenylamine (TPA) groups, whose stochastic resistance fluctuations are converted into binary outputs by a simple voltage-divider/comparator circuit. The resulting probability distributions follow logistic transfer functions, characteristic of stochastic binary neurons. Separately, ensembles of pulsed IV measurements were analyzed to construct binned current distributions, from which the discrete Shannon entropy was calculated. Peaks in this entropy coincide with bias conditions that maximize variability in the memristor voltage drop, directly linking device-level stochasticity to intrinsic material properties. Dielectric analysis shows that pendant TPA units provide dynamically active relaxation modes, while energy-resolved electrochemical impedance spectroscopy and density functional theory calculations indicate that the frontier orbitals of DTP, TPA and ITO align within the transport gap to produce a bifurcated percolation network. The correspondence between microscopic relaxation dynamics, electronic energetics and macroscopic probabilistic response highlights how organic semiconductors can serve as chemically tunable entropy sources, opening a polymer-based pathway toward thermodynamic computing.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Emerging Technologies (cs.ET), Applied Physics (physics.app-ph), Chemical Physics (physics.chem-ph)
29 pages, 14 figures, 3 tables. Extended study of polymer-based probabilistic bits, following up on earlier work reporting the first polymeric p-bit (Advanced Physics Research, 2025)
Interface and Thermophysical Properties of R32 Refrigerant
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Abibat Adekoya-Olowofela, Sukriti Manna, Subramanian KRS Sankaranarayanan
Driven by the urgent demand for efficient cooling in microelectronics and advanced thermal management systems, difluoromethane (R32/CH2F2) has emerged as a promising candidate owing to its favorable thermophysical properties, including high heat transfer efficiency and low viscosity. While bulk properties such as density, viscosity, and thermal conductivity have been widely studied, interfacial properties including surface tension and interfacial thickness remain comparatively underexplored, despite their importance in phase-transition dynamics. Here, we perform molecular dynamics (MD) simulations from 180 K-300 K using an optimized transferable force field for fluoropropenes with enhanced electrostatics to assess both bulk and interfacial behavior of R32. Simulations reproduced density within +/- 2.1%, viscosity within 3.05%, and thermal conductivity within 7.41% of NIST reference data. Heat capacities (Cp and Cv) were predicted within 5%. For interfacial properties, surface tension trends were reproduced within 15.8% deviation, and the vapor-liquid coexistence curve closely matched reference data, yielding a critical temperature of 345.7 K (1.6% deviation) and a critical density of 0.397 g/cm3 (6.4% deviation). Importantly, the vapor-liquid interface exhibited strong temperature dependence, with interfacial thickness increasing by 290% between 180 K and 290 K. These validated results provide predictive molecular-level insights, particularly for interfacial properties that remain less characterized. By reducing property prediction errors in key parameters such as critical temperature, this work provides reliable inputs for heat-exchanger and system models. Beyond R32, the methodology offers a transferable framework for blended and next-generation low-GWP refrigerants, contributing to sustainable thermal management aligned with the 2027 EU F-Gas regulation and 2030 Kigali Amendment.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Transfer tensor analysis of localization in the Anderson and Aubry-André-Harper models
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-09-29 20:00 EDT
Michelle C. Anderson, Chern Chuang
We use the transfer tensor method to analyze localization and transport in simple disordered systems, specifically the Anderson and Aubry-André-Harper models. Emphasis is placed on the memory effects that emerge when ensemble-averaging over disorder, even when individual trajectories are strictly Markovian. We find that memory effects are necessary to remove fictitious terms that would correspond to redrawing static disorder at each time step, which would create a temporally uncorrelated dynamic disorder. Our results show that while eternal memory is a necessary condition for localization, it is not sufficient. We determine that signatures of localization and transport can be found within the transfer tensors themselves by defining a metric called “outgoing-pseudoflux”. This work establishes connections between theoretical research on dynamical maps and Markovianity and localization phenomena in physically realizable model systems.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Chemical Physics (physics.chem-ph), Quantum Physics (quant-ph)
8 pages, 3 figures
Viscous Growth Law in Bubble Coarsening: A Molecular Dynamics Perspective
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Parameshwaran A, Bhaskar Sen Gupta
We investigate the kinetics of bubble coarsening in a single component Lennard-Jones fluid using large-scale molecular dynamics simulations. A homogeneous high-temperature system is quenched below the critical temperature to induce the nucleation and growth of vapor bubbles within a dense liquid matrix. The structural evolution is characterized by two point correlation functions and the static structure factor, both of which exhibit dynamic scaling and sharp interfaces consistent with Porod law. The time-dependent characteristic length scale, extracted from the correlation function, shows a robust power law growth $ \ell(t) \sim t^{\alpha}$ . Finite size scaling analysis across different system sizes yields $ \alpha \approx 1.0$ , establishing that coarsening is dominated by viscous hydrodynamic interactions rather than classical diffusion-limited Ostwald ripening predicted by the Lifshitz-Slyozov-Wagner theory. These results provide atomistic evidence for fluid flow controlled coarsening in vapor-liquid systems and emphasize the need to go beyond diffusion-based theories to describe bubble dynamics in dense fluids.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Strain-tunability of the multipolar Berry curvature in altermagnet MnTe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Shane Smolenski, Ning Mao, Dechen Zhang, Yucheng Guo, A.K.M. Ashiquzzaman Shawon, Mingyu Xu, Eoghan Downey, Trisha Musall, Ming Yi, Weiwei Xie, Chris Jozwiak, Aaron Bostwick, Nobumichi Tamura, Eli Rotenberg, Lu Li, Kai Sun, Yang Zhang, Na Hyun Jo
The anomalous Hall effect describes the generation of a transverse voltage by a longitudinal current even in the absence of an external magnetic field. While typically observed in ferromagnets, it has also been predicted to arise in altermagnets, materials characterized by rotational symmetries that enable broken time reversal symmetry despite compensated collinear magnetic ordering. These symmetries enforce band (anti)crossings that can generate significant contributions to the Berry curvature that drives the anomalous Hall effect. This Berry curvature is predicted to exhibit a characteristic multipolar order, resulting in a symmetry-enforced distribution at or near net compensation which is highly sensitive to perturbations that distort this balance. However, exploring the predicted multipolar Berry curvature of altermagnets and its reversible manipulation remains challenging. Here, we demonstrate evidence for the multipolar nature of the altermagnetic Berry curvature in MnTe by tuning the anomalous Hall effect via uniaxial stress. Upon straining, the magnitude of the anomalous Hall conductivity changes and, at a critical strain of 0.14%, the sign is reversed. Symmetry analysis and density functional theory calculations reveal that this tunability is a direct consequence of the altermagnetic multipolar Berry curvature. Our results provide insight into the role of crystal and magnetic symmetries in the realization of higher-order Berry curvature distributions and their unique tunability.
Materials Science (cond-mat.mtrl-sci)
Electro-mechanical wrinkling of soft dielectric films bonded to hyperelastic substrates
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Bin Wu, Linghao Kong, Weiqiu Chen, Davide Riccobelli, Michel Destrade
Active control of wrinkling in soft film-substrate composites using electric fields is a critical challenge in tunable material systems.
Here, we investigate the electro-mechanical instability of a soft dielectric film bonded to a hyperelastic substrate, revealing the fundamental mechanisms that enable on-demand surface patterning. For the linearized stability analysis, we use the Stroh formalism and the surface impedance method to obtain exact and sixth-order approximate bifurcation equations that signal the onset of wrinkles.
We derive the explicit bifurcation equations giving the critical stretch and critical voltage for wrinkling, as well as the corresponding critical wavenumber.
We look at scenarios where the voltage is kept constant and the stretch changes, and vice versa.
We provide the thresholds of the shear modulus ratio $ r_{\rm c}^0$ or pre-stretch $ \lambda_{\rm c}^0$ below which the film-substrate system wrinkles mechanically, prior to the application of a voltage.
These predictions offer theoretical guidance for practical structural design, as the shear modulus ratio $ r$ and/or the pre-stretch $ \lambda$ can be chosen to be slightly greater than $ r_{\rm c}^0$ and/or $ \lambda_{\rm c}^0$ , so that the film-substrate system wrinkles with a small applied voltage.
Finally, we simulate the full nonlinear behavior using the Finite Element method (FEniCS) to validate our formulas and conduct a post-buckling analysis. This work advances the fundamental understanding of electro-mechanical wrinkling instabilities in soft material systems. By enabling active control of surface morphologies via applied electric fields, our findings open new avenues for adaptive technologies in soft robotics, flexible electronics, smart surfaces, and bioinspired systems.
Soft Condensed Matter (cond-mat.soft), Pattern Formation and Solitons (nlin.PS)
Bananas for Tonks’ gas: structural transitions in bent-core molecule bi-layers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
We study the role of particle geometry in the ordering of bilayers of bent-core particles using a simplified two-dimensional model. Particles are confined to two parallel one-dimensional layers and can adopt only two discrete orientations of their bent cores. By mapping the system exactly onto a pair of coupled Ising chains in the thermodynamic limit, we may obtain closed-form expressions for all correlation functions. The coupling between orientational and layer degrees of freedom produces remarkably rich behaviour, including crossovers between ferromagnetic and antiferromagnetic orientational order, and states with polarised layers. Despite its simplicity, this exactly soluble model reproduces qualitative features of bent-core smectic liquid crystals and confined colloids, providing insight into the subtle role of particle geometry in driving structural correlations.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
25 pages, 22 figures - nearly one per page
Anisotropy of the chiral, semiconducting phase LaRhC$_{2}$: a handedness resolved study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Volodymyr Levytskyi, Ulrich Burkhardt, Markus König, Christoph Hennig, Eteri Svanidze, Yuri Grin, Roman Gumeniuk
Chirality in quantum materials is a topic of significant importance due to its profound effects on the electronic, magnetic, and optical properties of these systems. However, it is non-trivial to decouple the behavior of two enantiomorphs within the same material – perhaps explaining why the influence of chirality on electrical properties has remained largely unexplored. In this work, we examine the electrical conductivity, magnetoresistance, and thermal expansion coefficient of LaRhC$ _{2}$ – a compound with a chiral crystal structure (tetragonal symmetry, space groups $ \textit{P}$ 4$ _{1}$ or $ \textit{P}$ 4$ _{3}$ ). The identification of a suitable monochiral domain was achieved via electron backscatter diffraction, which simultaneously determines crystallographic orientation and handedness. Both enantiomorphs are confirmed by single-crystal X-ray diffraction on monochiral specimens. The analysis of electrical resistivity was made possible through the single-domain extraction of enantiopure specimens from a polycrystalline sample using focused ion beam techniques. We establish that LaRhC$ _{2}$ is a semiconductor with band gaps of approximately 20 meV and 33 meV parallel and perpendicular to the fourfold screw axis of the crystal structure, respectively – consistent with band structure calculations. A significant anisotropy is also observed in the thermal expansion, electrical resistivity as well as angular-dependent magnetoresistance parallel and perpendicular o [001] crystallographic directions.
