CMP Journal 2025-08-12
Statistics
Physical Review Letters: 7
Physical Review X: 2
arXiv: 121
Physical Review Letters
Exact Nonequilibrium Steady State of $XXZ$ Circuits Boundary Driven with Arbitrary Resets or Fields
Research article | Open quantum systems & decoherence | 2025-08-11 06:00 EDT
Vladislav Popkov and Tomaž Prosen
We propose a spatially inhomogeneous matrix product Ansatz for an exact many-body density operator of a boundary-driven $XXZ$ quantum circuit. The Ansatz has formally infinite bond dimension and is fundamentally different from previous constructions. The circuit is driven by a pair of reset quantum channels applied on the boundary qubits, which polarize the qubits to arbitrary pure target states. Moreover, one of the reset channels can be replaced by an arbitrary local unitary gate, thus representing a hybrid case with coherent and incoherent driving. Analyzing the Ansatz, we obtain a family of relatively robust separable nonequilibrium steady states, which can be viewed as a circuit extension of spin-helix states and are particularly suited for experimental investigations.
Phys. Rev. Lett. 135, 070401 (2025)
Open quantum systems & decoherence, Quantum circuits, Quantum simulation
Observation of Three Resonant Structures in the Cross Section of ${e}^{+}{e}^{- }\rightarrow {\pi }^{+}{\pi }^{- }{h}_{c}$
Research article | Quark model | 2025-08-11 06:00 EDT
M. Ablikim et al. (BESIII Collaboration)
Using ${e}^{+}{e}^{- }$ collision data collected with the BESIII detector operating at the Beijing electron positron collider, the cross section of ${e}^{+}{e}^{- }\rightarrow {\pi }^{+}{\pi }^{- }{h}{c}$ is measured at 59 points with center-of-mass energy $\sqrt{s}$ ranging from 4.009 to 4.950 GeV with a total integrated luminosity of $22.2\text{ }\text{ }{\mathrm{fb}}^{- 1}$. The cross section between 4.3 and 4.45 GeV exhibits a plateaulike shape and drops sharply around 4.5 GeV, which cannot be described by two resonances only. Three coherent Breit-Wigner functions are used to parametrize the $\sqrt{s}$-dependent cross section line shape. The masses and widths are determined to be ${M}{1}=\phantom{\rule{0ex}{0ex}}({4223.6}{- 3.7- 2.9}^{+3.6+2.6})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, ${\mathrm{\Gamma }}{1}=({58.5}{- 11.4- 6.5}^{+10.8+6.7})\text{ }\text{ }\mathrm{MeV}$, ${M}{2}=({4327.4}{- 18.8- 9.3}^{+20.1+10.7})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, ${\mathrm{\Gamma }}{2}=\phantom{\rule{0ex}{0ex}}({244.1}{- 27.1- 18.3}^{+34.0+24.2})\text{ }\text{ }\mathrm{MeV}$, and ${M}{3}=({4467.4}{- 5.4- 2.7}^{+7.2+3.2})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, and ${\mathrm{\Gamma }}{3}=({62.8}_{- 14.4- 7.0}^{+19.2+9.9})\text{ }\text{ }\mathrm{MeV}$. The first uncertainties are statistical and the second are systematic. The inclusion of the relatively narrower third component proves crucial for reproducing the drop at around 4.5 GeV. The statistical significance of the three-resonance assumption over the two-resonance assumption is greater than $5\sigma $.
Phys. Rev. Lett. 135, 071901 (2025)
Quark model, Exotic mesons, Quarkonia, Lepton colliders, Particle production
Onset of Constituent Quark Number Scaling in Heavy-Ion Collisions at RHIC
Research article | QCD phase transitions | 2025-08-11 06:00 EDT
B. E. Aboona et al. (STAR Collaboration)
Partonic collectivity is one of the necessary signatures for the formation of quark-gluon plasma in high-energy nuclear collisions. Number of constituent quarks (NCQ) scaling has been observed for hadron elliptic flow ${v}{2}$ in top energy nuclear collisions at the Relativistic Heavy Ion Collider and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In this Letter, a systematic analysis of ${v}{2}$ of ${\pi }^{\pm{}}$, ${K}^{\pm{}}$, ${K}{S}^{0}$, $p$, and $\mathrm{\Lambda }$ in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{ {s}{\mathrm{NN}}}=3.2$, 3.5, 3.9, and 4.5 GeV, with the STAR experiment at the Relativistic Heavy Ion Collider, is presented. NCQ scaling is markedly violated at 3.2 GeV, consistent with a hadronic-interaction dominated equation of state. However, as the collision energy increases, a gradual evolution to NCQ scaling is observed. This beam-energy dependence of ${v}{2}$ for all hadrons studied provides evidence for the onset of dominant partonic interactions by $\sqrt{ {s}{\mathrm{NN}}}=4.5\text{ }\text{ }\mathrm{GeV}$.
Phys. Rev. Lett. 135, 072301 (2025)
QCD phase transitions, Quark matter, Relativistic heavy-ion collisions
Lifetimes of the Metastable $6\mathrm{d}\text{ }^{2}{\mathrm{D}}{5/2}$ and $6\mathrm{d}\text{ }{^{2}\mathrm{D}}{3/2}$ State of ${\mathrm{Ra}}^{+}$
Research article | Electronic structure of atoms & molecules | 2025-08-11 06:00 EDT
Haoran Li, Huaxu Dan, Mingyu Fan, Spencer Kofford, Robert Kwapisz, Roy A. Ready, Akshay Sawhney, Merrell Brzeczek, Craig Holliman, Andrew M. Jayich, S. G. Porsev, and M. S. Safronova
We report lifetime measurements of the metastable $6\mathrm{d}\text{ }^{2}{\mathrm{D}}{5/2}$ and $6\mathrm{d}\text{ }^{2}{\mathrm{D}}{3/2}$ states of ${\mathrm{Ra}}^{+}$. The measured lifetimes, ${\tau }{5}=303.8(1.5)\text{ }\text{ }\mathrm{ms}$ and ${\tau }{3}=642(9)\text{ }\text{ }\mathrm{ms}$, are important for optical frequency standards and for benchmarking high-precision relativistic atomic theory. Independent of the reported measurements, the D state lifetimes were calculated using the coupled-cluster single double triple method, in which the coupled-cluster equations for both core and valence triple excitations were solved iteratively. The method was designed for precise prediction of atomic properties, especially for heavy elements, where relativistic and correlation corrections become large, making their treatment more challenging. This Letter presents the first tests of the method for transition properties. Our prediction agrees with experimental values within the uncertainties. The ability to accurately predict the atomic properties of heavy elements is important for many applications, from tests of fundamental symmetries to the development of optical clocks.
Phys. Rev. Lett. 135, 073001 (2025)
Electronic structure of atoms & molecules, Lifetimes & widths
Quantum-Size Effect Induced Andreev Bound States in Ultrathin Metallic Islands Proximitized by a Superconductor
Research article | Andreev bound states | 2025-08-11 06:00 EDT
Guanyong Wang, Li-Shuo Liu, Zhen Zhu, Yue Zheng, Bo Yang, Dandan Guan, Shiyong Wang, Yaoyi Li, Canhua Liu, Wei Chen, Hao Zheng, and Jinfeng Jia
While Andreev bound states (ABSs) have been realized in engineered superconducting junctions, their direct observation in normal metal-superconductor heterostructures—enabled by quantum confinement—remains experimentally elusive. Here, we report the detection of ABSs in ultrathin metallic islands (Bi, Ag, and SnTe) grown on the $s$-wave superconductor NbN. Using high-resolution scanning tunneling microscopy and spectroscopy, we clearly reveal in-gap ABSs with energies symmetric about the Fermi level. While the energies of these states show no position dependence, their wave functions exhibit spatial oscillations, demonstrating a quantum size effect. Both the energy levels and spatial distribution of the ABSs can be reproduced by our effective model in which a metallic island is coupled to the superconducting substrate via the proximity effect. We demonstrate that the coupling strength plays a critical role in determining the ABS energies. Our work introduces a novel physical platform for implementing ABSs, which hold promise for significant device applications.
Phys. Rev. Lett. 135, 076201 (2025)
Andreev bound states, Proximity effect, Superconductivity, Superconductors, Bogoliubov-de Gennes equations, Scanning tunneling microscopy, Scanning tunneling spectroscopy
Dimensionality-Driven Anomalous Metallic State with Zero-Field Nonreciprocal Transport in Layered Ising Superconductors
Research article | Superconducting fluctuations | 2025-08-11 06:00 EDT
Yanwei Cui, Zenglin Liu, Qin Liu, Junlin Xiong, Yongqin Xie, Yudi Dai, Ji Zhou, Lizheng Wang, Hanyan Fang, Haiwen Liu, Shi-Jun Liang, Bin Cheng, and Feng Miao
The anomalous metal state (AMS), observed in ‘’failed’’ superconductors, provides insights into superconductivity and quantum criticality, with studies revealing unconventional quantum phases like the Bose metal. Recently, layered transition metal dichalcogenide (TMD) superconductors approaching the two-dimensional limit have garnered significant attention for the enhanced phase fluctuations and electronic correlations. Investigating AMSs in these systems, particularly in the absence of an external magnetic field, could offer valuable insights into the dimensionality-driven emergence of exotic quantum phenomena, including triplet Cooper pairing, phase fluctuation dynamics, and especially the recently discovered field-free superconducting diode effects. However, the field-free AMS has yet to be observed in TMD superconductors. Here, we report the dimensionality-tunable AMS near the superconducting quantum phase transitions in a layered TMD superconductor $2\mathrm{H}\text{- }{\mathrm{Ta}}{2}{\mathrm{S}}{3}\text{Se}$. In samples with thicknesses below 10 nm, we demonstrate magnetic field-driven AMS under external magnetic field, characterized by the vanishing of the Hall resistance and the presence of finite longitudinal resistance. Remarkably, an unexpected zero-field AMS emerges as the sample thickness is reduced to 3 nm. This AMS aligns well with the quantum vortex creep model and exhibits nonreciprocal transport behaviors, suggesting the onset of spontaneous time-reversal symmetry breaking accompanied by vortex motion as the system approaches the two-dimensional limit. Our findings open new avenues for exploring dimensionality-driven exotic superconducting quantum critical phases and pave the way for a deeper understanding of zero-field superconducting diode effects.
Phys. Rev. Lett. 135, 076501 (2025)
Superconducting fluctuations, Superconductors, Transition metal dichalcogenides, Two-dimensional electron system, Transport techniques
Substrate Contribution to Ultrafast Spin Dynamics in 2D van der Waals Magnets
Research article | Spin dynamics | 2025-08-11 06:00 EDT
Mara Strungaru, Richard F. L. Evans, and Roy W. Chantrell
We propose a model that is able to reproduce the type-II ultrafast demagnetization dynamics observed in 2D magnets. The spin system is coupled to the electronic thermal bath and is treated with atomistic spin dynamics, while the electron and phonon heat baths are described phenomenologically by coupled equations via the two-temperature model. Our proposed two-temperature model takes into account the effect of the heated substrate, which for 2D systems results in a slow demagnetization regime. We applied the framework to a generic 2D system, ${\mathrm{CrI}}{3}$, and we are able to observe a type-II demagnetization process characterized by two steps, the first step being attributed to the free electrons generated when the system behaves as a quasimetal under optical excitation, and the second step, the slower demagnetization region, due to the heated substrate. Finally, after laser excitation, we are able to observe domain formation in ${\mathrm{CrI}}{3}$, similar to recent experimental observations. Our generalized two-temperature model enhances the modeling of ultrafast magnetization dynamics processes by effectively describing the quasimetallic behavior of certain magnetic materials and the influence of a heated adjacent layer.
Phys. Rev. Lett. 135, 076701 (2025)
Spin dynamics, Ultrafast magnetization dynamics, Van der Waals systems
Physical Review X
On the Quantum Mechanics of Entropic Forces
Research article | Quantum fluctuations & noise | 2025-08-11 06:00 EDT
Daniel Carney, Manthos Karydas, Thilo Scharnhorst, Roshni Singh, and Jacob M. Taylor
A detailed quantum model of how gravity might emerge from microscopic spacetime constituents, like spacetime “molecules,” offers testable predictions that distinguish it from particle-based gravity and paves the way for experimental probes.
Phys. Rev. X 15, 031038 (2025)
Quantum fluctuations & noise, Quantum gravity, Quantum measurements, Thermal & statistical models
Algebraic Non-Hermitian Skin Effect and Generalized Fermi Surface Formula in Arbitrary Dimensions
Research article | Edge states | 2025-08-11 06:00 EDT
Kai Zhang, Chang Shu, and Kai Sun
A newly identified algebraic non-Hermitian skin effect reveals that in higher-dimensional quantum systems, boundary-localized modes can decay by a power law, unlocking new ways to control quantum transport and entanglement.
Phys. Rev. X 15, 031039 (2025)
Edge states, Skin effect, High dimensional systems, Non-Hermitian systems
arXiv
Fracture toughness and auxeticity in disordered metamaterials
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-08-12 20:00 EDT
Hannes Holey, Andrea Lorenzo Henri Sergio Detry, Silvia Bonfanti, Roberto Guerra, Anshul D. S. Parmar, Jacopo Fiocchi, Ausonio Tuissi, Michael Zaiser, Stefano Zapperi
Auxetic metamaterials are commonly thought to exhibit favorable mechanical properties, notably high energy absorption. Here we investigate disordered metamaterials obtained from random beam networks by optimizing simultaneously auxeticity and the energy absorbed before fracture. By giving different weights to these optimization targets, we demonstrate that the optimal configurations are connected along a Pareto front where high auxeticity implies comparatively low energy absorption and vice versa. We study the mechanical properties of the resulting metamaterials and characterize the different deformation modes obtained for distinct optimization targets. The simulation and optimization results are validated by comparison with the deformation behavior of additively manufactured samples. Our work provides an illustration of the potentials and limitations of multi-objective optimization in the design of disordered mechanical metamaterials
Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci)
Defect Networks for Topological Phases Protected By Modulated Symmetries
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Modulated symmetries are internal symmetries which do not commute with spatial symmetries; dipolar symmetries are a prime example. We give a general recipe for constructing topological phases protected by modulated symmetries via a defect network construction, generalizing the crystalline equivalence principle to modulated symmetries. We demonstrate that modulated symmetries can be treated identically to unmodulated symmetries in the absence of spatial symmetries, but in the presence of spatial symmetries, some defect networks which are non-anomalous for unmodulated symmetries become anomalous for modulated symmetries. We apply this understanding to classify symmetry-protected topological phases protected by translation symmetry plus either discrete or continuous dipolar symmetries in (1+1)D and (2+1)D and obtain a number of other (1+1)D classification results for modulated symmetry-protected topological phases.
Strongly Correlated Electrons (cond-mat.str-el), Mathematical Physics (math-ph)
34 pages, 12 figures
Gapless fracton quantum spin liquid and emergent photons in a 2D spin-1 model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Nils Niggemann, Meghadeepa Adhikary, Yannik Schaden-Thillmann, Johannes Reuther
Gapless fracton quantum spin liquids are exotic phases of matter described by higher-rank U(1) gauge theories which host gapped and immobile fracton matter excitations as well as gapless photons. Despite well-known field theories, no spin models beyond purely classical systems have been identified to realize these phases. Using error-controlled Green function Monte Carlo, here we investigate a square lattice spin-1 model that shows precise signatures of a fracton quantum spin liquid without indications of conventional ordering. Specifically, the magnetic response exhibits characteristic patterns of suppressed pinch points that accurately match the prediction of a rank-2 U(1) field theory and reveals the existence of emergent photon excitations in 2+1 spacetime dimensions. Remarkably, this type of fracton quantum spin liquid is not only identified in the system’s ground state but also in generic low-energy sectors of a strongly fragmented Hilbert space.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas)
main: 11 pages, 6 figures, supplement: 7 pages, 3 figures
Classical fracton spin liquid and Hilbert space fragmentation in a 2D spin-$1/2$ model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Nils Niggemann, Meghadeepa Adhikary, Yannik Schaden-Thillmann, Johannes Reuther
Classical U(1) fracton spin liquids feature an extensive ground state degeneracy and follow an effective description in terms of a tensor Gauss’ law where charges, so-called fractons, have restricted mobility. Here we introduce a simple spin model that realizes such a state by straightforward discretization of the higher-rank gauge theory on a square lattice. The simplicity of this construction offers direct insights into the system’s fundamental fractonic properties, such as real-space fracton configurations, height-field representation of the classical ground state manifold as well as properties of local and non-local fluctuations within the fracton-free subspace. By sampling classical Ising states from the extensive ground state manifold, we show that the effective tensor Gauss’ law remains intact when explicitly enforcing the spin-1/2 length constraint, demonstrating the existence of a classical Ising fracton spin liquid. However, we observe that perturbative quantum effects are insufficient to efficiently tunnel between classical ground states, leading to severe Hilbert space fragmentation which obscures fractonic quantum behavior. Specifically, by simulating the spin-1/2 quantum model with Green function Monte Carlo as a function of the Rokhsar-Kivelson potential, we find that the system supports either magnetic long-range order or a classical spin liquid. Our findings highlight the crucial role of Hilbert-space fragmentation in fractonic spin systems but also indicate ways to mitigate such effects via increasing the spin magnitude to $ S=1$ , investigated in a companion paper.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas)
Real-time scattering and freeze-out dynamics in Rydberg-atom lattice gauge theory
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-12 20:00 EDT
De-Sheng Xiang, Peng Zhou, Chang Liu, Hao-Xiang Liu, Yao-Wen Zhang, Dong Yuan, Kuan Zhang, Biao Xu, Marcello Dalmonte, Dong-Ling Deng, Lin Li
Understanding the non-equilibrium dynamics of gauge theories remains a fundamental challenge in high-energy physics. Indeed, most large scale experiments on gauge theories intrinsically rely on very far-from equilibrium dynamics, from heavy-ion to lepton and hadron collisions, which is in general extremely challenging to treat ab initio. Quantum simulation holds intriguing potential in tackling this problem and pioneering experiments have observed different characteristic features of gauge theories, such as string breaking and false vacuum decay. Here, using a programmable Rydberg atom array, we observe real-time scattering and freeze-out dynamics in a (1+1)-dimensional U(1) lattice gauge theory. Through spatiotemporal Hamiltonian engineering, we demonstrate dynamical confinement-deconfinement transitions, revealing string fragmentation and symmetry restoration during quenches. We track scattering processes with single-site resolution across a range of parameter regimes. Utilizing a double quench protocol, we observe dynamical freeze-out: upon quenching the Hamiltonian after scattering, despite the injection of an extensive energy, the system evolution – in terms of both low-order correlations and entanglement – freezes, effectively stabilizing a highly correlated equilibrium state – a situation that reminisces that of collisions between heavy ions. Our work establishes a high-resolution approach for probing non-perturbative gauge dynamics, opening alternative pathways toward studying far-from-equilibrium phenomena in high-energy physics.
