CMP Journal 2025-07-29
Statistics
Nature: 1
Nature Nanotechnology: 1
Physical Review Letters: 9
Physical Review X: 1
arXiv: 109
Nature
The Virtual Lab of AI agents designs new SARS-CoV-2 nanobodies
Original Paper | Computational models | 2025-07-28 20:00 EDT
Kyle Swanson, Wesley Wu, Nash L. Bulaong, John E. Pak, James Zou
Science frequently benefits from teams of interdisciplinary researchers1-3, but many scientists do not have easy access to experts from multiple fields4,5. While large language models (LLMs) have shown an impressive ability to aid researchers across diverse domains, their uses have been largely limited to answering specific scientific questions rather than performing open-ended research6-11. Here, we expand the capabilities of LLMs for science by introducing the Virtual Lab, an AI-human research collaboration to perform sophisticated, interdisciplinary science research. The Virtual Lab consists of an LLM principal investigator agent guiding a team of LLM scientist agents through a series of research meetings, with a human researcher providing high-level feedback. We apply the Virtual Lab to design nanobody binders to recent variants of SARS-CoV-2. The Virtual Lab creates a novel computational nanobody design pipeline that incorporates ESM, AlphaFold-Multimer, and Rosetta and designs 92 new nanobodies. Experimental validation reveals a range of functional nanobodies with promising binding profiles across SARS-CoV-2 variants. In particular, two new nanobodies exhibit improved binding to the recent JN.1 or KP.3 variants12,13 while maintaining strong binding to the ancestral viral spike protein, suggesting exciting candidates for further investigation. This demonstrates how the Virtual Lab can rapidly make an impactful, real-world scientific discovery.
Computational models, Computer science
Nature Nanotechnology
A nanoengineered lithium-hosting carbon/zinc oxide composite electrode material for efficient non-aqueous lithium metal batteries
Original Paper | Batteries | 2025-07-28 20:00 EDT
Lequan Deng, Yaoyao Liu, Haoying Qi, Yushuang Yang, Zhaofen Wang, Lu-Tan Dong, Jun Zhan, Ke-Peng Song, Dongqing Qi, Yayang Xu, Yuanhua Sang, Jinlong Yang, Jian-Jun Wang, Zhaoke Zheng, Shuhua Wang, Chao Gao, Hong Liu, Hao Chen
Achieving Coulombic efficiency values greater than 99.9% for Li metal cells is considered one of the most important requirements for the technology development of long cycle life in energy-dense Li metal batteries. However, owing to the volume changes in Li metal electrodes and Li reservoir loss during battery operation, this requirement has not yet been realized in Li metal cells. Here, to overcome these issues, we propose a zero-volume-change, complete-sealing design for a nanoengineered composite material consisting of multilayer reduced graphene oxide and zinc oxide. This composite electrode material can accommodate Li metal without showing negligible volume changes while promoting the formation of an inorganic-rich solid-electrolyte interphase. When the nanoengineered Li/reduced graphene oxide/zinc oxide electrode is tested in combination with a Li metal electrode in a coin cell configuration using non-aqueous electrolyte solutions, Li plating/stripping Coulombic efficiency values ranging from 99.9900% to 99.9999%, for almost 2,000 cycles at a current density of 1 mA cm-2, can be calculated. Testing of the nanoengineered Li/reduced graphene oxide/zinc oxide electrode in combination with high-potential electrodes (for example, LiNi0.8Co0.1Mn0.1O2 or LiFePO4) in non-aqueous coin cell configuration also demonstrates improved performance compared with the high-potential coin cells utilizing pristine Li metal electrodes.
Batteries
Physical Review Letters
Efficient Preparation of Entangled States in Cavity QED with Grover’s Algorithm
Research article | Quantum computation | 2025-07-28 06:00 EDT
Omar Nagib, M. Saffman, and K. Mølmer
We propose to employ the amplification mechanism of Grover’s search algorithm to efficiently prepare entangled states of an ensemble of qubits. The conditional change of sign employed in the algorithm can be implemented by the phase shift of photons scattered on an optical cavity hosting an atomic ensemble. We show that collective Dicke states, Greenberger-Horne-Zeilinger states, and Schr"odinger cat superpositions of $N$ atoms may be prepared deterministically by few ($\sim {N}^{1/4}$) photon scattering events without individual addressing of the atoms.
Phys. Rev. Lett. 135, 050601 (2025)
Quantum computation, Quantum feedback, Quantum protocols
Observation of Residual Entanglement in Entanglement Purification
Research article | Entanglement manipulation | 2025-07-28 06:00 EDT
Lan Zhou, Cen-Xiao Huang, Yu-Bo Sheng, Yu Guo, Xiao-Min Hu, Yun-Feng Huang, Chuan-Feng Li, Guang-Can Guo, and Bi-Heng Liu
An experimental implementation of entanglement purification protocols with nonidentical input mixed states confirms the existence of residual entanglement in different error models.
Phys. Rev. Lett. 135, 050801 (2025)
Entanglement manipulation, Quantum communication, Quantum communication, protocols & technology
Towards a Robust Model-Independent Test of the $\mathrm{DAMA}/\mathrm{LIBRA}$ Dark Matter Signal: ANAIS-112 Results with Six Years of Data
Research article | Particle dark matter | 2025-07-28 06:00 EDT
Julio Amaré, Jaime Apilluelo, Susana Cebrián, David Cintas, Iván Coarasa, Eduardo García, María Martínez, Ysrael Ortigoza, Alfonso Ortiz de Solórzano, Tamara Pardo, Jorge Puimedón, María Luisa Sarsa, and Carmen Seoane
The nature of dark matter, which constitutes 27% of the Universe’s matter-energy content, remains one of the most challenging open questions in physics. Over the past two decades, the $\mathrm{DAMA}/\mathrm{LIBRA}$ experiment has reported an annual modulation in the detection rate of $\approx 250\text{ }\text{ }\mathrm{kg}$ of NaI(Tl) detectors operated at the Gran Sasso Laboratory, which the collaboration interprets as evidence of the galactic dark matter detection. However, this claim has not been independently confirmed and is refuted under certain dark matter particle and halo model scenarios. Therefore, it is crucial to perform an experiment with the same target material. The ANAIS experiment uses 112.5 kg of NaI(Tl) detectors at the Canfranc underground laboratory and it has been collecting data since August 2017 to model-independently test the $\mathrm{DAMA}/\mathrm{LIBRA}$ result. This Letter presents the results of the annual modulation analysis corresponding to six years of ANAIS-112 data. Our results, the most sensitive to date with the same target material, NaI(Tl), are incompatible with the $\mathrm{DAMA}/\mathrm{LIBRA}$ modulation signal at a $4\sigma $ confidence level. Such a discrepancy strongly challenges the $\mathrm{DAMA}/\mathrm{LIBRA}$ dark matter interpretation and highlights the need to address systematic uncertainties affecting the comparison, particularly those related to the response of detectors to nuclear recoils, which may require further characterization of the DAMA crystals.
Phys. Rev. Lett. 135, 051001 (2025)
Particle dark matter, Weakly interacting massive particles, Scintillators
Origin of Quasinormal Modes in Semi-Open Systems
Research article | Classical black holes | 2025-07-28 06:00 EDT
Leonardo Solidoro, Sam Patrick, Silke Weinfurtner, and Ruth Gregory
Astrophysical black holes are open systems which, when perturbed, radiate quasinormal modes (QNMs) to infinity. By contrast, laboratory analogs are necessarily finite sized, presenting a potential obstacle to exciting QNMs in experiments. We explore how the QNM spectrum of a toy-model black hole changes when enclosed by a partially reflecting wall with adjustable reflectivity. Our results reveal a continuous connection between the QNM spectra of open and finite-sized systems. Additionally, we demonstrate that QNMs in this setup are easily excited by incoherent background noise. This Letter opens new avenues for studying QNMs of black holes and compact objects in laboratory settings, where finite-size effects and noise are unavoidable.
Phys. Rev. Lett. 135, 051401 (2025)
Classical black holes, Wave scattering, Astronomical black holes, Perturbative methods
Universal Efimov Scaling in the Rabi-Coupled Few-Body Spectrum
Research article | Cold and ultracold molecules | 2025-07-28 06:00 EDT
Anthony N. Zulli, Brendan C. Mulkerin, Meera M. Parish, and Jesper Levinsen
We investigate the behavior of the Efimov effect—a universal quantum few-body phenomenon—in the presence of an external driving field. Specifically, we consider up to three bosonic atoms, such as $^{133}\mathrm{Cs}$, interacting with a light atom, such as $^{6}\mathrm{Li}$, where the latter has two internal spin states ${\uparrow ,\downarrow }$ that are Rabi coupled. Assuming that only the spin-$\uparrow $ light atom interacts with the bosons, we find that the Rabi drive transposes the entire Efimov spectrum such that the Efimov trimers and tetramers are centered around the Rabi-shifted two-body scattering resonance. Crucially, we show that the Rabi drive preserves the trimers’ discrete scaling symmetry, while universally shifting the Efimov three-body parameter, leading to a log-periodic modulation in the spectrum as the Rabi drive is varied. Our results suggest that Efimov physics can be conveniently explored using an applied driving field, opening up the prospect of an externally tunable three-body parameter.
Phys. Rev. Lett. 135, 053401 (2025)
Cold and ultracold molecules, Ultracold collisions, Ultracold gases
Reversible Phase Transition Enables Rapid Electrical Switching in Multilayer ${\mathrm{MoTe}}_{2}$ under Cyclic Strain
Research article | Dynamical phase transitions | 2025-07-28 06:00 EDT
Bolin Yang, Zhilong Peng, Cun Zhang, Yin Yao, Shaohua Chen, and Huajian Gao
${\text{MoTe}}{2}$, a promising material for flexible electronics and straintronics, exhibits rapid strain-induced conductivity changes. However, the underlying mechanisms remain poorly understood. Here, through deep-learning molecular dynamics and density-functional theory calculations, we identify a reversible phase transition between the semiconductive ${\mathrm{T}}{\mathrm{b}}^{‘ }$ phase and the semimetallic ${\mathrm{T}}^{\ast}$ phase as the key mechanism driving this phenomenon. This transition, which is highly sensitive to the direction of applied strain, provides valuable insights for optimizing ${\text{MoTe}}_{2}$-based high-frequency nanoelectronic devices and reducing fabrication-related failures.
Phys. Rev. Lett. 135, 056101 (2025)
Dynamical phase transitions, Resistive switching, Strain, Nanomechanical devices, Transition metal dichalcogenides, Density functional calculations, Molecular dynamics, Training models
Quasiparticle Gap Renormalization Driven by Internal and External Screening in a ${\mathrm{WS}}_{2}$ Device
Research article | Electronic structure | 2025-07-28 06:00 EDT
Chakradhar Sahoo, Yann in ‘t Veld, Alfred J. H. Jones, Zhihao Jiang, Greta Lupi, Paulina E. Majchrzak, Kimberly Hsieh, Kenji Watanabe, Takashi Taniguchi, Philip Hofmann, Jill A. Miwa, Yong P. Chen, Malte Rösner, and Søren Ulstrup
Angle-resolved photoemission spectroscopy reveals band gap renormalization in a WS2/h-BN device.
Phys. Rev. Lett. 135, 056401 (2025)
Electronic structure, Polarons, Graphene, Transition metal dichalcogenides, Two-dimensional electron system, GW method, Photoemission spectroscopy
Non-Abelian Phases from the Condensation of Abelian Anyons
Research article | Anyons | 2025-07-28 06:00 EDT
Misha Yutushui, Maria Hermanns, and David F. Mross
The observed fractional quantum Hall (FQH) plateaus follow a recurring hierarchical structure that allows an understanding of complex states based on simpler ones. Condensing the elementary quasiparticles of an Abelian FQH state results in a new Abelian phase at a different filling factor, and this process can be iterated ad infinitum. We show that condensing clusters of the same quasiparticles into an Abelian state can instead realize non-Abelian FQH states. In particular, condensing quasiparticle pairs in the $\nu =\frac{2}{3}$ Laughlin state yields the anti-Pfaffian phase at half filling. We moreover show that the successive condensation of Laughlin quasiparticles produces quantum Hall states whose fillings coincide with the most prominent plateaus in the first excited Landau level of GaAs. More generally, such condensation can realize any non-Abelian FQH state that admits a parton representation. This surprising result is supported by an exact analysis of explicit wave functions, field theory arguments, conformal-field theory constructions of trial states, and numerical simulations.
Phys. Rev. Lett. 135, 056501 (2025)
Anyons, Fractional quantum Hall effect, Quantum Hall effect, Topological order, Conformal field theory, Monte Carlo methods
Manipulation of Topology by Electric Field in Breathing Kagome Lattice
Research article | Chern insulators | 2025-07-28 06:00 EDT
Yu Xie, Ke Ji, Jun He, Xiaofan Shen, Dinghui Wang, and Junting Zhang
Magnetic kagome lattices have attracted much attention because the interplay of band topology with magnetism and electronic correlations give rise to various exotic quantum states. A common structural distortion in the kagome lattice is the breathing mode, which can significantly influence the magnetism and band characteristics. However, the control of breathing mode and the associated topological phenomena remain rarely explored. Here, we demonstrate that the coupling of breathing modes with ferroelectricity, magnetism, and band topology in the ${M}{3}{X}{8}$ monolayer system enables electric field manipulation of topological spin structure and electronic states. The breathing mode mainly occurs in materials containing early $4d/5d$ transition metal elements and can be reversed or even suppressed via ferroelectric switching in low-barrier materials. Importantly, electric field-induced switching of the breathing mode can alter the chirality of the topological spin structure, or trigger a transition from a topological trivial insulator to a Chern insulator. This work paves the way for exploring novel physical phenomena driven by breathing mode in kagome materials.
Phys. Rev. Lett. 135, 056701 (2025)
Chern insulators, Ferroelectricity, Skyrmions, Topological phase transition, 2-dimensional systems, Kagome lattice, Multiferroics, First-principles calculations, Tight-binding model
Physical Review X
Construction and Classification of Crystalline Topological Superconductor and Insulators in Three-Dimensional Interacting Fermion Systems
Research article | Symmetry protected topological states | 2025-07-28 06:00 EDT
Jian-Hao Zhang, Shang-Qiang Ning, Yang Qi, and Zheng-Cheng Gu
A new framework classifies 3D crystalline topological phases in interacting fermion systems, revealing experimentally relevant surface states and nuanced connections between spinless and spin-1/2 fermions.
Phys. Rev. X 15, 031029 (2025)
Symmetry protected topological states, Topological insulators, Topological superconductors, Topological materials
arXiv
Accelerating magnonic simulations with the pseudospectral Landau-Lifshitz equation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
A. Roxburgh, M. Copus, E. Iacocca
The pseudospectral Landau-Lifshitz (PS-LL) model can describe atomic-scale magnetic exchange interactions within a continuum framework. This is achieved by employing a convolution kernel that models the nonlocal interaction in a grid-independent manner. Even though the PS-LL was originally introduced to address atomic exchange, any nonlocal kernel can be modeled. In the field of magnonics, the dipole field is fundamental to describe the dispersion relation of magnons, the quasiparticle representation of angular momentum. Because dipole-dipole interactions are long-range, numerical approaches typically rely on convolutions. Here, we demonstrate that the PS-LL model can be used to perform magnonic simulations with a single convolution kernel derived from analytical solutions. We demonstrate a twofold increase in computational speed compared with the full dipole calculation. This approach is valid insofar as the excitations are linear, which is typically the case for magnons. Our results have the potential to accelerate magnonic research, particularly for the inverse design method, where several simulations must be performed to achieve the desired outcome.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Cyclotron reonance in a kagome spin liquid candidate material
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
We propose cyclotron resonance as an optical probe for emergent fractionalized excitations in $ \mathrm{U}(1)$ quantum spin liquids, focusing on kagome antiferromagnets. In contrast to conventional systems, where cyclotron resonance directly couples to charged carriers, spinons in spin liquids are charge-neutral and interact only through an emergent gauge field. We identify two key mechanisms by which an external physical electromagnetic field induces emergent electric and magnetic fields, enabling indirect coupling to spinons. Using these mechanisms, we compute the absorption rate of the cyclotron resonance response for Dirac spinons forming Landau levels. Our analysis shows that, although the absorption per layer is small, the absence of a skin-depth limitation in insulating spin liquids allows for cumulative absorption comparable to graphene in realistic sample sizes for the recently discovered spin-liquid candidate material YCu$ {}_3$ (OH)$ {}_6$ Br$ {}2$ [Br$ {}{1-y}$ (OH)$ {}_y$ ]. Our findings shows that cyclotron resonance is a viable experimental probe of spinon Landau quantization and emergent gauge fields, providing powerful positive experimental signatures of quantum spin liquids.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
6 pages, 1 figure
Chern-Simons-matter conformal field theory on fuzzy sphere: Confinement transition of Kalmeyer-Laughlin chiral spin liquid
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Zheng Zhou, Chong Wang, Yin-Chen He
Gauge theories compose a large class of interacting conformal field theories in 3d, among which an outstanding category is critical Chern-Simons-matter theories. In this paper, we focus on one of the simplest instances: one complex critical scalar coupled to $ \mathrm{U}(1)_2$ Chern-Simons gauge field. It is theoretically interesting as it is conjectured to exhibit dualities between four simple Lagrangian descriptions, but also practically important as it describes the transition between Kalmeyer-Laughlin chiral spin liquid (or $ \nu=1/2$ bosonic Laughlin state) and trivially gapped phase. Using the fuzzy sphere regularisation, we realise this theory as a transition on the spherical lowest Landau level between a $ \nu_f=2$ fermionic integer quantum Hall state and a $ \nu_b=1/2$ bosonic fractional quantum Hall state. We show that this transition is continuous and has emergent conformal symmetry. By studying the operator spectrum, we show that there exists only one relevant singlet with scaling dimension $ \Delta_S=1.52(18)$ . We also discuss other higher operators and the consequences of our results.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
15+12 Pages, 4+3 figures, 0+4 tables
Local Potential Functional Embedding Theory of Molecular Systems: Localized Orbital-Based Embedding from an Exact Density-Functional Perspective
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
W. Makhlouf, B. Senjean, E. Fromager
Localized orbital-based quantum embedding, as originally formulated in the context of density matrix embedding theory (DMET), is revisited from the perspective of lattice density functional theory (DFT). An in-principle exact (in the sense of full configuration interaction) formulation of the theory, where the occupations of the localized orbitals play the role of the density, is derived for any (model or ab initio) electronic Hamiltonian. From this general formalism we deduce an exact relation between the local Hartree-exchange-correlation (Hxc) potential of the full-size Kohn-Sham (KS) lattice-like system and the embedding chemical potential that is adjusted on each embedded fragment, individually, such that both KS and embedding cluster systems reproduce the exact same local density. When well-identified density-functional approximations (that find their justification in the strongly correlated regime) are applied, a practical self-consistent local potential functional embedding theory (LPFET), where the local Hxc potential becomes the basic variable, naturally emerges from the theory. LPFET differs from previous density embedding approaches by its fragment-dependent embedding chemical potential expression, which is a simple functional of the Hxc potential. Numerical calculations on prototypical systems show the ability of such an ansatz to ease convergence and improve substantially the description of density profiles (localized orbital occupations in this context) in strongly correlated systems.