Materials Science (cond-mat.mtrl-sci)
27 pages, 6 figures, 1 table, and Supplementary materials (16 p., 6 fig., 9 tab.)
The correlated cluster mean-field approach to the frustrated Ising model on the honeycomb lattice
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-29 20:00 EDT
Carlos H. D. Batista, M. Schmidt, F. M. Zimmer
We study the $ J_1$ -$ J_2$ Ising model on the honeycomb lattice, considering ferromagnetic interactions between first neighbors ($ J_1$ ) and antiferromagnetic interactions between second neighbors ($ J_2$ ). Our analysis is based on the correlated cluster mean field theory, which is adapted to incorporate competing interactions, providing estimates for the behavior of magnetization, internal energy, entropy, specific heat, and short-range correlations of the model. Our results indicate that the transition temperature of the ferromagnetic-paramagnetic phase transition decreases toward zero as the frustration maximum ($ J_2/J_1 = -1/4$ ) is approached, and the thermodynamic quantities indicate only continuous phase transitions for $ -1/4<J_2/J_1 \leq 0$ . The critical temperature and the nature of phase transitions provided by the correlated cluster mean-field method are in excellent agreement with very recent Monte Carlo simulations for the model. Furthermore, the specific heat exhibits a broad maximum within the PM phase under strong frustration, suggesting the onset of a correlated paramagnetic state with high entropy content at low temperatures. Therefore, our findings support that frustration not only suppresses the ferromagnetic long-range order, but also drives significant changes in the thermodynamics and short-range correlations of the model.
Statistical Mechanics (cond-mat.stat-mech)
High-accuracy low-noise electrical measurements in a closed-cycle pulse-tube cryostat
New Submission | Other Condensed Matter (cond-mat.other) | 2025-09-29 20:00 EDT
Mathieu Taupin, Kamel Dougdag, Djamel Ziane, Francois Couedo
A shift of paradigm to obtain (sub-)Kelvin environment is currently on-going with the democratization of cryogen-free cryocoolers, boosted by their easy-to-use and continuous operation without the need of liquid helium whose cost and scarcity globally increase. Thanks to their large sample space and cooling power, they can host a superconducting magnet and are an adapted platform for quantum technologies, material science, low temperature detectors and even medical fields. The drawback is that this type of system is inherently based on gas compression that induces a certain level of vibrations and electromagnetic perturbations, which can potentially prevent the determination of low amplitude signals or spoil their stability. In this paper we demonstrate that pulse-tube based cryocoolers can be used for electrical precision measurements, using a commercial cryomagnetic system combined with our home-made a coaxial cryoprobe. In particular, parts-per-billion level of measurement uncertainties in resistance determination, based on quantum Hall resistance standards, is achievable at the level of state-of-the-art measurements involving conventional cryostats based on liquid helium. We performed an extensive characterization of the cryomagnetic system to determine the level of vibrations and electromagnetic perturbations, and revealed that although the magnetic field has a drastic effect on the noise level, only marginal interplays on the measurement are observed as long as the working frequencies of the instrumentation are not in the vicinity of the ones of the perturbations. The set of characterization measurements presented here are easily implementable in laboratories, which can help to determine the vibrations and electromagnetic pollution generated by any cryocooler.
Other Condensed Matter (cond-mat.other), Instrumentation and Detectors (physics.ins-det)
Critical dynamics and superconducting state preparation in the quenched Kitaev chain with pairing imbalance
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-29 20:00 EDT
Y. B. Shi, Y. X. Zhang, S. W. Liu, Z. Song
The dynamical balance of the pairing term plays a crucial role in the emergence of topological superconductivity in the p-wave spinless Kitaev chain, particularly in the non-Hermitian regime. In this work, we systematically investigate the effects of non-Hermitian pairing terms on both equilibrium and nonequilibrium phenomena in the Kitaev chain. Our analysis focuses on two representative forms of pairing imbalance: uniform and staggered. We demonstrate that a uniform imbalance induces only minor perturbations to the spectrum and dynamical properties, without significantly affecting its equilibrium phase or nonequilibrium steady behavior. In contrast, even a slight staggered imbalance leads to drastic changes. At the symmetry point, it enables the resonant generation of two distinct superconducting states through critical dynamics, with the realized state determined by the direction of the bias. Both states exhibit exact off-diagonal long-range order (ODLRO) in the thermodynamic limit. Our results emphasize the fragility of coherent dynamics in non-Hermitian topological systems and elucidate the interplay among non-Hermiticity, topology, and dynamical criticality in quench processes.
Superconductivity (cond-mat.supr-con), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
12 pages, 5 figures
Real Space Imaging of Spin Scattering in Chirality-Induced Spin Selectivity
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-29 20:00 EDT
Jaehyun Lee, Sang-hyuk Lee, Uiseok Jeong, Daryll J. C. Dalayoan, Soobeom Shin, Hu Young Jeong, Hosub Jin, Binghai Yan, Noejung Park, Seon Namgung
The interaction between electron spin and molecular chirality plays a fundamental role in quantum phenomena, with significant implications for spintronics and quantum computing. The chirality-induced spin selectivity (CISS) effect, where chiral materials preferentially transmit electrons of a particular spin, has sparked intense interest and debate regarding its underlying mechanism. Despite extensive research, the spatial distribution of spin polarization in chiral systems, the key evidence to reveal the spin scattering mechanism in CISS, has remained experimentally elusive particularly due to complications arising from spin-orbit coupling in metal electrodes typically used in such studies. Here we show, through reflective magnetic circular dichroism measurements on chiral tellurium nanowires with graphene electrodes, that current-induced spin polarization exhibits identical signs in both the nanowire and electrodes, distinct from the presumed spin filter scenario. The observed spin polarization scales linearly with current amplitude, aligns parallel to the current direction, reverses with chirality or current flow, and demonstrates spin relaxation lengths of several micrometers into graphene. Our findings provide the first direct visualization of spatial spin distribution in chiral devices. This work establishes a new paradigm for investigating spin-dependent phenomena in chiral materials and opens avenues for developing chirality-based spintronic and quantum devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Smearing of dynamical quantum phase transitions in dissipative free-fermion systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-29 20:00 EDT
We investigate the Lindblad dynamics of the reduced Loschmidt echo (RLE) in dissipative quadratic fermion systems. Focusing on the case of gain and loss dissipation, we derive general conditions for the persistence of nonanalyticities (so-called dynamical quantum phase transitions) in the time evolution of the RLE. We show that nonanalyticities that are present in the corresponding unitary dynamics can survive under purely gain or purely loss processes, but are completely smeared out as soon as both channels are active, even if one is infinitesimally small. These results hold for generic dissipative Gaussian evolutions, and are illustrated explicitly for the quench from the Néel state in the tight-binding chain, as well as for the quantum Ising chain. We also show that the subtle interplay between dissipative and unitary dynamics gives rise to a nested lightcone structure in the dynamics of the RLE, even in cases where this structure is not present in the corresponding unitary evolution, due to coherent cancellations in the phase structure of the wavefunction.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
8 pages, 3 figures
Pathways from a chiral superconductor to a composite Fermi liquid
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
Yunchao Zhang, Leyna Shackleton, T. Senthil
Recent experiments have reported chiral time-reversal broken superconductivity in $ n$ -layer rhombohedral graphene for $ n = 4,5, 6$ . Introducing a moiré potential by alignement with a hexagonal boron nitride substrate suppresses the superconductivity but leads instead to various fractional quantum anomalous Hall phenomena. Motivated by these observations, we consider the fate of the phase transition between (a chiral) Landau Fermi liquid (LFL) metal and a Composite Fermi Liquid (CFL) metal in the presence of attractive interactions. These are parent states, respectively, for the superconductor and the fractional quantum Hall states. For weak attractive interactions, the LFL is usually unstable to superconductivity while the CFL is stable. This raises the possibility of a direct continuous phase transition between the chiral superconductor and the CFL. However, we show that generically the LFL close to the transition to the CFL is stable against superconductivity. Thus the evolution between the CFL and chiral superconductor goes through an intermediate stable LFL phase for weak attractive interactions. With stronger interactions, the evolution can instead go through a non-Abelian paired quantum Hall state.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
25 pages, 3 figures
Emergent Isotropic-Nematic Transition in 3D Semiflexible Active Polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Twan Hooijschuur, Ehsan Irani, Antoine Deblais, Sara Jabbari-Farouji
Active semiflexible filament collectives, ranging from motor-driven cytoskeletal filaments to slender organisms such as cyanobacteria and worm aggregates, abound in nature, yet how activity and flexibility jointly govern their organization, especially Isotropic-nematic (I-N) transition, remains poorly understood. Using large-scale Brownian dynamics simulations of 3D active semiflexible polymers with varying flexibility degrees, we show that tangential active forces systematically shift the I-N transition to higher densities, with the shift controlled by the flexibility degree and activity strength. Strikingly, activity alters the nature of the transition: discontinuous at low strengths, continuous at moderate strengths, and ultimately suppressed at high activity levels. At high densities, this suppression generates an active nematic state, sustained by continuous defect creation and annihilation but lacking global order. The delayed I-N transition originates from enhanced collective bending fluctuations, which reduce the effective persistence length and enlarge the effective confinement tube. At moderate activity levels, these fluctuations trigger large-scale excitations that stochastically drive temporal transitions between nematic and isotropic states. We summarize this behavior in non-equilibrium state diagrams of density and activity for different flexibility degrees.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
5 pages, 6 figures
Multiferroicity of oxygen-deficient Hf$x$Zr${1-x}$O$_{2-y}$ nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Anna N. Morozovska, Andrii V. Bodnaruk, Oleksandr S. Pylypchuk, Denis O. Stetsenko, Andrii D. Yaremkevich, Oksana V. Leshchenko, Victor N. Pavlikov, Yuri O. Zagorodniy, Lesya P. Yurchenko, Lesya Demchenko, Myroslav V. Karpets, Olena M. Fesenko, Victor V. Vainberg, Eugene A. Eliseev
We observed a superparamagnetic-type response of ultra-small (5 - 10 nm in size) Hf$ _x$ Zr$ _{1-x}$ O$ _{2-y}$ nanoparticles prepared by the solid-state organonitrate synthesis. The Raman spectra indicate the decisive role of surface defects, presumably oxygen vacancies, for all studied x = 1, 0.6, 0.5, 0.4 and significant degree “y” of oxygen deficiency. At the same time elemental analysis did not reveal any noticeable concentration of magnetic impurities in theHf$ _x$ Zr$ _{1-x}$ O$ _{2-y}$ nanopowders, and the X-ray diffraction analysis reveals the dominant presence (from 87 to 96 wt. %) of the orthorhombic phase. Therefore, the superparamagnetic response of the nanoparticles is explained by the appearance of magnetic state of oxygen vacancies accumulated near their surface. The Landau-Ginzburg-Devonshire approach, density functional theory calculations and dielectric measurements reveal that the studied ultra-small Hf$ _x$ Zr$ _{1-x}$ O$ _{2-y}$ nanoparticles may have ferroelectric-like properties and giant dielectric permittivity (> 10^3 - 10^5) in the frequency range 4 Hz - 10 kHz. In this work we observed that the static relative dielectric permittivity of the Hf$ _x$ Zr$ _{1-x}$ O$ _{2-y}$ nanopowders overcomes 10^6 and related the colossal values with the superparaelectric states of the ultra-small cores of the this http URL, obtained results open the way for the creation of silicon-compatible multiferroics - oxygen-deficient Hf$ _x$ Zr$ _{1-x}$ O$ _{2-y}$ nanoparticles with the superparamagnetic and superparaelectric properties, indispensable ultra-high k nanomaterials for advanced FETs and electronic logic elements.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
22 pages, including 8 figures and Supplementary Materials
Charge, heat, and spin transport phenomena in metallic conductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Nynke Vlietstra, Sebastian T. B. Goennenwein, Rudolf Gross, Hans Huebl
In solid state materials, gradients of the electro-chemical potential, the temperature, or the spin-chemical potential drive the flow of charge, heat, and spin angular momentum, resulting in a net transport of energy. Beyond the primary transport processes - such as the flow of charge, heat, and spin angular momentum driven by gradients in their respective potentials - a wide range of coupled or cross-linked transport responses can occur, giving rise to a rich variety of transport phenomena. These transport phenomena are commonly categorized under (anomalous) thermoelectric, thermomagnetic, and galvanomagnetic effects, along with their spin-dependent counterparts. However, establishing a systematic classification and comparison among them remains a complex and nontrivial task. This paper attempts a didactic overview of the different transport phenomena, by categorizing and briefly discussing each of them based on charge, heat, and spin transport in conducting solids. The phenomena are structured in three categories: collinear, transverse, and so-called `planar’ transport effects. The resulting overview attempts to categorize all effects in a consistent manner.