Quantum Gases (cond-mat.quant-gas), High Energy Physics - Lattice (hep-lat), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
21 pages, 12 figures
Benchmarking Self-Driving Labs
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Adedire D. Adesiji, Jiashuo Wang, Cheng-Shu Kuo, Keith A. Brown
A key goal of modern materials science is accelerating the pace of materials discovery. Self-driving labs, or systems that select experiments using machine learning and then execute them using automation, are designed to fulfil this promise by performing experiments faster, more intelligently, more reliably, and with richer metadata than conventional means. This review summarizes progress in understanding the degree to which SDLs accelerate learning by quantifying how much they reduce the number of experiments required for a given goal. The review begins by summarizing the theory underlying two key metrics, namely acceleration factor AF and enhancement factor EF, which quantify how much faster and better an algorithm is relative to a reference strategy. Next, we provide a comprehensive review of the literature, which reveals a wide range of AFs with a median of 6, and that tends to increase with the dimensionality of the space, reflecting an interesting blessing of dimensionality. In contrast, reported EF values vary by over two orders of magnitude, although they consistently peak at 10-20 experiments per dimension. To understand these results, we perform a series of simulated Bayesian optimization campaigns that reveal how EF depends upon the statistical properties of the parameter space while AF depends on its complexity. Collectively, these results reinforce the motivation for using SDLs by revealing their value across a wide range of material parameter spaces and provide a common language for quantifying and understanding this acceleration.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Data Analysis, Statistics and Probability (physics.data-an)
Radiative Heat Transfer and 2D Transition Metal Dichalcogenide Materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Long Ma, Dai-Nam Le, Lilia M. Woods
Radiative heat transfer is of great interest from a fundamental point of view and for energy harvesting applications. This is a material dependent phenomenon where confined plasmonic excitations, hyperbolicity and other properties can be effective channels for enhancement, especially at the near field regime. Materials with reduced dimensions may offer further benefits of enhancement compared to the bulk systems. Here we study the radiative thermal power in the family of transition metal dichalcogenide monolayers in their H- and T-symmetries. For this purpose, the computed from first principles electronic and optical properties are then used in effective models to understand the emerging scaling laws for metals and semiconductors as well as specific materials signatures as control knobs for radiative heat transfer. Our combined approach of analytical modeling with properties from ab initio simulations can be used for other materials families to build a materials database for radiative heat transfer.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Optics (physics.optics), Quantum Physics (quant-ph)
28 pages, 4 figures
Digital generation of the 3-D pore architecture of isotropic membranes using 2-D cross-sectional scanning electron microscopy images
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Sima Zeinali Danalou, Hooman Chamani, Arash Rabbani, Patrick C. Lee, Jason Hattrick Simpers, Jay R Werber
A major limitation of two-dimensional scanning electron microscopy (SEM) in imaging porous membranes is its inability to resolve three-dimensional pore architecture and interconnectivity, which are critical factors governing membrane performance. Although conventional tomographic 3-D reconstruction techniques can address this limitation, they are often expensive, technically challenging, and not widely accessible. We previously introduced a proof-of-concept method for reconstructing a membrane’s 3-D pore network from a single 2-D SEM image, yielding statistically equivalent results to those obtained from 3-D tomography. However, this initial approach struggled to replicate the diverse pore geometries commonly observed in real membranes. In this study, we advance the methodology by developing an enhanced reconstruction algorithm that not only maintains essential statistical properties (e.g., pore size distribution), but also accurately reproduces intricate pore morphologies. Applying this technique to a commercial microfiltration membrane, we generated a high-fidelity 3-D reconstruction and derived key membrane properties. Validation with X-ray tomography data revealed excellent agreement in structural metrics, with our SEM-based approach achieving superior resolution in resolving fine pore features. The tool can be readily applied to isotropic porous membrane structures of any pore size, as long as those pores can be visualized by SEM. Further work is needed for 3-D structure generation of anisotropic membranes.
Materials Science (cond-mat.mtrl-sci), Computer Vision and Pattern Recognition (cs.CV), Applied Physics (physics.app-ph)
Potassium polytungstate nanoparticles by combustion aerosol technology for benzene sensing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Adrien Baut, Sebastian Kravecz, Andreas T. Guentner
Polytungstates are oxygen-linked assemblies of highly oxidized tungsten polyhedra, valued for their tunability and stability in diverse applications. Traditional synthesis methods (hydrothermal, solvothermal, solid-state) offer material variety but are limited in scalability and their ability to yield nanostructured materials due to long reaction times and high temperatures. Here, we introduce flame aerosol synthesis as a single-step, rapid and dry method to prepare K$ _2$ W$ _7$ O$ _{22}$ nanoparticulate powders and coatings. Thereby, monocrystalline and phase-pure K$ _2$ W$ _7$ O$ _{22}$ with varying crystal-sizes were obtained by controlling flame temperature, residence time and metal ion concentration during particle formation by nucleation, coagulation and sintering. X-ray diffraction and electron microscopy identified the high potassium tolerance of the K$ _2$ W$ _7$ O$ _{22}$ lattice (K/W ratio up to 0.6) and phase stability up to 400 $ ^\circ$ C, before other polytungstates and WO$ _3$ polymorphs were formed, respectively. Porous films of such K$ _2$ W$ _7$ O$ _{22}$ nanoparticles featured n-type semiconductor behavior that was utilized for the chemoresistive quantification of the air pollutant benzene down to 0.2 parts-per-million at 20% relative humidity. Such sensors were quite selective over other compounds (e.g. alcohols, aldehydes, ketones, CO, NH$ _3$ or H$ _2$ ), in particular to chemically similar toluene and xylene (>18).
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Engineering snags for spatial curvature in weaves: Fabrication, mechanics, and inverse design
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
Guowei Wayne Tu, Evgueni T. Filipov
Weaving as an old craft has extensive applications in modern science and technology such as smart textiles and intelligent soft robots. However, weaving irregular curved surfaces has been difficult, with prior alternatives requiring curved ribbons and triaxial weaving patterns. In this work, we present a simple strategy to achieve complex spatial curvature by purposely introducing ‘snags’, a traditionally unwanted textile defect, into dense plain weaves consisting of straight ribbons assembled in a straightforward biaxial network. We detail the fabrication methodology where we pull out ribbons of initially smooth two- (2D) and three-dimensional (3D) plain weaves to form local snags. We show that these local defects cause global curvatures through the propagation of geometric frustration. We then use a reduced-order bar & hinge model to simulate the mechanics-guided deformation of snagged plain weaves, and we investigate how the curvature scales with system parameters such as the thickness and Young’s modulus of the ribbons. Finally, we introduce an inverse design platform where an evolutionary algorithm is used to inversely compute the optimal snag patterns of smooth plain weaves to approximate arbitrary target surfaces including 2D and 3D woven exoskeletons that fit human legs and elbows, respectively. Engineering snags in plain weaves as a general strategy can pave the way for future design of customizable wearable devices, adaptive soft robots, reconfigurable architecture, and more.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Computational Physics (physics.comp-ph), Popular Physics (physics.pop-ph)
Role of Large Language Models and Retrieval-Augmented Generation for Accelerating Crystalline Material Discovery: A Systematic Review
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Agada Joseph Oche, Arpan Biswas
Large language models (LLMs) have emerged as powerful tools for knowledge-intensive tasks across domains. In materials science, to find novel materials for various energy efficient devices for various real-world applications, requires several time and cost expensive simulations and experiments. In order to tune down the uncharted material search space, minimizing the experimental cost, LLMs can play a bigger role to first provide an accelerated search of promising known material candidates. Furthermore, the integration of LLMs with domain-specific information via retrieval-augmented generation (RAG) is poised to revolutionize how researchers predict materials structures, analyze defects, discover novel compounds, and extract knowledge from literature and databases. In motivation to the potentials of LLMs and RAG in accelerating material discovery, this paper presents a broad and systematic review to examine the recent advancements in applying LLMs and RAG to key materials science problems. We survey state-of-the-art developments in crystal structure prediction, defect analysis, materials discovery, literature mining, database integration, and multi-modal retrieval, highlighting how combining LLMs with external knowledge sources enables new capabilities. We discuss the performance, limitations, and implications of these approaches, and outline future directions for leveraging LLMs to accelerate materials research and discovery for advancement in technologies in the area of electronics, optics, biomedical, and energy storage.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
10 pages, 2 figures
Incommensuration in odd-parity antiferromagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Changhee Lee, Nico A. Hackner, P. M. R. Brydon
Inversion-asymmetric antiferromagnets (AFMs) with odd-parity spin-polarization pattern have been proposed as a new venue for spintronics. These AFMs require commensurate ordering to ensure an effective time-reversal symmetry, which guarantees a strictly antisymmetric spin polarization of the electronic states. Recently, nonsymmorphic centrosymmetric crystals have been identified as a broad class of materials which could exhibit unit-cell doubling magnetism with odd-parity spin-polarization. Here we investigate the stability of these states against incommensuration. We first demonstrate that the symmetry conditions which permit a p-wave spin polarization pattern also permit the existence of a non-relativistic Lifshitz invariant in the phenomenological Ginzburg-Landau free energy. This implies magnetism with an incommensurate ordering vector, independent of its microscopic origin. AFMs with f- or h-wave spin-polarization are also prone to incommensurability, especially when they have an itinerant origin. Here the symmetry which ensures the odd-parity spin-polarization also guarantees the existence of van Hove saddle points off the time-reversal-invariant momenta, which promote incommensurate spin fluctuations in quasi-two-dimensional electronic systems. Finally, we study the effect of weak spin-orbit coupling in locally noncentrosymmetric materials and find that it favors antiferromagnetic phases with in-plane magnetic moments. However, the inclusion of the spin-orbit coupling also introduces a new mechanism for driving incommensuration. Our results imply that odd-parity AFMs are likely to be preceded by an incommensurate phase, or emerge directly from the normal state via a first order transition. These conclusions are consistent with the phase diagram of several candidate materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
15 pages, 4 figures, 5 tables
Models for polymer dynamics from dimensionality reduction techniques
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
Polymer dynamics is analyzed through the lens of linear dimensionality reduction methods, in particular principal (PCA) and time-lagged independent component analysis (tICA). For a polymer undergoing ideal Rouse dynamics, the slow modes identified by these transformations coincide with the conventional Rouse modes. When applied to the Fourier modes of the segment density, we show that tICA generates dynamics equivalent to dynamic self-consistent field theory (D-SCFT) with a wavevector-dependent Onsager coefficient and a free energy functional subject to the random phase approximation (RPA). We then introduce a hidden variable method and a time-local approach to include temporal memory in the tICA-generated dynamics, and generalize it to construct continuum models for the nonequilibrium case of spinodal decomposition of a symmetric diblock copolymer melt.
Soft Condensed Matter (cond-mat.soft)
Design of high-mobility p-type GaN via the piezomobility tensor
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Jie-Cheng Chen, Joshua Leveillee, Chris G. Van de Walle, Feliciano Giustino
Gallium nitride (GaN) is a wide-bandgap semiconductor of significant interest for applications in solid-state lighting, power electronics, and radio-frequency amplifiers. An important limitation of this semiconductor is its low intrinsic hole mobility, which hinders the development of \textit{p}-channel devices and the large-scale integration of GaN CMOS in next-generation electronics. Prior research has explored the use of strain to improve the hole mobility of GaN, but a systematic analysis of all possible strain conditions and their impact on the mobility is lacking. In this study, we introduce a piezomobility tensor notation to characterize the relationship between applied strain and hole mobility in GaN. To map the strain-dependence of the hole mobility, we solve the \textit{ab initio} Boltzmann transport equation, accounting for electron-phonon scattering and GW quasiparticle energy corrections. We show that there exist three optimal strain configurations, two uniaxial strains and one shear strain, that can lead to significant mobility enhancement. In particular, we predict room-temperature hole mobility of up to 164\mob\ for 2% uniaxial compression and 148\mob\ for 2% shear strain. Our methodology provides a general framework for investigating strain effects on the transport properties of semiconductors from first principles.
Materials Science (cond-mat.mtrl-sci)
Topological hydrodynamics in spin-triplet superconductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Chau Dao, Eric Kleinherbers, Bjørnulf Brekke, Yaroslav Tserkovnyak
Due to the structure of the underlying SO(3) $ \mathbf d$ -vector order parameter, spin triplet superconductors exhibit a bulk-edge correspondence linking the circulation of supercurrent to the bulk magnetic skyrmion density, giving rise to topological hydrodynamics of magnetic skyrmions. To probe the interplay of charge and spin dynamics, we propose a blueprint for a spin-triplet superconducting quantum interference device (SQUID), which functions without a Josephson weak link. The triplet SQUID undergoes nonsingular $ 4\pi$ phase slips, in which current relaxation is facilitated by spin dynamics that trace out a magnetic skyrmion texture. Inductively coupling the device to a tank circuit and probing the nonlinear supercurrent response via Oersted field measurements could provide an experimental signature of ferromagnetic spin-triplet superconductivity.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
20 pages including the supplemental material, 6 figures
Impact of Ge substrate Thicknesses and Epitaxy Growth Conditions on the Optical and Material Properties of Ge- and GaAs-based VCSELs
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Wenhan Dong, Zeyu Wan, Yun-Cheng Yang, Chao-Hsin Wu, Yiwen Zhang, Rui-Tao Wen, Guangrui Xia
We present a comparative study of the optical and material property dependences of VCSELs on Ge or GaAs substrate thicknesses and epitaxy process conditions. It was found that adjusting the Ge substrate thickness and optimizing the epitaxy process can shift the stopband center and cavity resonance wavelength by several nanometers. Ge-based VCSELs exhibit improved epitaxial uniformity, smaller deviations from design specifications, reduced stoichiometry variations, and strain magnitudes comparable to those of GaAs-based counterparts. In the selected 46.92 square micron sample area, no defects were observed in the quantum well (QW) regions of Ge-based VCSELs, and the threading dislocation density (TDD) was measured to be below 2.13e6 per square cm. These results highlight the potential of Ge substrates as promising candidates for advanced VCSELs.
Materials Science (cond-mat.mtrl-sci)
Magnetically Mediated Cross-Layer Pairing in Pressurized Trilayer Nickelate La$_4$Ni$3$O${10}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Jialin Chen, Chuanshu Xu, Qiaoyi Li, Wei Li
The recently discovered trilayer nickelate superconductor La$ _4$ Ni$ 3$ O$ {10}$ under pressure has emerged as a promising platform for exploring unconventional superconductivity. However, the pairing mechanism remains a subject of active investigations. With large-scale density matrix renormalization group calculations on a realistic two-orbital trilayer Hubbard model, we elucidate the superconducting (SC) mechanism in this system. Our results reveal distinct magnetic correlations in the two different orbitals: while the $ d{z^2}$ orbital exhibits both interlayer and cross-layer antiferromagnetic (AFM) correlations, the $ d{x^2-y^2}$ orbital shows exclusively cross-layer AFM correlations, rendering a quasi-long-range SC order in the latter. We demonstrate that the Hund’s rule coupling is essential for forming the SC order, and discuss the effects of kinetic AFM correlation and Hubbard repulsive $ U$ . Our findings motivate a further simplification of the trilayer Hubbard to an effective bilayer mixed-dimensional $ t$ -$ J$ model, providing a unified framework for understanding interlayer SC in both trilayer and bilayer nickelates.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 6 figures
Observation of anomalous Floquet non-Abelian topological insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Huahui Qiu, Shuaishuai Tong, Qicheng Zhang, Kun Zhang, Chunyin Qiu
Non-Abelian topological phases, which go beyond traditional Abelian topological band theory, are garnering increasing attention. This is further spurred by periodic driving, leading to predictions of many novel multi-gap Floquet topological phases, including anomalous Euler and Dirac string phases induced by non-Abelian Floquet braiding, as well as Floquet non-Abelian topological insulators (FNTIs) that exhibit multifold bulk-edge correspondence. Here, we report the first experimental realization of anomalous FNTIs, which demonstrate topological edge modes in all three gaps despite having a trivial bulk charge. Concretely, we construct an experimentally feasible one-dimensional three-band Floquet model and implement it in acoustics by integrating time-periodic coupling circuits to static acoustic crystals. Furthermore, we observe counterintuitive topological interface modes in the domain-wall formed by an anomalous FNTI and its counterpart with swapped driving sequences, modes previously inaccessible in Floquet Abelian systems. Our work paves the way for further experimental exploration of the uncharted non-equilibrium topological physics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Observation of Anti-helical Edge States in Acoustic Metamaterials
New Submission | Other Condensed Matter (cond-mat.other) | 2025-08-12 20:00 EDT
Tianzhi Xia, Qicheng Zhang, Chunyin Qiu
As a hallmark of the quantum Hall effect, chiral edge modes (CEMs) counterpropagate along the two parallel edges of a ribbon structure. However, recent studies demonstrate counterintuitive antiCEMs that copropagate along the parallel edges. Analogous to the established extension of the CEMs to helical edge modes (HEMs) in the quantum spin Hall effect, it is natural to extend the antiCEMs to antiHEMs, which comprise a pair of time-reversal-related antiCEMs. In this Letter, we report the first observation of the antiHEMs based on a bilayer model that features staggered positive and negative interlayer hoppings. Experimentally, we implement this anti-helical model on an acoustic platform and provide compelling evidence for the antiHEMs by selectively exciting different spin subspaces, along with identifying the energybiased Dirac points in bulk spectra. Our findings may offer new insights into topological phases of matter and potentially pave the way for designing novel devices with unique edge transport properties.
Other Condensed Matter (cond-mat.other)
Phys. Rev. Lett. 135, 056601 Published 30 July, 2025
Observation and Control of Chiral Spin Frustration in BiYIG Thin Films
New Submission | Other Condensed Matter (cond-mat.other) | 2025-08-12 20:00 EDT
Jinlong Wang, Hanchen Wang, Zhewen Xu, Artim L. Bassant, Junfeng Hu, Wenjie Song, Chaozhong Li, Xiangrui Meng, Mengqi Zhao, Song Liu, Guozhi Chai, Peng Gao, Wanjun Jiang, Desheng Xue, Dapeng Yu, William Legrand, Christian L. Degen, Rembert A. Duine, Pietro Gambardella, Haiming Yu
Chiral interactions within magnetic layers stabilize the formation of noncollinear spin textures, which can be leveraged to design devices with tailored magnetization dynamics. Here, we introduce chiral spin frustration in which energetically degenerate magnetic states frustrate the Dzyaloshinskii-Moriya interaction. We demonstrate magnon-driven switching of the chirally frustrated spin states in Bi-substituted yttrium iron garnet thin films. These states are defined by an in-plane macrospin neighboring two out-ofplane spins on either side with opposing chirality. Using scanning nitrogen-vacancy magnetometry and spin pumping, we identified four degenerate frustrated states and achieved their controllable switching via magnon spin torque. Crucially, the switching is unidirectional, with selectivity determined by the incoming magnon direction. This mechanism provides a powerful approach to manipulate frustrated spin states with magnons. Chiral spin frustration unlocks the geometry constraints of conventional frustration, and therefore opens new horizons for frustrated magnetism, paving the way for energy-efficient spintronic devices based on frustratio
Other Condensed Matter (cond-mat.other), Applied Physics (physics.app-ph)
Accepted version, 8 pages, 5 figures
Physical Review Letters 135, 066705 (2025)
Grain Boundaries in Ceramic Solid-State Lithium Metal Batteries: A Review
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Md Salman Rabbi Limon, Abrar Fahim Navid, Curtis Wesley Duffee, Zeeshan Ahmad
It is now widely accepted that grain boundaries play a critical role in the performance and reliability of solid-state batteries with lithium metal anodes. Understanding and controlling grain boundaries is essential for enabling safe, high-rate operation of solid-state batteries. This review explores the multifaceted influence of grain boundaries in ceramic solid electrolytes and metal anodes, including their impact on ionic and electronic transport, dendrite and void formation, connecting them to the failure mechanisms. We discuss the formation and structure of space charge layers at grain boundaries, their role in modulating local defect chemistry, and the conditions under which grain boundaries may serve as fast-ion pathways or as vulnerable sites for failure. We highlight key differences in the grain boundaries of different classes of solid electrolytes and advances in modeling, experimental characterization, and processing techniques to understand the complexity and engineer grain boundaries in solid electrolytes. Finally, we outline key open questions and opportunities for grain boundary engineering to stimulate further progress in the field.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
67 pages, 22 figures
Ab-initio heat transport in defect-laden quasi-1D systems from a symmetry-adapted perspective
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Yu-Jie Cen, Sandro Wieser, Georg K. H. Madsen, Jesús Carrete
Due to their aspect ratio and wide range of thermal conductivities, nanotubes hold significant promise as heat-management nanocomponents. Their practical use is, however, often limited by thermal resistance introduced by structural defects or material interfaces. An intriguing question is the role that structural symmetry plays in thermal transport through those defect-laden sections. To address this, we develop a framework that combines representation theory with the mode-resolved Green’s function method, enabling a detailed, symmetry-resolved analysis of phonon transmission through defected segments of quasi-1D systems. To avoid artifacts inherent to formalisms developed for bulk 3D systems, we base our analysis on line groups, the appropriate description of the symmetries of quasi-1D structures. This categorization introduces additional quantum numbers that partition the phonon branches into smaller, symmetry-distinct subsets, enabling clearer mode classification. We employ an Allegro-based machine learning potential to obtain the force constants and phonons with near-ab-initio accuracy. We calculate detailed phonon transmission profiles for single- and multi-layer MoS$ _\mathrm{2}$ -WS$ _\mathrm{2}$ nanotubes and connect the transmission probability of each mode to structural symmetry. Surprisingly, we find that pronounced symmetry breaking can suppress scattering by relaxing selection rules and opening additional transmission channels. That higher disorder introduced through defects can enhance thermal transport, and not just suppress it, demonstrates the critical role of symmetry in deciphering the nuances of nanoscale thermal transport.