Strongly Correlated Electrons (cond-mat.str-el)
19 pages
Van der Waals injection-molded crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Vinh Tran, Amy X. Wu, Laisi Chen, Ziyu Feng, Vijay Kumar, Takashi Taniguichi, Kenji Watanabe, Javier Sanchez-Yamagishi
Shaping low-dimensional crystals into precise geometries with low disorder is an outstanding challenge. Here, we present a method to grow single crystals of arbitrary geometry within van der Waals (vdW) materials. By injecting molten material between atomically-flat vdW layers within an SiO2 mold, we produce ultraflat and thin crystals of bismuth, tin, and indium that are shaped as hallbars, rings, and nanowires. The crystals are grown fully encapsulated in hexagonal boron nitride, a vdW material, providing protection from oxidation. Varying the depth of the mold allows us to control the crystal thickness from ten to a hundred nanometers. Structural measurements demonstrate large single-crystals encompassing the entire mold geometry, while transport measurements show reduced disorder scattering. This approach offers a means to produce complex single-crystal nanostructures without the disorder introduced by post-growth nanofabrication.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 4 figures
Learning disentangled latent representations facilitates discovery and design of functional materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Jaehoon Cha, Tingyao Lu, Matthew Walker, Keith T. Butler
The discovery of new materials is often constrained by the need for large labelled datasets or expensive simulations. In this study, we explore the use of Disentangling Autoencoders (DAEs) to learn compact and interpretable representations of spectral data in an entirely unsupervised manner. We demonstrate that the DAE captures physically meaningful features in optical absorption spectra, relevant to photovoltaic (PV) performance, including a latent dimension strongly correlated with the Spectroscopic Limited Maximum Efficiency (SLME)–despite being trained without access to SLME labels. This feature corresponds to a well-known spectral signature: the transition from direct to indirect optical band gaps. Compared to Principal Component Analysis (PCA) and a beta-Variational Autoencoder (beta-VAE), the DAE achieves superior reconstruction fidelity, improved correlation with efficiency metrics, and more compact encoding of relevant features. We further show that the DAE latent space enables more efficient discovery of high-performing PV materials, identifying top candidates using fewer evaluations than both VAE-guided and random search. These results highlight the potential of DAEs as a powerful tool for unsupervised structure-property learning and suggest broad applicability to other areas of materials discovery where labeled data is limited but rich structure is present in raw signals.
Materials Science (cond-mat.mtrl-sci)
Exciton dynamics and exciton-phonon coupling in bulk and thin flakes of layered van der Waals antiferromagnet Ni2P2S6
New Submission | Other Condensed Matter (cond-mat.other) | 2025-07-29 20:00 EDT
Nasaru Khan, Yuliia Shemerliuk, Sebastian Selter, Bernd Büchner, Saicharan Aswartham, Pradeep Kumar
The Zhang-Rice (ZR) singlet is an intriguing quantum state offering potential to realize a spin-orbit-entangled bosonic quasiparticle, which gives rise to the Zhang-Rice exciton. Its formation is attributed to the correlation between a localized d-orbital of a transition metal and the p-orbitals of the neighbouring ligands. The layered two-dimensional (2D) antiferromagnetic Ni2P2S6 system provide an excellent platform to probe the ZR exciton dynamics along with the role of exciton-phonon coupling. Here, we present a comprehensive study of ZR exciton and coupling with the phonons in bulk and few-layered single crystals of Ni2P2S6 using temperature, polarization and power-dependent photoluminescence (PL) spectroscopy. At cryogenic temperatures, the PL spectra reveal distinct phonon sidebands spaced by an energy difference of nearly 117 cm-1, indicative of exciton-phonon hybridization. Polarization-resolved measurements demonstrate a strong optical anisotropy, with a linear polarization degree of ~ 40 % at 4 K. Excitation power variation highlights linear scaling of PL intensity in the low-power regime, followed by spectral deformation at higher powers attributed to the phonon-assisted recombination and exciton saturation effects. ZR exciton and phonon side bands survival temperature decreases with decreasing flake thickness suggesting their tunability. The emergence and suppression of phonon sidebands with temperature and flake thickness emphasize dimensional sensitivity and coherence limits of excitonic states. Our findings position Ni2P2S6 as a promising candidate for tunable and anisotropic optoelectronic applications, while offering insight into quasiparticle interactions in 2D magnetic systems.
Other Condensed Matter (cond-mat.other), Strongly Correlated Electrons (cond-mat.str-el)
Data-efficient machine-learning of complex Fe-Mo intermetallics using domain knowledge of chemistry and crystallography
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Mariano Forti, Alesya Malakhova, Yury Lysogorskiy, Wenhao Zhang, Jean-Claude Crivello, Jean-Marc Joubert, Ralf Drautz, Thomas Hammerschmidt
Atomistic simulations of multi-component systems require accurate descriptions of interatomic interactions to resolve details in the energy of competing phases. A particularly challenging case are topologically close-packed (TCP) phases with close energetic competition of numerous different site occupations even in binary systems like Fe-Mo. In this work, machine learning (ML) models are presented that overcome this challenge by using features with domain knowledge of chemistry and crystallography. The resulting data-efficient ML models need only a small set of training data of simple TCP phases $ A$ 15, $ \sigma$ , $ \chi$ , $ \mu$ , $ C$ 14, $ C$ 15, $ C$ 36 with 2-5 WS to reach robust and accurate predictions for the complex TCP phases $ R$ , $ M$ , $ P$ , $ \delta$ with 11-14 WS. Several ML models with kernel-ridge regression, multi-layer perceptrons, and random forests, are trained on less than 300 DFT calculations for the simple TCP phases in Fe-Mo. The performance of these ML models is shown to improve systematically with increased utilization of domain knowledge. The convex hulls of the $ R$ , $ M$ , $ P$ and $ \delta$ phase in the Fe-Mo system are predicted with uncertainties of 20-25 meV/atom and show very good agreement with DFT verification. Complementary X-ray diffraction experiments and Rietveld analysis are carried out for an Fe-Mo R-phase sample. The measured WS occupancy is in excellent agreement with the predictions of our ML model using the Bragg Williams approximation at the same temperature.
Materials Science (cond-mat.mtrl-sci)
Dynamics of current-induced switching in the quantum anomalous Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Alina Rupp, Daniel Rosenbach, Torsten Röper, Dominik Hoborka, Alexey A. Taskin, Yoichi Ando, Erwann Bocquillon
Ferromagnetic topological insulators in the quantum anomalous Hall (QAH) regime host chiral, dissipationless edge states whose propagation direction is determined by the internal magnetization. Under suitable conditions, a strong electrical bias can induce magnetization reversal, and thus flip the propagation direction. In this work, we perform time-resolved measurements to investigate the switching dynamics. Our results reveal characteristics consistent with a disordered magnetic landscape and demonstrate that the reversal process is thermally activated, driven by Joule heating during the current pulse. The understanding of the magnetization dynamics in QAH systems opens pathways for local, controlled manipulation of chiral edge states via thermal effects.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Making atomistic materials calculations accessible with the AiiDAlab Quantum ESPRESSO app
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Xing Wang, Edan Bainglass, Miki Bonacci, Andres Ortega-Guerrero, Lorenzo Bastonero, Marnik Bercx, Pietro Bonfà, Roberto De Renzi, Dou Du, Peter N. O. Gillespie, Michael A. Hernández-Bertrán, Daniel Hollas, Sebastiaan P. Huber, Elisa Molinari, Ifeanyi J. Onuorah, Nataliya Paulish, Deborah Prezzi, Junfeng Qiao, Timo Reents, Christopher J. Sewell, Iurii Timrov, Aliaksandr V. Yakutovich, Jusong Yu, Nicola Marzari, Carlo A. Pignedoli, Giovanni Pizzi
Despite the wide availability of density functional theory (DFT) codes, their adoption by the broader materials science community remains limited due to challenges such as software installation, input preparation, high-performance computing setup, and output analysis. To overcome these barriers, we introduce the Quantum ESPRESSO app, an intuitive, web-based platform built on AiiDAlab that integrates user-friendly graphical interfaces with automated DFT workflows. The app employs a modular Input-Process-Output model and a plugin-based architecture, providing predefined computational protocols, automated error handling, and interactive results visualization. We demonstrate the app’s capabilities through plugins for electronic band structures, projected density of states, phonon, infrared/Raman, X-ray and muon spectroscopies, Hubbard parameters (DFT+$ U$ +$ V$ ), Wannier functions, and post-processing tools. By extending the FAIR principles to simulations, workflows, and analyses, the app enhances the accessibility and reproducibility of advanced DFT calculations and provides a general template to interface with other first-principles calculation codes.
Materials Science (cond-mat.mtrl-sci)
Bonding and the dynamics of glassy network liquids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-29 20:00 EDT
The Random First Order Transition (RFOT) theory of glasses provides a unified framework for explaining the observed correlations of the kinetic and thermodynamic behaviors of glass-forming liquids having a wide variety of chemical compositions and interactions. The theory also provides a solid starting point for calculating glassy dynamics starting from the microscopic forces. Network liquids, which interact via long-lived, geometrically constraining interactions, such as covalent bonding, have competing energy scales for bond breaking events and for collective particle rearrange- ment events. In this paper, we show microscopic calculations via the RFOT theory can predict how glassy dynamics depends on the degree of bonding, focusing on mixtures of network-forming particles with non-bonding impurities as in familiar window glass. By introducing soft-core nonbonding interactions, we show the viscosity and fragility of the network liquid model can be computed as a function of composition, temperature, and density or pressure. We find that the fragility in the strong-bond limit depends only on composition and not on the bond breaking energy and describes well corresponding measurements in sodium or potassium silicates. The model predicts that materials with weaker bonds may show a non-monotonic trend in the fragility as a function of composition.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Current-induced Magnetoexcitons in Mesoscopic Electron-hole Plasma
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Yu. A. Pusep, M. A. T. Patricio, G. M. Jacobsen, M. D. Teodoro, G. M. Gusev, A. K. Bakarov
A radical restructuring of the optical response of highly excited electron-hole plasma formed in a mesoscopic GaAs/AlGaAs channel in a quantizing magnetic field when an electric current flows in the channel has been discovered. In the absence of current, the emission spectra are caused by transitions between Landau levels formed in the conduction band and in the valence band of heavy holes. A critical electric current leads to a drastic change in the emission spectra with a predominant contribution from light holes. It is shown that the current causes local accumulation of light holes due to Coulomb drag, which leads to strong electron-hole coupling and, as a consequence, the formation of excitons and trions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Towards Environmentally Responsive Hypersound Materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Edson Rafael Cardozo de Oliveira, Gastón Grosman, Chushuang Xiang, Michael Zuarez-Chamba, Priscila Vensaus, Abdelmounaim Harouri, Cédric Boissiere, Galo J. A. A. Soler-Illia, Norberto Daniel Lanzillotti-Kimura
The engineering of acoustic phonons in the gigahertz (GHz) range holds significant potential for technological breakthroughs in areas such as data processing, sensing and quantum communication. Novel approaches for nanophononic resonators responsive to external stimuli provide additional control and functionality for these devices. Mesoporous thin films (MTFs) for example, featuring nanoscale ordered pores, support GHz-range acoustic resonances. These materials are sensitive to environmental changes, such as liquid and vapor infiltration, modifying their effective optical and elastic properties. Here, a SiO$ _{2}$ MTF-based open-cavity nanoacoustic resonator is presented, in which the MTF forms the topmost layer and is exposed to the environment. Using a transient reflectivity setup, acoustic responses under varying humidity conditions are investigated. A pronounced shift in acoustic resonance frequency with changes in relative humidity is observed for the first time, demonstrating a simple way to tune hypersound confinement. In addition, resonators with varying pore sizes and thicknesses are compared, revealing that resonance frequencies are primarily influenced by material properties and film thickness, rather than pore size. The proposed open-cavity resonator design provides a versatile platform for future studies on the mechanical response of MTFs to liquid and vapor infiltration, opening the gate to environment-responsive hypersound devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 4 figures. supplemental material: 4 pages, 3 figures
Electron-phonon coupled Langevin dynamics for Mott insulators
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Rico Pohle, Yukitoshi Motome, Terumasa Tadano, Shintaro Hoshino
The Landau-Lifshitz-Gilbert (LLG) equations are widely used to study spin dynamics in Mott insulators. However, because energy dissipation is typically introduced phenomenologically, its validity for describing nonequilibrium processes and long-time dynamics in real materials remains questionable. In this paper, we derive a generalized stochastic LLG equation from first principles for spin-orbital coupled Mott insulators, explicitly incorporating the coupling between electronic degrees of freedom and lattice vibrations. Our approach is based on the path-integral formalism formulated along the Keldysh contour, which naturally accounts for dissipation and thermal fluctuations through interactions with a phonon bath and emergent stochastic noise. We benchmark our theoretical framework by numerically integrating the equations of motion for a two-orbital spin chain coupled to Einstein phonons. The resulting energy relaxation mimics realistic cooling dynamics, exhibits nontrivial transient behavior during thermalization, and accurately reproduces thermodynamic properties upon equilibration. This demonstrates the robustness and reliability of our formalism for capturing both equilibrium and nonequilibrium aspects of dissipative spin dynamics in strongly correlated systems. We further show how electron-phonon coupling induces hybridization between electronic and phononic modes in the excitation spectrum. Finally, we demonstrate how the conventional LLG equations can be recovered as a limiting case of our microscopic theory, and discuss their applicability to real materials.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
29 pages, 7 figures
Prediction of Ambient-Pressure High-Temperature Superconductivity in Doped Transition-Metal Hydrides
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
Haowei Xu, Olivia Schneble, Rafael Jaramillo, Marek Polański, Ju Li
The search for conventional superconductors with high transition temperatures ($ T_c$ ) has largely focused on intrinsically metallic compounds. In this work, we explore the potential of intrinsically non-metallic compounds to exhibit high-$ T_c$ superconductivity under ambient pressure through carrier doping. We identify $ \rm MgAlFeH_6$ , a representative of carrier-doped transition-metal hydrides like $ \rm Mg_2FeH_6$ , as a promising example with a predicted $ T_c \approx 130~\rm K$ . We propose that the average projected electron density of states, defined as the geometric mean of the total and hydrogen-projected density of states at the Fermi level, serves as a simple and computationally inexpensive indicator of high-$ T_c$ behavior. We also highlight the tradeoff between high-$ T_c$ and dynamic stability, both of which depend on the electron density of states. Our findings thus expand the pool of potential superconducting materials and offer a practical route for accelerating the discovery of superconductors suitable for real-world applications.
Superconductivity (cond-mat.supr-con)
15 pages, 6 figures
Magnetic ground state, critical analysis of magnetization, and large magnetocaloric effect in the ferromagnetically coupled kagome lattice YCa$_3$(MnO)$_3$(BO$_3$)$_4$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
A. Choudhary, A. Magar, S. Ghosh, S. Kanungo, R. Nath
We report a detailed study of the magnetic properties, critical analysis of magnetization, and magnetocaloric effect of a spin-$ 2$ kagome lattice YCa$ _3$ (MnO)$ _3$ (BO$ 3$ )$ 4$ . The experiments are complemented by the density functional band structure calculations. The magnetic measurements suggest a highly frustrated nature of the compound due to competing ferro- and antiferromagnetic interactions with the dominant one being ferromagnetic. It undergoes a unconventional ferromagnetic ordering at $ T^\ast \simeq 7.8$ K and a field induced metamagnetic transition in low fields, implying spin canting. A $ H$ -$ T$ phase diagram is constructed that features three phase regimes. Indeed, the band structure calculations reveal dominant ferromagnetic interaction along the chains that are coupled antiferromagnetically yielding a frustrated kagome geometry. This compound shows a large magnetocaloric effect with isothermal entropy change $ \Delta S{\rm m} \simeq 12$ J/kg-K, adiabatic temperature change $ \Delta T{\rm ad} \simeq 8.4$ K, and relative cooling power $ RCP \simeq 349$ J/kg for a field change of 7 T. The critical analysis of magnetization and magnetocaloric parameters suggests that the transition is a second order phase transition and it is tricritical mean field type. Owing to it’s large magnetocaloric parameters, second order phase transition, and no thermal hysteresis, YCa$ _3$ (MnO)$ _3$ (BO$ _3$ )$ _4$ emerges as a potential rare-earth free material for magnetic refrigeration.
Materials Science (cond-mat.mtrl-sci)
14 pages, 11 figures
Theoretical study of the electronic correlation and superconducting pairing in La${2.85}$Pr${0.15}$Ni$_2$O$_7$ film grown on SrLaAlO$_4$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
We investigate the electronic correlation effects in La$ _{2.85}$ Pr$ _{0.15}$ Ni$ _2$ O$ _7$ film grown on SrLaAlO$ 4$ by fluctuation-exchange approximation. The $ \gamma$ and $ \delta$ bands are found to shift down with correlation while their Fermi surfaces become highly damped and cannot to be resolved experimentally. In contrast, the $ \alpha$ and $ \beta$ Fermi surfaces do not vary much with correlation and they are sharp enough to be detected in experiments. The spin susceptibility peaks at a wave vector in the odd channel, connecting the symmetric $ \gamma$ band and the asymmetric $ \delta$ band. The superconducting pairing symmetry is robustly $ s$ -wave and the $ \delta$ band has the largest pairing magnitude. All the findings suggest a dominant role of the $ 3d{z^{2}}$ orbital in this material.
Superconductivity (cond-mat.supr-con)
Band-selective Plasmonic Polaron in Thermoelectric Semimetal Ta$_2$PdSe$_6$ with ultra-high power factor
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Daiki Ootsuki, Akitoshi Nakano, Urara Maruoka, Takumi Hasegawa, Masashi Arita, Miho Kitamura, Koji Horiba, Teppei Yoshida, Ichiro Terasaki
We report the electronic structure of the thermoelectric semimetal Ta$ _2$ PdSe$ _6$ with a large thermoelectric power factor and giant Peltier conductivity by means of angle-resolved photoemission spectroscopy (ARPES). The ARPES spectra reveal the coexistence of a sharp hole band with a light electron mass and a broad electron band with a relatively heavy electron mass, which originate from different quasi-one-dimensional (Q1D) chains in Ta$ _2$ PdSe$ _6$ . Moreover, the electron band around the Brillouin-zone (BZ) boundary shows a replica structure with respect to the energy originating from plasmonic polarons due to electron-plasmon interactions. The different scattering effects and interactions in each atomic chain lead to asymmetric transport lifetimes of carriers: a large Seebeck coefficient can be realized even in a semimetal. Our findings pave the way for exploring the thermoelectric materials in previously overlooked semimetals and provide a new platform for low-temperature thermoelectric physics, which has been challenging with semiconductors.
Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
Multiscale analysis and lifetime prediction of adhesive lap joints in contact with aggressive environments
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-29 20:00 EDT
We formulate a multiscale model of adhesive layers undergoing impurity-dependent cohesive fracture. The model contemplates three scales: i) at the atomic scale, fracture is controlled by interatomic separation and the thermodynamics of separation depends on temperature and impurity concentration; ii) the mesoscale is characterized by the collective response of a large number of interatomic planes across the adhesive layer, resulting in a thickness-dependence strength; in addition, impurities are uptaken from the environment and diffuse through the adhesive layer; and iii) at the macroscale, we focus on lap joints under the action of static loads and aggressive environments. Within this scenario, we obtain closed form analytical solutions for: the dependence of the adhesive layer strength on thickness; the length of the edge cracks, if any, as a function of time; the lifetime of the joint; and the dependence of the strength of the joint on time of preexposure to the environment. Overall, the theory is found to capture well the experimentally observed trends. Finally, we discuss how the model can be characterized on the basis of atomistic calculations, which opens the way for the systematic exploration of new material specifications.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Enhancing Materials Discovery with Valence Constrained Design in Generative Modeling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Mouyang Cheng, Weiliang Luo, Hao Tang, Bowen Yu, Yongqiang Cheng, Weiwei Xie, Ju Li, Heather J. Kulik, Mingda Li
Diffusion-based deep generative models have emerged as powerful tools for inverse materials design. Yet, many existing approaches overlook essential chemical constraints such as oxidation state balance, which can lead to chemically invalid structures. Here we introduce CrysVCD (Crystal generator with Valence-Constrained Design), a modular framework that integrates chemical rules directly into the generative process. CrysVCD first employs a transformer-based elemental language model to generate valence-balanced compositions, followed by a diffusion model to generate crystal structures. The valence constraint enables orders-of-magnitude more efficient chemical valence checking, compared to pure data-driven approaches with post-screening. When fine-tuned on stability metrics, CrysVCD achieves 85% thermodynamic stability and 68% phonon stability. Moreover, CrysVCD supports conditional generation of functional materials, enabling discovery of candidates such as high thermal conductivity semiconductors and high-$ \kappa$ dielectric compounds. Designed as a general-purpose plugin, CrysVCD can be integrated into diverse generative pipeline to promote chemical validity, offering a reliable, scientifically grounded path for materials discovery.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
13 pages, 4 figures
A comprehensive first principles investigation of A2BH6 type (A= Li,Na, and K; B= Al, and Si) double perovskite hydrides for high capacity hydrogen storage
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
R. Zosiamliana, Lalhriat Zuala, Shivraj Gurung, R. Lalmalsawma, A. Laref, A. Yvaz, D.P.Rai
Recent breakthroughs in vacancy-ordered double perovskite hydride materials have underscored their significant potential for integration into next-generation high-capacity hydrogen energy storage systems. We perform extensive first principles calculations leveraging both the GGA and hybrid-HSE06 functionals to systematically explore the intrinsic properties of A2BH6 complex hydrides. Thermodynamic stability for each hydride is demonstrated and confirmed by negative formation energies, determined by both the GGA and HSE06 formalisms. Additionally, mechanical stability is validated through compliance with Born’s stability criteria. Electronic properties analysis reveals a semiconducting behavior in Si based hydrides (A2SiH6 ), whereas Al based (A2AlH6) display metallic nature, regardless of the A site atoms and functionals adopted. For the semiconducting hydrides, we have observed higher optical absorption peak greater than 106 (1/cm) in the UV regime indicating potential application in UV-optoelectronic devices. Furthermore, all studied compounds adhere to Debye’s low-temperature specific heat behavior and converge to the classical Dulong-Petit limit at elevated temperatures, in accordance with fundamental thermodynamic principles. For hydrogen storage applications, both Al- and Si-based hydrides. meet key benchmarks set by the U.S. Department of Energy (DOE), achieving gravimetric hydrogen capacities (Cwt) exceeding 5.5 percent when A = Li or Na, and exhibiting volumetric hydrogen densities greater than 40 g.H2/L. Among all studied hydrides, Li2AlH6 and Li2SiH6 emerge as the two most promising candidates due to their outstanding Cwt greater than 12.0 percent , elevated density greater than 140 g.H2/L, and favorable hydrogen desorption temperature ranges TD = 450 to 650 K.
Materials Science (cond-mat.mtrl-sci)
Macroscopic fluctuation theory and the absorption of Brownian particles by partially reactive targets
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
We use macroscopic fluctuation theory (MFT) to analyse current fluctuations in a non-interacting Brownian gas with one or more partially absorbing targets within a bounded domain $ \Omega \subset \R^d$ . We proceed by coarse-graining a generalised Dean-Kawasaki equation with Robin boundary conditions at the target surfaces. The exterior surface $ \partial \Omega$ is maintained at a constant density $ \owp$ . We first derive MFT equations for the optimal noise-induced path for a single target under a saddle-point approximation of the associated path integral action. We then obtain the Gaussian distribution characterising small current fluctuations by linearising the MFT equations about the corresponding deterministic or noise-averaged system and solving the resulting stationary equations. The Robin boundary conditions are handled using the spectrum of a Dirichlet-to-Neumann operator defined on the target surface. We illustrate the theory by considering the finite interval and a circular annulus. In both cases we determine how the variance of the current depends on the rate of absorption $ \kappa$ . Finally, we extend our analysis to multiple partially absorbing targets. First, we obtain the general result that, in the case of partially absorbing targets ($ 0<\kappa<\infty$ ), the covariance matrix for current fluctuations supports cross correlations even in the absence of particle interactions. (These cross-correlations vanish in the totally absorbing limit $ \kappa\rightarrow \infty$ .) We then explicitly calculate the covariance matrix for circular targets in a 2D domain by assuming that the targets are much smaller than the characteristic size $ L$ of the domain $ \Omega$ and applying methods from singular perturbation theory.
Statistical Mechanics (cond-mat.stat-mech)
36 pages, 7 figures
Spin-flop-like transition as quantum critical point in Cs$_2$RuO$_4$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
S. D. Nabi, M. Zhu, K. Yu. Povarov, D. G. Mazzone, J. Lass, Y. Wu, Z. Yan, S. Gvasaliya, A. Zheludev
We report thermodynamic, neutron diffraction, and inelastic neutron scattering measurements on Cs$ _2$ RuO$ _4$ , a member of the celebrated family of frustrated magnets Cs$ _2$ MX$ _4$ (M = Cu, Co, X = Br, Cl). Unlike the previously studied members, it is based on $ 4d$ transition metal ions with $ S=1$ . Mapping out the $ H-T$ magnetic phase diagram reveals an unusual continuous spin-flop-like phase transition associated with a quantum critical point within the antiferromagnetically ordered phase. A quantitative analysis of the complex magnetic excitation spectrum measured in zero field allows us to derive a model magnetic Hamiltonian for this compound. Its main feature is a frustration of magnetic anisotropy on a level that is much higher than in any of the previously studied species. This frustration naturally explains the peculiar phase transition observed.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 11 figures
Excitation of vortex core gyration in nanopillars through driven Floquet magnons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Gauthier Philippe, Joo-Von Kim
The dynamics of vortex states in confined geometries like thin-film disks are characterized by a sub-GHz gyration, representing the damped oscillatory motion of the vortex core about the disk center. It has recently been shown that interactions between the core and azimuthal spin waves, lying in the GHz range and driven by magnetic fields, can result in steady-state core gyration. The gyration in turn provides a time-periodic modulation for the spin waves, resulting in the emergence of Floquet states. Here, we present results of a theoretical and computational study in which we examine how Floquet modes sustain this core gyration. In particular, we find that multiple steady-state gyration radii are possible under certain field conditions, resulting from the nonlinear interactions between the core and Floquet modes. Different gyration radii result in distinct Floquet frequency comb spectra and allow for hysteretic effects, as reported in recent experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 5 figures
Unraveling a chemical-bond-driven root of topology in three-dimensional chiral crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Shungo Aoyagi, Shunsuke Kitou, Yuiga Nakamura, Motoaki Hirayama, Hideki Matsuoka, Ryotaro Arita, Shuichi Murakami, Taka-hisa Arima, Naoya Kanazawa
Chirality manifests across multiple scales, yielding unique phenomena that break mirror symmetry. In chiral materials, unexpectedly large spin-filtering or photogalvanic effects have been observed even in materials composed of light elements, implying crucial influence of their topological electronic states. However, an underlying framework that links chemical bonding and electronic topology remains elusive, preventing the rational design of quantum chiral properties. Here we identify the chiral bonding network responsible for multifold topological fermions by combining synchrotron X-ray diffraction and first-principles calculations on cubic chiral crystals, CoSi and FeSi. Based on the observations of asymmetric valence electron distributions around the transition metals, together with analyses of their bonding to sevenfold-coordinated silicon atoms, we develop a three-dimensional Su-Schrieffer-Heeger model, showing that inter-site hopping on this chiral network creates multifold fermions with doubled topological invariants. Topological features can be switched by reversing the crystalline chirality or tuning electron filling. Our results highlight that implementing strong spin-orbit coupling is not the sole route to realize robust topological phases at elevated temperatures and offer a practical design principle for exploiting chiral topology. Moreover, this real-space framework naturally extends to other elementary excitations or artificial metamaterials, enabling various quantum functionalities through an intuitive approach to chirality engineering.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
19 pages, 4 figures
Anomalous superconductivity and unusual normal state properties of bilayer and twisted graphene (Brief review)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
M. Yu. Kagan, M. M. Korovushkin, V. A. Mitskan, K. I. Kugel, A. L. Rakhmanov, A. V. Rozhkov, A. O. Sboychakov
It has been shown that the Kohn–Luttinger superconductivity mechanism interplaying with other types of ordering can be implemented in systems with a hexagonal lattice. A number of unusual properties of such systems in the normal phase have also been considered. Our previous results on Kohn–Luttinger superconductivity with $ p$ -, $ d$ -, and $ f$ -wave pairing in monolayer and AB bilayer graphene, obtained disregarding the effect of substrate potential and impurities, have been presented in the first part. Then, the interplay of the superconducting Kohn–Luttinger state with the spin density wave state in actual AB, AA, and twisted bilayer graphene has been discussed in detail. In the last parts, a number of anomalous properties in the normal phase and the appearance of nematic superconductivity alongside with the spin density wave in the twisted bilayer graphene have been presented.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 11 figures; submitted to JETP Letters
Density-dependent transport coefficients in two-dimensional cellular aggregates
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
Subhadip Chakraborti, Vasily Zaburdaev
The large-scale collective behavior of biological systems can be characterized by macroscopic transport, which arises from the non-equilibrium microscopic interactions among individual constituents. A prominent example is the formation of dynamic aggregates by motile eukaryotic cells or bacteria mediated by active contractile forces. In this work, we develop the two-dimensional fluctuating hydrodynamics theory based on the microscopic dynamics of a model system of aggregation by \textit{Neisseria gonorrhoeae} bacteria. The derivation of two macroscopic transport coefficients of bulk diffusivity and conductivity which determine hydrodynamic current of cells is the central result of this work. By showing how transport coefficients depend on cell density and microscopic parameters of the system we predict transport slowdown during the colony formation process. This study provides valuable analytical tools for quantifying hydrodynamic transport in experimental systems involving cellular aggregation occurring due to intermittent contractile dipole forces.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
2D complete analytical version of arXiv:2409.03039
Exploration and aging of non-Markovian processes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
This thesis explores a central question: how does memory affect the way random walkers explore space? By analyzing various non-Markovian models, where past behavior directly influences future dynamics, we uncover new mechanisms and universal patterns in space exploration.
In the first part, we study Locally Activated Random Walks (LARWs), where motion depends on the time spent at visited sites. These walks, though simply defined, display rich behaviors such as dynamical trapping, aging, and non-Gaussian diffusion. We identify confinement criteria, reveal a dynamical phase transition, and derive exact analytical results in several regimes.
The second part focuses on Self-Interacting Random Walks (SIRWs), where the walker’s own history governs future steps. Using advanced probabilistic tools, especially Ray-Knight theory, we compute exact results for observables such as splitting probabilities, persistence, first-passage times, number of visited sites, and aging effects. This includes the first exact expressions for aged observables in the saturating Self-Attracting Walk (SATW) model.
In the third part, we propose a unified framework to describe memory effects in space exploration, based on the walker’s tendency to reverse direction over time. This approach reveals robust patterns across a wide class of non-Markovian models, including fractional Brownian motion and the strongly self-interacting True Self-Avoiding Walk (TSAW), where we derive the first exact result for an aged observable in a non-saturating system.
Together, these results show that memory-driven systems, though complex, can exhibit universal structures. This work offers new tools to analyze such dynamics and lays the groundwork for future research across physics, probability, and beyond.
Statistical Mechanics (cond-mat.stat-mech)
PhD Thesis defended on July 3d, 2025 at Sorbonne Université, supervised by Raphaël Voituriez and Olivier Bénichou
Specifics of ITO properties deposited on cerium-doped glass for space-grade solar cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Danil D. Gren, Lev O. Luchnikov, Dmitri Yu. Dorofeev, Prokhor A. Alekseev, Ildar R. Sayarov, Alexey R. Tameev, Mikhail S. Dunaevskiy, Vladislav Kalinichenko, Vladimir Ivanov, Danila S. Saranin, Eugene I. Terukov
Ce-doped glass is a well-established solution for ultraviolet and ionizing radiation shielding of solar cells in space. Traditionally, Ce-glass protected Si or III-V based devices as an overlaying cap. However, for emerging photovoltaics such as halide perovskites, thin Ce-glass coated with transparent conductive layers could serve as a lightweight carrier with an electrode. While indium-tin oxide (ITO) is widely used in solar cells for charge collection, its optical, structural, and electrical properties depend on the substrate quality. In this work, we demonstrated significant differences in properties of ITO deposited on Ce-glass (100 micron thick) compared to standard soda lime glass. ITO on Ce-glass exhibited pronounced compressive strain because of higher oxygen vacancy concentrations, reduced transparency and charge carrier concentration (10^19 cm-3) resulting from altered stoichiometry. Electrical analysis showed increased Hall mobility (66 cm2V-1s-1) but decreased conductivity due to excess tin incorporation. These specific ITO features originated from inelastic collisions with the substrate during deposition. Variations in wettability and surface potential underscore substrate-induced differences critical for developing optimized ITO coatings for space-grade photovoltaics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 7 figures
Spin-Type Photonic Topological Insulators on a Rhombic Lattice
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Robert J. Davis, Daniel F. Sievenpiper
A simplified model of a metallic spin-type photonic topological insulator on a rhombic lattice is presented and analyzed. Instead of the more commonly used hexagonal unit cells, a reduced symmetry rhombus is employed, which is both simpler and allows for easier integration into more traditional microwave systems. The non-trivial nature of the transport is shown via direct calculation of the structure’s spin-projected Berry curvature and Wilson loop spectra, as well as by a systematic investigation of a reduced symmetry tight-binding model based off the Kane-Mele Hamiltonian. Device implementations are shown for a range of non-trivial configurations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 16 figures
A first-principles study on the early-stage corrosion of a NiWNb alloy in a chloride salt environment
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Tyler D. Doležal, Adib J. Samin
In this work a representative nickel superalloy, Ni70W20Nb10, was investigated in the presence of chlorine to quantify its early-stage dissolution behavior. Surface structures were generated from a bulk configuration sampled in equilibrium using a multi-cell Monte Carlo method for phase prediction. The predicted solid-phase at 800 C was Ni72W19Nb9 in a body-centered tetragonal crystal structure closely resembling the Ni4W structure. Chlorine adsorption onto the energetically favored (110) surface showed preference to niobium which acted as a trapping sink on the top surface of the slab model. Our findings suggested that niobium and tungsten enhanced the corrosion resistance of nickel as their presence created regions that were thermodynamically preferred by the incoming chlorine and less susceptible to chlorine-facilitated dissolution from the alloy. Nickel, niobium, and tungsten resisted chlorine-induced dissolution from the surface model up to a 1/3 monolayer coverage of chlorine indicating that all constituents of this alloy possessed superior resistance to localized surface degradation such as corrosive pitting. Further analysis and comparisons between the corrosion resistance of the three metallic species was performed. This work may provide insights that aid in the development of improved structural materials for molten salt reactors.
Materials Science (cond-mat.mtrl-sci)
Journal of Nuclear Materials, vol. 582, Aug. 2023, 154457
On the adsorption of oxygen to high entropy alloy surfaces up to 2ML coverage using Density Functional Theory and Monte Carlo calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Tyler D. Doležal, Adib J. Samin
To enhance our understanding of oxidation in high-entropy alloys, the early stages of oxidation on the surface of Al10Nb15Ta5Ti30Zr40 were studied using density functional theory and thermodynamic modeling. Surface slabs were generated from bulk configurations sampled from equilibrium using a multicell Monte Carlo method for phase prediction. The bulk structure was found to be a single BCC phase in good agreement with experimental observations. The oxygen adsorbed with a strong preference for sites with Ti and Zr and avoided sites with Nb-Al and Nb-Ta. The surface was shown to be highly reactive to oxygen, yielding a dominating oxygen coverage of two monolayers over the temperature range of 100 to 2600 K and an oxygen pressure range of 10-30 to 105 bar. Inward oxygen diffusion at low coverage was preferred in regions rich with Zr but slowed with the addition of Ti and Al. Diffusion rates drastically decreased at 1 ML, especially in the region rich with Ti and Zr, where strong metal-oxygen bonds were reported. Our results indicated that a high content of Ti and Zr increased the reactivity of the HEA surface to oxygen. The presence of Nb also enhanced the resistance to oxygen adsorption, especially when partnered with Al and Ta. Inward oxygen diffusion was likely to occur at low coverage in regions rich with Zr but could be protected against with the addition of Al and Ti. The limitations of the present work are discussed. This study may provide insights that assist with devising short- and long-term mitigation strategies against material degradation related to high-temperature oxidation.
