CMP Journal 2025-06-17
Statistics
Nature Materials: 1
Nature Physics: 1
Physical Review Letters: 6
Physical Review X: 2
arXiv: 104
Nature Materials
Nanoscale phonon dynamics in self-assembled nanoparticle lattices
Original Paper | Imaging techniques | 2025-06-16 20:00 EDT
Chang Qian, Ethan Stanifer, Zhan Ma, Lehan Yao, Binbin Luo, Chang Liu, Jiahui Li, Puquan Pan, Wenxiao Pan, Xiaoming Mao, Qian Chen
Geometry and topology endow mechanical frames with unusual properties from shape morphing to phonon wave manipulation, enabling emerging technologies. Despite important advances in macroscopic frames, the realization and phonon imaging of nanoscale mechanical metamaterials has remained challenging. Here we extend the principle of topologically engineered mechanical frames to self-assembled nanoparticle lattices, resolving phonon dynamics using liquid-phase transmission electron microscopy. The vibrations of nanoparticles in Maxwell lattices are used to measure properties that have been difficult to obtain, such as phonon band structures, nanoscale spring constants and nonlinear lattice deformation paths. Studies of five different lattices reveal that these properties are modulated by nanoscale colloidal interactions. Our discrete mechanical model and simulations capture these interactions and the critical role of effects beyond nearest neighbours, bridging mechanical metamaterials with nanoparticle self-assembly. Our study provides opportunities for understanding and manufacturing self-assembled nanostructures for phonon manipulation, offering solution processability, transformability and emergent functions at underexplored scales of length, frequency and energy density.
Imaging techniques, Metamaterials, Nanoparticles
Nature Physics
Emergent exchange-driven giant magnetoelastic coupling in a correlated itinerant ferromagnet
Original Paper | Magnetic properties and materials | 2025-06-16 20:00 EDT
Carolina A. Marques, Luke C. Rhodes, Weronika Osmolska, Harry Lane, Izidor Benedičič, Masahiro Naritsuka, Siri A. Berge, Rosalba Fittipaldi, Mariateresa Lettieri, Antonio Vecchione, Peter Wahl
The interaction between the electronic and structural degrees of freedom is central to several intriguing phenomena observed in condensed-matter physics. In magnetic materials, magnetic interactions couple to lattice degrees of freedom, resulting in magnetoelastic coupling, which is typically small and only detectable in macroscopic samples. Here we demonstrate a giant magnetoelastic coupling in the correlated itinerant ferromagnet Sr4Ru3O10. We establish an effective control of magnetism in the surface layer and utilize it to probe the impact of magnetism on its electronic and structural properties. By using scanning tunnelling microscopy, we reveal subtle changes in the electronic structure dependent on ferromagnetic or antiferromagnetic alignment between the surface and subsurface layers. We further determine the consequences of the exchange force on the relaxation of the surface layer, which exhibits giant magnetostriction. Our results provide a direct measurement of the impact of exchange interactions and correlations on structural details in a quantum material, revealing how electronic correlations result in a strong electron-lattice coupling.
Magnetic properties and materials, Surfaces, interfaces and thin films
Physical Review Letters
Quantum-Classical Correspondence of Non-Hermitian Symmetry Breaking
Research article | PT-symmetric quantum mechanics | 2025-06-16 06:00 EDT
Zhuo-Ting Cai, Hai-Dong Li, and Wei Chen
Real-to-complex spectral transitions and the associated spontaneous symmetry breaking of eigenstates are central to non-Hermitian physics, yet a comprehensive and universal theory that precisely describes the underlying physical mechanisms for each individual state remains elusive. Here, we resolve the mystery by employing the complex path integral formalism and developing a generalized Gutzwiller trace formula. These methodologies enable us to establish a universal quantum-classical correspondence that precisely links the real or complex nature of individual energy levels to the symmetry properties of their corresponding semiclassical orbits. Specifically, in systems with a general $\eta $-pseudo-Hermitian symmetry, real energy levels are quantized along periodic orbits that preserve the corresponding classical ${S}{\eta }$ symmetry. In contrast, complex conjugate energy levels arise from semiclassical orbits that individually break the ${S}{\eta }$ symmetry but together form ${S}_{\eta }$-symmetric pairs. This framework provides a unified explanation for the spectral behaviors in various continuous non-Hermitian models and for the $\mathcal{P}\mathcal{T}$ transition in two-level systems. Moreover, we demonstrate that the exceptional point is inherently a quantum phenomenon, as it cannot be described by a single classical orbit. Our Letter uncovers the physical mechanism of non-Hermitian symmetry breaking and introduces a new perspective with broad implications for the control and application of non-Hermitian phenomena.