Materials Science (cond-mat.mtrl-sci)
Strange-like Metallicity in a Toy Model with Selective-Mottness
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
The interplay between band and atomic aspects in materials with co-existing wide-band and flat-band states, or wide-band and effectively dispersionless electronic states is increasingly expected to lead to novel behavior. Using dynamical mean-field theory (DMFT), we investigate strange-metal-like behavior and emergence of unconventional superconductivity in a toy model that captures this interplay. Surprisingly, we find good accord with transport features seen in underdoped cuprates and ladder Fe-arsenides. We connect our findings to proposals of FL$ ^{\ast}$ and orthogonal Fermi liquids, and present a route to it’s direct instability to novel, competing orders.
Strongly Correlated Electrons (cond-mat.str-el)
A hinge effect that anomalously decreases the stiffness of slender fiber-reinforced composite structures
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
Vivek Khatua, Debashish Das, G. K. Ananthasuresh
We present experimental evidence for an anomalous decrease in stiffness in a fiber-reinforced polymer composite because of the embedded fiber. A shell with carbon fiber showed about 20% less stiffness and 100% more strength under compressive loading. We ruled out the role of debonding of fiber due to imperfect impregnation by using a fiber-pullout test, which revealed that the fiber-matrix interface is strong in the direction of the fiber. Therefore, we hypothesize that a fiber allows the matrix material to rotate around it as in a hinge. We corroborate this phenomenon, which we call the hinge effect, with analytical modelling and experimental data for small and large deformations of a fiber embedded in slender composite beams. We also demonstrate the design of foldable and deployable sheets with hill and valley folds enabled by the embedded fibers. Moreover, the hinge effect warrants further research into physics of how fibers in slender composite structures give rise to the anomalous flexibility. This effect can be gainfully used in designing novel origami structures and compliant mechanisms should be flexible and strong.
Soft Condensed Matter (cond-mat.soft)
Letter format; 6 Figures 9 Pages
Performance of the Extended Ising Machine for the Quadratic Knapsack Problem
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Haruka Akishima, Hirotaka Tamura, Kazue Kudo
The extended Ising machine (EIM) enhances conventional Ising models, which handle only binary quadratic forms by allowing constraints through real-valued dependent variables. We address the quadratic knapsack problem (QKP), hard to solve using Ising machines when formulated as a quadratic unconstrained binary optimization (QUBO). We demonstrated the EIM’s superiority by comparing it with the conventional Ising model-based approach, a commercial exact solver, and a state-of-the-art heuristic solver for QKP.
Statistical Mechanics (cond-mat.stat-mech)
6 pages
J. Phys. Soc. Jpn. 94, 095002 (2025)
Probing Fermi surface topology by ultrafast pump pulse dynamics
New Submission | Other Condensed Matter (cond-mat.other) | 2025-08-12 20:00 EDT
We present a dynamical approach to detect changes in Fermi surface topology in a two-band model. Specifically, we show that the system’s response to a low intensity light pulse can precisely identify topological Lifshitz transitions. At a suitable frequency, the light resonantly couples valence and conduction electrons, leading to an oscillation in the interband coherence term. This, in turn, generate a persistent oscillatory current which survives even after the end of the pulse. Notably, the relative amplitude of the oscillatory current during the pulse with that of the post-pulse reaches a minimum when the Fermi energy aligns with the saddle point, providing a robust framework for dynamically identifying Lifshitz transitions.
Other Condensed Matter (cond-mat.other)
8 pages, 7 figures
Unveiling the Puzzle of Brittleness in Single Crystal Iridium
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Qing Cheng, Sergey V. Erohin, Konstantin V. Larionov, Bin Gan, Pavel B. Sorokin, Xiandong Xu
Iridium is critical for extreme-environment applications due to its exceptional thermal stability and corrosion resistance, but its intrinsic brittleness remains a decades-old puzzle. Combining atomic-resolution scanning transmission electron microscopy, density first-principles calculations, and discrete dislocation dynamics simulations, we identify high-density, sessile Frank dislocation loops with zero-net Burgers vectors as the key mechanism. These loops form via an energetically favorable transformation from mixed perfect dislocations under stress, a process unique to iridium among face-centered cubic metals. The immobile loops act as potent barriers, drastically increasing yield strength and work hardening by impeding dislocation glide and consuming mobile dislocations. This dominance of these findings deepens the understanding of iridium’s brittleness and offers a pathway for designing more ductile variants of this critical material.
Materials Science (cond-mat.mtrl-sci)
36 pages, 16 figues
Efficient GW calculations for metals from an accurate ab initio polarizability
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Giacomo Sesti, Alberto Guandalini, Andrea Ferretti, Pino D’Amico, Claudia Cardoso, Massimo Rontani, Daniele Varsano
Despite its success in the study of spectroscopic properties, the $ GW$ method presents specific methodological challenges when applied to systems with metallic screening. Here, we present an efficient and fully ab-initio implementation for the calculation of the screened potential, specifically designed for 3D and 2D metals. It combines a Monte Carlo integration with an appropriate interpolation of the screened potential between the calculated grid points (W-av), complemented with an extrapolation to the long-wavelength limit, able to seamlessly account for the so-called intraband term. This method greatly accelerates the convergence of GW calculations for metals while improving their accuracy, due to the correct description of the intraband transitions in the long wavelength limit, as shown here for 3D metals and doped monolayers, such as MoS$ _2$ and graphene. The use of W-av results in an excellent agreement with ARPES measurements for monolayer doped MoS$ _2$ . Furthermore, for graphene we show that more robust results are found with the use of higher-order Lorentzians in the description of the self-energy, together with the solution of the QP equation beyond the linearized approximation.
Materials Science (cond-mat.mtrl-sci)
18 pages 13 figures
Optically Tunable Spin Transport in Bilayer Altermagnetic Mott Insulators
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Niklas Sicheler, Roberto Raimondi, Giorgio Sangiovanni, Lorenzo Del Re
Altermagnets are a novel class of materials that combine antiferromagnetic spin ordering with non-relativistic spin splitting (NRSS) in their band structure, making them promising candidates for spintronics applications without requiring strong spin-orbit coupling. In this work, we investigate a two-dimensional bilayer Mott insulator that exhibits altermagnetic order. The interplay between spin and layer degrees of freedom gives rise to a complex symmetry-breaking pattern involving both magnetic and interlayer-coherent components. A key control parameter in the system is the layer polarization, which can be tuned via an external gate voltage. We show that applying an in-plane electric field with opposite signs in the two layers induces a polarization current that drives a spin current in each layer. While the polarization current is isotropic, the resulting spin current exhibits strong anisotropy and can be reversed by adjusting the photon energy. These findings suggest new avenues for manipulating spin transport in altermagnetic systems via electric and optical means.
Strongly Correlated Electrons (cond-mat.str-el)
Coulombic control of charge transfer in luminescent radicals with long-lived quartet states
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Lujo Matasovic, Petri Murto, Shilong Yu, Wenzhao Wang, James D. Green, Giacomo Londi, Weixuan Zeng, Laura Brown, William K. Myers, David Beljonne, Yoann Olivier, Feng Li, Hugo Bronstein, Timothy J. H. Hele, Richard H. Friend, Sebastian Gorgon
Excitons in organic materials are emerging as an attractive platform for tunable quantum technologies. Structures with near-degenerate doublet and triplet excitations in linked trityl radical, acene and carbazole units can host quartet states. These high spin states can be coherently manipulated, and later decay radiatively via the radical doublet transition. However, this requires controlling the deexcitation pathways of all metastable states. Here we establish design rules for efficient quartet generation in luminescent radicals, using different connection arrangements of the molecular units. We discover that electronic coupling strength between these units dictates luminescence and quartet formation yields, particularly through the energetics of an acene-radical charge transfer state, which we tune Coulombically. This state acts as a source of non-radiative decay when acene-radical separation is small, but facilitates doublet-quartet spin interconversion when acene-radical separation is large. Using these rules we report a radical-carbazole-acene material with 55% luminescence yield, where 94% of emitting excitons originate from the quartet at microsecond times. This reveals the central role of molecular topology in luminescent quantum materials.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
22 pages, 4 figures
Anomalous Hall and Nernst effects in the Two-Dimensional ferromagnetic metal FePd2Te2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Yazhou Li, Jiaxing Liao, Jiajun Ma, Yuwei Zhang, Tao Li, Jialu Wang, Hangdong Wang, Hanjie Guo, Jianhui Dai, Yuke Li
The transverse thermoelectric effect enables simpler, more flexible thermoelectric devices by generating electricity perpendicular to heat flow, offering promising solutions for waste heat recovery and solid-state cooling applications. Here, we report a striking observation of zero-field anomalous Hall effect (AHE) and anomalous Nernst effect (ANE) below TC in the two-dimensional metallic magnet FePd2Te2. The anomalous Nernst signal Syx^A peaks a maximum value of 0.15 {\mu}V/K at 100 K, much larger than that of conventional FM materials. Remarkably, the derived ratio alpha_ij/sigma_ij in FePd2Te2 approaches the fundamental limit of 86 {\mu}V/K. Our findings suggest a dominant Berry curvature contribution to the ANE. The observed giant zero-field anomalous Nernst response in 2D FePd2Te2 not only advances fundamental understanding of transverse thermoelectricity in layered magnets, but also provides this material as a promising candidate for practical thermoelectric spintronic applications.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 4 figures
Solid State Sciences 168,108044,(2025)
Mechanism of Anisotropic Crystallization and Phase Transitions under Van der Waals Squeezing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Mechanical confinement strategies, such as van der Waals (vdW) squeezing, have emerged as promising routes for synthesizing non-vdW two-dimensional (2D) layers, surprisingly yielding high-quality single crystals with lateral sizes approaching 100 micrometer. However, the underlying mechanisms by which such a straightforward approach overcomes the long-standing synthesis challenges of non-vdW 2D materials remains a puzzle. Here, we investigate the crystallization dynamics and phase evolution of Bi under vdW confinement through molecular dynamics (MD) simulations powered by a machine-learning force filed fine-tuned and distilled from a pre-trained model with DFT-level accuracy. We reveal that pressure-dependent layer modulation arises from a quantum confinement-driven anisotropic crystallization mechanism, in which out-of-plane layering occurs nearly two orders of magnitude faster than in-plane ordering. Two critical transitions are identified: an alpha-to-beta phase transformation at 1.64 GPa, and a subsequent collapse into a single-atomic layer at 2.19 GPa. The formation of large-area single crystals is enabled by substrate-induced orientational selection and accelerated grain boundary migration, driven by atomic diffusion at elevated temperatures. These findings resolve the mechanistic origin of high-quality 2D crystal growth under confinement and establish guiding principles for the controlled synthesis of metastable 2D single crystals, with implications for next-generation quantum and nanoelectronic devices.
Materials Science (cond-mat.mtrl-sci)
5 pages, 4 figures
Explainable AI for Curie Temperature Prediction in Magnetic Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
M. Adeel Ajaib, Fariha Nasir, Abdul Rehman
We explore machine learning techniques for predicting Curie temperatures of magnetic materials using the NEMAD database. By augmenting the dataset with composition-based and domain-aware descriptors, we evaluate the performance of several machine learning models. We find that the Extra Trees Regressor delivers the best performance reaching an R^2 score of up to 0.85 $ \pm$ 0.01 (cross-validated) for a balanced dataset. We employ the k-means clustering algorithm to gain insights into the performance of chemically distinct material groups. Furthermore, we perform the SHAP analysis to identify key physicochemical drivers of Curie behavior, such as average atomic number and magnetic moment. By employing explainable AI techniques, this analysis offers insights into the model’s predictive behavior, thereby advancing scientific interpretability.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
6 pages, 5 figures
Randomly twisted bilayer graphene – the cascade transitions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Baruch Horovitz, Pierre Le Doussal
Twisted bilayer graphene (TBG) is known to have disorder in its twist angle. We show that in terms of a Dirac equation with a random gauge potential $ {\bf A}({\bf r})$ this disorder becomes huge when the average twist angle is near the magic angle where the Dirac velocity vanishes. The density of states (DOS) then diverges at the Dirac point as $ \rho(E)\sim E^{(2/z)-1}$ with $ z\gg 1$ and we deduce that all electrons occupy energies very near $ E=0$ . We prove a sum rule on the disorder averaged eigenfunctions from which we deduce that each added electron contributes equal intraband Coulomb interaction energy. The various bands in TBG are related by either $ {\bf A}({\bf r})\rightarrow {\bf A}({-\bf r})$ or $ {\bf A}({\bf r})\rightarrow -{\bf A}({\bf r})$ which affects the interband interaction energy. We find, within Hartree-Fock, jumps in the chemical potential at each integer filling, accounting for the cascade transitions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn)
14 pages, 2 tables, Supplementary added
VASPilot: MCP-Facilitated Multi-Agent Intelligence for Autonomous VASP Simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Jiaxuan Liu, Tiannian Zhu, Caiyuan Ye, Zhong Fang, Hongming Weng, Quansheng Wu
Density-functional-theory (DFT) simulations with the Vienna Ab initio Simulation Package (VASP) are indispensable in computational materials science but often require extensive manual setup, monitoring, and postprocessing. Here, we introduce VASPilot, an open-source platform that fully automates VASP workflows via a multi-agent architecture built on the CrewAI framework and a standardized Model Context Protocol (MCP). VASPilot’s agent suite handles every stage of a VASP study-from retrieving crystal structures and generating input files to submitting Slurm jobs, parsing error messages, and dynamically adjusting parameters for seamless restarts. A lightweight Flask-based web interface provides intuitive task submission, real-time progress tracking, and drill-down access to execution logs, structure visualizations, and plots. We validate VASPilot on both routine and advanced benchmarks: automated band-structure and density-of-states calculations (including on-the-fly symmetry corrections), plane-wave cutoff convergence tests, lattice-constant optimizations with various van der Waals corrections, and cross-material band-gap comparisons for transition-metal dichalcogenides. In all cases, VASPilot completed the missions reliably and without manual intervention. Moreover, its modular design allows easy extension to other DFT codes simply by deploying the appropriate MCP server. By offloading technical overhead, VASPilot enables researchers to focus on scientific discovery and accelerates high-throughput computational materials research.
Materials Science (cond-mat.mtrl-sci)
9 pages, 5 figures
Interplay of distinct modes of charge regulation on poly-acid ionization and conformation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
Souradeep Ghosh, Aritra Chowdhury, Dylan T. Tomares, Benjamin Schuler, Arindam Kundagrami, Rohit V. Pappu
We adapt the Edwards-Muthukumar theoretical framework for a single polymer chain to investigate the interplay between proton binding and counterion condensation for poly-acids. We find that changes to pH enable non-monotonic transitions between anti- and conventional polyelectrolyte behaviors. In the former, the net charge and the overall dimensions increase with increasing salt concentration, while the converse is true for conventional polyelectrolytes. The polymeric nature and local solvent polarization drive significant pKa shifts when compared to the values of reference monoacids. These pKa shifts are enhanced in semi-flexible chains.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
A Class of Exclusion Processes Capable of Exhibiting Current Reversal
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Ngo Phuoc Nguyen Ngoc, Lam Thi Nhung
A century after Ising introduced the Ising measure to study equilibrium systems, its relevance has expanded well beyond equilibrium contexts, notably appearing in non-equilibrium frameworks such as the Katz–Lebowitz–Spohn (KLS) model. In this work, we investigate a class of generalized asymmetric simple exclusion processes (ASEP) for which the Ising measure serves as the stationary state. We show that the average stationary current in these models can display current reversal and other unconventional behaviors, offering new insights into transport phenomena in non-equilibrium systems. Moreover, although long-range interaction rates often give rise to long-range interactions in the potential function, our model provides a counterexample: even with long-range interactions in the dynamics, the resulting potential remains short-ranged. Finally, our framework encompasses several well-known models as special cases, including ASEP, the KLS model, the facilitated exclusion process, the cooperative exclusion process, and the assisted exchange model.
Statistical Mechanics (cond-mat.stat-mech)
Giant spin Hall effects and topological surface states in ternary-layered MAX carbides Mn+1AlCn (M= Nb, Ta, n=1, 2, 3)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Yanhui Chen, Hong-Yan Lu, Wenjin Yang, Meifeng Liu, Bin Cui, Desheng Liu, Bing Huang, Xi Zuo
In this work, we report a systematic study of the electronic structures, band topology, and intrinsic spin Hall effect (SHE) of the layered MAX carbides Mn+1AlCn (M= Nb, Ta, n=1, 2, 3) and explore the correlation effects on the SHE. The results show that M3AlC2 and M4AlC3 (M= Nb, Ta) share similar Dirac-band-crossing features near the Fermi level (EF) and form nodal lines in the absence of spin-orbit coupling (SOC). When the SOC is included, the Dirac band crossings are fully gapped, resulting in nontrivial Z2 topological invariants (1;000) with a pair of surface states on the (001) plane. Remarkably, the multiple gapped Dirac points contribute to locally strong spin Berry curvatures, which lead to large spin Hall conductivities and a giant spin Hall angle up to ~ 60% for Ta3AlC2. Moreover, we also elucidate the impact of Hubbard U correction on SHC. Our findings indicate that Ta3AlC2 might represent an intriguing layered Z2 topological metal with superior charge-to-spin conversion efficiency.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Electron Energy Loss Spectra Simulations of Coupled Phonon and Magnon Excitations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
José Ángel Castellanos-Reyes (1), Anders Bergman (1), Ivan P. Miranda (2), Ján Rusz (1) ((1) Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden, (2) Department of Physics and Electrical Engineering, Linnaeus University, Kalmar, Sweden)
We simulate momentum-resolved electron energy loss spectra (EELS) in body-centered cubic iron at 300 K, capturing the effects of coupled phonon and magnon excitations within a unified dynamical formalism. By extending the Time Autocorrelation of Auxiliary Wavefunctions (TACAW) method to incorporate atomistic spin-lattice dynamics (ASLD), we simulate the full EELS signal - including interaction effects, dynamical diffraction, and multiple scattering. Our results reveal non-additive spectral features arising from phonon-magnon coupling, including interference and energy redistribution effects, and predict experimental detectability of magnon signals under optimized detector conditions. This framework advances quantitative magnon spectroscopy in STEM, establishing a direct link between dynamical theory and low-energy experimental EELS signatures.