Materials Science (cond-mat.mtrl-sci)
40 pages, 24 figures, 3 tables
Mean-field theory of the general-spin Ising model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-29 20:00 EDT
Lourens Waldorp, Tuan Pham, Han L. J. van der Maas
Motivated by modelling in physics and other disciplines, such as sociology and psychology, we derive the mean field of the general-spin Ising model from the variational principle of the Gibbs free energy. The general-spin Ising model has $ 2k+1$ spin values, generated by $ -(k-j)/k$ , with $ j=0,1,2\ldots,2k$ , such that for $ k=1$ we obtain $ -1,0,1$ , for example; the Hamiltonian is identical to that of the standard Ising model. The general-spin Ising model exhibits spontaneous magnetisation, similar to the standard Ising model, but with the location translated by a factor depending on the number of categories $ 2k+1$ . We also show how the accuracy of the mean field depends on both the number of nodes and node degree, and that the hysteresis effect decreases and saturates with the number of categories $ 2k+1$ . Monte Carlo simulations confirm the theoretical results.
Statistical Mechanics (cond-mat.stat-mech), Classical Physics (physics.class-ph)
A comprehensive equivalent circuit model for high overtone bulk acoustic resonators (HBARs)
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-29 20:00 EDT
Vikrant J. Gokhale, Brian P. Downey
This paper presents a new and comprehensive equivalent circuit model for high overtone bulk acoustic resonators (HBARs). HBARs demonstrate several very sharp resonance modes distributed nearly periodically over a very wide frequency range. This spectrum response of HBARs offers unique advantages but poses significant modeling challenges. The proposed circuit incorporates and models the unique physical components of the HBAR: piezoelectric transducer, substrate (a perfectly periodic multimode cavity), piezoelectric coupling, and critically, the imperfectly matched transducer-substrate interface which imparts characteristic aperiodicity to the HBAR mode spectrum. By judicious use of fixed, periodic, or tightly constrained virtual lumped-element branches, and sets of branches, the model retains clear and intuitive links to the physical device, while reducing the complexity needed for fitting dense, broadband datasets. We demonstrate the validity and power of this model by simultaneously fitting measured data for 61 modes of a GaN/NbN/sapphire HBAR over a span of 1 GHz, and extracting modal parameters such as quality factors and coupling coefficients. We show that this new model is compact and yet scalable: by leveraging the inherent internal relationships in an HBAR, the model can be easily expanded to include multiple transducer overtones and envelopes, multiple distinct transducers, and spurious modes. In addition to fitting measured datasets, the new model can also be used to easily analyze various perturbations to the nominal state of the HBAR. We expect the new model to be useful for the design of classical HBAR-based oscillators, filters, and sensors, and for the integration of HBARs into quantum circuits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), Systems and Control (eess.SY), Applied Physics (physics.app-ph), Instrumentation and Detectors (physics.ins-det)
20 pages, 9 figures
Automated Machine Learning Pipeline for Training and Analysis Using Large Language Models
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Adam Lahouari, Jutta Rogal, Mark E. Tuckerman
Machine learning interatomic potentials (MLIPs) have become powerful tools to extend molecular simulations beyond the limits of quantum methods, offering near-quantum accuracy at much lower computational cost. Yet, developing reliable MLIPs remains difficult because it requires generating high-quality datasets, preprocessing atomic structures, and carefully training and validating models. In this work, we introduce an Automated Machine Learning Pipeline (AMLP) that unifies the entire workflow from dataset creation to model validation. AMLP employs large-language-model agents to assist with electronic-structure code selection, input preparation, and output conversion, while its analysis suite (AMLP-Analysis), based on ASE supports a range of molecular simulations. The pipeline is built on the MACE architecture and validated on acridine polymorphs, where, with a straightforward fine-tuning of a foundation model, mean absolute errors of ~1.7 meV/atom in energies and ~7.0 meV/Å in forces are achieved. The fitted MLIP reproduces DFT geometries with sub-Å accuracy and demonstrates stability during molecular dynamics simulations in the microcanonical and canonical ensembles.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Direct Deoxygenation of Phenol over Fe-based Bimetallic Surfaces using On-the-fly Surrogate Models
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
We present an accelerated nudged elastic band (NEB) study of phenol direct deoxygenation (DDO) on Fe-based bimetallic surfaces using a recently developed Gaussian process regression (GPR) calculator. Our test calculations demonstrate that the GPR calculator achieves up to 3x speedup compared to conventional density functional theory (DFT) calculations while maintaining high accuracy, with energy barrier errors below 0.015 eV. Using GPR-NEB, we systematically examine the DDO mechanism on pristine Fe(110) and surfaces modified with Co and Ni in both top and subsurface layers. Our results show that subsurface Co and Ni substitutions preserve favorable thermodynamics and kinetics for both C-O bond cleavage and C-H bond formation, comparable to those on the pristine Fe(110) surface. In contrast, top-layer substitutions generally increase the C-O bond cleavage barrier, render the step endothermic, and result in significantly higher reverse reaction rates, making DDO unfavorable on these surfaces. This work demonstrates both the effectiveness of GRR-accelerated transition state searches for complex surface reactions and provides insights into rational design of bimetallic catalysts for selective deoxygenation.
Materials Science (cond-mat.mtrl-sci)
8 pages, 6 figures
Scalable Foundation Interatomic Potentials via Message-Passing Pruning and Graph Partitioning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Lingyu Kong, Jaeheon Shim, Guoxiang Hu, Victor Fung
Atomistic foundation models (AFMs) have great promise as accurate interatomic potentials, and have enabled data-efficient molecular dynamics simulations with near quantum mechanical accuracy. However, AFMs remain markedly slower at inference and are far more memory-intensive than conventional interatomic potentials, due to the need to capture a wide range of chemical and structural motifs in pre-training datasets requiring deep, parameter-rich model architectures. These deficiencies currently limit the practical use of AFMs in molecular dynamics (MD) simulations at extended temporal and spatial scales. To address this problem, we propose a general workflow for accelerating and scaling AFMs containing message-passing architectures. We find that removing low-contribution message-passing layers from AFM backbones serves as an effective pruning method, significantly reducing the parameter count while preserving the accuracy and data-efficiency of AFMs. Once pruned, these models become more accessible for large scale simulations via a graph-partitioned, GPU-distributed strategy, which we implement and demonstrate within the AFM fine-tuning platform MatterTune. We show that this approach supports million-atom simulations on both single and multiple GPUs, and enables task-specific large-scale simulations at nanosecond timescales with AFM-level accuracy.
Materials Science (cond-mat.mtrl-sci)
Strain-Induced Antiferromagnetic-to-Altermagnetic Phase Transition and Topology in $(\mathrm{CrO}_2)_1/(\mathrm{TaO}_2)_2$ Superlattice
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Wanfei Shan, Qun Yang, Prineha Narang
Topological aspects in altermagnets have come into focus recently, and tuning the antiferromagnetic (AFM) state into an altermagnetic phase remains an active frontier. We realize both within a rutile superlattice here in this paper. With first principles calculation, we show that a uniaxial strain of only 0.5$ %$ along the c axis converts the $ (\mathrm{CrO}_2)_1/(\mathrm{TaO}_2)_2$ rutile superlattice from a trivial antiferromagnet into an altermagnet with topology accompanied by a weak SOC. The strain opens a spin-dependent band splitting of $ \sim 1.1 eV$ and, despite the weak SOC together with in-plane magnetic moment orientation, generates an intrinsic anomalous Hall conductivity of order $ 10^3 S/cm$ , comparable magnitude to that in ferromagnetic Weyl semimetals. Tiny SOC here with in-plane (\text{Néel}) orientation gaps out the Weyl nodal rings, giving rise to 16 Weyl points in the superlattice. Thus, we point out a simple route toward strain and field tunable, low-dissipation altermagnetic electronics.