Materials Science (cond-mat.mtrl-sci)
Langmuir, vol. 38, 3158-3169, 2022
Mo-Re-W Alloys for High Temperature Applications: Phase Stability, Elasticity, and Thermal Property Insights via Multi-Cell Monte Carlo and Machine Learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Tyler D. Doležal, Nick A. Valverde, Jodie Yuwono, Ryan Kemnitz
The increasing demand for materials capable of withstanding high temperatures and harsh environments necessitates the discovery of advanced alloys. This study introduces a computational routine to predict solid-state phase stability and calculates elastic constants to determine high temperature viability. With it, machine learning models were trained on 1,014 Mo-Re-W structures to enable a large compilation of elastic and thermal properties over the complete Mo-Re-W compositional domain with extreme resolution. A series of heat maps spanning the full compositional domain were generated to visually present the impact of alloy constituents on the alloy properties. Our findings identified a balanced (Mo,W) + Re blend as a promising composition for high temperature applications, attributed to a strong and stable (Mo,W) matrix with high Re content and the formation of strengthening (W,Re) precipitates that enhanced mechanical performance at 1600oC. Several Mo-Re-W compositions were manufactured to experimentally validate the computational predictions. This approach provides an efficient and system-agnostic pathway for designing and optimizing alloys for high-temperature applications.
Materials Science (cond-mat.mtrl-sci)
Materials and Design, vol. 244, 113226 2024
Energy-Resolved EBSD using a Monolithic Direct Electron Detector
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Nicolò M. Della Ventura, Kalani Moore, McLean P. Echlin, Matthew R. Begley, Tresa M. Pollock, Marc De Graef, Daniel S. Gianola
Accurate quantification of the energy distribution of backscattered electrons (BSEs) contributing to electron backscatter diffraction (EBSD) patterns remains as an active challenge. This study introduces an energy-resolved EBSD methodology based on a monolithic active pixel sensor direct electron detector and an electron-counting algorithm to enable the energy quantification of individual BSEs, providing direct measurements of electron energy spectra within diffraction patterns. Following detector calibration of the detector signal as a function of primary beam energy, measurements using a 12 keV primary beam on Si(100) reveal a broad BSE energy distribution across the diffraction pattern, extending down to 3 keV. Furthermore, an angular dependence in the weighted average BSE energy is observed, closely matching predictions from Monte Carlo simulations. Pixel-resolved energy maps reveal subtle modulations at Kikuchi band edges, offering insights into the backscattering process. By applying energy filtering within spectral windows as narrow as 2 keV centered on the primary beam energy, significant enhancement in pattern clarity and high-frequency detail is observed. Notably, electrons in the 2–8 keV range, despite having undergone substantial energy loss ({\Delta}E = 4–10 keV), still produce Kikuchi patterns. By enabling energy determination at the single-electron level, this approach introduces a versatile tool-set for expanding the quantitative capabilities of EBSD, thereby offering the potential to deepen the understanding of diffraction contrast mechanisms and to advance the precision of crystallographic measurements.
Materials Science (cond-mat.mtrl-sci)
19 pages, 11 figures
Absence of nontrivial local conserved quantities in the Hubbard model on the two or higher dimensional hypercubic lattice
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
By extending the strategy developed by Shiraishi in 2019, we prove that the standard Hubbard model on the $ d$ -dimensional hypercubic lattice with $ d\ge2$ does not admit any nontrivial local conserved quantities. The theorem strongly suggests that the model is non-integrable. To our knowledge, this is the first extension of Shiraishi’s proof of the absence of conserved quantities to a fermionic model. Although our proof follows the original strategy of Shiraishi, it is essentially more subtle compared with the proof by Shiraishi and Tasaki of the corresponding theorem for $ S=\tfrac12$ quantum spin systems in two or higher dimensions; our proof requires three steps, while that of Shiraishi and Tasaki requires only two steps. It is also necessary to partially determine the conserved quantities of the one-dimensional Hubbard model to accomplish our proof.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
24 pages, 8 figures
Cluster dynamics modeling of hydrogen saturation retention in tungsten with a universal trapping-site sink strength
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Yuanyuan Zhang, Xiaoru Chen Chuanguo Zhang, Yonggang Li
Hydrogen isotope (HI) retention poses a key issue for tungsten (W)-based plasma-facing materials (PFMs) in fusion devices, where microstructures such as dislocations (DLs) and grain boundaries (GBs) play a dominant role. Existing theoretical sink strength models for microstructures like DLs and GBs fail to account for the observed saturation of HI retention. In this study, we propose a novel universal trapping-site model that dynamically represents sink strengths as time-dependent site concentrations, which is incorporated into an improved cluster dynamics model for high-fluence HI irradiation. Our simulations quantitatively reproduce the saturated low-energy deuterium (D) retention and depth profiles in W, in good agreement with experiments. A critical saturation fluence of approximately 1023 m-2 is identified, below which unsaturated D retention is governed by both GBs and ion-induced defects, whereas above this threshold GBs dominate D retention by trapping free D and approaching their theoretical saturation limit. The trapping-site sink strength model enables quantification of H trapping by diverse microstructures via unified effective site concentrations, providing mechanistic insights into microstructural effects and facilitating direct evaluation of HI retention in PFMs under different irradiation conditions.
Materials Science (cond-mat.mtrl-sci)
30 pages, 9 Figures
Superconductivity emerging from the N${é}$el state in ${\it infinite}$-${\it stage}$ single-layer cuprate La$2$CuO${4+δ}$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
Yoshihiko Ihara, Ramender Kumar, Kota Miyakoshi, Migaku Oda, Kenji Ishida
In copper oxides (cuprates) with single CuO$ _2$ layer such as La$ _{2-x}$ Ba(Sr)$ _x$ CuO$ _4$ , antiferromagnetism coexists with superconductivity at small doping levels $ x$ , where chemical disorders are significant. Here, we report that superconductivity occurs in a uniform and fully ordered N$ {é}$ el state in a single-layer cuprate La$ _2$ CuO$ _{4+\delta}$ with a small amount of excess oxygen $ (\delta = 0.015)$ as demonstrated by the $ ^{139}$ La nuclear quadrupole resonance measurement. A uniform oxygen distribution in the crystal is crucial for achieving microscopic phase coexistence and overcoming the miscibility gap associated with the staging instability; self-organized periodic oxygen arrangement driven by mobile oxygen atoms. This finding prompts the reconsideration of superconductivity in cuprates, highlighting that it can emerge in a robust N$ {é}$ el state that retains sizable magnetic moments and hosts only a small carrier density.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
32 pages, 8 figures
Quasiparticle interaction originating from Bogoliubov Fermi Surfaces under pressure in 18%-S substituted FeSe studied via NMR
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
Zhongyu Yu, Xiaoling Shen, Koya Nakamura, Kazuya Inomata, Kohei Matsuura, Yuta Mizukami, Shigeru Kasahara, Yuji Matsuda, Takasada Shibauchi, Yoshiya Uwatoko, Naoki Fujiwara
S-substituted FeSe superconductors in the tetragonal phase display several unique features among iron-based superconductors, particularly the presence of zero-energy excitations in the superconducting (SC) this http URL recent concept of Bogoliubov Fermi Surfaces (BFSs), a theoretical model describing ultranodal states, has attracted considerable interest. Nuclear magnetic resonance (NMR) studies on FeSe$ _{1-x}$ S$ _x$ (x=0.18) have revealed an anomalous low-energy spin fluctuations deep in the SC state. The low-energy spin fluctuations are enhanced with decreasing temperature, supporting strong Bogoliubov quasiparticle interactions associated with BFSs. Here, we further investigate these correlation effects through $ ^{77}$ Se-NMR measurements of FeSe$ _{1-x}$ S$ _x$ (x=0.18) under pressures up to 2.0 GPa and temperatures down to ~100 mK. The results demonstrate that the anomalous enhancement is suppressed but persists under pressure, implying that quasiparticle interactions become weak by applying pressure. Furthermore, spin fluctuations in the normal state exhibit different temperature dependence from those deep in the SC state, suggesting that the nesting properties of normal electrons differ from those of Bogoliubov quasiparticles. These findings are consistent with the theoretical model of BFSs with C$ _2$ symmetry and strengthen evidence for Bogoliubov quasiparticle interactions, providing insights into the unconventional pairing state of this system.
Superconductivity (cond-mat.supr-con)
Finite size effect in the persistence probability of the Edwards-Wilkinson model of surface growth and effect of non-linearity
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
Anirban Ghosh, Dipanjan Chakraborty
The dynamical evolution of the surface height is controlled by
either a linear or a nonlinear Langevin equation, depending on the
underlying microscopic dynamics, and is often done theoretically
using stochastic coarse-grained growth equations. The persistence
probability $ p(t)$ of stochastic models of surface growth that are
constrained by a finite system size is examined in this work. We
focus on the linear Edwards-Wilkinson model (EW) and the nonlinear
Kardar-Parisi-Zhang model, two specific models of surface
growth. The persistence exponents in the continuum version of these
two models have been widely investigated. Krug et al.[Phys. Rev. E ,
56:2702-2712, (1997)] and Kallabis et al. [EPL (Europhysics Letters)
, 45(1):20, 1999] had shown that, the steady-state persistence
exponents for both these models are related to the growth exponent
$ \beta$ as $ \theta=1-\beta$ . It is numerically found that the values
of persistence exponents for both these models are close to the
analytically predicted values. While the results of the continuum
equations of the surface growth are well known, we focus to study
the persistence probability expressions for discrete models with a
finite size effect. In this article, we have investigated the
persistence probabilities for the linear Edwards-Wilkinson(EW) model
and for the non-linear Kardar-Parisi-Zhang(KPZ) model of surface
growth on a finite one-dimensional lattice. The interesting
phenomenon which is found in this case is that the known scenario of
$ p(t)$ of the following algebraic decay vanishes as we introduce a
finite system size.
Statistical Mechanics (cond-mat.stat-mech)
13 pages, 3 figures
Biorthogonal quench dynamics of entanglement and quantum geometry in PT-symmetric non-Hermitian systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
We explore the quench dynamics of PT-symmetric non-Hermitian systems by utilizing the biorthogonal formalism. We analyze quench dynamics of observable quantities, the quantum geometric tensor, and various entanglement quantities, including the entanglement entropy, the SVD entropy, and the Tu-Tzeng-Chang entropy. Our results show that a sudden quench into a PT-broken phase generally leads to exponential growth in these quantities, driven by the biorthogonal density matrix’s non-positivity. In contrast to generic interacting systems, we observe a surprising linear decay in the TTC entropy for non-interacting fermionic systems. This finding originates from the approximate spectral symmetry of the biorthogonal reduced density matrix, and we confirm our findings using the Yang-Lee and non-Hermitian XXZ models.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
12 pages, 6 figures, 1 table. Based on Hsueh-Hao Lu’s Master’s thesis (National Tsing Hua University Library) and preliminary results presented by Hsueh-Hao Lu at APS March Meeting 2025
Inelastic Neutron Scattering for Direct Detection of Chiral Phonons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Tingting Wang, Jun Zhou, Qingyong Ren, Lifa Zhang
Chiral phonons have attracted significant attention due to their potential applications in spintronics, superconductivity, and advanced materials, but their detection has predominantly relied on indirect photon-involved processes. Here, we propose inelastic neutron scattering (INS) as a direct and versatile approach for chiral phonon detection over a broad momentum-energy space. Leveraging INS sensitivity to phonon eigenmodes, we clearly distinguish linear, elliptical, and chiral phonons and determine phonon handedness through angle-resolved measurements. Using right-handed tellurium (Te) as a model system, we identify characteristic INS fingerprints that clearly separate chiral from linear phonons. Moreover, we show that INS can directly access phonon magnetic moments and the effective magnetic fields generated by chiral phonons, as evidenced by the pronounced mode splitting in CeF$ _3$ . Collectively, these results position INS as a powerful platform for comprehensive investigations of chiral-phonon dynamics and their associated quantum phenomena.
Materials Science (cond-mat.mtrl-sci)
Knot-Driven Spin Selectivity: Topological Chirality-Induced Robust Spin Polarization in Molecular Knots
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Xi Sun, Kai-Yuan Zhang, Shu-Zheng Zhou, Hua-Hua Fu
Compared to traditional structural chiral materials (e.g., DNA, helicene), topological chirality in trefoil knot molecules has demonstrated multiple remarkable advantages in chirality-induced spin selectivity (CISS), including ultra-high spin polarization of nearly 90%, conductivity increased by two orders of magnitude, and high-temperature stability (up to 350$ ^{\circ}$ C). However, the underlying physical mechanism remains elusive. This work establishes, for the first time, a fundamental theoretical framework for topological chirality-induced spin selectivity (TCISS) in trefoil knot molecules and identifies the necessary conditions for knot-driven spin selectivity. Our calculation results reveal that a trefoil knot molecule can exhibit spin polarization exceeding 60% along with significant conductivity. Notably, neither reducing the lattice number nor applying strain regulation significantly diminishes this ultra-high spin polarization, highlighting its robustness. Importantly, when the topological knot degenerates into a trivial structure, accompanied by the transition from topological chirality to structural chirality, the spin polarization sharply declines, demonstrating a strong correlation between the ultrahigh spin polarization and the knot topology. Our theory not only successfully elucidates the physical mechanism of TCISS, but also uncovers a new spin-polarized transport phenomenon termed knot-driven spin selectivity, offering new guiding principles for designing nonmagnetic materials for spintronics device applications.
Materials Science (cond-mat.mtrl-sci)
13 pages, 5 figures
Time-bin qubit architecture using quantum Hall edge channels
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
David Pomaranski, Michihisa Yamamoto
We present the basic elements for a modular architecture for time-bin encoded qubits based on quantum Hall edge channels, forming the foundation of a scalable electronic quantum information platform named TEMPO (Time-binned Electronic Modular Platform for Qubits). Quantum states are encoded in temporally separated edge magnetoplasmon (EMP) wave packets propagating along a single chiral edge, eliminating the need for spatial path separation and enhancing coherence. The platform supports full qubit operations$ \unicode{x2013}$ including initialization, phase modulation, readout, and two-qubit entangling gates$ \unicode{x2013}$ by leveraging dynamically tunable quantum point contacts and electrostatic control of interferometric loops. We consider the linear dispersion and gate-induced velocity control on EMP propagation and describe strategies for maintaining waveform integrity. Various single-electron sources, including ohmic injection and capacitive excitation, are discussed in the context of coherence. Multi-qubit operations are enabled through synchronized injection and engineered Coulomb interactions between adjacent channels, while single-qubit readout is addressed via spin-based or capacitive charge sensors. Our approach integrates gate-tunable coherent control of chiral edge states, offering a comprehensive pathway toward scalable electron quantum optics in solid-state platforms.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
High-reflectivity homoepitaxial distributed Bragg reflectors for photonic applications
New Submission | Other Condensed Matter (cond-mat.other) | 2025-07-29 20:00 EDT
Helena Janowska, Anna Musiał, Grzegorz Sęk
Distributed Bragg reflectors (DBRs) are one of the basic photonic structures used to define microcavities for fundamental light-matter coupling studies, as well as to optimize performance of optoelectronic and photonic devices, e.g., lasers or non-classical light sources. The reflectivity of these structures depends critically on the refractive index contrast between the two quarter-wavelength thick layers constituting the DBR. At the same time, epitaxial fabrication process limits the choice of materials to those with the same, or very similar lattice constant to avoid strain accumulation in the relatively thick multilayer structure. This becomes very often a bottleneck for the DBR designs at certain wavelengths or for some of the material systems. Therefore, we explore theoretically DBR designs employing the reflective index contrast between undoped and doped layers of the same material, making the entire growth process homoepitaxial. The refractive index for a doped layer is calculated taking into account the free carrier absorption, carrier-carrier interaction, the Burnstein-Moss and plasma effects. The reflectivity spectrum of a DBR is further calculated using transfer matrix method. Exemplary results for three application relevant materials - hBN, InP and Si suitable for different spectral ranges, i.e. ultraviolet, telecommunication and mid-infrared, respectively, are presented. We report reflectivities on the level of 90% for technologically achievable doping concentrations and moderate number of layer pairs.
Other Condensed Matter (cond-mat.other)
12 pages, 5 figures
Eigenvalue spectral tails and localization properties of asymmetric networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-07-29 20:00 EDT
Pietro Valigi, Joseph W. Baron, Izaak Neri, Giulio Biroli, Chiara Cammarota
In contrast to the neatly bounded spectra of densely populated large random matrices, sparse random matrices often exhibit unbounded eigenvalue tails on the real and imaginary axis, called Lifshitz tails. In the case of asymmetric matrices, concise mathematical results have proved elusive. In this work, we present an analytical approach to characterising these tails. We exploit the fact that eigenvalues in the tail region have corresponding eigenvectors that are exponentially localised on highly-connected hubs of the network associated to the random matrix. We approximate these eigenvectors using a series expansion in the inverse connectivity of the hub, where successive terms in the series take into account further sets of next-nearest neighbours. By considering the ensemble of such hubs, we are able to characterise the eigenvalue density and the extent of localisation in the tails of the spectrum in a general fashion. As such, we classify a number of different asymptotic behaviours in the Lifshitz tails, as well as the leading eigenvalue and the inverse participation ratio. We demonstrate how an interplay between matrix asymmetry, network structure, and the edge-weight distribution leads to the variety of observed behaviours.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
36 pages and 10 figures in main text, 35 pages and 1 figure in supplemental material
A Gross-Pitaevskii theory for an excitonic incompressible Bose solid
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-07-29 20:00 EDT
Sara Conti, Andrey Chaves, Alexander R. Hamilton, Jacques Tempere, Milorad V. Milosevic, David Neilson
We show that interlayer excitons in double-layer semiconductor heterostructures can form a Bose solid, which is an incompressible supersolid characterized by exactly one boson per lattice site. This exciton Bose solid would be the first realization of an incompressible supersolid, unlike the generally compressible cluster supersolids seen in dipolar quantum gases. Capturing its characteristics and associated emergent phenomena requires extending the Gross-Pitaevskii formalism to include strong two-particle correlations and exclude exciton self-interactions. We develop such a formalism, we apply it across experimentally accessible exciton densities and interlayer separations, and we show that it incorporates both superfluid and incompressible supersolid ground states. This extended framework allows us to determine the superfluid-supersolid transition and explore the low-temperature properties of the exciton supersolid across its complete parameter space.