Materials Science (cond-mat.mtrl-sci)
A Novel Computational Thermodynamics Framework with Intrinsic Chemical Short-Range Order
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Chemical short-range order (SRO) provides new opportunities for tuning alloy properties, but conventional computational thermodynamics frameworks such as CALPHAD, based on Bragg-Williams mean-field approximations, cannot properly describe SRO or order-disorder transformations in multicomponent ($ \geq$ 3) alloys. First-principles approaches combined with the cluster variation method (CVM) or cluster expansion method (CEM) can capture SRO but suffer from high computational cost. Here we present a hybrid CVM-CALPHAD framework with a thermodynamic solid solution model named as FYL-CVM, enabled by the Fowler-Yang-Li (FYL) transform to reduce the number of variables required in free-energy minimization. This achieves efficient modeling of SRO in multicomponent systems within the CALPHAD formalism. Benchmark tests on fcc AB binaries show that FYL-CVM reproduces CVM phase diagrams with much higher efficiency, while non-configurational contributions from vibrational, elastic, and electronic terms are also incorporated to capture their physical effects on order-disorder boundaries. Applied to the Cu-Au system, this method produces phase diagrams with experimental data in an efficient parameterization and elucidates the temperature-composition dependence of SRO parameters via the SRO diagram. Its applicability to ternary alloys is also demonstrated for the Cu-Au-Ag system. Overall, this framework strikes a balance between accuracy and efficiency, extends CALPHAD to account for chemical SRO, and enables a comprehensive physics-informed modeling of ordering phenomena. (This dissertation was submitted to the University of Virginia in 2023 as the author’s doctoral research. For the original complete abstract, please refer to the PDF version.)
Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
PhD Dissertation, University of Virginia (2023.08); Official DOI: https://doi.org/10.18130/gfty-sr91
Wannier Center Analysis on Possible Three-Dimensional Topological Phases in α-Type Layered Organic Conductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Topological features of possible three-dimensional (3D) states in \alpha-type layered organic conductors are investigated within a unified framework based on Wannier charge centers (WCCs), aiming to identify their actual topological states. Among the 3D Dirac/Weyl semimetal states of multilayered \alpha-(ET)2I3, the type-I Dirac semimetal state, induced by interlayer spin-orbit coupling (SOC), most effectively explains the observed chiral transport phenomena attributed to the chiral magnetic effect, which originates from the spiral structures of the WCC sheets. In multilayered \alpha-(BETS)2I3, a 3D weak topological insulator (TI) state consistently emerges, irrespective of the presence of interlayer SOC and/or inversion symmetry breaking. The strong TI state suggested by experimental observations appears unlikely to be realized.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 4 figures
Ferroelectric switching of interfacial dipoles in $α$-RuCl$_3$/graphene heterostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Soyun Kim, Jo Hyun Yun, Takashi Taniguchi, Kenji Watanabe, Joseph Falson, Jun Sung Kim, Kyung-Hwan Jin, Gil Young Cho, Youngwook Kim
We demonstrate electrically switchable, non-volatile dipoles in graphene/thin hBN/$ \alpha$ -RuCl$ _3$ heterostructures, stabilized purely by interfacial charge transfer across an atomically thin dielectric barrier. This mechanism requires no sliding or twisting to explicitly break inversion symmetry and produces robust ferroelectric-like hysteresis loops that emerge prominently near 30~K. Systematic measurements under strong in-plane and out-of-plane magnetic fields reveal negligible effects on the hysteresis characteristics, confirming that the primary mechanism driving the dipole switching is electrostatic. Our findings establish a distinct and robust route to electrically tunable ferroelectric phenomena in van der Waals heterostructures, opening opportunities to explore the interplay between interfacial charge transfer and temperature-tuned barrier crossing of dipole states at the atomic scale.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Deformation of semi-circle law for the correlated time series and Phase transition
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Masato Hisakado, Takuya Kaneko
We study the eigenvalue of the Wigner random matrix, which is created from a time series with temporal correlation. We observe the deformation of the semi-circle law which is similar to the eigenvalue distribution of the Wigner-Lèvy matrix. The distribution has a longer tail and a higher peak than the semi-circle law. In the absence of correlation, the eigenvalue distribution of the Wigner random matrix is known as the semi-circle law in the large $ N$ limit. When there is a temporal correlation, the eigenvalue distribution converges to the deformed semi-circle law which has a longer tail and a higher peak than the semi-circle law. When we created the Wigner matrix using financial time series, we test the normal i.i.d. using the Wigner matrix. We observe the difference from the semi-circle law for FX time series. The difference from the semi-circle law is explained by the temporal correlation. Here, we discuss the moments of distribution and convergence to the deformed semi-circle law with a temporal correlation. We discuss the phase transition and compare to the Marchenko-Pastur distribution(MPD) case.
Statistical Mechanics (cond-mat.stat-mech), Statistical Finance (q-fin.ST)
18 pages, 4 figures
Experimental evidence for strong emergent correlations between particles in a switching trap
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Marco Biroli, Sergio Ciliberto, Manas Kulkarni, Satya N. Majumdar, Artyom Petrosyan, Gregory Schehr
We experimentally study a gas of $ N = 8$ one-dimensional Brownian particles, each confined in a harmonic trap with identical stiffness. The stiffness switches simultaneously between two values at random Poissonian times. This collective switching drives the system into a non-equilibrium stationary state (NESS) with strong long-range correlations between the positions of the particles. Remarkably, we find that these switching-induced emergent correlations completely overwhelm the hydrodynamic interactions between the particles mediated via the surrounding fluid. Comparing with exact theoretical predictions for noninteracting particles, we observe excellent agreement between theory and experiments for multiple observables, including the correlations between particles, extreme value and order statistics (maxima, minima and ranked positions) and the full counting statistics (i.e., the distribution of the number of particles in a finite interval $ [-L, L]$ around the trap center).
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
7+2 pages, 5 figures
Magnetic Moment vs Angular Momentum: Spin Hall Response in Bismuth
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Junji Fujimoto, Yuki Izaki, Yuki Fuseya
Spin currents can carry either spin angular momentum or its associated magnetic moment, which are no longer strictly proportional in multiband systems. Using a multiband $ k \cdot p$ model, we compute the intrinsic spin Hall conductivity tensors of elemental Bi. The magnetic-moment tensor emerges about two orders of magnitude larger and far less anisotropic than the angular-momentum tensor, while quasiparticle damping activates otherwise longitudinal components. The magnetic-moment spin Hall angle exceeds unity, demonstrating that a clear distinction between the two currents is indispensable for multiband systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
5 pages, 3 figures
Reproducibility of high-throughput density-functional-theory calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Chenxi Lu, Musen Li, Jeffrey R. Reimers
While standard computational protocols for density functional theory (DFT) have universal applicability, differences exist in code implementations. Specific applications require manual parameter optimization, whereas high-throughput calculations employ predefined workflows. This paper uses the bandgap as a key property to reveal the impact of computational workflow differences on the reproducibility of high-throughput calculation results. The study proposes basic requirements for ensuring reproducibility: using structures optimised using the same procedure as used to calculate properties and ensuring Brillouin zone (k-point) integration grid accuracy. This research establishes a foundation for the reproducibility of DFT calculations and reliable application of results, which is of great significance for method development and artificial intelligence model training.
Materials Science (cond-mat.mtrl-sci)
Light-Wave Engineering for Selective Polarization of a Single $\mathbf{Q}$ Valley in Transition Metal Dichalcogenides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
The selective control of specific momentum valleys lies at the core of valleytronics, a field that has thus far focused primarily on the $ \mathbf{K}$ and $ \mathbf{K’}$ valleys in transition metal dichalcogenides (TMDs). However, direct optical access to other low-lying yet conventionally inaccessible valleys such as the sixfold degenerate $ \mathbf{Q}$ valleys has remained an outstanding challenge, fundamentally limiting the exploitation of the full valley degree of freedom for information processing. Here, we theoretically introduce an emergent light-wave valley selection rule that enables deterministic and high fidelity excitation of any single $ \mathbf{Q}$ valley in monolayer TMDs. By coherently combining a circularly polarized pump pulse with a linearly polarized driver pulse, we engineer distinct quantum pathways that unambiguously excited electrons into a targeted $ \mathbf{Q}$ valley, completely decoupled from the conventional $ \mathbf{K}/\mathbf{K’}$ valleys. This all-optical scheme achieves near-unity ($ \sim$ 100%) valley polarization across an exceptionally broad ultrafast window, from the terahertz ($ 10^{12}$ ~Hz) to petahertz ($ 10^{15}$ ~Hz) regimes, enabling single $ \mathbf{Q}$ valley polarization on femtosecond timescales. Our findings establish a new paradigm of light-wave quantum metrology in valleytronics, unlocking the $ \mathbf{Q}$ -valley subspace for scalable multi-state valley information processing.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
20 pages, 3 figures
Observation of gapless collective charge fluctuations in an Anderson insulating state
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Jong Mok Ok, Beom Jun Park, Junik Hwang, Seonghoon Park, Myeongjun Kang, Jun Sung Kim, Ki-Seok Kim, Seung-Ho Baek
Understanding the nature of collective charge dynamics in the Coulomb gap phase is essential for revealing the existence of many-body localization. However, the corresponding many-particle excitation spectra remain poorly understood. Here, we present a comprehensive investigation of $ ^{27}$ Al and $ ^{63}$ Cu nuclear magnetic/quadrupole resonance (NMR/NQR), along with specific heat ($ C_p$ ) measurements, in the $ p$ -type semiconductor CuAlO$ _2$ . Our study unveils distinct changes in charge dynamics at two crossover temperature scales which separate three regimes associated with Anderson localization of charge carriers: thermally activated transport ($ T>150$ K) $ \rightarrow$ Mott variable-range hopping (VRH) $ \rightarrow$ Efros-Shklovskii (ES) VRH with Coulomb gap formation ($ T<50$ K). In the ES VRH regime, we observe a striking divergence in the zero-field $ ^{63}$ Cu spin-lattice relaxation rate, $ (T_1T)^{-1}$ , which is strongly suppressed by an applied magnetic field, indicative of quantum critical charge fluctuations. This is further supported by a distinct magnetic field-dependence of $ C_p/T$ deep within the Coulomb gap phase. Taken together, these results provide compelling evidence for the emergence of strong, gapless collective charge fluctuations within the Anderson insulating phase where single-particle excitations are gapped.
Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 5 figures
On the Néel Vector Dependence of X-ray Magnetic Circular Dichroism in Altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Dependence of x-ray magnetic circular dichroism on the experimental geometry is described by a frequency-dependent Hall vector. Using group theory, we derive a general relationship between the Hall vector and the orientation of the Néel vector $ \bL$ in altermagnets within the free valence spin (FVS) approximation, where the spin-orbit coupling of the valence electrons and their exchange interaction with the core electrons are neglected. For a given spin point group, the full $ \bL$ -dependence of the Hall vector can be expressed in terms of several irreducible spectral functions. This derivation generalizes earlier results for the special cases of MnTe and MnF$ _2$ . Depending on the system symmetry, XMCD in the FVS approximation may be present, emerge only when the neglected terms are included, or be completely forbidden.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
5 pages, no figures
Controlling Single-Pulse Magnetization Switching through Angular Momentum Reservoir Engineering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
B. Kunyangyuen, G. Malinowski, D. Lacour, B. Seng, W. Zhang, S. Mangin, J. Hohlfeld, J. Gorchon, M. Hehn
We report a systematic study of single pulse all optical helicity independent switching in CoGd bilayers, revealing that the magnetization reversal dynamics can be tuned over more than three orders of magnitude. By varying the Gd thickness or inserting a Pt spacer layer between Co and Gd, we control the angular momentum transferred from the rare earth sublattice to the transition metal sublattice. Our results show that when Gd is abundant and strongly coupled to Co, angular momentum is efficiently transferred during Gd demagnetization, leading to ultrafast Co reversal. In contrast, reducing the Gd thickness or introducing a Pt barrier impedes this transfer, resulting in a domain growth mediated reversal on nanosecond and possibly to microsecond timescales as previously observed in CoDy and CoHo alloys. As a result, in rare earth transition metal systems, replacing Gd with heavier rare-earth elements such as Dy or Ho slows down the switching due to a reduced angular momentum transfer towards Co upon demagnetization as demonstrated in CoGdDy alloys. Our findings establish angular momentum availability and transfer pathways as key parameters governing AO HIS dynamics, offering a unified framework for fast and slow magnetization reversal across rare earth transition metal systems.
Materials Science (cond-mat.mtrl-sci)
14 pages, 5 figures
Bipartite entanglement and surface criticality
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Yanzhang Zhu, Zenan Liu, Zhe Wang, Yan-Cheng Wang, Zheng Yan
Recent works on the scaling behaviors of entanglement entropy at the SO(5) deconfined quantum critical point (DQCP) sparked a huge controversy. Different bipartitions gave out totally different conclusions for whether the DQCP is a unitary conformal field theory. In this work, we connect two previously disconnected fields – the many-body entanglement and the surface criticality – to reveal the behaviors of entanglement entropy in various bipartite scenarios, and point out what kind of bipartition truly reflects the criticality of the bulk. We have found that the correspondence between the entanglement spectrum and the edge energy spectrum still persists even at a bulk-gapless point (e.g. critical point), thereby influencing the behavior of entanglement entropy.
Strongly Correlated Electrons (cond-mat.str-el)
Intercalation-Induced Near Room-Temperature Ferromagnetism in CrI3 via Synergistic Exchange Pathways
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Qing-Han Yang, Jia-Wen Li, Xin-Wei Yi, Xiang Li, Jing-Yang You, Gang Su, Bo Gu
The development of room-temperature magnetic semiconductors is critical for advancing spintronic technologies, yet van der Waals magnets like CrI3 exhibit intrinsically low Curie temperatures (Tc = 45 K). This study employs first-principles calculations to demonstrate that atom intercalation, particularly lithium (Li), dramatically enhances magnetic exchange couplings in CrI3, achieving near room-temperature ferromagnetism with a predicted Tc of 286 K-aligning with experimental reports of 420 K. The underlying mechanism involves synergistic superexchange and double-exchange interactions: intercalation reduces the |Ep-Ed| energy difference between iodine p-orbitals and chromium d-orbitals, strengthening superexchange pathways, while charge transfer induces valence mixing (e.g., Cr3+ to Cr2+, as confirmed by experimental X-ray photoelectron spectrometry data), promoting double-exchange. Theoretical predictions extend to other intercalants including Cu and Na, with Cu0.25CrI3 and Na0.25CrI3 exhibiting Tc of 267 K and 247 K, respectively, establishing a versatile strategy for designing high-Tc magnetic semiconductors. This work bridges theoretical insights with experimental validation, offering a transferable framework for intercalation-driven material design and accelerating practical spintronic device realization.
Materials Science (cond-mat.mtrl-sci)
Linear and nonlinear optical responses in Green’s function formula
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Maoyuan Wang, Jianhui Zhou, Yugui Yao
Linear and nonlinear optical effect has been widely discussed in large quantity of materials using theoretical or experimental methods. Except linear optical conductivity, higher-order nonlinear responses are not studied fully. Starting from density operator method, we derive optical conductivities of different orders in Green’s function formula, and also connect them to novel physical quantities, such as Berry curvature, Berry curvature dipole, third-order nonlinear Hall conductivity and so on. Based on the advantages of Green’s function formulas, we believe that these formulas have a lot of benefits for many-body effect study in high-order nonlinear optical responses.
Materials Science (cond-mat.mtrl-sci)
21 pages, 5 figures
Conical Intersections Shed Light on Hot Carrier Cooling in Quantum Dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Caitlin V. Hetherington, Nila Mohan T. M., Shanu A. Shameem, Warren F. Beck, Benjamin G. Levine
Experimental observations of vibronic coherences in electronically excited colloidal semiconductor nanocrystals offer a window into the ultrafast dynamics of hot carrier cooling. In previous work, we showed that, in amine-passivated quantum dots (QDs), these coherences arise during relaxation through a cascade of conical intersections between electronically excited states. Here, we demonstrate the generality of this framework by application to QDs with surface-bound carboxylate ligands. A model involving a similar cascade of conical intersections accurately reproduces the frequencies of vibronic coherences observed with broadband multidimensional spectroscopy. The impact of ligands on the relaxation dynamics is attributed to two distinct mechanisms involving either electronic or vibrational coupling between the core and ligands. Compared to the amine-passivated QDs studied previously, the electronic coupling mechanism is less prominent in carboxylate-passivated QDs. Furthermore, comparison of acetate and formate ligands reveals that truncating the ligand alkyl chains alters the relaxation behavior predicted by the model.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Experimental Realization of the Topologically Nontrivial Phase in Monolayer Si$_2$Te$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Xiaochun Huang, Lingxiao Zhao, Rui Xiong, Wenbin Li, Bao-tian Wang, Baisheng Sa, Matthias Bode
The free-standing monolayer Si$ _2$ Te$ _2$ (ML-Si$ _2$ Te$ _2$ ) has been theoretically predicted to host a room-temperature quantum spin Hall phase. However, its experimental realization remains challenge due to the absence of a three-dimensional counterpart. Here, we demonstrate that HfTe$ _2$ serves as an ideal substrate for the epitaxial growth of ML-Si$ _2$ Te$ _2$ , preserving its topological phase. Scanning tunneling microscopy and spectroscopy confirm a strain-free $ {(1 \times 1)}$ lattice of ML-Si$ _2$ Te$ _2$ , along with a sizable band gap, which is well captured by first-principles calculations. Moreover, distinct edge states, independent of step geometry and exhibiting a broad spatial distribution, are observed at ML-Si$ _2$ Te$ _2$ step edges, underscoring its topological nature.
Materials Science (cond-mat.mtrl-sci)
6 pages, 5 figures
Nonequilibrium Work Fluctuations in Force-induced Melting of a Short B-DNA
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
S. Siva Nasarayya Chari, Prabal K. Maiti
A system of a solvated canonical B-DNA of 12 base pairs with the specified sequence is initially equilibrated in a state of zero external force $ f$ acting on it. After equilibration, a switching experiment is performed over the system by pulling one end of the DNA while restraining its other end. The finite time pulling process is performed at a constant rate of the applied force until a maximum value of 400 pN. The associated nonequilibrium work done $ (W)$ during this process is determined by numerically integrating the force-extension curve as a function of the applied force. An ensemble of the work values, $ P(W)$ , is obtained by repeating the pulling experiment a large number of times. We determine the free energy difference $ (\Delta F)$ between the equilibrium and force-induced melted states of the DNA by employing the Jarzynski equality. The value of $ \Delta F$ is found to be in close agreement with the conventional equilibrium methods.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Probing the limits of effective temperature consistency in actively driven systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Dima Boriskovsky, Rémi Goerlich, Benjamin Lindner, Yael Roichman
We investigate the thermodynamic properties of a single inertial probe driven into a nonequilibrium steady-state by random collisions with self-propelled active walkers. The probe and walkers are confined within a gravitational harmonic potential. We evaluate the robustness of the effective temperature concept in this active system by comparing values of distinct, independently motivated definitions: a generalized fluctuation-dissipation relation, a kinetic temperature, and a work fluctuation relation. Our experiments reveal that, under specific conditions, these independent measurements yield a remarkably consistent effective temperature over a wide range of system configurations. Furthermore, we also identify regimes where this consistency breaks down, which delineates the fundamental limits of extending equilibrium-like thermodynamic concepts to athermal, actively driven systems.