Phys. Rev. Lett. 134, 240201 (2025)
PT-symmetric quantum mechanics, Symmetry breaking states, Non-Hermitian systems, PT-symmetry
Thermal Dilepton Polarization and Dynamics of the QCD Plasma in Relativistic Heavy-Ion Collisions
Research article | Finite temperature field theory | 2025-06-16 06:00 EDT
Xiang-Yu Wu, Han Gao, Bailey Forster, Charles Gale, Greg Jackson, and Sangyong Jeon
We present the first theoretical study of the polarization of lepton pairs produced in $\sqrt{ {s}_{\mathrm{NN}}}=5.02\text{ }\text{ }\mathrm{TeV}$ $\mathrm{Pb}+\mathrm{Pb}$ collisions at the LHC, using next-to-leading order (NLO) dilepton emission rates. These calculations employ a multistage framework to simulate the evolution of relativistic heavy-ion collisions, and to explore the sensitivity of polarization to early times. It is found that the intermediate invariant-mass dileptons are indeed probes of the thermal equilibration process, and go beyond the reach of hadronic observables. We compute the polarization anisotropy coefficient obtained with LO dilepton rates, and show that the LO and NLO results differ radically, both in trend and in magnitude, at low and intermediate lepton pair invariant masses.
Phys. Rev. Lett. 134, 242301 (2025)
Finite temperature field theory, Hydrodynamic models, Photon, lepton & quark production, Quark-gluon plasma, Relativistic heavy-ion collisions
Few-Electron Highly Charged Muonic Ar Atoms Verified by Electronic $K$ X Rays
Research article | Atomic spectra | 2025-06-16 06:00 EDT
T. Okumura et al.
*et al.*Precision x-ray spectroscopy reveals the formation of highly charged muonic argon ions, which are exotic few-body systems composed of a muon, a few electrons, and a nucleus.
Phys. Rev. Lett. 134, 243001 (2025)
Atomic spectra, Electronic structure of atoms & molecules, Ions, Muonic atoms & molecules, Energy-dispersive x-ray spectroscopy
Measurement Uncertainty in Infrared Spectroscopy with Entangled Photon Pairs
Research article | Laser spectroscopy | 2025-06-16 06:00 EDT
Xue Zhang, Zhucheng Zhang, and Hui Dong
Spectroscopy with entanglement has shown great potential to break limitations of traditional spectroscopic measurements, yet the role of entanglement in spectroscopic multiparameter joint measurement, particularly in the infrared optical range, remains elusive. Here, we find an uncertain relation that constrains the precision of infrared spectroscopic multiparameter measurements using entangled photon pairs. Under such a relation, we demonstrate a trade-off between the measurement precisions of the refractive index and the absorption coefficient of the medium in the infrared range, and also illustrate how to balance their respective estimation errors. Our work shall provide guidance toward future experimental designs and applications in entanglement-assisted spectroscopy.
Phys. Rev. Lett. 134, 243601 (2025)
Laser spectroscopy, Light-matter interaction, Photon pairs & parametric down-conversion, Quantum description of light-matter interaction, Quantum states of light, Infrared techniques
Hybrid Sub- and Superradiant States in Emitter Arrays with Quantized Motion
Research article | Collective effects in atomic physics | 2025-06-16 06:00 EDT
Beatriz Olmos and Igor Lesanovsky
Ensembles of dipolar emitters which couple collectively to the radiation field display sub- and superradiance. These terms refer to a reduction or an enhancement of photon emission rates due to the interference of emission channels. Arrays of trapped neutral atoms constitute a promising platform for harnessing this phenomenon in technological applications, e.g., for excitation storage, single-photon switches, and mirrors. However, quantum and thermally induced vibrations of the atoms within their traps lead to position fluctuations that entangle the motion and the internal atomic degrees of freedom. We develop here a theory for collective atom-light coupling in the presence of this quantized motion within the Lamb-Dicke limit. We show the existence of sub- and superradiant states that are hybrids of electronic and vibrational excitations, investigate their properties for analytically and numerically efficiently solvable cases, and discuss how a finite temperature affects the collective photon emission.