Quantum Gases (cond-mat.quant-gas), Other Condensed Matter (cond-mat.other)
Electron transport through mesoscopic junctions revisited
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Theoretical foundations of electron transport in mesoscopic systems, based on Landauer theory, Master equations or Onsager linear thermodynamics, are revisited to show that the noniteracting electrons model is insufficient to describe neither passive transport, nor generation of electromotive force (active transport). It is argued that 2-body electrostatic interactions creating double layers and surface charge distributions are crucial for the electron transport through a junction. Phenomenological modifications of the passive transport formulas based on the carefull analysis of the fundamental notions of chemical, electrostatic, electrochemical, build-in potentials, band bending and bias voltage, are proposed. On the other hand active transport can be generated by a self-oscillating double layer (a pump ) driven by an external heat, light or chemical energy source.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 4 figures
Quantum Imaging of Ferromagnetic van der Waals Magnetic Domain Structures at Ambient Conditions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Bindu, Amandeep Singh, Amir Hen, Lukas Drago Cavar, Sebastian Maria Ulrich Schultheis, Shira Yochelis, Yossi Paltiel, Andrew F. May, Angela Wittmann, Mathias Klaui, Dmitry Budker, Hadar Steinberg, Nir Bar-Gill
Recently discovered 2D van der Waals magnetic materials, and specifically Iron-Germanium-Telluride ($ \rm Fe_{5}GeTe_{2}$ ), have attracted significant attention both from a fundamental perspective and for potential applications. Key open questions concern their domain structure and magnetic phase transition temperature as a function of sample thickness and external field, as well as implications for integration into devices such as magnetic memories and logic. Here we address key questions using a nitrogen-vacancy center based quantum magnetic microscope, enabling direct imaging of the magnetization of $ \rm Fe_{5}GeTe_{2}$ at sub-micron spatial resolution as a function of temperature, magnetic field, and thickness. We employ spatially resolved measures, including magnetization variance and cross-correlation, and find a significant spread in transition temperature yet with no clear dependence on thickness down to 15 nm. We also identify previously unknown stripe features in the optical as well as magnetic images, which we attribute to modulations of the constituting elements during crystal synthesis and subsequent oxidation. Our results suggest that the magnetic anisotropy in this material does not play a crucial role in their magnetic properties, leading to a magnetic phase transition of $ \rm Fe_{5}GeTe_{2}$ which is largely thickness-independent down to 15 nm. Our findings could be significant in designing future spintronic devices, magnetic memories and logic with 2D van der Waals magnetic materials.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Nonequilibrium Dynamics in a Quantum Spin Chain with Pump-Probe Resonant Inelastic X-ray Scattering
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Menglian Shi, Zhengzhong Du, Yi Lu
We investigate the nonequilibrium dynamics of the transverse field Ising chain (TFIC) using time-resolved resonant inelastic X-ray scattering (tr-RIXS) in a pump-probe setup within a condensed matter setting. The tr-RIXS spectra reveal distinctive features, including two-kink continua at high energies and oscillatory spectral weight at low energies, both strongly influenced by the pump dynamics. By systematically analyzing the nonequilibrium tr-RIXS cross section under various pump configurations, we demonstrate how the spectra encode detailed information about the system’s transient states, capturing instantaneous Hamiltonian parameters and the traversal of equilibrium quantum critical points during dynamic evolution. Notably, we uncover a one-to-one correspondence between oscillatory features in the low-energy spectra and dynamical quantum phase transitions, offering a novel and experimentally accessible approach for their detection. These findings highlight the versatility of tr-RIXS as a powerful tool for studying quantum systems far from equilibrium and their critical phenomena.
Strongly Correlated Electrons (cond-mat.str-el)
Type-II Antiferroelectricity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Yang Wang, Chaoxi Cui, Yilin Han, Tingli He, Weikang Wu, Run-Wu Zhang, Zhi-Ming Yu, Shengyuan A. Yang, Yugui Yao
Antiferroelectricity (AFE) is a fundamental concept in physics and materials science. Conventional AFEs have the picture of alternating local electric dipoles defined in real space. Here, we discover a new class of AFEs, termed type-II AFEs, which possess opposite polarizations defined in momentum space across a pair of symmetry decoupled subspaces. Unlike conventional AFEs, the order parameter of type-II AFEs is rigorously formulated through Berry-phase theory and can be quantitatively extracted from the electronic band structure. Focusing on a subclass of type-II AFEs that preserve spin-rotation symmetry, we establish the relevant symmetry constraints and identify all compatible spin point groups. Remarkably, we find that type-II AFE order intrinsically coexists with antiferromagnetism, revealing a robust form of magnetoelectric coupling. We construct an altermagnetic model and identify several concrete antiferromagnetic/altermagnetic materials, such as FeS, Cr2O3, MgMnO3, monolayer MoICl2 and bilayer CrI3, that exhibit this novel ordering. Furthermore, we uncover unique physical phenomena associated with type-II spin-AFE systems, including spin current generation upon AFE switching and localized spin polarization at boundaries and domain walls. Our findings reveal a previously hidden class of quantum materials with intertwined ferroic orders, offering exciting opportunities for both fundamental exploration and technological applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Pairing without $γ$-Pocket in the La$_3$Ni$_2$O$_7$ Thin Film
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
Zhi-Yan Shao, Chen Lu, Min Liu, Yu-Bo Liu, Zhiming Pan, Congjun Wu, Fan Yang
The recent discovery of high-temperature superconductivity (HTSC) in the La$ 3$ Ni$ 2$ O$ 7$ ultrathin film at ambient pressure has aroused great research interest. The $ \gamma$ -pocket formed by the bonding $ d{z^2}$ band, which was previously proposed to be crucial in the pairing mechanism of pressurized bulk La$ 3$ Ni$ 2$ O$ 7$ , is reported to be either present or absent here by different experimental groups, giving rise to the problem: what is the pairing mechanism and pairing nature without the $ \gamma$ -pocket? Here, we start from a band structure obtained via density-functional-theoretical calculation, which exhibits no $ \gamma$ -pocket. Then, equipped with electron interactions, we study the pairing nature via combined weak- and strong- coupling approaches, which provide consistent results. In the weak-coupling study, the nesting between the $ \alpha$ - and $ \beta$ - pockets leads to an $ s^\pm$ -wave pairing in which the gap signs on the two pockets are opposite, as provided by our random-phase-approximation based calculations. In real-space, the pairing pattern is dominated by the interlayer pairing of the $ d{x^2-y^2}$ orbital. In the strong-coupling study, as the $ d{z^2}$ orbitals are nearly half-filled and hence localized, the $ d{x^2-y^2}$ orbitals carry the HTSC. Driven by the interlayer superexchange transferred from the $ d{z^2}$ orbital through the Hund’s rule coupling, the $ d{x^2-y^2}$ orbital electrons form interlayer $ s$ -wave pairing, as suggested by our slave-boson-mean-field study on the related two-orbital $ t$ -$ J$ model. Projected onto the Fermi surface, this pairing just gives the $ s^\pm$ -wave pattern consistent with that obtained in the weak-coupling study. Our result is consistent with that obtained in recent scanning tunneling microscopy experiment.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Spectral shadows of a single GaAs quantum dot
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Kai Hühn, Lena Klar, Fei Ding, Arne Ludwig, Andreas D. Wieck, Jens Hübner, Michael Oestreich
Semiconductor quantum dots are a promising platform for generating single and entangled this http URL, their use is limited even in the most advanced structures by changes in the charge state of the quantum dot and its environment. Here, we present detailed time-resolved resonance fluorescence measurements on a single charge-tunable GaAs quantum dot, shedding new light on the spectral shadows invoked by the complex impurity environment. Detuning-dependent measurements reveal the existence of multiple Stark-shifted resonances, which are associated with rare spectral jumps smaller than the homogeneous linewidth and, therefore, typically concealed in the measurement noise. We observe similar environmentally induced Stark shifts for both the neutral exciton and negatively charged trion transitions, while the positively and doubly negatively charged trions exhibit significant differences. Our investigation quantifies the underlying impurity charge dynamics over a range from well below milliseconds to seconds, revealing that the hole occupation of the positively charged trion transition is constrained by rapid hole loss and slow hole recapture dynamics. Utilizing a second non-resonant laser, we increase the hole occupancy by over an order of magnitude and identify both a prolonged hole residence time and an enhanced hole tunneling rate into the quantum dot. These findings are supported by complementary spin noise spectroscopy measurements, which offer a significantly higher bandwidth compared to the time-resolved resonance fluorescence measurements.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Variational study of the magnetization plateaus of the spin-$\frac{1}{2}$ kagome Heisenberg antiferromagnet and its implication on YCOB
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Numerical simulations find that there are multiple plateaus in the magnetization curve of the spin-$ \frac{1}{2}$ Kagome antiferromagnetic Heisenberg model(KAFH) at fractional magnetization $ m=1/9,1/3,5/9,7/9$ . While it is well known that the $ m=1/3,5/9,7/9$ plateau feature a $ \sqrt{3}\times\sqrt{3}$ valence bond crystal(VBC) ordering pattern with a David-star-shaped motif, the origin of the narrow plateau at $ m=1/9$ remains elusive. Some researchers claim that a subtle translational symmetry breaking pattern with the same $ \sqrt{3}\times\sqrt{3}$ periodicity occurs at the $ m=1/9$ plateau. On the other hand, it has also been argued that the $ m=1/9$ plateau may harbor a novel $ Z_{3}$ chiral spin liquid phase. To resolve this controversy, we have proposed the most general variational ansatz based on the resonating valence bond(RVB) picture that is consistent with the spin symmetry of the system and developed a new algorithm to optimize such a complicated ansatz. We find that a peculiar VBC state with a $ 3\times3$ periodicity and a windmill-shaped motif has significantly lower energy than the claimed $ Z_{3}$ chiral spin liquid state and other proposed VBC states around the $ m=1/9$ plateau. We find that there are strong spatial modulation in the local magnetization at the $ 1/9$ plateau, so strong that even its polarization can be reversed. Our general RVB ansatz also well reproduces all other more conventional magnetization plateaus of the spin-$ \frac{1}{2}$ KAFH. We find that the local magnetization is always strongly inhomogeneous below the saturating field for such a strongly frustrated quantum magnet.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages,6 figures
Two fluctuating interfaces with sticking interactions: Invariant measures and dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
Samvit Mahapatra, Malay Bandyopadhyay, Mustansir Barma
We introduce and study a non-equilibrium stochastic model of two fluctuating interfaces which interact through short-range attractive interactions at their points of contact. Beginning from an entangled state, the system exhibits diverse dynamics – ranging from fast transients with small lifetimes to ultraslow evolution through quasi-stationary states – and reaches stuck, entangled, or detached steady states. Near the stuck-detached transition, two distinct dynamical modes of evolution co-occur. When the two surfaces evolve through similar dynamics (both Edwards-Wilkinson or both Kardar-Parisi-Zhang), the invariant measure is determined and found to have an inhomogeneous product form. This exact steady state is shown to be the measure of the equilibrium Poland-Scheraga model of DNA denaturation.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
5+2 pages, 7 figures, 5 pages supplemental materials
Third-order strong-coupling impurity solver for real-frequency DMFT: Accurate spectral functions for antiferromagnetic and photo-doped states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Lei Geng, Aaram J. Kim, Philipp Werner
We present a real-frequency third-order strong-coupling impurity solver which employs quantics tensor cross interpolation (QTCI) for an efficient evaluation of the diagram weights. Applying the method to dynamical mean-field theory (DMFT) calculations of the single-band Hubbard model on the Bethe lattice, we clarify the interaction and temperature range in which the third-order approach yields accurate results. Since the calculations are implemented on the real-time/frequency axis, the detailed structure of spectral functions can be obtained without analytical continuation, as we demonstrate with examples for paramagnetic, antiferromagnetic and photo-doped states. Our work establishes a viable path toward high-order, real-frequency impurity solvers for both equilibrium and non-equilibrium DMFT studies.
Strongly Correlated Electrons (cond-mat.str-el)
Angle-dependent chiral tunneling in biased twisted bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Nadia Benlakhouy, El Mustapha Feddi, Abdelouahed El Fatimy
In twisted bilayer graphene (TBLG), chiral tunneling can be tuned by parameters such as the twist angle, barrier height, and Fermi energy. This differs from the tunneling behavior observed in monolayer and Bernal bilayer graphene, where electrons either pass completely through or are fully blocked due to the Klein paradox. Here we investigate the effect of a perpendicular interlayer bias on electron tunneling through electrostatic barriers in TBLG. Using a dual-gated model, which controls the carrier density and interlayer potential difference independently, we compute the transmission and reflection probabilities of electrons at different angles and energies for representative twist angles of $ \theta = 1.8^{\circ}$ , $ 3.89^{\circ}$ , and $ 9.43^{\circ}$ . We find that a moderate bias suppresses normal-incidence transmission by opening a band gap in the low-energy spectrum. Our results show this leads to near-total reflection at low energy, with transmission starting to increase just above the gap due to twist-dependent conducting channels. The applied bias breaks the system’s effective inversion symmetry, resulting in pronounced direction-dependent and valley-specific asymmetries in the angular distribution of transmitted electrons. We show that electrons incident at different angles show notable variations in transmission under bias. Furthermore, interlayer bias modulates Fabry–Pérot–like resonances in the TBLG barrier, shifting the energies of transmission peaks and altering their intensity.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 4 figures
Low-energy atomic scattering: s-wave relation between the interaction potential and the phase shift
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-07-29 20:00 EDT
Francesco Lorenzi, Luca Salansich
We investigate the on-shell approximation in the context of s-wave scattering for ultracold two-body collisions. Our analysis systematically covers spatial dimensions D=1,2,3 , with the aim of identifying the regimes in which the approximation remains valid when applied to commonly used model interaction potentials. Specifically, we focus on the square well and delta shell potentials, both of which admit analytical solutions for the s-wave scattering problem in all dimensions considered. By employing the exact analytical expressions for the s-wave scattering phase shift, we perform a direct comparison between the exact on-shell matrix element of the interaction potential and their corresponding approximations across a range of collision momenta. Particular attention is given to the low-energy regime. Our findings indicate that, although the on-shell approximation generally improves with increasing momentum, its accuracy also improves for weaker potentials. Remarkably, in the limit of weak interactions, we demonstrate that the on-shell approximation becomes exact at leading order. In this regime, the approximation offers a controlled means of deriving the low-momentum expansion of the potential and may serve as a useful tool in constructing effective interactions for quantum field theories.
Quantum Gases (cond-mat.quant-gas), Nuclear Theory (nucl-th)
11 pages, 4 figures. To appear in Annalen der Physik
Entanglement Halos
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Nadir Samos Sáenz de Buruaga, Silvia N. Santalla, Germán Sierra, Javier Rodríguez-Laguna
We introduce the concept of entanglement halos, a set of strongly entangled distant sites within the ground state of a quantum many-body system. Such halos emerge in star-like systems with exponentially decaying couplings, as we show using both free-fermions and the spin-1/2 antiferromagnetic Heisenberg model. Depending on the central connectivity, entanglement halos may exhibit trivial and non trivial symmetry-protected topological features. Our findings highlight how geometry and connectivity can generate complex entanglement structures with rich physical content, which can be experimentally accessible via state-of-the-art technologies.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
5 pages + 9 pages of SM. 5 figures main text
Adjudicating Conduction Mechanisms in High Performance Carbon Nanotube Fibers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
John Bulmer, Chris Kovacs, Thomas Bullard, Charlie Ebbing, Timothy Haugan, Ganesh Pokharel, Stephen D. Wilson, Fedor F. Balakirev, Oscar A. Valenzuela, Michael A. Susner, David Turner, Pengyu Fu, Teresa Kulka, Jacek Majewski, Irina Lebedeva, Karolina Z. Milowska, Agnieszka Lekawa-Raus, Magdalena Marganska
The performance of carbon nanotube (CNT) cables, a contender for copper-wire replacement, is tied to its metallic and semi-conducting-like conductivity responses with temperature; the origin of the semi-conducting-like response however is an underappreciated incongruity in literature. With controlled aspect-ratio and doping-degree, over 61 unique cryogenic experiments including anisotropy and Hall measurements, CNT cable performance is explored at extreme temperatures (65 mK) and magnetic fields (60 T). A semi-conducting-like conductivity response with temperature becomes temperature-independent approaching absolute-zero, uniquely demonstrating the necessity of heterogeneous fluctuation induced tunneling; complete de-doping leads to localized hopping, contrasting graphite’s pure metallic-like response. High-field magneto-resistance (including +22% longitudinal magneto-resistance near room-temperature) is analyzed with hopping and classical two-band models, both similarly yielding a parameter useful for conductor development. Varying field-orientation angle uncovers two-and four-fold symmetries from Aharonov-Bohm-like corrections to curvature-induced bandgap. Tight-binding calculations using Green’s Function formalism model large-scale, coherent transport in commensurate CNT bundles in magnetic field, revealing non-uniform transmission across bundle cross-sections with doping restoring uniformity; independent of doping, transport in bundle-junction-bundle systems are predominantly from CNTs adjacent to the other bundle. The final impact is predicting the ultimate conductivity of heterogeneous CNT cables using temperature and field-dependent transport, surpassing conductivity of traditional metals.
Materials Science (cond-mat.mtrl-sci)
Predicting Chemically Accurate Adsorption Energy Using an Interpretable Deep Learning Model Pretrained by GGA Calculation Data
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-07-29 20:00 EDT
Molecular adsorption energy is a critical descriptor for high-throughput screening of heterogeneous catalysts and electrode materials. However, precise experimental adsorption energies are scarce due to the complexity of experiments, while density functional theory (DFT) calculations remain computationally expensive for large-scale material screening. Machine learning models trained on DFT data have emerged as a promising alternative, but face challenges such as functional dependency, limited labeled high-fidelity data, and interpretability issues. Herein, we present DOS Transformer for Adsorption (DOTA), a novel deep learning model that leverages local density of states (LDOS) as input to predict chemically accurate adsorption energies across metallic and intermetallic surfaces. DOTA integrates multi-head self-attention mechanisms with LDOS feature engineering to capture orbital interaction patterns, achieving superior accuracy and transferability. Pretrained on PBE-level DFT data, DOTA can be fine-tuned using minimal high-fidelity experimental or hybrid functional data to predict adsorption energies with chemical accuracy. The model resolves long-standing challenges, such as the “CO puzzle” and outperforms traditional theories, like the d-band center and Fermi softness models. It provides a robust framework for efficient catalyst and electrode screening, bridging the gap between computational and experimental approaches.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci)
Synchronized Circular Motion of Optically Confined Marangoni Microswimmers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-29 20:00 EDT
Sabera M. Borno, Robin Khisa, Israt H. Zarin, Md Hasan Mahmud, Nicholas D. Brubaker, Ryan C. Hayward, Nabila Tanjeem
Understanding the collective actuation of microscopic structures driven by external fields can lead to the development of next-generation autonomous machines. With this goal in mind, we investigated light-induced collective motion of thermocapillary microswimmers at the air-water interface. We found that Marangoni forces, which lead to long-ranged repulsive interparticle interactions, can cause microswimmers to synchronize their circular motion in a collective chase mode that resembles predator-prey behavior often observed in nature. We examined different degrees of confinement in small systems containing 2-6 particles of different individual swimming velocities and shapes. Thanks to the strong repulsive interactions between particles, a sustained chasing mode was observed for particle packing fractions above a critical value of 0.25. At lower packing fractions, swimmers transition between chasing, bouncing, and intermittent pausing, likely due to time-varying activity levels. Additionally, we report that a new synchronized mode can be introduced by incorporating chirality in particle shapes, where the microswimmers collectively reverse the direction of their circular motion periodically. Our results point to a simple but powerful mechanism of obtaining collective synchronization in synthetic confined systems where particles are designed with different shapes and activity levels.