Statistical Mechanics (cond-mat.stat-mech)
Magnetic Field Induced Quantum Metric Dipole in Dirac Semimetal Cd3As2
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Tong-Yang Zhao, An-Qi Wang, Zhen-Tao Zhang, Zheng-Yang Cao, Xing-Yu Liu, Zhi-Min Liao
The quantum geometry, comprising Berry curvature and quantum metric, plays a fundamental role in governing electron transport phenomena in solids. Recent studies show that the quantum metric dipole drives scattering-free nonlinear Hall effect in topological antiferromagnets, prompting the questions of whether this effect can occur in nonmagnetic systems and be externally tuned by a magnetic field. Our work addresses these frontiers by demonstrating that the quantum metric dipole is actively tuned by an external magnetic field to generate a time-reversal-odd nonlinear Hall response in a nonmagnetic topological Dirac semimetal Cd3As2. Alongside the well-known chiral-anomaly-induced negative longitudinal magnetoresistance, an exotic nonlinear planar Hall effect emerges with increasing magnetic field. Careful scaling analysis indicates that this nonlinear planar Hall effect is controlled by the magnetic-field-modulated quantum metric dipole. Constructing a k.p effective model of the Dirac bands under Zeeman and orbital coupling, we derive the evolution of the quantum metric dipole as a function of the magnetic field, providing a comprehensive explanation of the experimental results. Our results establish a band-structure-based strategy for engineering nonlinear magnetotransport in nonmagnetic materials via the quantum metric dipole, opening a pathway toward magnetic-field-tunable nonlinear quantum devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Physical Review Letters 135, 026601 (2025)
Non-Abelian Chern band in rhombohedral graphene multilayers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Taketo Uchida, Takuto Kawakami, Mikito Koshino
Moiré flat bands in rhombohedral multilayer graphene provide a platform for exploring interaction-driven topological phases, where a single isolated band often forms a Chern band. However, non-Abelian degenerate Chern bands with internal symmetries such as SU($ N$ ) have so far been realized only in highly engineered systems. Here, we show that a doubly degenerate non-Abelian Chern band with Chern number $ |C|=1$ emerges spontaneously at filling $ \nu=2$ in rhombohedral 3-, 4-, and 5-layer graphene, regardless of the presence of an hBN substrate. Using self-consistent Hartree-Fock calculations, we map out phase diagrams as functions of displacement field and electronic periodicity, and analytically demonstrate that the Fock term drives spontaneous symmetry breaking and generates non-Abelian Berry curvature. Our findings unveil a new class of interaction-driven non-Abelian topological phases, distinct from quantum anomalous Hall and fractional Chern phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Insulator-bad metal transition in RNiO$_3$ nickelates beyond Hubbard model and density functional theory
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
The insulator-bad metal transition observed in the Jahn-Teller (JT) magnets orthonickelates RNiO$ _3$ (R = rare earth or yttrium Y) is considered to be a canonical example of the Mott transition, traditionally described in the framework of the Hubbard $ U$ -$ t$ -model and the density functional theory. However, actually the real insulating phase of nickelates is the result of charge disproportionation (CD) with the formation of a system of spin-triplet (S=1) electron [NiO$ _6$ ]$ ^{10-}$ and spinless (S=0) hole [NiO$ _6$ ]$ ^{8-}$ centers, equivalent to a system of effective spin-triplet composite bosons moving in a nonmagnetic lattice. Taking account of only charge degree of freedom we develop a novel minimal $ U$ -$ V$ -$ t_b$ -model for nickelates making use of the charge triplet model with the pseudospin formalism and effective field approximation. We show the existence of two types of CD-phases, high-temperature classical CO-phase with the G-type charge ordering of electron and hole centers, and low-temperature quantum CDq-phase with charge and spin density transfer between electron and hole centers, uncertain valence and spin value for NiO$ _6$ centers. Model $ T$ -R phase diagram reproduces main features of the phase diagram found for RNiO$ _3$ .
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
12 pages, 4 figures, 1 table
JETP Lett. 2025, 121, 411
Asymmetric-gate Mach–Zehnder interferometry in graphene: Multi-path conductance oscillations and visibility characteristics
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Graphene provides an excellent platform for investigating electron quantum interference due to its outstanding coherent properties. In the quantum Hall regime, Mach–Zehnder (MZ) electronic interferometers are realized using p–n junctions in graphene, where electron interference is highly protected against decoherence. In this work, we present a phenomenological framework for graphene-based MZ interferometry with asymmetric p–n junction configurations. We show that the enclosed interferometer area can be tuned by asymmetric gate potentials, and additional MZ pathways emerge in higher-filling-factor scenarios, e.g. $ \left(\nu_{n},\nu_{p}\right)=\left(-3,+3\right)$ . The resulting complicated beat oscillations in asymmetric-gate MZ interference are efficiently analyzed using a machine-learning–based Fourier transform, which yields improved peak-to-background ratios compared to conventional signal-processing techniques. Furthermore, we examine the impact of the asymmetric gate on the interference visibility, finding that interference visibility is enhanced under symmetric gate conditions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Supercritical fluids as a distinct state of matter characterized by sub-short-range structural order
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Sha Jin, Xinyang Li, Xue Fan, Matteo Baggioli, Yuliang Jin
A supercritical fluid (SCF)–the state of matter at temperatures and pressures above the critical point–exhibits properties intermediate between those of a liquid and a gas. However, whether it constitutes a fundamentally distinct phase or merely a continuous extension of the liquid and gas states remains an open question. Here we show that a SCF is defined by sub-short-range (SSR) structural order in the spatial arrangement of particles, setting it apart from the gas (disordered), liquid (short-range ordered), and solid (long-range ordered) states. The SSR structural order can be characterized by a length scale effectively quantified by the number of observable peaks in the radial distribution function. This length grows from a minimum microscopic value, on the order of the inter-particle distance at the gas-SCF boundary, to a diverging value at the SCF-liquid boundary. Based on the emergence of SSR order, we demonstrate that the transport and dynamical properties of the SCF state, including the diffusion coefficient, shear viscosity, and velocity autocorrelation function, also clearly distinguish it from both the liquid and gas states. Theoretical predictions are validated by molecular dynamics simulations of argon and further supported by existing experimental evidence. Our study confirms and assigns physical significance to the refined phase diagram of matter in the supercritical region, consisting of three distinct states (gas, supercritical fluid, and liquid) separated by two crossover boundaries that follow universal scaling laws.
Statistical Mechanics (cond-mat.stat-mech)
19 pages, 12 figures
Singular zero-temperature system
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Q. H. Liu, S. F. Xiao, D. Guo, K. J. Yin
It has long been taken for granted that there is only one type of thermodynamic system near absolute zero temperature: the ordinary one compatible with all statements of the third law, with a fundamental yet tacit assumption that all heat capacities in the system vanish as absolute temperature approaches zero. However, in the strict sense, the statements are not mutually equivalent. Once the tacit assumption is released, the inequivalence must remain, and we may have some systems that are only compatible with one or two statements but not all, defining a singular zero-temperature system which can never be excluded from physical feasibility. We revisit some previously proposed theoretical models and identify that they belong to the singular system.
Statistical Mechanics (cond-mat.stat-mech)
6 pages, no figure
A Spin Glass Characterization of Neural Networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-08-12 20:00 EDT
This work presents a statistical mechanics characterization of neural networks, motivated by the replica symmetry breaking (RSB) phenomenon in spin glasses. A Hopfield-type spin glass model is constructed from a given feedforward neural network (FNN). Overlaps between simulated replica samples serve as a characteristic descriptor of the FNN. The connection between the spin-glass description and commonly studied properties of the FNN – such as data fitting, capacity, generalization, and robustness – has been investigated and empirically demonstrated. Unlike prior analytical studies that focus on model ensembles, this method provides a computable descriptor for individual network instances, which reveals nontrivial structural properties that are not captured by conventional metrics such as loss or accuracy. Preliminary results suggests its potential for practical applications such as model inspection, safety verification, and detection of hidden vulnerabilities.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Artificial Intelligence (cs.AI), Machine Learning (cs.LG)
Dissipation-induced Half Quantized Conductance in One-dimensional Topological Systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Bozhen Zhou, Pan Zhang, Yucheng Wang, Chao Yang
Quantized conductance from topologically protected edge states is a hallmark of two-dimensional topological phases. In contrast, edge states in one-dimensional (1D) topological systems cannot transmit current across the insulating bulk, rendering their topological nature invisible in transport. In this work, we investigate the transport properties of the Su-Schrieffer-Heeger model with gain and loss, and show that the zero-energy conductance exhibits qualitatively distinct behaviors between the topologically trivial and nontrivial phases, depending on the hybridization and dissipation strengths. Crucially, we analytically demonstrate that the conductance can become half-quantized in the topologically nontrivial phase, a feature absent in the trivial phase. We further show that the half quantization predominantly originates from transport channels involving gain/loss and edge states. Our results uncover a new mechanism for realizing quantized transport in 1D topological systems and highlight the nontrivial role of dissipation in enabling topological signatures in open quantum systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
6 pages, 4 figures
Strong and selective magnon-phonon coupling in van der Waals antiferromagnet CoPS$_3$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Dipankar Jana, Diana Vaclavkova, Rajesh Kumar Ulaganathan, Raman Sankar, Milan Orlita, Clement Faugeras, Maciej Koperski, M. E. Zhitomirsky, Marek Potemski
The Raman scattering response of the biaxial antiferromagnet CoPS$ _3$ has been investigated as a function of both magnetic field and temperature. The peaks observed in the low-frequency spectral range (90–200cm$ ^{-1}$ ) have been identified as hybrid magnon–phonon excitations. The energies of the bare magnon and phonon modes, as well as the effective coupling strengths between different excitation pairs, have been determined. The strong and selective magnon–phonon interaction largely accounts for the pronounced splitting of two phonon-like modes observed at 152cm$ ^{-1}$ and 158~cm$ ^{-1}$ in the antiferromagnetic phase of CoPS$ 3$ . Based on the identification of bare magnon excitations and their magnetic-field dependence, we propose an updated set of parameters for the effective exchange ($ J{\mathrm{eff}} = 9.9$ ~meV) and biaxial magnetic anisotropy ($ D = 4.3$ ~meV and $ E = -0.7$ ~meV) and advocate for an apparent anisotropic $ g$ -factor ($ g_x = g_y = 2$ , $ g_z = 4$ ) in the CoPS$ _3$ antiferromagnet.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 6 figures, and supplemental material
Electronic band structure of a nodal line semimetal candidate ErSbTe
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Iftakhar Bin Elius, Nathan Valadez, Dante James, Sami Elgalal, Grzegorz Chajewski, Tetiana Romanova, Andrzej Ptok, Dariusz Kaczorowski, Madhab Neupane
The LnSbTe family is well known for hosting a plethora of intriguing characteristics stemming from its crystalline symmetry, magnetic structure, 4f electronic correlations and spin orbit coupling (SOC) phenomena. In this paper, we have systematically studied the bulk electrical and thermodynamic properties and electronic structure of the nodal line semimetal candidate ErSbTe using angle resolved photoemission spectroscopy (ARPES) corroborated with first principles based theoretical band structure calculations with and without considering the effect of SOC, a critical factor dictating the band degeneracy which depends on the choice of the Ln atom. Corroborative temperature dependent susceptibility, electrical resistivity and thermodynamic measurements, coherently exhibit paramagnetic to antiferromagnetic phase transition approximately at 1.94 K, and another sharp anomaly at 1.75 K. The zero field cooled resistivity measurement does not show the characteristic hump like feature in the other LnSbTe materials. The electronic band structure of ErSbTe, exhibits a diamond shaped Fermi surface. Along the high symmetry direction GX, electronic bands are projected to cross over the Fermi energy, necessitated by the nonsymmorphic symmetry of the system. The other crossing along this direction is gapped, which evolves along the momentum space reaching its maximum along the GM direction.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
8 pages, 4 figures
Effective toughness estimation by FFT based phase field fracture: application to composites and polycrystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
An estimate of the effective toughness of heterogeneous materials is proposed based on the Phase Field Fracture model implemented in an FFT homogenization solver. The estimate is based on the simulation of the deformation of representative volume elements of the microstructure, controlled by a constant energy dissipation rate using an arc-length type control. The definition of the toughness corresponds to the total energy dissipated after the total fracture of the RVE – which can be accurately obtained thanks to the dissipation control – divided by the RVE transverse area (length in 2D). The proposed estimate accounts for both the effect of heterogeneity in toughness and elastic response on the overall fracture energy and allows as well to account for phases with anisotropic elastic and fracture response (fracture by cleavage). To improve toughness predictions, crack-tip enrichment is used to model initial cracks. The method is applied to obtain the effective toughness of composites and elastic polycrystals in a series of examples. In the two types of materials, it is found that both heterogeneity in elastic response and fracture energy contribute to increase the effective toughness. Microscopically, it is found that toughening mechanisms are related to the passage of the crack through tougher phases and deviation of the crack path. It is also found that the latter is the controlling mechanism for cases with marked heterogeneity and high anisotropy, eventually provoking toughening saturation for sufficiently high values of heterogeneity or anisotropy.
Materials Science (cond-mat.mtrl-sci)
accepted for publication in Materials Research Communications, Special Issue in Honor of Ricardo Lebensohn
Aging in a two-dimensional swarmalator crystal with delayed interactions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Chanin Kumpeerakij, Thiparat Chotibut, Oleg Kogan
Time delay can have a significant impact on the properties of collective organization of active matter. In the previous paper [1], we discussed delay-induced breathing in a system of swarmalators - a model coupling particles’ internal phases to spatial interactions. Here we build on that study to investigate the aging phenomenon in this system. It is the aging of a two-dimensional crystal with defects and inhomogeneous lattice constants, and takes place after the breathing transients subside. We show that aging proceeds through the gradual elimination of five-fold and seven-fold coordination number defects, which merge pairwise or migrate to the cluster boundary, incrementally increasing the hexatic order parameter in the bulk. Despite this process, defects usually do not fully disappear; some residual number of defects remain frozen in the interior. However, we found that it is possible to achieve a nearly total elimination of coordination number defects at sufficiently low delay - when the surface of the cluster develops a sufficeintly thick fluidized ``boiling layer’’. This mechanism of boundary-mediated annealing reveals a non-equilibrium pathway to achieving high crystalline order in the bulk, and raises a tantalizing possibility for controlling defects in active matter with free boundaries.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft)
12 pages, 13 figures, 2 supplementary videos
Correlated electrons in flat bands: Concepts and Developments
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
When the electronic dispersion in a material is independent of momentum, it gives rise to strongly correlated flat bands, with the single particle energy, quenched. Though the notion of flat bands had been known since long, their experimental realization is achieved much later with the advent of ultra cold atomic gases, followed by photonic lattices, coordination polymers and more recently solid state materials. By the virtue of their quenched kinetic energy scales the flat band materials provide an ideal platform to engineer, customize and investigate the interplay between topology, geometry and strong electronic correlations; giving rise to exotic quantum phases such as, unconventional superconductivity, Mott insulator, non Fermi liquid metals etc. This review presents a comprehensive overview of the theoretical foundation and material realization of the many body systems with flat electronic bands. We discuss the origin of the flat bands and their mathematical construction in prototypical lattices, particularly focussing on those with Lieb and Kagome geometries. Observations made and inferences drawn based on the recent experimental and theoretical investigations are presented along with the framework for a non perturbative numerical approach to address the quantum phases in the flat band materials. By synthesizing insights from both theory and experiment, this review aims to provide a unifying perspective on the emergent many-body phenomena in flat band systems and to outline future directions for the field.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Quantum Gases (cond-mat.quant-gas), Superconductivity (cond-mat.supr-con)
69 pages, 8 figures. Invited review article in Journal of Physics: Condensed Matter
Unified Semiclassical Theory of Nonlinear Hall Effect:Bridging Ballistic and Diffusive Transport Regime
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Xinyu Liu, Haozhi Liao, Guangyun Qi, Hao Geng, Li Sheng, Dingyu Xing
The nonlinear Hall effect has attracted considerable attention and undergone extensive investigation in recent years. However, theoretical studies addressing size-dependent effects remain largely unexplored. In this work, we establish a unified semiclassical framework based on the Boltzmann transport equation, incorporating generalized boundary conditions to bridge the ballistic and diffusive transport regimes. Our analysis reveals that the nonlinear Hall effect arises from the combined action of two distinct mechanisms: the Berry curvature dipole and the Fermi-surface integral of Berry curvature. Furthermore, we investigate the Hall effect in topological crystalline insulators (TCIs), elucidating that the size dependence originates from competition between the two transport mechanisms. By connecting the two distinct regimes, our theoretical framework provides a comprehensive understanding of the nonlinear Hall effect in finite-sized systems, offering both fundamental insights and a useful analytical tool for more size-dependent investigations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Experimental and Computational Demonstration of a Highly Stable, in-situ Pt Decorated Sputtered ZnO Hydrogen Sensor for sub-ppm Level Detection
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Puja Ghosh, Pritam Ghosh, Rizwin Khanam, Chandra Shekhar Prajapati, Aarti Nagarajan, Shreeja Das, Rakesh Paleja, Sharan Shetty, Gopalakrishnan Sai Gautam, Navakanta Bhat
In this work, we present a Pt decorated ZnO thin film-based gas sensor for hydrogen detection, fabricated using a sputtering technique and an in-situ Pt decoration approach. Specifically, we deposit a ZnO thin film on an interdigitated electrode substrate, with Pt nanoclusters added to the (002) polar plane by brief sputtering (1 to 6 s) to create an active sensing interface. Our sensor demonstrates optimal performance at an operating temperature of 498 K, with rapid response and recovery times (10 and 3 s), high selectivity, and long-term stability. We find the Pt decorated ZnO sensor, with a Pt deposition time of 2 s, to exhibit enhanced response (52,987%) to 1% hydrogen concentration, indicating its suitability for industrial and environmental monitoring applications. Additionally, our device demonstrates reliable detection of low hydrogen concentrations (100 ppb), with a response of ~38% and no response drift over one year of testing, underscoring the long-term stability of the sensor. To elucidate the role of Pt deposition and pristine ZnO in hydrogen sensing, we perform density functional theory calculations, analysing adsorption and reaction energetics involving H2, O2, O, OH, and H2O, and lattice oxygen atoms on the ZnO (002) surface with and without Pt decoration. Our computational data is in agreement with our experiments, identifying the oxygen-exposed (002) surface to be most active for hydrogen sensing in both pristine and Pt decorated ZnO. Further, our computations highlight the role of Pt in enhancing hydrogen sensitivity via i) activating an autoreduction pathway of adsorbed OH, ii) spontaneous dissociation of adsorbed molecular H2, and iii) keeping the lattice oxygen pathway of forming H2O active. Our systematic approach of designing sensors combining an experimental setup with theoretical insights, is key in developing and optimizing efficient hydrogen gas sensors.
Materials Science (cond-mat.mtrl-sci)
Lack of collisional hydrodynamics in a harmonically trapped one-dimensional Bose gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-12 20:00 EDT
Caroline Mauron, Karen V. Kheruntsyan, Giulia De Rosi
Using the theory of generalized hydrodynamics, we study the dipole compression collective oscillations of a harmonically trapped one-dimensional Bose gas in the crossover from weak to strong repulsive interactions. In the uniform limit, the system is described by the integrable Lieb-Liniger model, while the presence of the trap breaks integrability. In contrast to previous predictions based on the classical hydrodynamic variational ansatz – which yields a single-frequency dipole compression mode – we observe a beating signal comprising two frequencies across all regimes of the gas. Furthermore, we find that the higher frequency crosses over from the low-temperature phononic hydrodynamic regime to the collisionless limit as the temperature increases – without saturating at the previously predicted value characteristic of the high-temperature collisional hydrodynamic regime. This crossover occurs around the so-called hole-induced anomaly temperature, above which the quasiparticle picture of excitations no longer applies. This explains the absence of the collisional hydrodynamic regime and resolves a long-standing open question about its validity at high temperatures in systems where integrability is nearly broken by weak confinement. Our findings reveal intricate connections between excitations, thermodynamics, correlations, dynamics, and interparticle collisions, and may prove relevant to other atomic, nuclear, solid-state, electronic, and spin systems that exhibit similar anomalies or thermal second-order phase transitions.