Materials Science (cond-mat.mtrl-sci)
Coarsening of biomimetic condensates in a self-stirring active fluid
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Jeremy Laprade, Layne Frechette, Christopher Amey, Adrielle Cusi, Aparna Baskaran, W. Benjamin Rogers, Guillaume Duclos
Coarsening, the process where larger structures grow at the expense of smaller ones, is a fundamental aspect of multiphase systems. The cell cytoplasm exemplifies an out-of-equilibrium multiphase system, where phase-separated condensates nucleate and expand within an active fluid made of biopolymers and energy-dependent enzymes. In this study, we explore how condensates grow in a self-stirring active fluid by examining the coarsening of biomimetic condensates embedded in a 3D reconstituted cytoskeleton composed of microtubules and molecular motors. The strong agreement among experiments, an active hydrodynamic model, and computer simulations offers a comprehensive framework that explains why self-similarity is absent in active coarsening and identifies the origins of the continuously changing coarsening exponents for both active and passive condensates. The dynamics of coarsening are primarily determined by the statistics of binary droplet collisions, which depend on their size-dependent motility, regardless of whether they are active or passive. These results reveal a unifying control parameter for the coarsening process and size distribution of active condensates, broadening our understanding of phase separation in out-of-equilibrium systems and potentially impacting materials science and biology.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Hexagonal boron nitride/bilayer graphene moiré superlattices in the Dirac-material family: energy-band engineering and carrier doping by dual gating
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-29 20:00 EDT
Takuya Iwasaki, Yoshifumi Morita
We review the fabrication and transport characterization of hexagonal boron nitride (hBN)/Bernal bilayer graphene (BLG) moiré superlattices. Due to the moiré effect, the hBN/BLG moiré superlattices exhibit an energy gap at the charge neutrality point (CNP) even in the absence of a perpendicular electric field. In BLG, the application of a perpendicular electric field tunes the energy gap at the CNP, which contrasts with single-layer graphene and is similar to the family of rhombohedral multilayer graphene. The hBN/BLG moiré superlattice is associated with non-trivial energy-band topology and a narrow energy band featuring a van Hove singularity. By employing a dual-gated device structure where both the perpendicular displacement field and the carrier density are individually controllable, systematic engineering of the energy-band structure can be achieved. The data presented here demonstrate the universality and diversity in the physics of hBN/BLG moiré superlattices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
42 pages, 13 figures, This is an invited review to appear in J. Phys.: Condens. Matter, which is based on a conference talk summarized as arXiv:2410.05649 (unpublished)
J. Phys.: Condens. Matter 37 393001 (2025)
Spin-basis wavefunctions for the one-dimensional Kitaev model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
Alwyn Jose Raja, Rajesh Narayanan, R. Ganesh
Magnetic phases with quantum entanglement are often expressed in terms of parton wavefunctions. Relatively few examples are known where wavefunctions can be directly written down in the spin basis. In this article, we consider the spin-$ S$ Kitaev model in one dimension. For $ S=1/2$ , its eigenstates can be written using a Jordan-Wigner fermionic representation. Here, we present ground state wavefunctions for any $ S$ directly in the spin basis. The states we propose are valence bond arrangements, with bonds having singlet or triplet character for $ S=1/2$ . For $ S>1/2$ , we use bond-states that serve as analogues of singlets and triplets. We establish the validity of our wavefunctions using a perturbative approach starting from an anisotropic limit, with key features surviving to all orders in perturbation theory. For half-integer $ S$ and periodic boundaries, we have exponential ground state degeneracy. The ground states have topological character, with an even number of triplets' superposed on a background of singlets’. For integer $ S$ , a unique ground state emerges, composed purely of `triplets’. Our spin-basis wavefunctions, while not exact, capture the dominant weight of the ground state(s). We obtain good agreement against exact diagonalization wavefunctions and Jordan-Wigner spectra.
Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 16 figures
Beyond Structure: Invariant Crystal Property Prediction with Pseudo-Particle Ray Diffraction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Bin Cao, Yang Liu, Longhan Zhang, Yifan Wu, Zhixun Li, Yuyu Luo, Hong Cheng, Yang Ren, Tong-Yi Zhang
Crystal property prediction, governed by quantum mechanical principles, is computationally prohibitive to solve exactly for large many-body systems using traditional density functional theory. While machine learning models have emerged as efficient approximations for large-scale applications, their performance is strongly influenced by the choice of atomic representation. Although modern graph-based approaches have progressively incorporated more structural information, they often fail to capture long-term atomic interactions due to finite receptive fields and local encoding schemes. This limitation leads to distinct crystals being mapped to identical representations, hindering accurate property prediction. To address this, we introduce PRDNet that leverages unique reciprocal-space diffraction besides graph representations. To enhance sensitivity to elemental and environmental variations, we employ a data-driven pseudo-particle to generate a synthetic diffraction pattern. PRDNet ensures full invariance to crystallographic symmetries. Extensive experiments are conducted on Materials Project, JARVIS-DFT, and MatBench, demonstrating that the proposed model achieves state-of-the-art performance.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI)
Low-energy photoexcitation inside the Mott gap in doped Hubbard and t-J ladders
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
Sumal Chandra, Kazuya Shinjo, Shigetoshi Sota, Seiji Yunoki, Takami Tohyama
We investigate changes in the optical conductivity of doped Mott insulators by tuning ultrashort pump pulses to target either the Drude or low-energy absorption regions. Using a hole-doped two-leg Hubbard ladder and a four-leg t-J ladders, we calculate the optical conductivity after pump by employing the time-dependent density matrix renormalization group. We find that a monocycle electric field pulse tuned to the Drude absorption reduces the Drude weight, accompanied by a slight enhancement in the mid-infrared (mid-IR) spectral weight. However, this enhancement diminishes as the pulse intensity increases. In contrast, a pump pulse tuned to the mid-IR absorption only affects the Drude weight. This behavior arises because the mid-IR absorption originates from magnetic excitations that do not couple directly to photons. These predictions can be tested experimentally by applying ultrashort low-energy pump pulses to cuprate materials.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 5 figures
Ab initio study of magnetoresistance effect in $\mathrm{Mn_{3}Sn}/\mathrm{MgO}/\mathrm{Mn_{3}Sn}$ antiferromagnetic tunnel junction
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-29 20:00 EDT
Katsuhiro Tanaka, Yuta Toga, Susumu Minami, Satoru Nakatsuji, Takuya Nomoto, Takashi Koretsune, Ryotaro Arita
The antiferromagnets with the time-reversal symmetry broken magnetic structures possess a finite spin splitting in the momentum space, and may contribute to a realization of a finite tunnel magnetoresistance (TMR) effect even with magnets with zero net spin polarization. In this paper, we study the TMR effect with the noncollinear antiferromagnet $ \mathrm{Mn_{3}Sn}$ whose inverse $ 120^{\circ}$ antiferromagnetic order breaks the time-reversal symmetry. In particular, we employ the representative barrier material $ \mathrm{MgO}$ as the tunnel insulator, and calculate the TMR effect in the $ \mathrm{Mn_{3}Sn}(01\bar{1}0)/\mathrm{MgO}(110)/\mathrm{Mn_{3}Sn}$ magnetic tunnel junctions (MTJs), which has an optimal geometry for the spin-orbit torque switching of the magnetic configurations. We show that a finite TMR ratio reaching $ \gtrsim 1000%$ appears in the $ \mathrm{Mn_{3}Sn}/\mathrm{MgO}/\mathrm{Mn_{3}Sn}$ MTJs, which is due to the spin splitting properties of $ \mathrm{Mn_{3}Sn}$ in the momentum space combined with the screening effect of $ \mathrm{MgO}$ .
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
12 pages, 8 figures
Gapless and ordered phases in spin-1/2 Kitaev-XX-Gamma chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
In this work, we study the spin-1/2 Kitaev chain with additional XX and symmetric off-diagonal Gamma interactions. By a combination of Jordan-Wigner transformation and density matrix renormalization group (DMRG) numerical simulations, we obtain the exact solution of the model and map out the phase diagram containing six distinct phases. The four gapped phases display ferromagnetic and antiferromagnetic magnetic orders along the (1, 1, 0)- and (1, -1, 0)-spin directions, whereas in the gapless phases, the low energy spectrum consists of two branches of helical Majorana fermions with unequal velocities. Transition lines separating different phases include deconfined quantum critical lines with dynamical critical exponent z = 1 and quadratic critical lines with z = 2. Our work reveals the rich interplay among symmetry, magnetic order, and quantum criticality in the Kitaev-XX-Gamma chain
Strongly Correlated Electrons (cond-mat.str-el)
13 Pages, 8 Figures
Emulating microbial run-and-tumble and tactic motion by stochastically reorienting synthetic active Brownian particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Sandip Kundu, Dibyendu Mondal, Arup Biswas, Arnab Pal, Manas Khan
Replicating efficient and adaptable microbial navigation strategies, such as run and tumble (RnT) and tactic motions to synthetic active agents has been an enduring quest. To this end, we introduce a stochastic orientational reset (SOR) protocol, in which the propulsion direction of an active Brownian particle (ABP) is reassigned to a random orientation within a defined reset-cone. When the reset-cone is aligned with the instantaneous propulsion direction, ABPs reproduce the RnT dynamics of E. coli; when set along an attractant gradient, they exhibit taxis - with extensive adaptability in persistence through the angular width of the reset-cone and reset rate. We establish the robustness of this protocol across a broad range of swimming speeds using experiments, simulations, and analytical theory.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Applied Physics (physics.app-ph), Biological Physics (physics.bio-ph)
9 pages, 7 figures, and Supplementary materials
Beyond Seamless: Unexpected Defective Merging in Single-Orientation Graphene
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Zhien Wang, Jiangtao Wang, Diego Exposito, Andrey Krayev, Shih-Ming He, Xudong Zheng, Zachariah Hennighausen, Ivan Brihuega, Se-Young Jeong, Jing Kong
Single-orientation stitching of graphene has emerged as the predominant method for growth of large-area, high-quality graphene films. Particularly noteworthy is graphene grown on single-crystalline Cu(111)/sapphire substrates, which exhibits exceptionally planar oriented stitching due to the atomically smooth substrate, facilitating the formation of continuous, high-quality graphene monolayer. These single-orientation stitches have conventionally been regarded as seamless with negligible defect concentrations. In this report, we present experimental observations regarding graphene grown on single-crystalline Cu(111)/sapphire substrates. Among the graphene flakes with single-orientation, our findings reveal two major merging behaviors: one producing the expected seamless stitching, and another unexpectedly generating structural defects that create nanoscale pathways permitting water permeation. Notably, we identify a unique merging structure–overlapped junction, in which the edge of one graphene flake overlaps and lies atop the edge of another flake, rather than forming a continuous atomic stitch. This discovery challenges the conventional anticipation of single-orientation stitched graphene films as seamless single crystalline film, while offers unique perspective for graphene applications in molecular sieving, selective filtration membranes, and protective coatings.
Materials Science (cond-mat.mtrl-sci)
17 pages 4 figures
Modeling the Equilibrium Vacancy Concentration in Multi-Principal Element Alloys from First-Principles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Damien K. J. Lee, Yann L. Müller, Anirudh Raju Natarajan
Multi-principal element alloys (MPEAs), also known as high-entropy alloys, have garnered significant interest across many applications due to their exceptional properties. Equilibrium vacancy concentrations in MPEAs influence diffusion and microstructural stability in these alloys. However, computing vacancy concentrations from ab-initio methods is computationally challenging due to the vast compositional space of MPEAs and the complexity of the local environment around each vacancy. In this work, we present an efficient approach to connect electronic structure calculations to equilibrium vacancy concentrations in MPEAs through embedded cluster expansions (eCE) and rigorous statistical mechanics methods. Using first-principles calculations and Monte Carlo simulations informed by eCE, we assess the variation in vacancy formation with alloy composition and temperature. Our method is demonstrated on a nine-component MPEA comprised of elements in groups 4, 5, and 6 of the periodic table. Correlations between alloy chemistry, short-range order, and equilibrium vacancy concentrations in alloys containing up to 9 different elements are analyzed. The vacancy concentration of refractory alloys increases with the addition of group 4 elements or elements whose mixing is energetically unfavorable. The insights into vacancy behavior and the efficient computational framework presented in this study serve as a guide for the design of complex concentrated alloys with controlled vacancy concentrations.