Soft Condensed Matter (cond-mat.soft)
Geometric Superfluid Weight in Quasicrystals
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
Junsong Sun, Huaiming Guo, Bohm-Jung Yang
We study the geometric contribution to the superfluidity in quasicrystals in which the conventional momentum-space quantum geometric tensor cannot be defined due to the lack of translational invariance. Based on the correspondence between the momentum and magnetic flux, we introduce the flux-space quantum metric in finite-size closed systems and reveal its contribution to the superfluid weight in quasicrystalline superconductors. As a toy model, we study the attractive Hubbard model on the Fibonacci quasiperiodic stub lattices that host flat energy spectra even in the presence of quasiperiodic hoppings. In the weak-coupling limit, we establish the relation between superfluid weight and the flux-space quantum metric in quasicrystal superconductors with flat energy spectra. Moreover, by analyzing the spread of Wannier functions, we propose a general fluctuation mechanism that explains how quasiperiodicity modulates the integrated flux-space quantum metric. Our theory provides a general way to examine the effect of the quantum geometry in systems lacking translational symmetry.
Superconductivity (cond-mat.supr-con)
7 pages, 3 figures
Revealing Atomic-Scale Switching Pathways in van der Waals Ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Xinyan Li, Kenna Ashen, Chuqiao Shi, Nannan Mao, Saagar Kolachina, Kaiwen Yang, Tianyi Zhang, Sajid Husain, Ramamoorthy Ramesh, Jing Kong, Xiaofeng Qian, Yimo Han
Two-dimensional van der Waals (vdW) materials hold the potential for ultra-scaled ferroelectric (FE) devices due to their silicon compatibility and robust polarization down to atomic scale. However, the inherently weak vdW interactions enable facile sliding between layers, introducing complexities beyond those encountered in conventional ferroelectric materials and presenting significant challenges in uncovering intricate switching pathways. Here, we combine atomic-resolution imaging under in-situ electrical biasing conditions with first-principles calculations to unravel the atomic-scale switching mechanisms in SnSe, a vdW group-IV monochalcogenide. Our results uncover the coexistence of a consecutive 90 degrees switching pathway and a direct 180 degrees switching pathway from antiferroelectric (AFE) to FE order in this vdW system. Atomic-scale investigations and strain analysis reveal that the switching processes simultaneously induce interlayer sliding and compressive strain, while the lattice remains coherent despite the presence of multidomain structures. These findings elucidate vdW ferroelectric switching dynamics at atomic scale and lay the foundation for the rational design of 2D ferroelectric nanodevices.
Materials Science (cond-mat.mtrl-sci)
Finite-momentum mixed singlet-triplet pairing in chiral antiferromagnets induced by even-parity spin texture
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
Non-relativistic spin-splitting in unconventional antiferromagnets has garnered much attention for its promising spintronic applications and open fundamental questions. Here, we uncover a unique even-parity spin texture in chiral non-collinear antiferromagnets, exemplified using a kagome lattice. We consider two distinct types of electrons in the system: one with Schrödinger-like dispersion and the other exhibiting Dirac-like behavior. Remarkably, we show that, for both electron types, this spin texture induces an exotic coexistence of opposite-spin singlet and equal-spin triplet Cooper pairs with finite momentum when proximity-coupled to conventional superconductors. The triplet pairing arises from the intrinsic spin rotation of the antiferromagnet and does not require net magnetization or spin-orbit coupling. Moreover, we identify an unprecedented and tunable phase difference between singlet and triplet pairings, controllable through junction orientation. This mixed pairing state can be experimentally probed via damped oscillations in order parameters and 0-$ \pi$ transitions in Josephson junctions. Additionally, we analyze the effect of out-of-plane spin canting, elucidating its role in generating spin-polarized supercurrents, and discuss Mn$ _3$ Ga and Mn$ _3$ Ge to test our predictions.
Superconductivity (cond-mat.supr-con)
7 pages, 3 figures; submitted in March 2024; Comments are welcome!
A set of nearly good real numbers to specify the eigenstates of a medium-body system with two kinds of spin-1 cold atoms and with the Hamiltonian containing non-commutable terms
New Submission | Other Condensed Matter (cond-mat.other) | 2025-07-29 20:00 EDT
Yanzhang He, Yimin Liu, Chengguang Bao
A distinguished feature of multi-species boson systems is the appearance of the odd channel, in which the coupled spin of two different bosons is given by an odd number. Through exact numerical solutions of the Schrödinger equation for a medium-body cold system containing two types of spin-1 atoms, the effect of the odd channel has been studied. It was found that, due to the odd channel, the terms in the Hamiltonian are no longer all commutable. Accordingly, the combined spin of a single species is no longer conserved. However, when the parameters of interactions lie in some specific and broad domains, instead of a set of good quantum numbers, the ground-state (g.s.) can be specified by a set of nearly good real numbers. Each of them is not exactly a number but a very narrow interval on the positive real axis. The widths of the intervals would tend to zero when the particle numbers tend to infinity. When the parameters vary, the nearly good numbers can jump suddenly from one narrow interval to another well-separated narrow interval. Since the results of this paper are extracted from the exact solution of a medium-body system and not from a many-body approach as usual, for general many-body systems with Hamiltonians containing non-commutable terms, it remains to be clarified whether specific domains exist in the parameter space in which a set of nearly good real numbers can be used to specify the eigenstates.
Other Condensed Matter (cond-mat.other)
Vacancy induced expansion of spin-liquid regime in J1-J2 Heisenberg model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Soumyaranjan Dash, Anish Koley, Sanjeev Kumar
We study the model for spin-1/2 J1-J2 Heisenberg antiferromagnets on a square lattice in the presence of spin vacancies. In order to overcome the methodological challenges associated with analyzing models with magnetic frustration and inhomogeneities, we introduce a new semi-classical approach in which singlet dimers are treated as effective classical degrees of freedom. The energetic and entropic aspects of the dimer formation are included via a classical Monte Carlo scheme that allows for the dynamical conversion of spin pairs into dimers and vice versa. We show that our semi-classical approach recovers the qualitative physics of the J1-J2 model in the absence of vacancies. The vacancies lead to a broadening of the spin-liquid regime between the Néel and the stripe antiferromagnetic phases. This suggests a possible new route to discover spin-liquid ground states by tuning the J2/J1 ratio in doped square lattice antiferromagnets.
Strongly Correlated Electrons (cond-mat.str-el)
8 figures
Magnetically controlled double-twist director configuration of lyotropic chromonic liquid crystals in cylinders: Energetics, topological defects, and instability
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-29 20:00 EDT
We study experimentally how the double-twist (DT) configuration of cylindrically confined lyotropic chromonic liquid crystals (LCLCs) responds to axial magnetic fields. Our director field model unveils the energetics behind the magnetic field-induced transition in the twist profile of the DT configuration. Additionally, we catalog three different types of topological defects – residing between the DT domains of opposite handedness – before and after the field application, and propose a new director field model for the defect with a ring disclination. Lastly, we report a symmetry-breaking instability occurring when the field strength exceeds a critical value, suggesting an eccentric DT director field model that reproduces a helix-like optical texture. Our systematic investigation not only enhances our understanding of LCLC energetics but also provides potential for precise control over DT configurations.
Soft Condensed Matter (cond-mat.soft)
Characterizing local Majorana properties using Andreev states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Miguel Alvarado, Alfredo Levy Yetati, Ramón Aguado, Rubén Seoane Souto
We propose using Andreev bound states (ABS) as spectroscopic probes to characterize Majorana zero modes (MZMs) in quantum-dot based minimal Kitaev chains. Specifically, we show that tunneling conductance measurements with a superconducting probe hosting an ABS reveal four subgap peaks whose voltage positions and relative heights enable extraction of the MZM energy splitting and Bogoliubov-de Gennes coherence factors. This provides direct access to zero-splitting regimes and to the local Majorana polarization - a measure of the Majorana character. The method is compatible with existing experimental architectures and remains robust in extended chains.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
16 pages, 7 figures
Perturbative Analysis of the Field-Free Josephson Diode Effect in a Multilayered Josephson Junction
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
The Josephson diode effect (JDE) is a novel phenomenon in which a superconducting junction exhibits asymmetric Josephson currents with respect to the superconducting phase difference. In this study, we theoretically investigate how the interplay between a static exchange field and Rashba spin-orbit interaction (RSOI) influences the JDE. By employing the quasiclassical Green’s function method and perturbative calculations, we derive analytical expressions for the Josephson current in a junction composed of a ferromagnetic layer and a normal metal with RSOI. Remarkably, the JDE is found to emerge even in the absence of any external magnetic field. In this regime, the Josephson current is exclusively carried by spin-triplet Cooper pairs, as spin-singlet components are strongly suppressed by the ferromagnet. Furthermore, our results show that the efficiency of the JDE can be enhanced by tuning the thickness of the normal metal and the strength of the RSOI. These findings offer valuable theoretical guidelines for the design of superconducting devices exhibiting nonreciprocal transport effects.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
23 pages, 9 figures
J. Phys. Soc. Jpn. 94, 094701 (2025)
Localized Edge States in Stacked Al/Ni Multilayers: Possible Evidence of Chiral Hinge Modes
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
M. Belogolovskii, I. P. Nevirkovets
Here, we report experimental evidence suggesting the emergence of robust, possibly chiral, edge states in artificially engineered multilayers composed of alternating nanometer-thick layers of nonmagnetic aluminum (Al) and ferromagnetic nickel (Ni). Using phase-sensitive Josephson interferometry, we observed distinct SQUID-like oscillations (instead of the conventional Fraunhofer patterns) in the maximum supercurrent versus in-plane probing magnetic field patterns, which can be associated with one-dimensional current-carrying modes localized at the sample boundaries. These results were obtained for multilayers consisting of up to ten Al/Ni bilayers sandwiched between superconducting Nb electrodes to form Josephson junctions. The spatially confined flow of supercurrent suggests the possible presence of chiral Andreev edge states reminiscent of those found in higher-order topological insulators, despite the absence of strong spin-orbit coupling or intrinsic topological band structure. The discovery of edge-localized charge transport in structures made of materials without intrinsic topological order challenges the prevailing understanding of topological phenomena and highlights the possibility of developing topological metamaterials as a tunable platform for exploring nontrivial edge physics.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
20 + 12 pages, 3 + 8 figures
Ultrafast transition from coherent to incoherent polariton nonlinearities in a hybrid 1L-WS2/plasmon structure
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Daniel Timmer, Moritz Gittinger, Thomas Quenzel, Alisson R. Cadore, Barbara L.T. Rosa, Wenshan Li, Giancarlo Soavi, Daniel C. Lünemann, Sven Stephan, Lara Greten, Marten Richter, Andreas Knorr, Antonietta De Sio, Martin Silies, Giulio Cerullo, Andrea C. Ferrari, Christoph Lienau
Exciton polaritons based on atomically thin semiconductors are essential building blocks of quantum optoelectronic devices. Their properties are governed by an ultrafast and oscillatory energy transfer between their excitonic and photonic constituents, resulting in the formation of polaritonic quasiparticles with pronounced nonlinearities induced by the excitonic component. In metallic nanoresonators, dissipation phenomena limit the polariton lifetime to a few ten femtoseconds, so short that the role of these polaritons for the nonlinearities of such hybrids is yet unexplored. Here, we use ultrafast two-dimensional electronic spectroscopy (2DES) to uncover coherent polariton dynamics in a hybrid monolayer (1L) WS2/plasmonic nanostructure. With respect to an uncoupled WS2 flake, we observe an over 20-fold, polarization-dependent enhancement of the optical nonlinearity and a rapid evolution of the 2DES spectra within ~70 fs. We relate these dynamics to a transition from coherent polaritons to incoherent excitations, unravel the microscopic optical nonlinearities, and show the potential of coherent polaritons for ultrafast all-optical switching.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 4 figures
High-fidelity modeling of interface crossing in the diffusion welding process at the polycrystalline scale
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Camille Godinot, Emmanuel Rigal, Frédéric Bernard, Philippe Emonot, Pierre-Eric Frayssines, Luc Védie, Marc Bernacki
Controlling the microstructure of a diffusion welded interface is a critical point to ensure optimum mechanical properties and the homogeneity of the joint. Beyond the intimate contact formation between bonded parts studied in the literature, this article focuses on the grain boundary crossing of the interface during this process and its measurement. Following this perspective, a Level-Set method has been used for full-field microstructure simulations in 2D with various interface parameters. Two crossing measurement models have been formulated, tested and discussed over the simulations.
Materials Science (cond-mat.mtrl-sci)
Pressure-Driven Moiré Potential Enhancement and Tertiary Gap Opening in Graphene/h-BN Heterostructure
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Yupeng Wang, Jiaqi An, Chunhui Ye, Xiangqi Wang, Di Mai, Hongze Zhao, Yang Zhang, Chiyu Peng, Kenji Watanabe, Takashi Taniguchi, Xiaoyu Sun, Rucheng Dai, Zhongping Wang, Wei Qin, Zhenhua Qiao, Zengming Zhang
Moiré superlattices enable engineering of correlated quantum states through tunable periodic potentials, where twist angle controls periodicity but dynamic potential strength modulation remains challenging. Here, we develop a high-pressure quantum transport technique for van der Waals heterostructures, achieving the ultimate pressure limit (~9 GPa) in encapsulated moiré devices. In aligned graphene/h-BN, we demonstrate that pressure induces a substantial enhancement of the moiré potential strength, evidenced by the suppression of the first valence bandwidth and the near-doubling of the primary band gap. Moreover, we report the first observation of a tertiary gap emerging above 6.4 GPa, verifying theoretical predictions. Our results establish hydrostatic pressure as a universal parameter to reshape moiré band structures. By enabling quantum transport studies at previously inaccessible pressure regimes, this Letter expands the accessible parameter space for exploring correlated phases in moiré systems.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Phys. Rev. Lett. 135, 046303 (2025)
Differentiation of Site-Specific Symmetry Breaking Orders in Y$_{1-x}$Pr$_x$Ba$_2$Cu$3$O${6+y}$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
L. Martinelli, S. Rüdiger, I. Bialo, J. Oppliger, F. Igoa Saldana, M. v. Zimmermann, E. Weschke, R. Arpaia, J. Chang
Solid matter is classified through symmetry of ordering phenomena. Experimentally, this approach is straightforward, except when distinct orderings occur with identical or almost identical symmetry breaking. Here we show that the cuprate system Y$ _{1-x}$ Pr$ _x$ Ba$ _2$ Cu$ _3$ O$ _{6+y}$ hosts two distinct orderings with almost identical translational symmetry breaking. Only when applying site-sensitive resonant elastic x-ray scattering (REXS), charge ordering can be conclusively differentiated from a super-lattice structure. These two orderings occur with almost the same in-plane symmetry but manifest at different atomic sites and display different temperature dependence. Differentiating these orders provides an important clue to the anomalous behavior of PrBa$ _2$ Cu$ _3$ O$ _7$ within the 123-series of high-temperature superconductors. We conclude that the symmetry breaking at the Pr-site is unfavorable for superconducting pairing.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Supplemental Material available upon request
hBN alignment orientation controls moiré strength in rhombohedral graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Matan Uzan, Weifeng Zhi, Matan Bocarsly, Junkai Dong, Surajit Dutta, Nadav Auerbach, Niladri Sekhar Kander, Mikhail Labendik, Yuri Myasoedov, Martin E. Huber, Kenji Watanabe, Takashi Taniguchi, Daniel E. Parker, Eli Zeldov
Rhombohedral multilayer graphene hosts a rich landscape of correlated symmetry-broken phases, driven by strong interactions from its flat band edges. Aligning to hexagonal boron nitride (hBN) creates a moiré pattern, leading to recent observations of exotic ground states such as integer and fractional quantum anomalous Hall effects. Here, we show that the moiré effects and resulting correlated phase diagrams are critically influenced by a previously underestimated structural choice: the hBN alignment orientation. This binary parameter distinguishes between configurations where the rhombohedral graphene and hBN lattices are aligned near 0° or 180°, a distinction that arises only because both materials break inversion symmetry. Although the two orientations produce the same moiré wavelength, we find their distinct local stacking configurations result in markedly different moiré potential strengths. Using low-temperature transport and scanning SQUID-on-tip magnetometry, we compare nearly identical devices that differ only in alignment orientation and observe sharply contrasting sequences of symmetry-broken states. Theoretical analysis reveals a simple mechanism based on lattice relaxation and the atomic-scale electronic structure of rhombohedral graphene, supported by detailed modeling. These findings establish hBN alignment orientation as a key control parameter in moiré-engineered graphene systems and provide a framework for interpreting both prior and future experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Tunneling Dynamics and Time Delay in Electron Transport through Time-Dependent Barriers with Finite-Bandwidth Reservoirs
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Shmuel Gurvitz, Dmitri Sokolovski
We present a transparent and analytically tractable approach to the problem of time-dependent electron transport through tunneling barriers. Using the Single-Electron Approach, we study a model system composed of a time-dependent tunneling barrier coupled to two reservoirs of finite bandwidth. Avoiding Floquet expansions, we derive simple expressions for the time-dependent tunneling current in both adiabatic and non-adiabatic regimes. Our formulation, based on the tunneling Hamiltonian framework, relates barrier modulation to measurable phase shifts in the steady-state current, offering a physically intuitive definition of the tunneling (or traversal) time. Remarkably, in the Markovian limit (wide-band reservoirs), we recover the well-known result of vanishing tunneling time. In contrast, for finite-bandwidth leads, we predict a finite time delay given by the inverse bandwidth. Our findings provide a robust foundation for understanding tunneling dynamics in non-Markovian environments and may serve as a benchmark for experimental investigations involving tunable band structures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
6 pages, 3 figures
Towards trustworthy AI in materials mechanics through domain-guided attention
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Jesco Talies, Eric Breitbarth, David Melching
Ensuring the trustworthiness and robustness of deep learning models remains a fundamental challenge, particularly in high-stakes scientific applications. In this study, we present a framework called attention-guided training that combines explainable artificial intelligence techniques with quantitative evaluation and domain-specific priors to guide model attention. We demonstrate that domain specific feedback on model explanations during training can enhance the model’s generalization capabilities. We validate our approach on the task of semantic crack tip segmentation in digital image correlation data which is a key application in the fracture mechanical characterization of materials. By aligning model attention with physically meaningful stress fields, such as those described by Williams’ analytical solution, attention-guided training ensures that the model focuses on physically relevant regions. This finally leads to improved generalization and more faithful explanations.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Configurational Entropy and Its Scaling Behavior in Lattice Systems with Number of States Defined by Coordination Numbers
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
Youshen Wu, Xin Guan, Shengli Zhang, Lei Zhang
We introduce an exactly solvable lattice model that reveals a universal finite-size scaling law for configurational entropy driven purely by geometry. Using exact enumeration via Burnside’s lemma, we compute the entropy for diverse 1D, 2D, and 3D lattices, finding that the deviation from the thermodynamic limit $ s_{\infty} = \ln (z)$ scales as $ \Delta s_{N} \sim N^{-1/d}$ , with lattice-dependent higher-order corrections. This scaling, observed across structures from chains to FCC and diamond lattices, offers a minimal framework to quantify geometric influences on entropy. The model captures the order of magnitude of experimental residual entropies (e.g., $ S_{\mathrm{molar}} = R \ln 12 \approx 20.7 , \mathrm{J/mol \cdot K}$ ) and provides a reference for understanding entropy-driven order in colloids, clusters, and solids.