Quantum Gases (cond-mat.quant-gas), Superconductivity (cond-mat.supr-con), Exactly Solvable and Integrable Systems (nlin.SI), Nuclear Theory (nucl-th)
Main Text: 8 pages, 2 figures, 1 table; Appendices: 2 pages, 2 figures, 1 table
Secondary finite-size effects and multi-barrier free energy landscapes in molecular simulations of hindered ion transport
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Omar Khalifa, Brian A. Shoemaker, Amir Haji-Akbari
Ion transport through nanoscale channels and pores is pivotal to numerous natural processes and industrial applications. Experimental investigation of the kinetics and mechanisms of such processes is, however, hampered by the limited spatiotemporal resolution of existing experimental techniques. While molecular simulations have become indispensable for unraveling the underlying principles of nanoscale transport, they also suffer from some important technical limitations. In our previous works, we identified strong polarization-induced finite-size effects in molecular dynamics simulations of hindered ion transport, caused by spurious long-range interactions between the traversing ion and the periodic replicates of other ions. To rectify these artifacts, we introduced the Ideal Conductor/Dielectric Model (\textsc{Icdm}), which treats the system as a combination of conductors and dielectrics, and constructs an analytical correction to the translocation free energy profile. Here, we investigate some limitations of this model. Firstly, we propose a generalized approach based on Markov State models that is capable of estimating translocation timescales in the thermodynamic limit for free energy profiles with multiple comparable barriers. Second, we identify a new category of polarization-induced finite-size effects, which significantly alter the spatial distribution of non-traversing ions in smaller systems. These secondary effects cannot be corrected by the ICDM model and must be avoided by selecting sufficiently large system sizes. Additionally, we demonstrate through multiple case studies that finite-size artifacts can reverse expected trends in ion transport kinetics. Our findings underscore the necessity for careful selection of system sizes and the judicious application of the \textsc{Icdm} model to rectify residual finite-size artifacts.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 6 figures, 5 tables
Symmetry-breaking perturbations in the Jahn-Teller-Hubbard model
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-12 20:00 EDT
Natsuki Okada, Tatsuya Miki, Yusuke Nomura, Philipp Werner, Shintaro Hoshino
We study the effect of symmetry-breaking perturbations in the multiorbital Hubbard model coupled to anisotropic Jahn-Teller phonons, which is relevant for the description of fulleride superconductors. This system is often approximated by a model with static antiferromagnetic (AFM) Hund’s coupling, in which the coupling to the Jahn-Teller phonon is effectively described, but the retardation effect associated with phonon propagation is neglected. We compare the properties of the models with static AFM Hund’s coupling and dynamical Jahn-Teller electron-phonon interaction by means of the Eliashberg theory. Considering the susceptibilities for the spin, magnetic orbital, electric orbital, and superconductivity, we reveal a qualitatively different behavior between the two models in the case of the magnetic orbital susceptibility. We further study the effect of a magnetic field on the $ s$ -wave spin-singlet superconducting state. In the presence of the field, the magnetic orbital susceptibility becomes nonzero due to a combination of multiorbital and retardation effects, while the spin susceptibility remains zero at low temperatures. By analyzing this phenomenon both numerically and analytically, we clarify that odd-frequency pairs induced by the magnetic field play a crucial role in the spin and orbital magnetic susceptibilities. Thus, the magnetic degrees of freedom produce interesting behaviors in the presence of retardation effects associated with electron-phonon coupling.
Superconductivity (cond-mat.supr-con)
20 pages, 11 figures
ΔSCF Excitation Energies Up a Ladder of Ground-State Density Functionals
New Submission | Other Condensed Matter (cond-mat.other) | 2025-08-12 20:00 EDT
Ethan Pollack, Rohan Maniar, John P. Perdew
Density functional theory (DFT) is a widespread and effective tool in electronic structure calculations for ground-state electron systems. Its success has prompted exploration into the use of DFT for non-collective excited states. The delta self-consistent field ($ \Delta$ SCF) method allows for the extension of DFT to excited-state energies by restricting the Kohn-Sham orbital occupations, producing an excited-state electron density, and then computing its energy. In this paper, we examine the performance of the LSDA, PBE generalized-gradient approximation (GGA), and SCAN/r2SCAN meta-GGA for the excitation energies of several important systems. We consider the energies of atoms with atomic number 1-18. For the hydrogen atom, where we use the exact electron density and have no multiplet splitting, we find significant improvement up the ladder from LSDA to PBE to SCAN. For the uniform gas, we find an effective mass different from the bare mass only with r2SCAN. We split the case of multi-electron atoms into non-aufbau excitations, where the highest-energy electron is excited to the lowest state in the next nl subshell (where accuracy is least limited by available basis sets), and spin-flip excitations, where the spin of an electorn is flipped, leading to a higher-energy state of the same nl configuration. We find reasonably accurate approximate excitation energies, except for the spin-flip cases where the auxiliary non-interacting wavefunction of a non-Hund’s-rule spin state is not well-described by a single determinant.
Other Condensed Matter (cond-mat.other)
Spin Phonon Coupling and Relaxation time in Lu(II) compound with 9.2GHz clock transition
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Electron spin qubits operating at atomic clock transitions exhibit exceptionally long coherence times, making them promising candidates for scalable quantum information applications. In solid-state systems, interactions between qubits and lattice phonons are known to play a critical role in spin relaxation (T1) and decoherence (T2). In this work, we perform first-principles calculations on a Lu(II) complex spin qubit featuring a prominent clock transition. By employing advanced electronic structure methods, we quantitatively evaluate the influence of phonons on the hyperfine interaction, which serves as the primary spin-lattice coupling mechanism. Treating these phonon-induced variations as first-order perturbations, we apply the Redfield master equation to compute both T1 and T2, along with their temperature dependencies. For T1, we adopt a second quantization formalism to describe phonon interactions, while T2 is evaluated by explicitly integrating acoustic phonon contributions across the full Brillouin zone. Our results reproduce the experimentally observed magnetic field dependence of T2, including the coherence peak near 0.43 T, though the absolute values of T1 and T2 differ by one to two orders of magnitude. Analysis reveals that T1 is primarily governed by longitudinal phonons, whereas T2 is most strongly influenced by mid-wavelength, mid-energy acoustic modes. These findings provide a quantitative demonstration of the clock transition protective effect on spin qubit coherence and offer a transferable computational framework for evaluating spin-phonon interactions in other molecular spin qubits.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Quantum Physics (quant-ph)
11 pages, 5 figures
Hydrazine-Free Precursor for Solution-Processed All-Inorganic Se and Se1-xTex Photovoltaics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Adam D. Alfieri, Swarnendu Das, Kim Kisslinger, Chloe Leblanc, Jamie Ford, Cherie R. Kagan, Eric A. Stach, Deep Jariwala
Selenium (Se) has reemerged as a promising absorber material for indoor and tandem photovoltaics (PVs), and its alloys with Te (Se1-xTex) offer a widely tunable bandgap. Solution processing of this materials system offers a route to low-cost fabrication. However, solution processing of Se has, thus far, only used hydrazine, which is an extremely hazardous solvent. In this work, we prepare and isolate propylammonium poly-Se and poly-Se-Te precursors from a safer thiol-amine solvent system. We formulate molecular inks by dissolving the precursor n,n-dimethylformamide (DMF) with a monoethanolamine (EA) additive and process high-quality Se and Se1-xTex films with bandgaps ranging from 1.20 eV to 1.86 eV. We fabricate PVs from these films using TiO2 and MoO3 charge transport layers (CTLs) to achieve power conversion efficiencies as high as 2.73% for Se and 2.33% for Se0.7Te0.3 under solar simulation. Se devices show excellent stability with no degradation after 1 month in air, enabled by the excellent stability of Se and the use of inorganic CTLs. This work represents an important step towards low-cost solution-phase processing of Se and Se1-xTex alloys for PVs and photodetectors with low toxicity and high bandgap tunability.
Materials Science (cond-mat.mtrl-sci)
Field-Tailoring Quantum Materials: Magneto-Synthesis of Metastable Metallic States in a Spin-Orbit-Coupled Trimer Iridate
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Tristan R. Cao, Hengdi Zhao, Xudong Huai, Arabella Quane, Varun Narayanan, Thao T. Tran, Feng Ye, Gang Cao
We demonstrate that modest magnetic fields (a fraction of a Tesls), when applied during high-temperature crystal growth, can profoundly alter the structural and electronic ground state of a spin-orbit-coupled, antiferromagnetic trimer lattice. Using an iridate as a model system, we show that magneto-synthesis, a field-assisted synthesis approach, stabilizes a structurally compressed, metastable metallic phase that cannot be accessed through conventional synthesis routes. This field-tailored phase exhibits a shortened Ir-Ir bond distance, reduced lattice distortion, and suppressed magnetic order, culminating in a robust insulator-to-metal transition. Electrical resistivity of the field-tailored phase drops by up to four orders of magnitude, while the low-temperature specific heat reveals a substantial enhancement in the Sommerfeld coefficient, consistent with the emergence of a highly correlated metallic state. First-principles calculations confirm that the field-stabilized phase lies significantly above the ground state in energy, underscoring its metastable nature. These findings establish magneto-synthesis as a powerful new pathway for accessing non-equilibrium quantum phases in strongly correlated materials.
Strongly Correlated Electrons (cond-mat.str-el)
4 figures
g-Factor Enhanced Upper Critical Field in Superconducting PdTe2 due to Quantum Confinement
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-12 20:00 EDT
Kota Yoshimura, Tzu-Chi Hsieh, Huiyang Ma, Dmitry V. Chichinadze, Shan Zou, Michael Stuckert, David Graf, Robert Nowell, Muhsin Abdul Karim, Daichi Kozawa, Ryo Kitaura, Xiaolong Liu, Xinyu Liu, Dafei Jin, Cyprian Lewandowski, Yi-Ting Hsu, Badih A. Assaf
The Pauli limiting field of superconductors determines the maximal possible value of magnetic field at which superconductivity remains possible. For weak-coupling superconductors, it is determined by an established relation that can be found by setting the condensation energy equal to the magnetization free energy. The latter is a function of the carrier g-factor. Here, we demonstrate in a van der Waals superconductor PdTe2, that quantum confinement can tune the effective g-factor causing the Pauli limit to become thickness dependent. We experimentally probe the in-plane upper critical field (Hc2||) of PdTe2 at intermediate thicknesses down to 20mK. Hc2|| is enhanced by more than an order of magnitude as the thickness is varied from 50nm down to 19nm. We model its temperature and thickness dependence, revealing that both orbital and spin Zeeman depairing mechanisms impact its value. While the variation of the orbital interaction is expected, our findings reveal how the Zeeman interaction impacts superconductivity in thin films. They aid in the search for mixed and odd pairing superconductivity where an enhancement of Hc2|| can be occasionally associated with those unconventional pairing symmetries.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Field-derivative torque induced magnetization reversal in ferrimagnetic Gd${3/2}$Yb${1/2}$BiFe$5$O${12}$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Pratyay Mukherjee, Arpita Dutta, Somasree Bhattacharjee, Shovon Pal, Ritwik Mondal
Understanding the mechanism of spin switching in ferrimagnets via the excitation of THz pulses holds promise for future-generation magnetic memory devices. Such spin switching can be accomplished by the Zeeman torque exerted by the THz pulses on the magnetic spins. Theoretical and experimental works have established that the field-derivative of a terahertz pulse also exerts a torque, field derivative torque (FDT). Here, we investigate the role of the FDT in the spin switching in ferrimagnetic Gd$ _{3/2}$ Yb$ _{1/2}$ BiFe$ _5$ O$ _{12}$ using a computational approach. Our results foresee that the spin switching in the presence of the FDT requires less THz magnetic fields than the spin switching without the FDT. Without the FDT terms, the spin switching in the considered system requires an extremely high magnetic field. Furthermore, we compute the switching and non-switching contour diagrams to show that the FDT tremendously enhances the possibility of spin switching. These results not only shed light on the significance of the FDT in magnetization switching but also suggest materials where the switching effect is pronounced.
Materials Science (cond-mat.mtrl-sci)
11 pages, 6 figures
Tunable Interfacial Thermal Conductance in Graphene/Germanene van der Waals Heterostructure using an Optimized Interlayer Potential
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Sapta Sindhu Paul Chowdhury, Sourav Thapliyal, Bheema Lingam Chittari, Santosh Mogurampelly
Accurately modeling interfacial thermal transport in van der Waals heterostructures is challenging due to the limited availability of interlayer interaction potentials. We develop a pairwise interlayer potential for graphene/germanene van der Waals heterostructure using the binding energy obtained from ab-initio density functional theory calculations and use it to calculate the interfacial thermal conductivity. Our calculations reveal that the interfacial thermal conductivity shows superior tunability with external strain. The phonon density of states calculations show a blueshift in the phonon spectra with an applied compressive strain in the direction of heat flow, increasing the interfacial thermal conductance to $ \sim$ 136% of the unstrained value. In contrast, a tensile strain is found to cause an opposite effect, reducing the conductance to $ \sim$ 70% of the unstrained value. Moreover, due to increased availability of phonons for heat transfer, both temperature and interaction strength are found to correlate positively with the interfacial thermal conductance for both directions of heat flow.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
To appear in The Journal of Chemmical Physics
Magnetic and Crystal Symmetry Effects on Spin Hall Conductivity in Altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Dameul Jeong, Seoung-Hun Kang, Young-Kyun Kwon
Altermagnets, which reconcile zero net magnetization with pronounced spin splitting, offer fresh opportunities for spin-based functionalities in next-generation electronic and spintronic devices. In this paper, we explore the unconventional spin Hall conductivity (USHC) in three prototypical altermagnets – RuO$ _2$ , CrSb, and MnTe – and elucidate how distinct magnetic and crystal symmetries modulate their spin Hall responses. RuO$ _2$ exhibits only trivial USHC contributions under a tilted geometry, demonstrating that symmetry projections alone can induce apparent unconventional elements. In contrast, CrSb and MnTe manifest robust, symmetry-driven USHC without structural tilts, enabled by easy-axis orientations that reduce magnetic symmetry. Through extensive first-principles calculations, we demonstrate the complementary roles of the time-reversal-even and time-reversal-odd components in determining the overall SHC. Our findings indicate that controlling the interplay between crystal and magnetic symmetry – for instance, by epitaxial strain or doping – can provide an experimental avenue to tune USHC magnitudes and directions in altermagnets. These results pave the way for the engineering of multifunctional spintronic devices, where enhanced coherence and robust spin transport are realized in zero-net-moment materials with easily tailored spin configurations.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Effect of Josephson junction parameter spread on the performance of SQUID arrays
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-12 20:00 EDT
O. A. Nieves, M. A. Galí Labarias, A. C. Keser, K.-H Müller, E. E. Mitchell
Josephson junctions based on grain boundaries, such as those made of Yttrium Barium Copper Oxide (YBCO), exhibit inherent parameter spreads in their critical current and normal state resistance. This variation in junction properties leads to a decrease in array performance for magnetic sensing applications. Therefore, we must develop a quantitative understanding of how junction parameter spreads impact arrays with different designs. In this paper, we use numerical simulations to investigate how the ensemble averaged voltage modulation depth (eta) of one-dimensional SQUID arrays varies with the statistical spread in the junction parameters. In these calculations for arrays we vary the number of junctions, loop inductance and thermal noise strength. We show that eta decreases with increasing spread, and that this reduction is accelerated further by the number of junctions and SQUID cell inductance, but is robust to changes in the thermal noise strength.
Superconductivity (cond-mat.supr-con)
Proximate spin-liquid behavior in the double trillium lattice antiferromagnet K$_2$Co$_2$(SO$_4$)$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
A. Magar, K. Somesh, M. P. Saravanan, J. Sichelschmidt, Y. Skourski, M. T. F. Telling, V. A. Ginga, A. A. Tsirlin, R. Nath
We report proximate quantum spin liquid behavior in K$ _2$ Co$ _2$ (SO$ 4$ )$ 3$ with the magnetic Co$ ^{2+}$ ions embedded on a highly frustrated three-dimensional double trillium lattice. Single-crystal and high-resolution synchrotron powder x-ray diffraction experiments reveal a structural phase transition at $ T{\rm t} \simeq 125$ K from high-temperature cubic to low-temperature monoclinic phase with the three-fold superstructure. Magnetization and heat capacity consistently show the formation of the $ J{\rm eff} =1/2$ state of Co$ ^{2+}$ below 50 K. In zero field, K$ _2$ Co$ _2$ (SO$ _4$ )$ _3$ shows signatures of static magnetic order formed below $ T^\ast \simeq 0.6$ K, but muon spin relaxation experiments reveal a large fluctuating component that persists down to at least 50 mK, reminiscent of quantum spin liquid (QSL). Static order is completely suppressed in the small magnetic field of $ \sim 1$ T, and low-temperature heat capacity demonstrates the $ T^2$ behavior above this field, another fingerprint of QSL. Ab initio calculations show a competition of several antiferromagnetic couplings that render K$ _2$ Co$ _2$ (SO$ _4$ )$ _3$ a promising pseudospin-$ \frac12$ material for studying quantum magnetism in the double trillium lattice geometry.
Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
Breakdown and polarization contrasts in ferroelectric devices observed by operando laser-based photoemission electron microscopy with the AC/DC electrical characterization system
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Hirokazu Fujiwara, Yuki Itoya, Masaharu Kobayashi, Cédric Bareille, Toshiyuki Taniuchi
We have developed an operando laser-based photoemission electron microscope (laser-PEEM) with a ferroelectric characterization system. A Sawyer-Tower circuit was implemented to measure the polarization-voltage ($ P-V$ ) characteristics of ferroelectric devices. Using this system, we successfully obtained the well-defined $ P-V$ hysteresis loops for a ferroelectric capacitor incorporating Hf$ _{0.5}$ Zr$ _{0.5}$ O$ _2$ (HZO), reproducing the typical field-cycling characteristics of HZO capacitors. After dielectric breakdown caused by field-cycling stress, we visualized a conduction filament through the top electrode without any destructive processing. Additionally, we successfully observed polarization contrast through the top electrode of an oxide semiconductor (InZnO$ _x$ ). These results indicate that our operando laser-PEEM system is a powerful tool for visualizing conduction filaments after dielectric breakdown, the ferroelectric polarization contrasts, and electronic state distribution of materials implemented in ferroelectric devices, including ferroelectric field-effect transistors and ferroelectric tunnel junctions.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
24 pages, 10 figures
Doping $S=1$ antiferromagnet in one-dimension
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Antiferromagnetic ground states, when doped, give rise to rich and complex phenomena, prompting detailed investigations in various spin systems. Here, we study the effect of doping on the one-dimensional $ S = 1$ antiferromagnetic Heisenberg model (AFM). Specifically, we investigate how the presence of holes affects the static and dynamic (frequency-dependent) spin-spin correlations of the two-orbital Hubbard-Kanamori chain. The latter, at half-filling and in the limit of strong interactions, maps onto an $ S = 1$ Heisenberg model. For moderate interactions, an orbital resonating-valence-bond (orbital-RVB) state emerges up to doping levels of $ x \lesssim 0.4$ . A detailed analysis of interaction strength $ U$ and doping concentration $ x$ reveals that this phase inherits the key features of spin excitations found in the half-filled case – namely, a gapped spin spectrum and ``coherent’’ magnon behavior up to a wavevector $ q$ determined by the Fermi vector, $ 2k_\mathrm{F} = \pi(1 - x)$ . Furthermore, our results uncover an additional broad, incoherent spectral weight for $ q \gtrsim 2k_\mathrm{F}$ at high frequencies. Finally, we show that near the transition to a ferromagnetic phase, a previously unidentified spiral-like state emerges, characterized by spin excitations reminiscent of the $ J_1$ -$ J_2$ Heisenberg model.