Materials Science (cond-mat.mtrl-sci)
Extending the optical absorption in a lumped element meander structure to far-infrared wavelengths
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-29 20:00 EDT
Shekhar Chandra Pandey, Shilpam Sharma, Anudeep Singh, Utkarsh Pandey, S. S. Prabhu, Bhaskar Biswas, Sona Chandran, M. K. Chattopadhyay
Superconducting radiation detectors typically exhibit detection and single photon sensitivity limited to the mid infrared wavelength range. Extending their detection capabilities into the far infrared range (>10 um) requires careful selection of substrate materials and detector geometries. The overall detection efficiency is linked to absorption and coupling efficiencies. In this study, the resonator geometry and absorption efficiency were estimated using electromagnetic simulations in CST Microwave Studio for a lumped-element meander structure. Simulations were performed for the 12 to 50 um wavelength range, corresponding to the Infrared Free Electron Laser (IR FEL) at RRCAT, Indore. Absorption in the meander inductor was influenced by the substrate material, thickness, and impedance matching between the detector and incident photon medium. The results indicate that SiO2 and diamond substrates are suitable for developing lumped-element kinetic inductance detectors (LEKID) in this range. Optimized meander geometries on diamond substrates demonstrated absorption efficiencies of up to 95% for narrow bandwidths and over 50% for wide bandwidths. A 30-pixel LEKID structure was fabricated using electron beam lithography on a 500 um SiO2 coated Si substrate, with a 20 nm thick Ti40V60 alloy resonator. Experimental absorption efficiency was determined through transmission and reflection measurements. Results show that in the 14 to 26 um IR-FEL range, the LEKID achieved up to 75% absorption efficiency. These studies demonstrate that the LEKID structure is ideal for detecting far infrared wavelengths above 10 um, with high absorption efficiency.
Superconductivity (cond-mat.supr-con)
Challenges and opportunities in proximity-driven exciton-spin engineering in van der Waals heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Mushir Thodika, Dimitar Pashov, Igor Zutic, Mark van Schilfgaarde, Swagata Acharya
van der Waals heterostructures consisting of transition metal dichalcogenides (TMDs) and two-dimensional (2D) magnets offer a versatile platform to study the coexistence and transformation of different excitons. By focusing on TMD WSe$ _2$ and 2D magnetic CrI$ _3$ , as a bilayer WSe$ _2$ /CrI$ _3$ and a trilayer CrI$ _3$ /WSe$ _2$ /CrI$ _3$ , we provide their description using a parameter-free, high-fidelity many-body perturbation theory. This ab initio approach allows us to elucidate the character of magnetic Frenkel excitons in CrI3 and how the nonmagnetic Wannier-Mott excitons in WSe2 are modified by the proximity of CrI3. We reveal novel proximity-induced interlayer excitons in these heterostructures. In contrast to the sensitivity of proximity-induced modifications of excitons in WSe$ _2$ , which depend on the interfacial details, the interlayer magnetic excitons are remarkably robust and are present across the different stacking configurations between WSe$ _2$ and CrI$ _3$ , simplifying their experimental demonstration. These findings suggest unexplored opportunities for information transduction using magnetic excitons and integrating photonics, electronics, and spintronics in proximitized materials.
Materials Science (cond-mat.mtrl-sci)
Electric-field effect on spin diffusion length in solids: An \textit{ab initio} study beyond the drift-diffusion model
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Recently, we developed an \textit{ab initio} approach of spin diffusion length (l_{s}) in solids [Phys. Rev. Lett. 135, 046705 (2025)], based on a linearized density-matrix master equation with quantum treatment of electron scattering processes. In this work, we extend the method to include the drift term due to an electric field along a periodic direction, implemented efficiently using a Wannier-representation-based covariant derivative. We employ this approach to investigate the electric-field effect on l_{s} of monolayer WSe_{2}, bulk GaAs, bulk GaN, and graphene-h-BN heterostructure. Our results show that l_{s} can be significantly enhanced or suppressed by a moderate downstream or upstream field respectively. Although the widely-used drift-diffusion model performs well for WSe_{2} and GaAs, it can introduce large errors of the electric-field-induced changes of l_{s} in both GaN and graphene-h-BN. Thus, to accurately capture the influence of electric fields on l_{s} in realistic materials, it is necessary to go beyond the drift-diffusion model and adopt a microscopic \textit{ab initio} methodology. Moreover, in graphene-h-BN, we find that the field-induced change of l_{s} is not only governed by the drift term in the master equation, but is also significantly affected by the electric-field modification of the equilibrium density matrix away from Fermi-Dirac distribution function.
Materials Science (cond-mat.mtrl-sci)
10 pages, 3 figures
Carrier-phonon decoupling via annealing enhances thermoelectric performance of Bi2(Te,Se)3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Xinxiu Cheng, Liqing Xu, Zhibin Gao, Wei Liu, Zhanxiang Yin, Xiangdong Ding, Yu Xiao
Thermoelectric cooling based on the Peltier effect requires high-performance materials near room temperature. In this work, Bi2Te2.6Se0.4 synthesized by melting-hot pressing followed by 100 h annealing (MT-HP-AN) at 723 K exhibits markedly improved performance. Annealing introduces cation vacancies via Te(Se) volatilization, lowering carrier density and enhancing mobility, while simultaneously increasing phonon scattering. A peak ZT of 1.06 at 373 K and an average ZT of 0.99 at 300-423 K are achieved. This MT-HP-AN approach offers a simple yet effective strategy to decouple carrier and phonon transport, advancing the potential of n-type BTS for thermo-electric cooling applications.
Materials Science (cond-mat.mtrl-sci), High Energy Physics - Experiment (hep-ex)
10 pages, 6 figures
Geometric decomposition of information flow: New insights into information thermodynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-29 20:00 EDT
Yoh Maekawa, Ryuna Nagayama, Kohei Yoshimura, Sosuke Ito
We propose a decomposition of information flow into housekeeping and excess components for autonomous bipartite systems subject to Markov jump processes. We introduce this decomposition by using the geometric structure of probability currents and the conjugate thermodynamic forces. The housekeeping component arises from the cyclic modes caused by the detailed balance violations and maintains the correlations between the two subsystems. In contrast, the excess component, is a contribution of conservative forces that alters the mutual information between the two subsystems. With this decomposition, we generalize previous results, such as the second law of information thermodynamics, the cyclic decomposition, and the information-thermodynamic extensions of thermodynamic trade-off relations.
Statistical Mechanics (cond-mat.stat-mech)
29 pages, 8 figures
An empirical potential to simulate helium and hydrogen in highly irradiated tungsten
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Samanyu Tirumala, Daniel R. Mason, Oliver Shattock, Duc Nguyen-Manh, Felix Hofmann, Max Boleininger
Materials used in commercial D-T fusion reactors will be exposed to irradiation and a mixture of helium and hydrogen plasma. Modeling the microstructural evolution of such materials requires the use of large-scale molecular dynamics simulations. The focus of this study is to develop a fast EAM potential for the interactions among the three elements (W, H, and He), fitted to accurately reproduce both the ab initio formation energies and relaxation volumes of small defect clusters containing light gases within tungsten. The potential enables the study of tungsten under irradiation and in the presence of light gases. To demonstrate the utility of the potential, we construct a thermodynamically motivated model for predicting the energetics of light-gas-filled voids. The model is then validated through molecular dynamics simulations with our new potential.
Materials Science (cond-mat.mtrl-sci)
24 pages, 16 figures
From gauging to duality in one-dimensional quantum lattice models
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
Bram Vancraeynest-De Cuiper, José Garre-Rubio, Frank Verstraete, Kevin Vervoort, Dominic J. Williamson, Laurens Lootens
Gauging and duality transformations, two of the most useful tools in many-body physics, are shown to be equivalent up to constant depth quantum circuits in the case of one-dimensional quantum lattice models. This is demonstrated by making use of matrix product operators, which provide the lattice representation theory for global (categorical) symmetries as well as a classification of duality transformations. Our construction makes the symmetries of the gauged theory manifest and clarifies how to deal with static background fields when gauging generalised symmetries.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph)
Vector Resonant Relaxation and Statistical Closure Theory. II. One-loop Closure
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-29 20:00 EDT
Sofia Flores, Jean-Baptiste Fouvry
We use stellar dynamics as a testbed for statistical closure theory. We focus on the process of “Vector Resonant Relaxation,” a long-range, non-linear, and correlated relaxation mechanism that drives the reorientation of stellar orbital planes around a supermassive black hole. This process provides a natural setting to evaluate the predictive power of generic statistical closure schemes for dynamical correlation functions, in the fully non-linear and non-perturbative regime. We develop a numerical scheme that explicitly implements the seminal “Martin-Siggia-Rose” formalism at one-loop order via an iterative fixed-point approach, thereby improving upon the bare order from the “Direct Interaction Approximation.” Using this framework, we quantitatively validate the ability of the formalism to predict (i) the two-point two-time correlation function; (ii) the renormalised three-point interaction vertex; (iii) the three-point three-time correlation function. These predictions are compared to direct measurements from numerical simulations. We conclude by discussing the limitations of this approach and presenting possible future venues.
Statistical Mechanics (cond-mat.stat-mech), Astrophysics of Galaxies (astro-ph.GA)
26 pages, 16 figures, submitted to APS
Predictor-corrector method based on dynamic mode decomposition for tensor-train nonequilibrium Green’s function calculations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
Maksymilian Środa, Ken Inayoshi, Michael Schüler, Hiroshi Shinaoka, Philipp Werner
The nonequilibrium Green’s function (NEGF) formalism is a powerful tool to study the nonequilibrium dynamics of correlated lattice systems, but its applicability to realistic system sizes and long timescales is limited by unfavorable memory scaling. While compressed representations, such as the recently introduced quantics tensor train (QTT) format, alleviate the memory bottleneck, the efficiency of QTT-NEGF calculations is hindered by poor initializations and slow or unstable convergence of globally updated self-consistent iterations. Here, we introduce a predictor-corrector solver for QTT-NEGF simulations that combines dynamic mode decomposition (DMD) extrapolation with the recently proposed causality-preserving block-time-stepping updates. The DMD predictor supplies accurate initial guesses that reduce the iteration count of the calculation, while the block-time-stepping correction ensures stable convergence even for long propagation intervals. Applying this method to the Hubbard model on a $ 32\times 32$ lattice within the nonequilibrium $ GW$ approximation, we demonstrate stable propagation up to times of $ t_\mathrm{max}=512$ inverse hoppings, surpassing the capabilities of both matrix-based implementations and previous QTT solvers. Our contribution is twofold. (i) We integrate tensor dynamic mode decomposition with the QTT representation, which establishes a general framework that is not limited to NEGFs. (ii) We demonstrate its practical benefits in NEGF simulations, where it enables stable and efficient access to unprecedented timescales at high momentum resolution, thereby advancing controlled studies of long-time dynamics and nonequilibrium steady states in correlated lattice systems.