Statistical Mechanics (cond-mat.stat-mech), Classical Physics (physics.class-ph)
Thermodynamics of the hyperkagome-lattice $S=1/2$ Heisenberg ferromagnet
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Maksym Parymuda, Taras Krokhmalskii, Oleg Derzhko
The hyperkagome-lattice $ S=1/2$ Heisenberg ferromagnet is studied by means of the linear spin-wave theory, the double-time temperature Green’s function method, high-temperature expansions series analysis, and quantum Monte Carlo simulations to examine the effect of lattice geometry on the finite-temperature properties. In particular, we have found that the Curie temperature $ T_c$ for the hyperkagome-lattice (frustrated lattice) ferromagnet is about $ 0.33\vert J\vert$ that is smaller than $ T_c$ for the diamond-lattice (another three-dimensional lattice with the same coordination number 4 but bipartite one) ferromagnet by about $ 25%$ .
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
9 pages, 6 figures
Flat-band projected versus fully atomistic twisted bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Miguel Sánchez Sánchez, Tobias Stauber
We benchmark the recently proposed projection method [Phys. Rev. B 111, 205133 (2025)] for magic-angle twisted bilayer graphene (MATBG) across various symmetry-breaking phases at charge neutrality. The flat-band projected solutions agree well with the full tight-binding, with band structures and total energies differing by only a few meV. The projection to the flat bands is justified, owing to the increased gap to the remote bands in the normal state. Moreover, we employ a novel set of order parameters that allow us to visualize the wave functions locally in real space and quantify the breaking of various symmetries in the correlated phases. These order parameters are suitable to characterize MATBG and generic honeycomb systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 5 figures, 2 tables
Sliding Engineering Spin-Valley-Layer Coupling and Altermagnetism in Bilayer Antiferromagnetic Honeycomb Lattices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Wen-Xin Jiang, Zhen-Hao Gong, Yuantao Chen, Zhigang Gui, Li Huang
Valley polarization and altermagnetism are two emerging fundamental phenomena in condensed matter physics, offering unprecedented opportunites for information encoding and processing in novel energy-efficient devices. By coupling valley and spin degrees of freedom with ferroic orders such as ferroelectricity, nonvolatile memory functionalities can be achieved. Here, we propose a way to realize ferroelectric-valley (FE-valley) and FE-altermagnetic coupling in a bilayer antiferromagnetic (AFM) honeycomb lattices based on an effective four-band spin-full $ k\cdot p$ model. Our proposal is validated in bilayer MnPTe$ _3$ through first-principles calculations. A spontaneous out-of-plane electric polarization occurs in AB- (BA-) stacking configuration, which is reversibly switchable via interlayer sliding. Remarkably, polarization reversal simultaneously inverts both layer-resolved valley polarization and altermagnetic spin splitting. This dual control enables tunable layer-spin-locked anomalous valley Hall effects and an unprecedented magnetoelectric response in 2D antiferromagnets. Our work establishes a general paradigm for electrically programmable valleytronic and spintronic functionalities of 2D AFM materials.
Materials Science (cond-mat.mtrl-sci)
Dynamical phase transition in a strongly hybridized phonon-triplon chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
We study a dimerized spin-1/2 chain, such as CuGeO$ _3$ , hosting triplon excitations coupled to optical phonons under weak terahertz laser driving. Both phonons and triplons weakly lose energy into the surrounding baths, forming a non-equilibrium steady state. In the strong phonon-triplon coupling regime, phonons near the two-triplon continuum hybridize strongly with triplons. Using mean-field Lindblad dynamics, we show that this strong hybridization induces sharp first-order phase transitions – either single or simultaneous double – in the emission spectrum, mainly due to dissipation-induced nonlinearities. Using mean-field Floquet analysis of harmonic modes in both sectors, we analytically confirm the existence of these phase transitions. Furthermore, we map the complete steady-state phase diagram by varying key control parameters and provide experimentally relevant parameters for observing these transitions in laser-driven CuGeO$ _3$ .
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 5 figures
Cascade of Even-Denominator Fractional Quantum Hall States in Mixed-Stacked Multilayer Graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Yating Sha, Kai Liu, Chenxin Jiang, Dan Ye, Shuhan Liu, Zhongxun Guo, Jingjing Gao, Ming Tian, Neng Wan, Kenji Watanabe, Takashi Taniguchi, Bingbing Tong, Guangtong Liu, Li Lu, Yuanbo Zhang, Zhiwen Shi, Zixiang Hu, Guorui Chen
The fractional quantum Hall effect (FQHE), particularly at half-filling of Landau levels, provides a unique window into topological phases hosting non-Abelian excitations. However, experimental platforms simultaneously offering large energy gaps, delicate tunability, and robust non-Abelian signatures remain scarce. Here, we report the observation of a cascade of even-denominator FQH states at filling factors $ {\nu}$ = $ {-5/2}$ , $ {-7/2}$ , $ {-9/2}$ , $ {-11/2}$ , and $ {-13/2}$ , alongside numerous odd-denominator states in mixed-stacked pentalayer graphene, a previously unexplored system characterized by intertwined quadratic and cubic band dispersions. These even-denominator states, representing the highest filling half-filled states reported so far in the zeroth Landau level (ZLL), emerge from two distinct intra-ZLL and exhibit unprecedented displacement field tunability driven by LL crossings in the hybridized multiband structure. At half fillings, continuous quasiparticle phase transitions between paired FQH states, magnetic Bloch states, and composite Fermi liquids are clearly identified upon tuning external fields. Numerical calculations, revealing characteristic sixfold ground-state degeneracy and chiral graviton spectral analysis, suggest the observed even-denominator FQH states belong to the non-Abelian Moore-Read type. These results establish mixed-stacked multilayer graphene as a rich and versatile crystalline platform for exploring tunable correlated topological phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Measuring coherence factors of states in superconductors through local current
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Rodrigo A. Dourado, Jeroen Danon, Martin Leijnse, Rubén Seoane Souto
The coherence factors of quasiparticles in a superconductor determine their properties, including transport and susceptibility to electric fields. In this work, we propose a way to infer the local coherence factors using local transport to normal leads. Our method is based on measuring the local current through a lead as the coupling to a second one is varied: the shape of the current is determined by the ratio between the local coherence factors, becoming independent of the coupling to the second lead in the presence of local electron-hole symmetry, {\it i.e.} coherence factors $ |u|=|v|$ . We apply our method to minimal Kitaev chains: arrays of quantum dots coupled via narrow superconducting segments. These chains feature Majorana-like quasiparticles (zero-energy states with $ |u|=|v|$ ) at discrete points in parameter space. We demonstrate that the local current allows us to estimate the local Majorana polarization (MP)–a measurement of the local Majorana properties of the state. We derive an analytical expression for the MP in terms of local currents and benchmark it against numerical calculations for 2- and 3-sites chains that include a finite Zeeman field and electron-electron interactions. These results provide a way to quantitatively assess the quality of Majorana states in short Kitaev chains.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
7 + 8 pages, 5 + 3 figures
Dislocation Dynamics and Shape in High Entropy Alloys: the Influence of Stress Correlations, Long-Range Interactions and Anisotropy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Dénes Berta, Péter Dusán Ispánovity
High entropy alloys gained significant scientific interest in recent years due to their enhanced mechanical properties including high yield strength combined with outstanding ductility. The strength of these materials originates from their highly heterogeneous pinning stress fields that hinder dislocation glide, that is, plastic deformation. This work investigates how the correlations and the anisotropy of the pinning stresses, and the long-range nature and the anisotropy of dislocation interactions influence the propagation of dislocations and the depinning transition in these alloys. Furthermore, it is studied how the impact of these factors manifest in the shape of dislocations. The implications to the wider scope of generic disordered systems and to possible experimental applications are also discussed.
Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
Light-induced Odd-parity Magnetism in Conventional Collinear Antiferromagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Shengpu Huang, Zheng Qin, Fangyang Zhan, Dong-Hui Xu, Da-Shuai, Rui Wang
Recent studies have drawn growing attention on non-relativistic odd-parity magnetism in the wake of altermagnets. Nevertheless, odd-parity spin splitting is often believed to appear in non-collinear magnetic configurations. Here, using symmetry arguments and effective model analysis, we show that Floquet engineering offers a universal strategy for achieving odd-parity magnetism in two-dimensional (2D) collinear antiferromagnets under irradiation of periodic driving light fields such as circularly polarized light, elliptically polarized light, and bicircular light. A comprehensive classification of potential candidates for collinear monolayer or bilayer antiferromagnets is established. Strikingly, the light-induced odd-parity spin splitting can be flexibly controlled by adjusting the crystalline symmetry or the polarization state of incident light, enabling the reversal or conversion of spin-splitting. By combining first-principles calculations and Floquet theorem, we present illustrative examples of 2D collinear antiferromagnetic (AFM) materials to verify the light-induced odd-parity magnetism. Our work not only offers a powerful approach for uniquely achieving odd-parity spin-splitting with high tunability, but also expands the potential of Floquet engineering in designing unconventional compensated magnetism.
Materials Science (cond-mat.mtrl-sci)
16pages, 11figures
Theory of off-diagonal disorder in multilayer topological insulator
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
We study multilayer topological insulators with random interlayer tunnelling, known as off-diagonal disorder. Within the Burkov-Balents model a single Hermitian defect creates a bound state whose energy crosses the middle of the gap in the trivial phase but never in the topological phase; a non-Hermitian defect splits this level yet preserves the same crossing rule, so the effect serves as a local marker of topology. However, the key distinction persists: the bound state crosses zero in the trivial phase but not in the topological phase. Two complementary diagrammatic approaches give matching densities of states for the normal, topological, Weyl and anomalous quantum Hall regimes. Off diagonal disorder inserts bulk states into the gap and can close it: the Weyl phase remains robust under strong disorder, whereas the anomalous quantum Hall phase survives only for weak fluctuations, and the added bulk states shrink the Hall plateau, clarifying experimental deviations. Finally, we analyse edge modes. Uniform disorder shortens their localization length slightly, while Gaussian and Lorentzian disorder enlarge it and in the Gaussian case can even delocalize the edges. Although chirality is maintained, the enhanced overlap permits tunnelling between opposite edges and pulls the longitudinal conductance away from its quantized value.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Electric-field control of two-dimensional ferromagnetic properties by chiral ionic gating
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Hideki Matsuoka, Amaki Moriyama, Tomohiro Hori, Yoshinori Tokura, Yoshihiro Iwasa, Shu Seki, Masayuki Suda, Naoya Kanazawa
Chiral molecular systems offer unique pathways to control spin and magnetism beyond conventional symmetry operations. Here, we demonstrate that chiral ionic liquids enable electric-field modulation of two-dimensional (2D) ferromagnetism in FeSi(111) thin films via electric double-layer transistor (EDLT) gating. FeSi hosts chemically-stable, surface-confined ferromagnetism without bulk moments, making the interfacial spins highly responsive to chiral-ion adsorption. Using both achiral and chiral ionic liquids, we systematically compare electrochemical and electrostatic gating effects. While both gating modes modulate magnetic properties such as anomalous Hall conductivity and coercive field, only chiral ionic gating biases the ratio of up- and down-magnetized domains in a handedness-dependent manner, evidencing chirality-induced symmetry breaking. This work establishes chiral ion gating as a novel strategy for controlling magnetic order and opens new directions for chiral spintronics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Chemical capacitor: its concept, functionalities and limits
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Łukasz Wolański, Dawid Ciszewski, Piotr Szkudlarek, José Lorenzana, Wojciech Grochala
We use density functional theory calculations to study simple but diverse stoichiometries within the novel chemical capacitor (CC) setup. We look at main effects occurring in this device, extremes of the physicochemical properties, and we study limits of applicability of this nano-object. In the cases studied, CC permits achieving charge transfer of up to 1.74 e per atom. Tuning of the charge transfer may be achieved via judicious choice of chemical constituents of the CC as well as use of a ferroelectric material as a separator layer. Different classes of chemical systems may be doped, including metallic and nonmetallic elements, and chemical compounds, in certain cases leading to the appearance of superconductivity.
Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
13 pages, 1 Table, 17 figures and GTOC figure, and supplement of 40 pages
Crystalline electric field and large anomalous Hall effect in the candidate topological material CeGaSi
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-29 20:00 EDT
Rajesh Swami, Daloo Ram, Anusree C.V, V. Kanchana, Z. Hossain
We report a comprehensive investigation of CeGaSi single crystals, including magnetic, thermodynamic, electronic, and magnetotransport properties. The powder x-ray diffraction refinement revealed that CeGaSi crystallizes in LaPtSi-type tetragonal structure with space group I41md. The electrical resistivity data show a metallic nature with a sharp drop occurring around T_m = 11 K, revealing a magnetic phase transition, which is confirmed by magnetic susceptibility and heat capacity data. The magnetic susceptibility, magnetization, and heat capacity data are analyzed through the crystalline electric field based on point charge model, suggesting that the six degenerate ground states of Ce3+ (J = 5/2) ion split into three doublets with an overall splitting energy = 288 K. The maximum negative magnetoresistance in CeGaSi for both B\parallel c and B\parallel ab field-direction is observed near T_m, it is attributed to the suppression of spin-disorder scattering by the magnetic field. The Hall resistivity data for B \parallel c and B\parallel ab show anomalous Hall signal. Our scaling analysis suggests that anomalous Hall effect in CeGaSi is dominated by the skew scattering mechanism. In addition, first-principles calculations identify CeGaSi as a nodal-line metal.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 7 figures
Physical Constraints on the Rhythmicity of the Biological Clock
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
Circadian rhythms in living organisms are temporal orders emerging from biochemical circuits driven out of equilibrium. Here, we study how the rhythmicity of a biochemical clock is shaped using the KaiABC system. A phase diagram constructed as a function of KaiC and KaiA concentrations reveals a sharply bounded limit-cycle region, which naturally explains arrhythmia upon protein over-expression. Beyond the Hopf bifurcation, intrinsic noise enables regular oscillation via coherence resonance. Within the limit-cycle region, greater rhythmic precision incurs a higher energetic cost, following the thermodynamic uncertainty relation. The cost-minimizing period of the KaiABC clock ($ \sim$ 21-hr) is close enough to entrain to 24-hr cycle of environment. Our study substantiates universal physical constraints on the robustness, precision, and efficiency of noisy biological clocks.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
13 pages, 11 figures
Near-field focusing and amplification of tip-substrate radiative heat transfer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Milo Vescovo, Philippe Ben-Abdallah, Riccardo Messina
The spatially resolved near-field radiative heat transfer between a nanoscale probe and a substrate is studied in the fluctuational electrodynamics framework within the dipolar approximation. It is shown that the introduction of a thin polar film atop a non-dispersive substrate can lead to both an enhancement and a lateral focusing of the heat exchange. The influence of the probe–substrate separation, film thickness and substrate permittivity is analyzed, revealing that the effect originates from near-field interactions governed by the interplay between film-induced modifications of electromagnetic mode dispersion and the distance-dependent coupling strength. The results highlight a viable route toward the active control of local radiative heat transfer at the nanoscale.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Nonequilibrium transport through an interacting monitored quantum dot
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
Daniel Werner, Matthieu Vanhoecke, Marco Schirò, Enrico Arrigoni
We study the interplay between strong correlations and Markovian dephasing, resulting from monitoring the charge or spin degrees of freedom of a quantum dot described by a dissipative Anderson impurity model. Using the Auxiliary master equation approach we compute the steady-state spectral function and occupation of the dot and discuss the role of dephasing on Kondo physics. Furthermore, we consider a two-lead setup which allows to compute the steady-state current and conductance. We show that the Kondo steady-state is robust to moderate charge dephasing but not to spin dephasing, which we interpret in terms of dephasing-induced heating of low-energy excitations. Finally, we show universal scaling collapse of the non-linear conductance with a dephasing-dependent Kondo scale.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Comments welcome
Three-boson scattering hypervolume for a nonzero orbital angular momentum
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-07-29 20:00 EDT
We analyze the zero energy collision of three identical bosons in the same internal state with total orbital angular momentum $ L=2$ , assuming short range interactions. By solving the Schrödinger equation asymptotically, we derive two expansions of the wave function when three bosons are far apart or a pair of bosons and the third boson are far apart. The scattering hypervolume $ D$ is defined for this collision. Unlike the scattering hypervolume defined by one of us in 2008, whose dimension is length to the fourth power, the dimension of $ D$ studied in the present paper is length to the eighth power. We then derive the expression of $ D$ when the interaction potentials are weak, using the Born’s expansion. We also calculate the energy shift of such three bosons with three different momenta $ \hbar \mathbf{k_{1}}$ , $ \hbar\mathbf{k_{2}}$ and $ \hbar\mathbf{k_{3}}$ in a large periodic box. The obtained energy shift depends on $ D^{(0)}/\Omega^{2}$ and $ D/\Omega^{2}$ , where $ D^{(0)}$ is the three-body scattering hypervolume defined for the three-body $ L=0$ collision and $ \Omega$ is the volume of the periodic box. We also calculate the contribution of $ D$ to the three-body T-matrix element for low-energy collisions. We then calculate the shift of the energy and the three-body recombination rate due to $ D^{(0)}$ and $ D$ in the dilute homogeneous Bose gas. The contribution to the three-body recombination rate constant from $ D$ is proportional to $ T^2$ if the temperature $ T$ is much larger than the quantum degeneracy temperature but still much lower than the temperature scale at which the thermal de Broglie wave length becomes comparable to the physical range of interaction.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
First principles study of [111]-oriented epitaxially strained Rare-Earth Nickelate NdNiO$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Alexander Lione, Jorge Íñiguez-González, Nicholas C. Bristowe
Density functional theory is used to investigate the effect of biaxial strain on the structural, electronic and magnetic properties of [111]-oriented NdNiO$ _3$ , as a representative of the rare-earth perovskites that undergo metal-to-insulator transitions. We find that this constraint on the system induces unique structural phase transitions not previously observed under the well-studied bulk or [001]-oriented strained systems. We also report unique electronic behaviour, including amplification of the electronic band-gap with tensile strain, and insulating, charge-ordered phases with non-orthorhombic tilt patterns. To provide clarity to the trends we observe, we also investigate the coupling between the breathing mode and strain, where we observe certain strains to directly favour and disfavour the creation of the breathing mode (and thus the associated charge-ordering). The amplification of the band gap with strain is understood in terms of a cooperative coupling between the elastic constraint and octahedral breathing, which expands on the previously reported triggered mechanism mediated by octahedral tilting.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Defect migration in supercrystalline nanocomposites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Dmitry Lapkin, Cong Yan, Emre Gürsoy, Hadas Sternlicht, Alexander Plunkett, Büsra Bor, Young Yong Kim, Dameli Assalauova, Fabian Westermeier, Michael Sprung, Tobias Krekeler, Surya Snata Rout, Martin Ritter, Satishkumar Kulkarni, Thomas F. Keller, Gerold A. Schneider, Gregor B. Vonbun-Feldbauer, Robert H. Meissner, Andreas Stierle, Ivan A. Vartanyants, Diletta Giuntini
Supercrystalline nanocomposites (SCNCs) are nanostructured hybrid materials with unique emergent functional properties. Given their periodically arranged building blocks, they also offer interesting parallelisms with crystalline materials. They can be processed in multiple forms and at different scales, and crosslinking their organic ligands via heat treatment leads to a remarkable boost of their mechanical properties. This study shows, via X-ray and in-situ scanning transmission (STEM) electron microscopy analyses, how each of these processing steps plays a distinct role in the generation, migration, interaction and healing of supercrystalline defects. Pressing of SCNCs into bulk pellets leads to a distortion of the otherwise fcc superlattice, while emulsion-templated self-assembly yields supraparticles (SPs) with stacking faults and size-dependent symmetries. Interestingly, heat treatment at the same temperatures as those applied for the organic crosslinking has significant effects on planar defects. Stacking faults migrate and get healed, as also confirmed via molecular dynamics simulations, and inter-supercrystalline ‘grain’ boundaries undergo structural changes. These rearrangements of defects at the supercrystalline scale (tens of nm) in nanocomposites with such remarkable mechanical properties (compressive strength of 100-500 MPa) provide new insights into the formation and evolution of ordered assemblies of functionalized nanoparticles.