Strongly Correlated Electrons (cond-mat.str-el)
Sagnac and Mashhoon effects in graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Yu.V. Shtanov, T.-H.O. Pokalchuk, S.G. Sharapov
We investigate the Sagnac and Mashhoon effects in graphene, taking into account both the pseudospin and intrinsic spin of electrons, within a simplified model of a rotating nanotube or infinitesimally narrow ring. Based on considerations of the relativistic phase of the wave function and employing the effective Larmor theorem, we demonstrate that the Sagnac fringe shift retains a form analogous to that for free electrons, governed by the electron’s vacuum mass. In the case of a narrow ring, an additional $ \pi$ -phase shift arises due to the Berry phase associated with the honeycomb graphene lattice. The Mashhoon fringe shift, which characterizes the dynamics of intrinsic spin, retains its conventional form in graphene, with its dependence on the Fermi velocity. Our analysis highlights both the similarities and differences between spin and pseudospin degrees of freedom in graphene.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), General Relativity and Quantum Cosmology (gr-qc), Quantum Physics (quant-ph)
18 pages, 3 figures
Anisotropy at twin interfaces in $RT_{12}$ ($R$=rare earth, $T$=transition metal) magnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
RT\textsubscript{12} materials continue to attract attention due to their potential use as rare-earth-lean'' permanent magnets, but converting their promising intrinsic properties into practical high performance remains an elusive goal. Sophisticated experimental characterization techniques are providing unprecedented insight into the structure of these materials at the atomistic scale. Atomistic spin dynamics or micromagnetics simulations could help unravel the links between these structures and resultant magnet performance, but require input data describing the intrinsic magnetic properties. Here, first-principles calculations based on density-functional theory are used to determine these properties for two model interface structures which have been derived from recently reported high resolution electron microscopy images. One model structure is a stoichiometric twin formed by mirroring the RT\textsubscript{12} structure in the (101) plane, and the other model structure is a stacking fault’’ involving the insertion of a RT\textsubscript{4} plane and a displacement along the [100] axis. Magnetic moments and crystal field coefficients have been calculated for the optimized structures. The interfaces modify the magnetic properties at the sub-nm scale. In particular, in the R-rich region of the ``stacking fault’’, the local easy axis of magnetization rotates by $ 49^\circ$ from its bulk direction, which may lead to reduced coercivity through the easier nucleation of reverse domains.
Materials Science (cond-mat.mtrl-sci)
11 pages, 8 figures
Revisiting the access conductance of a charged nanopore membrane
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
Holly C. M. Baldock, David M. Huang
Electric-field-driven electrolyte transport through nanoporous membranes is important for applications including osmotic power generation, sensing and iontronics. We derive an analytical equation in the Debye–Hückel regime and a semi-analytical equation for arbitrary surface potentials for the electric-field-driven electric current through a pore in an ultrathin membrane, which predict scaling with fractional powers of the pore size and Debye length. We show that our theory for arbitrary electric potentials accurately quantifies the ionic conductance through an ultrathin membrane in finite-element method numerical simulations for a wide range of parameters, and generalizes a widely used theory for the access electrical conductance of a membrane nanopore to a broader range of conditions. Our theory predicts that fractional scaling of the ionic conductance with electrolyte concentration at low concentrations is a general property of charged ultrathin membranes and also occurs for thicker membranes for which the access contribution to the conductance dominates, which could explain experimental observations of this widely debated phenomenon.
Soft Condensed Matter (cond-mat.soft)
Mechanistic Insight into BEOL Thermal Transport via Optical Metrology and Multiphysics Simulation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Yang Shen, Shangzhi Song, Tao Chen, Kexin Zhang, Yu Chen, Lu Zhao, Puqing Jiang
As integrated circuits continue to scale down and adopt three-dimensional (3D) stacking, thermal management in the back-end-of-line (BEOL) has emerged as a critical design constraint. In this study, we present a combined experimental and simulation framework to quantitatively characterize and mechanistically understand thermal transport in BEOL multilayers. Using the Square-Pulsed Source (SPS) method, a time-resolved optical metrology technique, we measure cross-plane thermal resistance and areal heat capacity in semiconductor chips at nanometer resolution. Two fabricated chip samples, polished to the M4 and M6 interconnection layers, are analyzed to extract thermal properties of distinct multilayer stacks. Results show that thermal resistance follows a series model, while areal heat capacity scales linearly with metal content. To uncover the underlying physical mechanisms, we perform finite element simulations using COMSOL Multiphysics, examining the influence of via connectivity and dielectric thermal conductivity on effective cross-plane heat transport. The simulations reveal that dielectric materials, due to their large volume fraction, are the primary limiting factor in BEOL thermal conduction, while the via structure plays a secondary but significant role. This combined experimental-simulation approach provides mechanistic insight into heat transport in advanced IC architectures and offers practical guidance for optimizing thermal pathways in future high-performance 3D-stacked devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 6 figures
QVNTVS, Open-Source Quantum Well Simulator
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Quantum Wells (QW) are of great importance in optoelectronic devices such as LEDs and LASERs, being the emissive this http URL the quantum particles in different QW topologies like rectangular finite potential wells, multiple potential wells, and triangular biased potential well heterojunctions enables faster modeling, theoretical characterization, and more. QVNTVS performs energy level and wavefunction calculations, recombination probability, transition energy, and optical emission computations quickly and accurately. Contrasting with the existing simulators, QVNTVS is an open-source project and can produce solutions for niche problems like potential wells under an electric field, heterojunctions, recombination, and transition matrices. QVNTVS simulates QWs by solving the Time-Independent Schrödinger Equation for different potential profiles in a discretized space using the finite-difference method and computes the properties of the device using the extracted information from the solution. The results align with the analytical calculations and the experimental data.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)
For the source code: this https URL
Generative Inversion for Property-Targeted Materials Design: Application to Shape Memory Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Cheng Li, Pengfei Danga, Yuehui Xiana, Yumei Zhou, Bofeng Shi, Xiangdong Ding, Jun Suna, Dezhen Xue
The design of shape memory alloys (SMAs) with high transformation temperatures and large mechanical work output remains a longstanding challenge in functional materials engineering. Here, we introduce a data-driven framework based on generative adversarial network (GAN) inversion for the inverse design of high-performance SMAs. By coupling a pretrained GAN with a property prediction model, we perform gradient-based latent space optimization to directly generate candidate alloy compositions and processing parameters that satisfy user-defined property targets. The framework is experimentally validated through the synthesis and characterization of five NiTi-based SMAs. Among them, the Ni$ _{49.8}$ Ti$ _{26.4}$ Hf$ _{18.6}$ Zr$ _{5.2}$ alloy achieves a high transformation temperature of 404 $ ^\circ$ C, a large mechanical work output of 9.9 J/cm$ ^3$ , a transformation enthalpy of 43 J/g , and a thermal hysteresis of 29 °C, outperforming existing NiTi alloys. The enhanced performance is attributed to a pronounced transformation volume change and a finely dispersed of Ti$ _2$ Ni-type precipitates, enabled by sluggish Zr and Hf diffusion, and semi-coherent interfaces with localized strain fields. This study demonstrates that GAN inversion offers an efficient and generalizable route for the property-targeted discovery of complex alloys.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Fulde-Ferrell-Larkin-Ovchinnikov States and Topological Bogoliubov Fermi Surfaces in Altermagnets: an Analytical Study
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-12 20:00 EDT
We present an analytical study of the ground-state phase diagram for dilute two-dimensional spin-1/2 Fermi gases exhibiting $ d$ -wave altermagnetic spin splitting under $ s$ -wave pairing. Within the Bogoliubov-de Gennes mean-field framework, four distinct phases are identified: a Bardeen-Schrieffer-Cooper-type superfluid, a normal metallic phase, a nodal superfluid with topological Bogoliubov Fermi surfaces (TBFSs), and Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states with finite center-of-mass momentum. Among these, the FFLO states and TBFSs exemplify two unconventional forms of superconductivity. Considering the simplicity of this model, with only one band, zero net magnetization, and $ s$ -wave paring, the emergence of both unconventional phases underscores the pivotal role of altermagnetic spin splitting in enabling exotic pairing phenomena. This analytical study not only offers a valuable benchmark for future numerical simulations, but also provides a concrete experimental roadmap for realizing FFLO states and TBFSs in altermagnets.
Superconductivity (cond-mat.supr-con), Quantum Gases (cond-mat.quant-gas)
16 pages, 7 figures
Condensed Spin Excitation of Quantized Dirac Fermions in the Quasi-Two-Dimensional semimetal BaMnBi$_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Masashi Kumazaki, Azimjon Temurjonov, Yukihiro Watanabe, Taku Matsuhita, Yoshiaki Kobayashi, Yasuhiro Shimizu
Three-dimensional Dirac semimetals enable the observation of bulk magnetism in topological quantum phases. We report site-selective NMR spectroscopy that probes local static and dynamic spin susceptibility on the magnetic semimetal BaMnBi$ _2$ . We find that spontaneous staggered fields from antiferromagnetic Mn moments are completely canceled at the Bi layer hosting Dirac fermions. In an in-plane field, the nuclear spin-lattice relaxation rate $ 1/T_1$ follows the cubic temperature dependence to low temperatures, manifesting the ideal Dirac semimetal with chemical potential close to the Dirac point. In an out-of-plane field, $ 1/T_1$ becomes a constant below 20 K, where the Laudau level appears, and is enhanced more than 100 times larger than under the in-plane field. The result demonstrates a condensation of quantized Dirac fermions in the quantum Hall regime.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 5 figures
Sokoban Random Walk: From Environment Reshaping to Trapping Transition
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Prashant Singh, David A. Kessler, Eli Barkai
We study the dynamics of a $ \textit{Sokoban random walker}$ moving in a disordered medium with obstacle density $ \rho$ . In contrast to the classic model of de Gennes with static obstacles that exhibits a percolation transition, the Sokoban walker is capable of modifying its environment by pushing a few surrounding obstacles. Surprisingly, even a limited pushing ability leads to a loss of the percolation transition. Through a combination of a rigorous large-deviation calculation and extensive numerical simulations, we demonstrate that the Sokoban model belongs to the Balagurov-Vaks-Donsker-Varadhan trapping universality class. The survival probability that the walker has not yet been trapped inside a cage exhibits stretched-exponential relaxation at late times. Furthermore, using the average trap size as a proxy, we identify a new trapping transition that replaces the classical percolation transition. This transition occurs at a threshold density $ \rho_\ast \approx 0.55$ and separates two qualitatively distinct trapping regimes: a self-trapping regime at low density, where the walker becomes dynamically localized within a self-formed trap, and a pre-existing trapping regime at high density, where confinement arises from the initial arrangement of obstacles.
Statistical Mechanics (cond-mat.stat-mech)
4 pages, 3 figures, and 2 pages of the End Matter
Impact of Ce Substitution on Structural and Electrochemical Properties of Ga Doped Garnet Li7La3Zr2O12 Solid Electrolyte
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Muktai Aote, A. V. Deshpande, Vaibhav Sirsulwar, Priya Padaganur, Neha, Abhishek Pradhan
In order to replace conventional liquid electrolytes, solid electrolyte should possess high ionic conductivity. In this study, the effects of Ga-Ce co-doping on the garnet Li7La3Zr2O12 solid electrolyte have been investigated. The series Li6.4Ga0.2La3Zr2-xCexO12 has been prepared with varying content of Ce from 0 to 0.30 atoms per formula unit (a.p.f.u.) by sintering at 1050^0C. Various structural characterizations namely X-diffraction, Scanning Electron Microscopy (SEM), density measurements were carried out. The electrochemical analysis suggested that, the sample with 0.10 a.p.f.u. of Ce offered the highest room temperature ionic conductivity of 4 x 10-4 S/cm with the minimum activation energy of 0.29 eV. Moreover, DC conductivity measurement proved the predominant ionic conduction in the prepared samples making it suitable for the application in all solid state Li-ion batteries (ASSLIBs).
Materials Science (cond-mat.mtrl-sci)
Multiple Adsorption of CO Molecules on Transition Metal Substitutional Impurities in Copper Surfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Magnus A. H. Christiansen, Wei Wang, Elvar Ö. Jónsson, Giancarlo Cicero, Hannes Jónsson
Copper-based catalysts are of particular interest for electrochemical reduction of CO$ _2$ (CO2RR) as products beyond CO can form. To improve activity and selectivity, several studies have focused on the addition of other elements as substitutional impurities. Although the adsorption of a single CO molecule has often been used as a descriptor for CO2RR activity, our recent calculations using the RPBE functional showed that multiple CO molecules can bind to first-row transition metal impurities. Here, we extend the study to second-row transition metals and also to a functional that explicitly includes dispersion interaction, BEEF-vdW. The binding energy of the first CO molecule on the impurity atom is found to be significantly larger than on the clean Cu(111) and Cu(100) surfaces, but the differential binding energy generally drops as more CO molecules adsorb. The dispersion interaction is found to make a significant contribution to the binding energy, in particular for the last and weakest bound CO molecule, the one that is most likely to participate in CO2RR. In some cases, four CO admolecules can bind more strongly on the impurity atom than on the clean copper surface. The adsorption of CO causes the position of the impurity atom to shift outwards and in some cases, even escape from the surface layer. The C-O stretch frequencies are calculated in order to identify possible experimental signatures of multiple CO adsorption.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
ChemCatChem 2025, e00765
Competition between mirror symmetry breaking and translation symmetry breaking in ferroelectric liquid crystals with increasing lateral substitution
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
Grant J. Strachan, Ewa Górecka, Damian Pociecha
The recently discovered heliconical ferroelectric nematic (NTBF) phase is a unique example of spontaneous chiral symmetry breaking in a proper ferroelectric fluid. In this study, we investigate four homologous series of mesogenic compounds, differing in the degree of fluorination of the mesogenic core and bearing lateral alkoxy substituents of varying lengths, to understand how molecular architecture influences the formation and stability of the NTBF phase. Increasing the length of the lateral chain lowers the phase transition temperatures and suppresses smectic layer formation, enabling the emergence of the NTBF phase which replaces the orthogonal ferroelectric smectic A (SmAF) phase. This indicates a competition between lamellar and heliconical polar ordering, driven by the interplay of strong molecular dipoles and the self-segregation of chemically incompatible molecular segments that typically favor layered structures. Notably, the NTBF phase in these compounds exhibits exceptionally short helical pitch lengths, on the order of a few hundred nanometers, as revealed by selective light reflection and atomic force microscopy (AFM). Furthermore, for one of the studied compounds AFM imaging of one compound revealed a regular array of screw dislocations within the NTBF phase, suggesting a possible link to more complex modulated or twist-grain-boundary-like structures.
Soft Condensed Matter (cond-mat.soft)
Optimizing the depth-dependent nitrogen-vacancy center quantum sensor in diamane
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Pei Li, Guanjian Hu, Xiao Yu, Bing Huang, Song Li
Negatively charged nitrogen-vacancy (NV) center in diamond is the representative solid state defect qubit for quantum information science, offering long coherence time at room temperature. To achieve high sensitivity and spatial resolution, shallow NV center near the surface are preferred. However, shallow NV center suffers from surface states and spin noise which reduce the photostability and coherence time. In this work, we systematically study the NV center in recently reported two-dimensional diamond, known as diamane–using first-principles calculations. We show that the quantum confinement in finite-layer diamane, with appropriate surface passivation, could significantly modify the band structure. In particular, we identify oxygen surface termination capable of hosting NV center in diamane while optimizing photostability compared to bulk diamond. Furthermore, layer-dependent NV center demonstrates tunable zero-phonon-line and suppressed phonon side band, while retaining long coherence time. Our findings highlight diamane as a promising platform for NV-based quantum information processing with improved optical properties and stability
Materials Science (cond-mat.mtrl-sci)
8 pages, 3 figures
Gate tunable spin-charge interconversion in a graphene/ReS$_{2}$ heterostructure up to room temperature
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Eoin Dolan, Zhendong Chi, Haozhe Yang, Luis E. Hueso, Fèlix Casanova
Graphene is a material with great potential in the field of spintronics, combining good conductivity with low spin–orbit coupling (SOC), which allows for the transport of spin currents over long distances. However, this lack of SOC also limits the capacity for manipulating spin current. A key strategy to address this limitation is to induce SOC in graphene via proximity to other two-dimensional (2D) materials. Such proximity-induced SOC can enable spin–charge interconversion (SCI) in graphene, with potential applications in next-generation logic devices. Here, we place graphene in close proximity to the room-temperature ferroelectric candidate ReS$ _\mathrm{2}$ , inducing SCI for both in-plane and out-of-plane polarized spin current. We attribute the SCI for in-plane polarized current to either the Rashba–Edelstein effect (REE) or the unconventional spin Hall effect (SHE) at the graphene/ReS$ _\mathrm{2}$ interface, and the SCI for out-of-plane polarized current to either the conventional SHE in the proximitised graphene, or the unconventional SHE in the bulk of the ReS$ _\mathrm{2}$ . SCI due to in-plane spin is characterised over a wide range of temperature, up to 300 K and a range of gate voltages.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 4 figures, and Supplemental Material. Marie Skłodowska-Curie Actions, H2020-MSCA-ITN-2020; Project acronym SPEAR; Grant Agreement No. 955671
Applied Physics Letters 127, 052401 (2024)
Rabi Oscillations Modulated Noise Squeezing in Active Quantum Dot Ensembles
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Ori Gabai, Amnon Willinger, Igor Khanonkin, Vitalii Sichkovskyi, Johann Peter Reithmaier, Gadi Eisenstein
Generation of squeezed light is usually implemented in nonlinear \c{hi}(2) or \c{hi}(3) materials. Semiconductor lasers and optical amplifiers (SOAs) also offer non-linearities but they differ from passive elements in that they add amplified spontaneous emission noise (ASE). In a semiconductor laser, squeezing to below the shot noise limit has been demonstrated. An SOA contains no cavity and it adds significant noise. Gain saturation can lead, in principle, to squeezing of the photon number quadrature to below the shot noise level but often the noise is reduced only to below the ASE level of a linear amplifier. At the same time, the noise in the phase quadrature increases according to the Heisenberg uncertainty principle. Short resonant pulses interacting with a quantum dot SOA induce coherent effects such as Rabi oscillations. Here, we demonstrate, for the first time, that Rabi oscillations cause cyclical noise squeezing which varies periodically with the excitation pulse area. The noise in the present experiments does not reach the quantum limit so we term this condition quasi squeezing. It occurs during the portions of the Rabi cycle when the quantum dots provide gain and repeats with every fourfold increase of the pulse excitation energy which amounts to a 2{\pi} increase in pulse area. In all other cases, the noise exhibits the properties of a coherent state.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Generalized Cutler-Mott relation in a two-site charge Kondo simulator
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
T. K. T. Nguyen, M. N. Kiselev
We analyze the validity of the Cutler-Mott relations outside the Landau Fermi-liquid concept. We consider a two-site charge Kondo circuit as a paradigmatic example of a system possessing both Fermi- and non-Fermi liquid properties. It is shown that the generalized Cutler-Mott-like relations derived in the paper hold in both operating regimes of the charge Kondo quantum circuit describing a smooth crossover between low- and high- temperature regimes. We discuss applicability of the generalized Cutler-Mott relations for computing a figure of merit of the non-Fermi liquid quantum simulators.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 6 figures
Gradient Electronic Landscapes in van der Waals Heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Nolan Lassaline, Camilla H. Sørensen, Giulia Meucci, Sander J. Linde, Kian Latifi Yaghin, Tuan K. Chau, Damon J. Carrad, Peter Bøggild, Thomas S. Jespersen, Timothy J. Booth
Two-dimensional (2D) materials such as graphene and hexagonal boron nitride (hBN) provide a versatile platform for quantum electronics. Experiments generally require encapsulating graphene within hBN flakes, forming a protective van der Waals (vdW) heterostructure that preserves delicate properties of the embedded crystal. To produce functional devices, heterostructures are typically shaped by electron beam lithography and etching, which has driven progress in 2D materials research. However, patterns are primarily restricted to in-plane geometries such as boxes, holes, and stripes, limiting opportunities for advanced architectures. Here, we use thermal scanning-probe lithography (tSPL) to produce smooth topographic landscapes in vdW heterostructures, controlling the thickness degree of freedom with nanometer precision. We electrically gate a sinusoidal topography to impose an electric-field gradient on the graphene layer to spatially modulate charge-carrier doping. We observe signatures of the landscape in transport measurements-resistance-peak spreading and commensurability oscillations-establishing tSPL for tailoring high-quality quantum electronics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
On Noise-Sensitive Automatic Tuning of Gate-Defined Sensor Dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Fabian Hader, Jan Vogelbruch, Simon Humpohl, Tobias Hangleiter, Chimezie Eguzo, Stefan Heinen, Stefanie Meyer, Stefan van Waasen
In gate-defined quantum dot systems, the conductance change of electrostatically coupled sensor dots allows the observation of the quantum dots’ charge and spin states. Therefore, the sensor dot must be optimally sensitive to changes in its electrostatic environment. A series of conductance measurements varying the two sensor-dot-forming barrier gate voltages serve to tune the dot into a corresponding operating regime. In this paper, we analyze the noise characteristics of the measured data and define a criterion to identify continuous regions with a sufficient signal-gradient-to-noise ratio. Hence, accurate noise estimation is required when identifying the optimal operating regime. Therefore, we evaluate several existing noise estimators, modify them for 1D data, optimize their parameters, and analyze their quality based on simulated data. The estimator of Chen et al. turns out to be best suited for our application concerning minimally scattering results. Furthermore, using this estimator in an algorithm for flank-of-interest classification in measured data shows the relevance and applicability of our approach.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
in IEEE Transactions on Quantum Engineering, vol. 4, pp. 1-18, 2023, Art no. 5500218
Optical Measurement of Mass Density of Biological Samples
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
Conrad Möckel, Jiarui Li, Giulia Zanini, Jochen Guck, Giuliano Scarcelli
Mass density is a vital property for improved biophysical understanding of and within biological samples. It is increasingly attracting active investigation, but still lacks reliable, non-contact techniques to accurately characterize it in biological systems. Contrary to popular belief, refractive index information alone is insufficient to determine a sample’s mass density, as we demonstrate here theoretically and experimentally. Instead, we measured the nonlinear gain of stimulated Brillouin scattering to provide additional information for mass density estimation. This all-optical method reduces the estimation error tenfold, offering a more accurate and universal technique for mass density measurements.