Strongly Correlated Electrons (cond-mat.str-el)
Molecular Dynamics Simulations of Collision Cascades in Niobium: Comparing Interatomic Potentials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
S. Mondal, U. Bhardwaj, A. Majalee, V. Mishra, M. Warrier
Radiation damage in structural materials is a major challenge for advanced nuclear energy systems, and niobium is of particular interest due to its high melting point, mechanical strength, and corrosion resistance. To better understand its radiation response, we carried out large-scale molecular dynamics simulations of collision cascades in pure niobium at 300 K over a primary knock-on atom (PKA) energy range of 1-75 keV, employing four interatomic potentials: an embedded atom method (EAM), two Finnis-Sinclair models (FS-1 and FS-2), and a machine learning-based spectral neighbor analysis potential (SNAP) we developed. All reproduce the general features of cascade formation but differ significantly in defect production, clustering, and morphology. At low energies, defect generation follows trends governed by threshold displacement energy (TDE) and the stiffness-to-range ratio (|S/R|). At higher energies, subcascade formation makes defect evolution dependent on the combined effects of |S/R|, average TDE, and other material-specific factors. Vacancy clustering dominates over interstitial clustering across all cases: EAM produces the largest vacancy clusters and the highest clustering fraction, while SNAP shows the strongest interstitial clustering. Morphological analysis indicates that EAM forms a balanced mix of 1/2<111>, 1/2<110> loops, C15 rings, and hybrid structures; FS-2 favors extended 1/2<111> dumbbells, crowdions, and dislocation loops; whereas FS-1 and SNAP generate more compact or disordered clusters, with SNAP produces a high fraction of C15-like rings (maximum size up to nine atoms) that may evolve into dislocation loops of 1/2<111> and <100>. These findings give clear insights into how niobium reacts when exposed to irradiation, especially at high energies.
Materials Science (cond-mat.mtrl-sci)
Quantum spin Hall effect in III-V semiconductors at elevated temperatures: advancing topological electronics
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-29 20:00 EDT
Manuel Meyer, Jonas Baumbach, Sergey Krishtopenko, Adriana Wolf, Monika Emmerling, Sebastian Schmid, Martin Kamp, Benoit Jouault, Jean-Baptiste Rodriguez, Eric Tournie, Tobias Müller, Ronny Thomale, Gerald Bastard, Frederic Teppe, Fabian Hartmann, Sven Höfling
The quantum spin Hall effect (QSHE), a hallmark of topological insulators, enables dissipationless, spin-polarized edge transport and has been predicted in various two-dimensional materials. However, challenges such as limited scalability, low-temperature operation, and the lack of robust electronic transport have hindered practical implementations. Here, we demonstrate the QSHE in an InAs/GaInSb/InAs trilayer quantum well structure operating at elevated temperatures. This platform meets key criteria for device integration, including scalability, reproducibility, and tunability via electric field. When the Fermi level is positioned within the energy gap, we observe quantized resistance values independent of device length and in both local and nonlocal measurement configurations, confirming the QSHE. Helical edge transport remains stable up to T = 60 K, with further potential for higher-temperature operation. Our findings establish the InAs/GaInSb system as a promising candidate for integration into next-generation devices harnessing topological functionalities, advancing the development of topological electronics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
The quantum XY chain with boundary fields: finite-size gap and phase behavior
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-29 20:00 EDT
Aldo Coraggio, Andrea Pelissetto
We present a detailed study of the finite-size one-dimensional quantum XY chain in a transverse field in the presence of boundary fields coupled with the order-parameter spin operator. We consider fields located at the chain boundaries that have the same strength and that are oppositely aligned. We derive exact expressions for the gap $ \Delta$ as a function of the model parameters for large values of the chain length $ L$ . These results allow us to characterize the nature of the ordered phases of the model. We find a magnetic (M) phase ($ \Delta \sim e^{-aL}$ ), a magnetic-incommensurate (MI) phase ($ \Delta \sim e^{-aL} f_{MI}(L)$ ), a kink (K) phase ($ \Delta \sim L^{-2}$ ), and a kink-incommensurate (KI) phase ($ \Delta \sim L^{-2} f_{KI}(L)$ ); $ f_{MI}(L)$ and $ f_{KI}(L)$ are bounded oscillating functions of $ L$ . We also analyze the behavior along the phase boundaries. In particular, we characterize the universal crossover behavior across the K-KI phase boundary. On this boundary, the dynamic critical exponent is $ z=4$ , i.e., $ \Delta \sim L^{-4}$ for large values of $ L$ .
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
36 pages, 8 figures
Features of the Electronic and Charge States of Monovalent-Doped Manganite Films Probed by Magnetic Circular Dichroism
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
Yulia E. Samoshkina, Dmitriy A. Petrov, Dmitry S. Neznakhin, Igor E. Korsakov, Andrei V. Telegin
Magnetic circular dichroism (MCD) spectroscopy in the range of 1.2 - 3.7 eV was studied for La1-xKxMnO3 (x = 0.05 - 0.18) epitaxial films over a wide temperature range. The thin films were grown using a two-step procedure: deposition of LaxMnO3-{\delta} and potassium K+ incorporation into the films via isopiestic annealing. The temperature behavior of the MCD effect in different spectral regions was analyzed alongside the temperature dependences of magnetization, resistivity, and magnetoresistance of the films. It was found that the MCD signal is sensitive not only to the magnetic but also to the charge sublattice of the material. Accordingly, a correlation between the magneto-optical and magnetoresistive responses of the system was identified. These findings underscore the high information content of MCD spectroscopy for investigating the magnetic and magnetotransport properties of strongly correlated magnetic oxides. The ground and excited electronic states in the La1-xKxMnO3 films were identified, and the obtained data were compared with magneto-optical data for divalent - doped and lanthanum-deficient manganite films. Good agreement was observed, indicating the universality of the electronic structure and the shared mechanisms underlying the observed effects in such materials. These results broaden the understanding of the band structure in manganites and provide a solid foundation for its theoretical description.
Strongly Correlated Electrons (cond-mat.str-el)
Journal of Alloys and Compounds Volume 1036, 20 July 2025, 181990
Antiferromagnetic domain walls under spin-orbit torque
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
George Theodorou, Stavros Komineas
Domain walls in antiferromagnets under a spin-polarized current present rich dynamics that is not observed in ferromagnets, and it is tunable by the current polarization. Precessional dynamics is obtained for perpendicular spin polarization, in agreement with expectations in older works. Propagating walls are obtained for an in-plane polarization. We obtain the velocity as a function of current by a perturbation method for low velocities, and the wall profile is found to lack a definite parity. For high velocities, the main features of the wall profile are obtained by a direct solution of an equation that is valid in a limiting case. We discuss the magnetization of the dynamical walls and find that this can become large, providing a potential method for observations. Oscillatory motion of domain walls is obtained for spin polarization that has both perpendicular and in-plane components, and an analytical description is given.
Materials Science (cond-mat.mtrl-sci)
11 Pages, 5 Figures
Scallop Theorem for Swimming in Anisotropic Fluids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Mojtaba Rajabi, Enej Caf, Qi Xing Zhang, Stephen A. Crane, Miha Ravnik, Gareth P. Alexander, Žiga Kos, Kathleen J. Stebe
In isotropic fluids like water, micrometer-scale swimmers have evolved swim strokes to translate despite their tiny size. As described by Purcell in his Scallop Theorem, reciprocal motions, like those performed by a scallop, cannot drive swimming when inertial effects are absent, as is typical at micrometer length scales. Thus, microswimmers have evolved complex structures that can perform non-reciprocal swim strokes or body displacements to generate motion. Microswimmer dynamics in structured fluids differ fundamentally from those in isotropic fluids because of their inherent asymmetry. The orientation of elongated constituents and the topological defects that spontaneously form near microswimmers provide broken symmetries, even atequilibrium. This is sufficient for the dynamic disturbance of even the simplest isotropic swimmers to generate propulsion. We combine experiments on magnetically rotated colloids in nematic liquid crystals with analytic non-equilibrium solutions to formulate propulsion strategies for microswimmers in nematic fluids and determine how swimming velocity depends on the rotation rate, materials parameters, and forcing regimes. For example, we find that micro-scale spherical colloids swim effectively under continuous rotation and under reciprocal this http URL, swim strokes that are ineffective in isotropic fluids are highly effective in nematic liquid crystals. In light of these observations, the Scallop Theorem is extended for structured fluids.
Soft Condensed Matter (cond-mat.soft)
Coherent control of nitrogen nuclear spins via the V$_B^-$-center in hexagonal boron nitride
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Adalbert Tibiássy, Charlie J. Patrickson, Thomas Poirier, James H. Edgar, Bruno Lopez-Rodriguez, Viktor Ivády, Isaac J. Luxmoore
Charged boron vacancies (V$ _\text{B}^-$ ) in hexagonal boron nitride (hBN) have emerged as a promising platform for quantum nanoscale sensing and imaging. While these primarily involve electron spins, nuclear spins provide an additional resource for quantum operations. This work presents a comprehensive experimental and theoretical study of the properties and coherent control of the nearest-neighbor $ ^{15}$ N nuclear spins of V$ _\text{B}^-$ -ensembles in isotope-enriched h$ ^{10}$ B$ ^{15}$ N. Multi-nuclear spin states are selectively addressed, enabled by state-specific nuclear spin transitions arising from spin-state mixing. We perform Rabi driving between selected state pairs, define elementary quantum gates, and measure longer than 10~$ \mu$ s nuclear Rabi coherence times. We observe a two orders of magnitude nuclear g-factor enhancement that underpins fast nuclear spin gates. Accompanying numerical simulations provide a deep insight into the underlying mechanisms. These results establish the foundations for leveraging nuclear spins in V$ _\text{B}^-$ center-based quantum applications, particularly for extending coherence times and enhancing the sensitivity of 2D quantum sensing foils.
Materials Science (cond-mat.mtrl-sci)
Antitoroidal magnets and anomalous Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-29 20:00 EDT
In this paper we introduce a theoretical model of a metallic magnetic system with an antitoroidal order. We introduce a mechanism of indirect interaction of conducting fermions with localized spins based on the tunneling processes of conducting fermions through the localized spins. We demonstrate that interaction of conducting fermions with an antitoroidal order results in odd in momentum spin-momentum locking. The interaction resembles Rashba spin-orbit coupling but breaks the time-reversal symmetry. As a result, we show that a ferromagnet with the antitoroidal order is an insulator with anomalous Hall effect occurring without any spin-orbit coupling.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Continuum theory for topological phase transitions in exciton systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
Xiaochan Cai, Armando Consiglio, Domenico Di Sante, Ronny Thomale, Werner Hanke
An effective continuum theory is constructed for the topological phase transition of excitons in quasi-two-dimensional systems. These topological excitons crucially determine the optoelectronic properties, because of their larger binding energies in 2D as well as their topologically enhanced exciton transport. The core idea of this letter is, that the essential physics determining the topological invariants across the phase transition is localized near $ N$ -fold band-crossing points (BCPs) in the interaction-induced exciton band structure. The construction of the continuum theory around these BCPs needs only the information of exciton states that build up these BCPs at both $ \mathbf{Q}=0$ and finite $ \mathbf{Q}$ points, and not the numerically challenging solution of the Bethe-Salpeter equation over the full exciton Brillouin zone. This theory applies to systems with and without spin conservation. Our theory is illustrated in two specific examples: the transition metal dichalcogenide twisted bilayer systems and the Bernevig-Hughes-Zhang (BHZ) model. These results offer a promising route toward studying complex systems, such as the room-temperature quantum spin Hall system Bismuthene (Bi/SiC) and other twisted bilayer systems.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 4 figures
Supercondutivity of Nb-Ta-Ti-Zr-Hf high entropy alloy polycrystalline and amorphous thin films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-29 20:00 EDT
P. Hruska, Z. Janu, J. Cizek, F. Lukac
We studied the superconductivity of high-entropy Hf-Nb-Ta-Ti-Zr alloy films affected by structural order. While films deposited from the same target on a substrate with a room temperature are amorphous, and if superconducting, only at temperatures below 1.9 K, films deposited on a substrate with a temperature of 740 $ ^o$ C and 630 $ ^o$ C are superconducting with a critical temperature of 6.61 K and 6.63 K, respectively. The observed effect of structural order on superconductivity can be explained by the theory of superconductivity in strongly bound amorphous materials recently published by Baggioli et al.