Materials Science (cond-mat.mtrl-sci)
When does hyperuniformity lead to uniformity across length scales?
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
Carlo Vanoni, Paul J. Steinhardt, Salvatore Torquato
Hyperuniform systems are distinguished by an unusually strong suppression of large-scale density fluctuations and, consequently, display a high degree of uniformity at the largest length scales. In some cases, however, enhanced uniformity is expected to be present even at intermediate and possibly small length scales. There exist three different classes of hyperuniform systems, where class I and class III are the strongest and weakest forms, respectively. We utilize the local number variance $ \sigma_N^2(R)$ associated with a window of radius $ R$ as a diagnostic to quantify the approach to the asymptotic large-$ R$ hyperuniform scaling of a variety of class I, II, and III systems. We find, for all class I systems we analyzed, including crystals, quasicrystals, disordered stealthy hyperuniform systems, and the one-component plasma, a faster approach to the asymptotic scaling of $ \sigma_N^2(R)$ , governed by corrections with integer powers of $ 1/R$ . Thus, we conclude this represents the highest degree of effective uniformity from small to large length scales. Class II systems, such as Fermi-sphere point processes, are characterized by logarithmic $ 1/\ln(R)$ corrections and, consequently, a lower degree of local uniformity. Class III systems, such as perturbed lattice patterns, present an asymptotic scaling of $ 1/R^{\alpha}$ , $ 0 < \alpha < 1$ , implying, curiously, an intermediate degree of local uniformity. In addition, our study provides insight into when experimental and numerical finite systems are representative of large-scale behavior. Our findings may thereby facilitate the design of hyperuniform systems with enhanced physical properties arising from local uniformity.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft)
15 pages
Anomalous Scaling Behaviors of the Green’s Function in Critical Skin Effects
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-29 20:00 EDT
We study the Green’s functions in non-Hermitian systems exhibiting the critical non-Hermitian skin effect (critical NHSE) using a double-chain Hatano-Nelson model with inter-chain coupling $ \Delta$ . For $ \Delta=0$ , the system decouples into two independent chains, and the Green’s functions follow predictable patterns based on the GBZ theory. For small $ \Delta$ ($ \Delta=1/10000$ ), in conventional regions with trivial OBC spectral winding numbers, inter-chain coupling induces a zigzag scaling structure in Green’s functions due to competition between the two chains, explainable by first-order perturbation theory. In anomalous regions with non-trivial winding numbers, Green’s functions match GBZ predictions in the bulk but diverge near boundaries, with residual contributions from the $ \Delta=0$ GBZ accounting for the deviations. These results reveal the unique non-perturbative features of critical NHSE and highlight the limitations of GBZ theory in capturing finite-size and boundary effects, emphasizing the need to consider both bulk and boundary dynamics in such systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 3 figures
Active Learning for Predicting the Enthalpy of Mixing inBinary Liquids Based on Ab Initio Molecular Dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-29 20:00 EDT
Quentin Bizot, Ryo Tamura, Guillaume Deffrennes
The enthalpy of mixing in the liquid phase is an important property for predicting phase formation in alloys. It can be estimated in a large compositional space from pair wise interactions between elements, for which machine learning has recently provided the most accurate predictions. Further improvements requires acquiring high quality data in liquids where models are poorly constrained. In this study, we propose an active learning approach to identify in which liquids additional data are most needed to improve an initial dataset that covers over 400 binary liquids. We identify a critical need for new data on liquids containing refractory elements, which we address by performing ab initio molecular dynamics simulations for 29 equimolar alloys of Ir, Os, Re and W. This enables more accurate predictions of the enthalpy of mixing, and we discuss the trends obtained for refractory elements of period 6. We use clustering analysis to interpret the results of active learning and to explore how our features can be linked to Miedema’s semi empirical theory.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Main : 21 pages, 5 figures. SI : 8 pages, 5 figures
Nonequilibrium fluctuations in a harmonic trap with annealed stochastic stiffness
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
Deepak Gupta, Sabine H. L. Klapp
We provide a comprehensive analysis of the positional dynamics and average thermodynamics of an overdamped Brownian particle subject to both, harmonic confinement and annealed disorder due to a temporarily fluctuating trap stiffness. We model this stiffness via a stationary Ornstein-Uhlenbeck (OU) process whose correlation time can be tuned from white noise to a quenched limit. We analytically calculate the positional distribution in these limits and provide exact expressions for the $ n$ th positional moments at finite correlation times, revealing important insights regarding stationarity. Further, we analyze the average work performed on the particle and the heat dissipated into the environment at all times, illustrating the nonequilibrium character of the system and its relaxation into a steady state. Our analytical results are validated by numerical Langevin simulations.
Statistical Mechanics (cond-mat.stat-mech)
21 pages (main text), 5 figures
Influence of Dispersity on the Relaxation of Entangled Polymers from Molecular Dynamics Simulations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-29 20:00 EDT
Taofeek Tejuosho, Janani Sampath
Nonequilibrium molecular dynamics simulations are used to study the deformation behavior of disperse polymer melts by tracking test chains of length N = Mw, the weight average molecular weight, in melts of varying dispersity. At high strain rates, stress decreases with increasing dispersity up to the critical stretch ratio. After flow cessation, relaxation is anisotropic: the parallel component of the radius of gyration decreases monotonically with dispersity, but the perpendicular component exhibits non-monotonic behavior, with fast relaxation at low to intermediate stretching ratios, and slower relaxation at higher stretching ratios as dispersity increases. Single-chain structure factor shows a similar trend in the perpendicular direction, with fast relaxation at intermediate length scales in disperse systems, while the parallel component remains unaffected by dispersity. These findings reveal the complex, dispersity-dependent anisotropic relaxation mechanisms in moderately entangled polymer melts far from equilibrium.
Soft Condensed Matter (cond-mat.soft)
5 figures
Collective filament wrapping and nested spiral formation in active polydisperse systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-29 20:00 EDT
Caterina Landi, Giulia Janzen, Francesco Sciortino, John Russo, Chantal Valeriani, Daniel A. Matoz-Fernandez
We investigate a two-dimensional polydisperse suspension of self-propelled semiflexible filaments and reveal a collective wrapping mechanism that is absent in monodisperse systems. At intermediate activity levels, long filaments coil around shorter ones, forming nested spiral structures stabilized by filament length disparity. These assemblies generalize the single-filament spiraling seen in active systems into cooperative, multi-filament configurations. As activity increases, the nested spirals undergo structural transitions: medium-length filaments unwind, longer filaments encapsulate shorter ones, and eventually all spiral structures dissolve. This reorganization is reflected in the dynamics, where van Hove distributions uncover coexisting confined and motile filament populations. Our findings identify filament length as a key control parameter for nonequilibrium self-assembly and establish inter-filament wrapping as a minimal mechanism for hierarchical organization in active matter. This mechanism provides a simple model for the cooperative confinement and structural hierarchy observed in both biological and synthetic active systems.
Soft Condensed Matter (cond-mat.soft)
Anomalous fluctuations of Bose-Einstein condensates in optical lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-07-29 20:00 EDT
Zahra Jalali-Mola, Niklas Käming, Luca Asteria, Utso Bhattacharya, Ravindra W. Chhajlany, Klaus Sengstock, Maciej Lewenstein, Tobias Grass, Christof Weitenberg
Fluctuations are fundamental in physics and important for understanding and characterizing phase transitions. In this spirit, the phase transition to the Bose-Einstein condensate (BEC) is of specific importance. Whereas fluctuations of the condensate particle number in atomic BECs have been studied in continuous systems, experimental and theoretical studies for lattice systems were so far missing. Here, we explore the condensate particle number fluctuations in an optical lattice BEC across the phase transition in a combined experimental and theoretical study. We present both experimental data using ultracold $ ^{87}$ Rb atoms and numerical simulations based on a hybrid approach combining the Bogoliubov quasiparticle framework with a master equation analysis for modeling the system. We find strongly anomalous fluctuations, where the variance of the condensate number $ \delta N_{\rm BEC}^2$ scales with the total atom number as $ N^{1+\gamma}$ with an exponent around $ \gamma_{\rm theo}=0.74$ and $ \gamma_{\rm exp}=0.62$ , which we attribute to the 2D/3D crossover geometry and the interactions. Our study highlights the importance of the trap geometry on the character of fluctuations and on fundamental quantum mechanical properties.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
12 pages, 8 figures, including supplementary material
Spectral distribution of sparse Gaussian Ensembles of Real Asymmetric Matrices
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-07-29 20:00 EDT
Theoretical analysis of biological and artificial neural networks e.g. modelling of synaptic or weight matrices necessitate consideration of the generic real-asymmetric matrix ensembles, those with varying order of matrix elements e.g. a sparse structure or a banded structure. We pursue the complexity parameter approach to analyze the spectral statistics of the multiparametric Gaussian ensembles of real asymmetric matrices and derive the ensemble averaged spectral densities for real as well as complex eigenvalues. Considerations of the matrix elements with arbitrary choice of mean and variances render us the freedom to model the desired sparsity in the ensemble. Our formulation provides a common mathematical formulation of the spectral statistics for a wide range of sparse real-asymmetric ensembles and also
reveals, thereby, a deep rooted universality among them.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
42 pages, 5 figures, supplementary file available on request
Superconducting density of states of PtPb4
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
Pablo García Talavera, Jose Antonio Moreno, Edwin Herrera, Alexander I. Buzdin, Sergey L. Bud’ko, Paul C. Canfield, Isabel Guillamón, Hermann Suderow
PtPb$ 4$ is a type II superconductor with a bulk critical temperature $ T{c}\approx 3 $ K and an upper critical field of $ H_{c2}=0.36 $ T. PtPb$ 4$ is related to non-superconducting PtSn$ 4$ , which presents nodal arc states at the surface. Here we measure the superconducting density of states of PtPb$ 4$ using millikelvin Scanning Tunneling Microscopy (STM). We observe a fully opened superconducting gap of $ \Delta=0.48$ \ meV similar to expectations from Bardeen Cooper and Schrieffer (BCS) theory ($ \Delta_0=1.76k_BT{c}=0.49 $ meV). Measurements under magnetic fields applied perpendicular to the surface show a spatially inhomogeneous gap structure, presenting superconducting signatures at fields as high as 1.5 T, significantly above $ H{c2}=0.36 $ T. On some locations we find that the superconducting density of states does not vanish above $ T{c}$ . We can find signatures of a superconducting gap up to 5K. We discuss possible reasons for the observation of superconducting properties above $ T_{c}$ and $ H_{c2}$ , emphasizing the role played by structural defects.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Journal of Superconductivity and Novel Magnetism, Vol.38, 158 (2025)
Dynamics of Irreversible Particle Adsorption to Fluid Interfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-29 20:00 EDT
Marina Pasquet, Yu Fu, Joelle Frechette
Understanding the dynamic adsorption of colloidal particles at fluid interfaces is essential for applications ranging from emulsion stabilization to interfacial assembly of functional materials. Adsorption dynamics is often described through diffusion-limited models (such as the Ward-Tordai framework) along with assuming dynamic equilibrium between the adsorbed and dispersed particles. However, most experiments show that particle adsorption is irreversible, and diffusion-limited models fail as the surface coverage goes beyond the dilute limit where particle crowding limits further adsorption. Here, we present a unified model that captures the transition from diffusion-limited to kinetic-limited regimes by coupling diffusion with a Random Sequential Adsorption (RSA)-based boundary condition that accounts for irreversible adsorption and particle blocking for a spherical droplet. Using both a microtensiometer and pendant drop tensiometry, we measure dynamic interfacial tension changes for 3-(Trimethoxysilyl)propyl methacrylate (TPM) particles at the toluene/water interface across a range of bulk concentrations, drop sizes, and particle functionalization. Our analysis shows that the adsorption flux becomes increasingly hindered as the surface area fills, in agreement with RSA predictions. Furthermore, we calculate the Thiele modulus as a dimensionless number that quantifies the relative importance of adsorption kinetics to diffusion. We find that above a critical surface coverage, adsorption becomes reaction-limited, marking a transition to kinetically controlled dynamics. This approach provides a predictive framework for particle adsorption at fluid interfaces and highlights the necessity of moving beyond equilibrium diffusion-limited models.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Approximate solutions to the shrinking core model
New Submission | Other Condensed Matter (cond-mat.other) | 2025-07-29 20:00 EDT
Cristian Moreno Pulido, Rachael Olwande, Tim Myers, Francesc Font
The shrinking core model describes the reaction of a spherical solid particle with a surrounding fluid. In this work, we revisit the SCM by deriving it from the underlying physical processes and performing a careful non-dimensionalisation, which highlights the limitations of the commonly used pseudo-steady-state approximation, particularly in liquid-solid systems where fluid and solid densities are comparable. To address these limitations, we derive approximate analytical solutions using a perturbation method that improves upon the pseudo-steady-state model. We also obtain a small-time solution capturing early transient behavior. A semi-implicit finite difference scheme is implemented to solve the full model numerically and benchmark the analytical approximations. We demonstrate that the perturbation solution provides significantly improved accuracy over the pseudo-steady-state model, especially in diffusion-limited regimes. Finally, we propose a simple fitting procedure combining the perturbation with the early-time solutions to estimate physical parameters from experimental data at minimal computational cost.
Other Condensed Matter (cond-mat.other)
Topological chiral superconductivity from antiferromagnetic correlations in moiré bands with extreme spin-orbit coupling
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-29 20:00 EDT
Chenyuan Li, Fang Xie, Jennifer Cano, Qimiao Si
Motivated by the strong-correlation phenomenology observed near the superconducting phase in twisted bilayer WSe$ _2$ , we study multi-orbital $ t$ -$ J$ models that are derived from different parameter regimes. The models contain effective antiferromagnetic interactions that are influenced by the strong underlying spin-orbit coupling. The possible superconducting pairing states are investigated in these models. We find that the preferred pairing order parameters are associated with the $ ^{1,2}E$ representations of the three-fold rotation symmetry operator $ C_3$ , with the $ p\pm i p$ component intermixing with the $ d\pm id$ component. The chiral superconducting states are shown to be topological, based on the Wilson loops of the corresponding Bogoliubov quasiparticles. We discuss the implications of our findings for experimental observations, as well as the new connections our results uncover between the moiré superconductivity and its counterpart in bulk quantum materials.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
7 + 10 pages, 4 + 6 figures
Emergence of a Boundary-Sensitive Phase in Hyperbolic Ising Models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-29 20:00 EDT
Xingzhi Wang, Zohar Nussinov, Gerardo Ortiz
Physical systems defined on hyperbolic lattices may exhibit phases of matter that only emerge due to negative curvature. We focus on the case of the Ising model under open boundary conditions and show that an intermediate'' phase emerges in addition to standard (high-temperature) paramagnetic and (low-temperature) ferromagnetic phases. When performing the Kramers-Wannier duality the fact that it alters boundary conditions becomes crucial, since a finite fraction of lattice sites lie on the boundary. We propose to characterize this intermediate’’ phase by its sensitivity to boundary conditions, wherein bulk ordering is not spontaneous but rather induced by boundary effects, setting it apart from the Landau paradigm of spontaneous symmetry breaking. By developing a $ \mathbb{Z}_2$ symmetry restricted extension of the Corner Transfer Matrix Renormalization Group method, we provide numerical evidence for the existence of all three distinct phases and their corresponding two-stage phase transitions, thereby establishing the complete phase diagram. We also establish how the (spontaneous) intermediate-to-ferromagnetic and the (induced) paramagnetic-to-intermediate transition points are related by the Kramers-Wannier duality relation.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft), Mathematical Physics (math-ph)
18 pages, 15 figures