Soft Condensed Matter (cond-mat.soft)
16 pages, 4 figures
Cr resonant impurity for studies of band inversion and band offsets in IV-VI semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
A. Królicka, K. Gas, W. Dobrowolski, H. Przybylińska, Y. K. Edathumkandy, J. Korczak, E. Łusakowska, R. Minikayev, A. Reszka, R. Jakieła, L. Kowalczyk, A. Mirowska, M. Gryglas-Borysiewicz, J. Kossut, M. Sawicki, A. Łusakowski, P. Bogusławski, T. Story, K. Dybko
Understanding the electronic structure of transition-metal dopants in IV-VI semiconductors is critical for tuning their band structure. We analyze properties of Cr dopant in $ Pb_{1-x}Sn_xTe$ and PbSe by magnetic and transport measurements, which are interpreted based on density functional calculations. We demonstrate that the pinning of the Fermi energy to the chromium resonant level occurs for both n-type and p-type $ Pb_{1-x}Sn_xTe$ in the whole composition range. This enables us to determine the valence band and conduction band offsets at the PbTe/SnTe/PbSe heterointerfaces, which is important for designing high-prformance 2D transistors. Furthermore, the magnetic measurements reveal the presence of Cr ions in three charge states, $ Cr^{3+}$ , $ Cr^{2+}$ , and $ Cr^{1+}$ . The last one corresponds to the Cr dopants incorporated at the interstitial, and not the substitutional, sites. The measured concentrations of the interstitial and substitutional Cr are comparable.
Materials Science (cond-mat.mtrl-sci)
64 pages, 29 figures
Sliding Ferroelectric Metal with Ferrimagnetism
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Zhenzhou Guo, Xiaodong Zhou, Wenhong Wang, Zhenxiang Cheng, Xiaotian Wang
Two-dimensional (2D) sliding ferroelectric (FE) metals with ferrimagnetism represent a previously unexplored class of spintronic materials, where the interplay of ferroelectricity, metallicity, and magnetism enables strong magnetoelectric (ME) coupling and electrically tunable spintronic functionalities. Here, based on antiferromagnetic (AFM) metallic bilayers, we propose a general strategy for constructing 2D sliding FE ferrimagnetic (FiM) metals that can achieve tri-state switching, in which the FE polarization, spin splitting, and net magnetization are reversed simultaneously through FE switching. As a prototypical realization, we design a bilayer sliding FE metal with FiM order, derived from monolayer Fe5GeTe2-a van der Waals metal with intrinsic magnetic order close to room temperature. The system exhibits a FE transition from a nonpolar (NP) AFM phase to a FE FiM phase via interlayer sliding. The in-plane mirror symmetry breaking in FE metallic states lift the spin degeneracy that exists in the NP phase, leading to a sizable net magnetic moment and strong linear ME coupling. The interplay between metallicity and FE FiM gives rise to pronounced sign-reversible transport responses near the Fermi level, all of which can be fully electrically controlled by FE switching without reorienting the Néel order. Our results establish sliding FE metals with FiM as a promising platform for electrically reconfigurable, high-speed, and low-dissipation spintronic devices.
Materials Science (cond-mat.mtrl-sci)
Drag Coefficient in Near-Critical Binary Mixtures: Solving Hydrodynamic Fields with Improved Numerics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
We calculate the drag coefficient of a spherical particle suspended in a near-critical binary fluid mixture. To capture the scaling behavior associated with critical adsorption in the strong adsorption regime, we employ the framework of local renormalized functional theory. Previous theoretical studies encountered numerical difficulties when attempting to solve the coupled hydrodynamic and chemical potential equations, expressed as integral equations, for systems with large bulk correlation lengths. These difficulties limited direct comparison with experimental results. In this study, we overcome those limitations by reformulating the hydrodynamic equations as a set of ordinary differential equations using a compactified radial coordinate. This approach enables more stable numerical computation and facilitates the implementation of appropriate boundary conditions at large distances from the particle. As a result, we successfully compute the drag coefficient over a broader range of bulk correlation lengths than in previous works and compare our theoretical predictions with available experimental data.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
21 pages, 8 figures
Physics of Fluids 37 (8) 2025
Extreme anharmonicity and thermal contraction of 1D wires
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Chiara Cignarella, Lorenzo Bastonero, Lorenzo Monacelli, Nicola Marzari
Ultrathin nanowires could play a central role in next-generation downscaled electronics. Here, we explore some of the most promising candidates identified from previous high-throughput screening: CuC$ _2$ , TaSe$ _3$ , and AuSe$ _2$ , to gain insight into the thermodynamic and anharmonic behaviors of nanowires that could be exfoliated from weakly-bonded three-dimensional materials. We analyze thermal stability, linear thermal expansion, and anharmonic heat capacity using the stochastic self-consistent harmonic approximation. Notably, our work unveils exotic features common among all the 1D wires: a colossal record negative thermal expansion and very large deviations from the Dulong-Petit law due to strong anharmonicity.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Cu2OSeO3 Turns Trigonal with Structural Transformation and Implications for Skyrmions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Alla Arakcheeva, Priya Ranjan Baral, Wen Hua Bi, Christian Jandl, Oleg Janson, Arnaud Magrez
The formation and characteristics of magnetic skyrmions are strongly governed by the symmetry of the underlying crystal structure. In this study, we report the discovery of a new trigonal polymorph of Cu2OSeO3, observed exclusively in nanoparticles. Electron diffraction and density functional theory calculations confirm its R3m space group, sharing C3v symmetry with Néel-type skyrmion hosts. This polymorph is likely stabilized by surface effects, suggesting that size-induced structural changes may drive a transformation from Bloch-type to Neel-type skyrmions in Cu2OSeO3. This hypothesis is consistent with prior unexplained observations of Neel-type skyrmions at the surfaces of bulk crystals, which may result from surface-specific structural distortions. Overall, these findings provide insights into the interplay between size, structure, and magnetism, opening pathways for controlling skyrmionic properties in nanoscale systems.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Terahertz range polarization rotation in the candidate time-reversal symmetry breaking superconductor BiNi
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-12 20:00 EDT
Ralph Romero III, Zhenisbek Tagay, Jiahao Liang, Jason Y. Yan, Di Yue, N. P. Armitage
Here we report the observation of time-reversal symmetry (TRS) breaking superconductivity in a BiNi bilayer using terahertz (THz) polarimetry. Leveraging a novel high-precision THz polarimetry technique, we detect, in the superconducting state and at zero magnetic field, the smallest polarization rotation of THz light measured to date. By using the MgO substrate itself as an optical resonator, we can reference the Faraday and Kerr rotations to each other. We observe a low-frequency Kerr rotation on the order of several hundred microradians in the superconducting phase, a clear signature consistent with TRS-breaking superconductivity. Our measurements enable direct access to the THz-range Hall conductivity. Through a Kramers-Kronig analysis, we link these low-energy measurements to prior high-frequency magneto-optic Kerr effect (MOKE) data. This connection provides critical insight into the nature of the TRS-breaking state, supporting a multiband superconducting scenario over a disordered single-band interpretation for the origin of the Kerr effect.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Main text: 6 pages, 4 figures. Supplemental Info: 6 pages, 4 figures
Simulation of Charge Stability Diagrams for Automated Tuning Solutions (SimCATS)
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Fabian Hader, Sarah Fleitmann, Jan Vogelbruch, Lotte Geck, Stefan van Waasen
Quantum dots must be tuned precisely to provide a suitable basis for quantum computation. A scalable platform for quantum computing can only be achieved by fully automating the tuning process. One crucial step is to trap the appropriate number of electrons in the quantum dots, typically accomplished by analyzing charge stability diagrams (CSDs). Training and testing automation algorithms require large amounts of data, which can be either measured and manually labeled in an experiment or simulated. This article introduces a new approach to the realistic simulation of such measurements. Our flexible framework enables the simulation of ideal CSD data complemented with appropriate sensor responses and distortions. We suggest using this simulation to benchmark published algorithms. Also, we encourage the extension by custom models and parameter sets to drive the development of robust, technology-independent algorithms. Code is available at this https URL.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
in IEEE Transactions on Quantum Engineering, vol. 5, pp. 1-14, 2024, Art no. 5500414
Short-Range Order and Li$x$TM${4-x}$ Probability Maps for Disordered Rocksalt Cathodes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-12 20:00 EDT
Tzu-chen Liu, Steven B. Torrisi, Chris Wolverton
Short-range order (SRO) in the cation-disordered state is a controlling factor influencing the probability of finding Li$ _{4}$ tetrahedron clusters in disordered rocksalt (DRX) cathode materials. However, the prevalent Li$ _4$ probability below the random limit across reported DRX compositions has not been systematically investigated, active strategies to surpass the random limit of Li$ _4$ probability are lacking, and the fundamental ordering behavior on the face-centered cubic (FCC) lattice remains insufficiently explored. This research quantitatively examines pair SRO parameters and Li$ _x$ TM$ _{4-x}$ probabilities via exhaustive Monte Carlo mapping across a simplified subset of the parameter space. The results indicate that, in the disordered state, the Li$ _4$ probability is governed by the nearest neighbor (NN) pair-wise SRO parameter, and that these quantities do not necessarily represent a simple attenuation of their corresponding low-temperature long-range order, particularly for the important cases of Layered and Spinel-like orderings. Strategies are proposed to mitigate or even reverse the lithium and transition metals mixing tendency of NN pair SRO to achieve Li$ _4$ probabilities that exceed the random limit. This study advances the fundamental thermodynamic understanding of ordering behaviors, which can be generalized to any FCC system.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
37 pages, 12 figures. This work was previously included in the dissertation of the first author
Straintronics across Lieb-Kagome interconversion and variable transport scaling exponents
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Shashikant Singh Kunwar, Madhuparna Karmakar
We propose a novel protocol of low-temperature, strain-tuned re-entrant metal-insulator transition and crossover between strongly correlated line-graph lattices (Lieb and Kagome). Using a non-perturbative numerical approach, we demonstrate for the first time that an applied shear strain stabilizes a metallic phase cradled in between a gapped magnetic insulator and a gapless flat band localized insulator, facilitating the Lieb/Kagome interconversion. Our results on transport signatures exhibit variable scaling exponents for electrical resistivity and optical conductivity, providing clear evidence of non-Fermi liquid physics. We also define a strain-dependent thermal scale to quantify the crossover between the non-Fermi liquid and bad metal phases.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
9 pages, 5 figures
An effective potential for generative modelling with active matter
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Score-based diffusion models generate samples from a complex underlying data distribution by time-reversal of a diffusion process and represent the state-of-the-art in many generative AI applications such as artificial image synthesis. Here, I show how a generative diffusion model can be implemented based on an underlying active particle process with finite correlation time. In contrast to previous approaches that use a score function acting on the velocity coordinate of the active particle, time reversal is here achieved by imposing an effective time-dependent potential on the position coordinate only. The effective potential is valid to first order in the persistence time and leads to a force field that is fully determined by the standard score function and its derivatives up to 2nd order. Numerical experiments for artificial data distributions confirm the validity of the effective potential.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Machine Learning (cs.LG)
Spin liquid and glass behavior in quantum spin models with all-to-all p-spin interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Shusei Wadashima, Yukitoshi Motome
Spin liquid and spin glass states represent two distinct phases of disordered quantum spin systems. These states are, in principle, distinguished by quantum-entangled fluctuations and spin-freezing, but identifying each state and characterizing the transition between them remain challenging. Here, we systematically explore the relationship between the spin liquid and spin glass states using a model with all-to-all random interactions among $ p$ spins, which interpolates between the Ising-like one-component, XY-like two-component, and isotropic three-component cases. By analyzing the system-size $ N$ dependence of the Edwards-Anderson order parameter and the density of states, we identify the transition from the spin liquid to the spin glass for various values of $ p$ . We show that the phase diagrams for different $ p$ can be unified through a scaling with $ N/p^2$ , revealing that increasing anisotropy in the interactions systematically suppresses the spin liquid phase and extends the spin glass regime. Furthermore, we examine the competition between multiple-spin interactions and anisotropy under an external magnetic field in the isotropic case, and find that the spin liquid phase transitions into the spin glass phase before entering a quantum paramagnetic phase. Our findings provide new insights into quantum disordered phases and the transitions between them.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
11 pages, 12 figures
A catastrophic approach to designing interacting hysterons
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-12 20:00 EDT
Gentian Muhaxheri, Victoria Antonetti, Christian D. Santangelo
We present a framework for analyzing collections of interacting hysterons through the lens of catastrophe theory. By modeling hysteron dynamics as a gradient system, we show how to construct hysteron transition graphs by characterizing the fold bifurcations of the dynamical system. Transition graphs represent the sequence of hysterons switching states, providing critical insights into the collective behavior of driven disordered media. Extending this analysis to higher codimension bifurcations, such as cusp bifurcations and crossings of fold curves, allows us to map out how the topology of transition graphs changes with variations in system parameters. This approach can suggest strategies for designing metamaterials capable of encoding targeted memory and computational functionalities, but it also highlights the rapid increase of design complexity with system size, further underscoring the computational challenges of controlling large hysteretic systems.
Soft Condensed Matter (cond-mat.soft)
Readout of multi-level quantum geometry from electronic transport
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-12 20:00 EDT
Raffael L. Klees, Mónica Benito
The quantum geometric tensor (QGT) of a quantum system in a given parameter space captures both the geometry of the state manifold and the topology of the system. While the local QGT elements have been successfully measured in various platforms, the challenge of detecting them in electronic transport systems - such as tunnel or molecular junctions - has yet to be resolved. To fill this gap, we propose a measurement protocol based on weak and resonant parameter modulations, and theoretically demonstrate how the local QGT in such systems can be directly probed from changes of the tunnel conductance. This approach enables the measurement of both geometrical and topological features of quantum states in a broad class of transport-based quantum systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages and 3 figures (main text); 2 pages and 1 figure (End Matter); 9 pages (Supplemental Material)
Symmetry-Enriched Topological Phases and Their Gauging: A String-Net Model Realization
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-12 20:00 EDT
Nianrui Fu, Yu Zhao, Yidun Wan
We present a systematic framework for constructing exactly-solvable lattice models of symmetry-enriched topological (SET) phases based on an enlarged version of the string-net model. We also gauge the global symmetries of our SET models to obtain string-net models of pure topological phases. Without invoking externally imposed onsite symmetry actions, our approach promotes the string-net model of a pure topological order, specified by an input unitary fusion category $ \mathscr{F}$ , to an SET model, specified by a multifusion category together with a set of isomorphisms. Two complementary construction strategies are developed in the main text: (i) promotion via outer automorphisms of $ \mathscr{F}$ and (ii) promotion via the Frobenius algebras of $ \mathscr{F}$ . The global symmetries derived via these two strategies are intrinsic to topological phases and are thus termed blood symmetries, as opposed to adopted symmetries, which can be arbitrarily imposed on topological phases. We propose the concept of symmetry-gauging family of topological phases, which are related by gauging their blood symmetries. With our approach, we construct the first explicit lattice realization of a nonabelian-symmetry-enriched topological phase – the $ S_3$ symmetry-enriched $ \mathbb{Z}_2 \times \mathbb{Z}_2$ quantum-double phase. The approach further reveals the role of local excitations in SET phases and establishes their symmetry constraints.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph)
33+39 pages, 4 figures
Identifying nonequilibrium degrees of freedom in high-dimensional stochastic systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-12 20:00 EDT
Catherine Ji, Ravin Raj, Benjamin Eysenbach, Gautam Reddy
Any coarse-grained description of a nonequilibrium system should faithfully represent its latent irreversible degrees of freedom. However, standard dimensionality reduction methods typically prioritize accurate reconstruction over physical relevance. Here, we introduce a model-free approach to identify irreversible degrees of freedom in stochastic systems that are in a nonequilibrium steady state. Our method leverages the insight that a black-box classifier, trained to differentiate between forward and time-reversed trajectories, implicitly estimates the local entropy production rate. By parameterizing this classifier as a quadratic form of learned state representations, we obtain nonlinear embeddings of high-dimensional state-space dynamics, which we term Latent Embeddings of Nonequilibrium Systems (LENS). LENS effectively identifies low-dimensional irreversible flows and provides a scalable, learning-based strategy for estimating entropy production rates directly from high-dimensional time series data.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)