Superconductivity (cond-mat.supr-con)
7 pages, 9 figures
Self-organization mechanism in Bridgman-grown MnBi2Te4/(Bi2Te3)n: influence on layer sequence and magnetic properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Paweł Skupiński, Kamil Sobczak, Katarzyna Gas, Anna Reszka, Yadhu K. Edathumkandy, Jakub Majewski, Krzysztof Grasza, Maciej Sawicki, Agnieszka Wołoś
The growth of high-quality magnetic topological insulator crystals by the Bridgman method remains challenging due to thermodynamic limitations inherent to this technique. Nevertheless, this approach continues to provide bulk materials with significantly reduced free carrier concentrations compared to epitaxial methods. Here, we investigate the Inverted Vertical Bridgman growth of MnBi2Te4/(Bi2Te3)n crystals, with particular emphasis on the structural ordering of MnBi2Te4 septuple layers within the Bi2Te3 quintuple-layer matrix and its influence on magnetic properties. Through a detailed analysis of growth dynamics, we identify four distinct stages, including a turbulent flow regime promoting pure MnBi2Te4 phase, rapid MnTe precipitation reducing Mn content in the melt, a stationary growth phase supporting ordered stacking of septuple and quintuple layers, and a final stage marked by flow cessation and defect formation. We demonstrate that septuple layer spacing is inversely correlated with MnTe supersaturation due to the diffusion-limited incorporation in stationary growth phase. Magnetic characterization reveals antiferromagnetic ordering in pure MnBi2Te4 phase and in MnBi2Te4/(Bi2Te3)n heterostructure, with ferromagnetism emerging for wider septuple layer spacing. We determine critical temperatures for observed antiferromagnetic and ferromagnetic phase transitions and magnetic anisotropy constants for ferromagnetic samples. Our findings highlight key growth parameters governing magnetic and structural quality, offering a pathway to scalable synthesis of layered topological insulators with tunable magnetic properties.
Materials Science (cond-mat.mtrl-sci)
13 pages and 7 figures
Selective bulk-boundary correspondence in higher-order topological insulators with anticommuting mirror and chiral symmetries
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-29 20:00 EDT
Suman Aich, Babak Seradjeh (IUB)
We investigate higher-order topological insulators protected by chiral and mirror symmetries. Using models in the BDI class, which include the prototypical topological quadrupole insulator, we show that breaking mirror symmetries that anticommute with the chiral operator leads to edge-selective bulk-boundary correspondence, with gap closings and bound states appearing only along a subset of boundaries of the same orientation. We define a new edge-sensitive topological invariant, distinguishing this mechanism from previous reports of non-topological edge-selection effects.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
4+ pages, appendix, 4 figures
Radiation Forces and Torques on Janus Cylinders
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Mohd. Meraj Khan, Sumesh P. Thampi, Anubhab Roy
The interaction of electromagnetic waves with dielectric Janus particles gives rise to radiation forces and torques, governed by the dielectric properties, interface orientation, and the size-to-wavelength ratio. In this study, we employ the Lattice Boltzmann Method to compute the radiation-induced drag, lift, and torque on circular Janus cylinders when illuminated by a transverse magnetic polarized plane wave. We analyze both metallo-dielectric and dielectric Janus cylinders. For metallo-dielectric Janus cylinders, LBM predictions are validated against analytical results, showing excellent agreement in far-field bistatic scattering width, radiation force, and torque across a range of dielectric constants and interface orientations. Extending the study to dielectric Janus cylinders, we explore how the dielectric contrast and interface orientation shape the optomechanical response. Our findings show that radiation-induced forces and torques can be harnessed to drive and control the motion of dielectric Janus particles in optofluidic, active, and self-assembling systems.
Soft Condensed Matter (cond-mat.soft)
Phase transition from localization to chaos in classical many-body system
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-29 20:00 EDT
Yusuf Kasim, Pavel Orlov, Tomaž Prosen
We report a dynamical phase transition in the information spreading within a classical 2D deterministic interacting many-body system. Specifically, the transition is observed in a recently introduced momentum-conserving parity check cellular automaton (MCPCA) on the square lattice. We characterize the transition using information-theoretic quantities such as the Hamming distance and the classical decorrelator. By introducing conserved local charges of the MCPCA, we show that selecting initial ensembles with specific charge values allows the system to transition from a localized information phase to a chaotic regime with ballistic information spreading. Importantly, our findings indicate that this transition is of second order, highlighting a sharp change in information spreading behavior. Furthermore, we revisit the multifractal behavior of the dynamical structure factor and show that, although present across both phases, it originates from effective local periodicities enforced by symmetry constraints.
Statistical Mechanics (cond-mat.stat-mech), Cellular Automata and Lattice Gases (nlin.CG)
12 pages, 13+2 figures, 1 table
Linear-scaling calculation of experimental observables for molecular augmented dynamics simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Tigany Zarrouk, Miguel A. Caro
Aligning theoretical atomistic structural models of materials with available experimental data presents a significant challenge for disordered systems. The configurational space to navigate is vast, and faithful realizations require large system sizes with quantum-mechanical accuracy in order to capture the distribution of structural motifs present in experiment. Traditional equilibrium sampling approaches offer no guarantee of generating structures that coincide with experimental data for such systems. An efficient means to search for such structures is molecular augmented dynamics (MAD) [arXiv:2508.17132], a modified molecular dynamics method that can generate ab-initio accurate, low-energy structures through a multi-objective optimization of the interatomic potential energy and the experimental potential. The computational scaling of this method depends on both the scaling of the interatomic potential and that of the experimental potential. We present the general equations for MAD with linear-scaling formulations for calculating and matching X-ray/neutron diffraction and local observables, e.g., the core-electron binding energies used in X-ray photoelectron spectroscopy. MAD simulations can both find metastable structures compatible with non-equilibrium experimental synthesis and lower energy structures than alternative computational sampling protocols, like the melt-quench approach. In addition, generalizing the virial tensor with the experimental forces enables generalized barostatting, allowing one to find structures whose density matches that compatible with the experimental observables. Scaling tests with the TurboGAP code demonstrate their linear-scaling nature for both CPU and GPU implementations, the latter of which has a 100$ \times$ speedup compared to the CPU.
Materials Science (cond-mat.mtrl-sci)
Directional strong coupling at the nanoscale between hyperbolic polaritons and organic molecules
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-29 20:00 EDT
Ana I. F. Tresguerres-Mata, Olga G. Matveeva, Christian Lanza, José Álvarez-Cuervo, Kirill V. Voronin, Francesco Calavalle, Garen Avedissian, Pablo Díaz-Núñez, Gonzalo Álvarez-Pérez, Aitana Tarazaga Martín-Luengo, Javier Taboada-Gutiérrez, Jiahua Duan, Javier Martín-Sánchez, Andrei Bylinkin, Rainer Hillenbrand, Artem Mishchenko, Luis E. Hueso, Valentyn S. Volkov, Alexey Y. Nikitin, Pablo Alonso-González
Strong coupling (SC) is a fundamental concept in physics that describes extreme interactions between light and matter. Recent experiments have demonstrated SC at the nanometer scale, where strongly confined polaritons, rather than photons, couple to quantum emitters or molecular vibrations. Coupling with the latter is generally referred to as vibrational SC (VSC) and is of significant fundamental and technological interest, as it can be an effective tool for modifying molecular properties. However, the implementation of VSC, especially at the nanoscale, depends on the development of tuning mechanisms that allow control over the coupling strength and, eventually, its directionality, opening the door for the selective coupling of specific molecular vibrations. Here we report the observation of directional VSC. Specifically, we show nanoscale images of propagating hyperbolic phonon polaritons (PhPs) coupled to pentacene molecules revealing that the fingerprint of VSC for propagating polaritons – a marked anti-crossing in their dispersion at the vibrational resonance – can be modulated as a function of the direction of propagation. In addition, we show that VSC can exhibit an optimal condition for thin molecular layers, characterized by a maximum coupling strength along one single direction. This phenomenon is understood by analysing the overlap of the polariton field with molecular layers of varying thicknesses. Apart from their fundamental importance, our findings promise novel applications for directional sensing or local directional control of chemical properties at the nanoscale.
Materials Science (cond-mat.mtrl-sci)
Nature Photonics (2025)
Tunable optical lattices for the creation of matter-wave lattice solitons
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-29 20:00 EDT
Robbie Cruickshank, Arthur La Rooij, Ethan Kerr, Timon Hilker, Stefan Kuhr, Elmar Haller
We present experimental techniques that employ an optical accordion lattice with dynamically tunable spacing to create and study bright matter-wave solitons in optical lattices. The system allows precise control of lattice parameters over a wide range of lattice spacings and depths. We detail calibration methods for the lattice parameters that are adjusted to the varying lattice spacing, and we demonstrate site-resolved atom number preparation via microwave addressing. Lattice solitons are generated through rapid quenches of the atomic interaction strength and the external trapping potential. We systematically optimize the quench parameters, such as duration and final scattering length, to maximize soliton stability. Our results provide insight into nonlinear matter-wave dynamics in discretized systems and establish a versatile platform for the controlled study of lattice solitons.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS), Optics (physics.optics), Quantum Physics (quant-ph)
10 pages, 8 figures
Competing $s$-wave pairing in overdoped $t$-$J$ model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-29 20:00 EDT
Wayne Zheng, Tao Cheng, Zheng-Yuan Yue, Fu-Chun Zhang, Wei-Qiang Chen, Zheng-Cheng Gu
The $ d$ -wave pairing symmetry has long been considered a defining feature of high-temperature superconductivity in cuprates. In this work, we reveal that $ s$ -wave pairing states exhibit variational energies comparable to the $ d$ -wave state in a square $ t$ -$ J$ model, particularly at high doping levels ($ \delta\gtrsim 15%$ ) by using the state-of-the-art tensor network simulation. This surprising result suggests that $ s$ -wave pairing may play an important role in the cuprate phase diagram, especially for the overdoped region. Our findings provide a potential resolution to discrepancies in recent Josephson tunneling experiments on twisted bilayer cuprates and offer new insights into the evolution of pairing symmetry with doping.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
8 pages, 7 figures
Cryogenic In-Memory Computing with Phase-Change Memory
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-29 20:00 EDT
Davide G. F. Lombardo (1, 2), Siddharth Gautam (1, 2), Alberto Ferraris (1, 2), Manuel Le Gallo (1), Abu Sebastian (1), Ghazi Sarwat Syed (1), ((1) IBM Research Europe, Ruschlikon, Switzerland, (2) Ecole polytechnique federale de Lausanne (EPFL), Lausanne, Switzerland)
In-memory computing (IMC) is an emerging non-von Neumann paradigm that leverages the intrinsic physics of memory devices to perform computations directly within the memory array. Among the various candidates, phase-change memory (PCM) has emerged as a leading non-volatile technology, showing significant promise for IMC, particularly in deep learning acceleration. PCM-based IMC is also poised to play a pivotal role in cryogenic applications, including quantum computing and deep space electronics. In this work, we present a comprehensive characterization of PCM devices across temperatures down to 5 K, covering the range most relevant to these domains. We systematically investigate key physical mechanisms such as phase transitions and threshold switching that govern device programming at low temperatures. In addition, we study attributes including electrical transport, structural relaxation, and read noise, which critically affect readout behavior and, in turn, the precision achievable in computational tasks.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Metric response of relative entropy: a universal indicator of quantum criticality
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-29 20:00 EDT
Pritam Sarkar, Diptiman Sen, Arnab Sen
The information-geometric origin of fidelity susceptibility and its utility as a universal probe of quantum criticality in many-body settings have been widely discussed. Here we explore the metric response of quantum relative entropy (QRE), by tracing out all but $ n$ adjacent sites from the ground state of spin chains of finite length $ N$ , as a parameter of the corresponding Hamiltonian is varied. The diagonal component of this metric defines a susceptibility of the QRE that diverges at quantum critical points (QCPs) in the thermodynamic limit. We study two spin-$ 1/2$ models as examples, namely the integrable transverse field Ising model (TFIM) and a non-integrable Ising chain with three-spin interactions. We demonstrate distinct scaling behaviors for the peak of the QRE susceptibility as a function of $ N$ : namely a square logarithmic divergence in TFIM and a power-law divergence in the non-integrable chain. This susceptibility encodes uncertainty of entanglement Hamiltonian gradients and is also directly connected to other information measures such as Petz-Rényi entropies. We further show that this susceptibility diverges even at finite $ N$ if the subsystem size, $ n$ , exceeds a certain value when the Hamiltonian is tuned to its classical limits due to the rank of the RDMs being finite; unlike the divergence associated with the QCPs which require $ N \rightarrow \infty$ .
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
v1; 28 pages, 8 figures; this work supersedes an earlier submission - arXiv:2412.02236
Cooperation, competition and emergence of hierarchy: assembly of active colloids under combined electric and magnetic fields
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-29 20:00 EDT
Indira Barros, Sayanth Ramachandran, Indrani Chakraborty
Field induced assembly of reconfigurable structures with complex hierarchical configurations has recently become an area of intense research with the promise for exciting applications in programmable self-assembly and nano/microstructure fabrication. While a wide variety of structures, from crystals to glasses, to chains and oligomers have been produced by activating colloidal particles with electric and magnetic fields, a combined approach utilizing the capabilities of multiple field types offers a richer parameter space, enabling precise structural control and a higher degree of reconfigurability. Here we demonstrate the assembly of complex hierarchical colloidal superstructures using an electric field (AC) and magnetic field (DC) combination. In our chosen frequency regime, dipolar (magnetic and electric) and electrohydrodynamic interactions are comparable, leading to a rich phase space with a wide number of configurations which are tunable by relatively small changes of the field parameters. This is in contrast to the existing small number of studies on multi-field induced assembly that work in size and frequency regimes where the dominant mechanism is dipolar interaction induced assembly. We show that depending upon the direction and frequency of the applied fields, there can be three possibilities in structure formation: a) a cooperation among the fields b) a competition among the fields and c) hierarchical reorganization in which micrometer-sized particles form chains that are part of larger clusters or ‘domains’ spanning tens of micrometers. This versatile, easy to set up and fully reconfigurable approach of multi-field induced structure formation opens up new opportunities for bottom-up fabrication of smart materials, switchable photonic crystals, and modular microswimmers for targeted drug delivery and environmental remediation.
Soft Condensed Matter (cond-mat.soft)
Superconductivity in cubic La3Al with interstitial anionic electrons
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-29 20:00 EDT
Zhijun Tu, Peihan Sun, Donghan Jia, Huiyang Gou, Kai Liu, Hechang Lei
We report the observation of superconductivity in cubic La3Al single crystal. It shows a metallic behavior at a normal state without observable structural transition and enters the superconducting state below Tc ~ 6.32 K. Detailed characterizations and analysis indicate that cubic La3Al is a bulk type-II BCS superconductor. Moreover, theoretical calculations show that it can host interstitial anionic electrons, which are located at the body center of cubic unit cell, and confirm the electron-phonon coupling as the superconducting mechamism. Thus, cubic La3Al can be regarded as an novel electride superconductor.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
7 page, 4 figure, 1 table
Chin. Phys. Lett. 42, 027302 (2025)
Investigation of Parasitic Two-Level Systems in Merged-Element Transmon Qubits
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-29 20:00 EDT
Etienne Daum, Benedikt Berlitz, Steffen Deck, Alexey V. Ustinov, Jürgen Lisenfeld
In conventional transmon qubits, decoherence is dominated by a large number of parasitic two-level systems (TLS) residing at the edges of its large area coplanar shunt capacitor and junction leads. Avoiding these defects by improvements in design, fabrication and materials proved to be a significant challenge that so far led to limited progress. The merged-element transmon qubit (‘’mergemon’’), a recently proposed paradigm shift in transmon design, attempts to address these issues by engineering the Josephson junction to act as its own shunt capacitor. With its energy mostly confined within the junctions, efforts required to improve qubit coherence can be concentrated on the junction barrier, a potentially easier to control interface compared to exposed circuit areas. Incorporating an additional aluminium deposition and oxidation into the in-situ bandaged Niemeyer-Dolan technique, we were able to fabricate flux-tunable mergemon qubits achieving mean $ T_{1}$ relaxation times of up to $ 130\mu s$ ($ Q \approx 3.3 \times 10^{6}$ ). TLS spectroscopy under applied strain and electric fields, together with systematic design variations, revealed that even for mergemon qubits - despite their significantly reduced footprint and increased junction barrier volume - careful design considerations are still essential to avoid coherence limitations due to surface loss.
Superconductivity (cond-mat.supr-con)
Probing Fractional Quantum Hall states in weakly interacting Fermi gases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-29 20:00 EDT
Viktor Bekassy, Mikael Fogelström, Johannes Hofmann
Quantum gases are used to simulate the physics of the lowest Landau level (LLL) with neutral atoms, which in the simplest setup is achieved by rotating the gas at the confining harmonic trap frequency, a requirement that is difficult to achieve in practice. We point out that for weakly interacting Fermi gases, this rapid-rotation limit is not needed to access the LLL: As a direct consequence of first-order perturbation theory, many-body wave functions of states in the LLL remain unchanged at any rotation, and only their energies shift. This implies that even in the absence of rotations or for moderate rotations frequencies, LLL states are present as excited states at finite angular momentum. For fermions with contact interactions, these states are exact eigenstates of a paradigmatic model of Fractional Quantum Hall (FQH) states described by a single Haldane pseudopotential ($ V_1$ for spin-polarized and $ V_0$ for spinful systems), which realizes exact Laughlin and Haldane wave functions. We suggest that recently developed excitation and imaging techniques for rotating few-fermion systems allow for a detailed experimental investigation of FQH wave functions and to study the crossover to large particle number. We illustrate this for $ N = 6$ spin-balanced fermions
Quantum Gases (cond-mat.quant-gas), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 3 figures
Limitations of detecting structural changes and time-reversal symmetry breaking in scanning tunneling microscopy experiments
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-29 20:00 EDT
Christopher Candelora, Ilija Zeljkovic
The family of kagome superconductors $ A$ V$ _3$ Sb$ _5$ ($ A$ =K, Cs, Rb) is an exciting playground for investigating various density waves, unusual superconductivity and a surprising time-reversal symmetry breaking despite the absence of spin magnetism. The origin of time-reversal symmetry breaking has been of particular interest, and conflicting results have been intensely debated. Scanning tunneling microscopy (STM) provided crucial evidence by the observation that apparent chirality associated with the 2 $ \times$ 2 charge density wave (CDW) may be modified by the direction of magnetic field, a phenomenon observed in select sample areas in some experiments, but not others. Related to this, Xing et al. investigated the effects of magnetic and electric fields on the 2 $ \times$ 2 CDW state and the lattice structure of kagome superconductor RbV$ _3$ Sb$ _5$ . They report a $ \sim$ 1% change in the in-plane lattice constants, concomitant with the CDW intensities modification, controlled by the field direction. This was interpreted as a rare case of piezomagnetism. Here we show how the apparent magnetic field induced lattice and CDW intensity change is a consequence of two independent experimental artifacts: reconfiguration of atoms at the STM tip apex that alter the amplitudes of CDW modulations, and piezo creep, hysteresis, and thermal drift that artificially distort STM topographs. We find no evidence supporting that magnetic field leads to intrinsic changes in the sample, which challenges reported piezomagnetism.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Comment on Nature 631, 60 (2024)
Toward a Physics of Deep Learning and Brains
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-09-29 20:00 EDT
Arsham Ghavasieh, Meritxell Vila-Minana, Akanksha Khurd, John Beggs, Gerardo Ortiz, Santo Fortunato
Deep neural networks and brains both learn and share superficial similarities: processing nodes are likened to neurons and adjustable weights are likened to modifiable synapses. But can a unified theoretical framework be found to underlie them both? Here we show that the equations used to describe neuronal avalanches in living brains can also be applied to cascades of activity in deep neural networks. These equations are derived from non-equilibrium statistical physics and show that deep neural networks learn best when poised between absorbing and active phases. Because these networks are strongly driven by inputs, however, they do not operate at a true critical point but within a quasi-critical regime – one that still approximately satisfies crackling noise scaling relations. By training networks with different initializations, we show that maximal susceptibility is a more reliable predictor of learning than proximity to the critical point itself. This provides a blueprint for engineering improved network performance. Finally, using finite-size scaling we identify distinct universality classes, including Barkhausen noise and directed percolation. This theoretical framework demonstrates that universal features are shared by both biological and artificial neural networks.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Artificial Intelligence (cs.AI), Adaptation and Self-Organizing Systems (nlin.AO), Biological Physics (physics.bio-ph)