Phys. Rev. Lett. 134, 243602 (2025)
Collective effects in atomic physics, Hybrid quantum systems, Light-matter interaction, Quantum description of light-matter interaction, Superradiance & subradiance, Atomic ensemble, Perturbative methods
Acceleration of Positive Muons by a Radio-Frequency Cavity
Research article | Beam cooling | 2025-06-16 06:00 EDT
S. Aritome et al.
*et al.*Researchers have demonstrated the slowing and subsequent reacceleration of a muon beam, increasing the potential of muon beams as a research tool.
Phys. Rev. Lett. 134, 245001 (2025)
Beam cooling, Beam diagnostics, Linear accelerators, Muon accelerators & neutrino factories, Muons, Particle beams, Photoionization
Physical Review X
Flat-Band (De)localization Emulated with a Superconducting Qubit Array
Research article | Anderson localization | 2025-06-16 06:00 EDT
Ilan T. Rosen, Sarah Muschinske, Cora N. Barrett, David A. Rower, Rabindra Das, David K. Kim, Bethany M. Niedzielski, Meghan Schuldt, Kyle Serniak, Mollie E. Schwartz, Jonilyn L. Yoder, Jeffrey A. Grover, and William D. Oliver
Quantum computers can emulate electronic materials when qubit interactions are tuned to mimic electron flow. This approach reveals how disorder and interactions affect conductivity in flat-band materials.
Phys. Rev. X 15, 021091 (2025)
Anderson localization, Flat bands, Quantum simulation, Synthetic gauge fields, Superconducting qubits
Bilinear Sequence Regression: A Model for Learning from Long Sequences of High-Dimensional Tokens
Research article | Phase transitions | 2025-06-16 06:00 EDT
Vittorio Erba, Emanuele Troiani, Luca Biggio, Antoine Maillard, and Lenka Zdeborová
A powerful new model to study learning in neural networks reveals a sharp learning phase transition in sequential data tasks, offering a solvable framework to probe the behavior of transformerlike architectures.
Phys. Rev. X 15, 021092 (2025)
Phase transitions, Physics of computation, Artificial neural networks, Cavity methods, Replica methods
arXiv
Quasiclassical electron transport in topological Weyl semimetals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
Weyl fermions are powerful yet simple entities that connect geometry, topology, and physics. While their existence as fundamental particles is still uncertain, growing evidence shows they emerge as quasiparticles in special materials called Weyl semimetals (WSMs). These materials possess unique electronic properties and hold promise for future technologies. This thesis investigates how electrons behave in WSMs, focusing on the chiral anomaly (CA). The CA remains central in condensed matter physics, typically observed via longitudinal magnetoconductance (LMC) and the planar Hall effect (PHE). Although finite intervalley scattering can reverse the LMC sign, we identify another mechanism: a smooth cutoff in the linear dispersion, inherent to real Weyl materials, introduces nonlinearity that causes negative LMC even without intervalley scattering. Using a lattice model of tilted Weyl fermions and the Boltzmann approximation, we explore LMC and PHE, mapping phase diagrams in key parameter spaces. We also study the effects of strain, which acts as an axial magnetic field and influences diffusive transport. Our results show that strain-induced gauge fields can cause a strong LMC sign-reversal, unlike external fields which need intervalley scattering. The interplay of strain and external fields produces rich LMC behavior. We further predict distinct PHE responses due to strain. Finally, we extend the study to nonlinear transport, developing a theory for the chiral anomaly-induced nonlinear Hall effect (CNLHE). In Weyl semimetals, the nonlinear Hall conductivity shows nonmonotonic behavior and strong sign-reversal with scattering. In contrast, spin-orbit coupled metals show consistently negative, quadratic responses. We also explore pseudospin-1 fermions, finding enhanced sensitivity to internode scattering, revealing new transport signatures and broadening the scope of chiral anomaly studies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Ph.D. thesis
Asymmetric Effects Underlying Dynamic Heterogeneity in Miscible Blends of Poly(methyl methacrylate) with Poly(ethylene oxide)
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Shannon Zhang, Michael A. Webb
The emergence of spatially variable local dynamics, or dynamic heterogeneity, is common in multicomponent polymer systems. Such heterogeneity is understood to arise from differences between the intrinsic dynamical fluctuations associated with one component versus another. However, the nature of the dynamic coupling between these components and how it depends on composition, temperature, and environmental fluctuations is not fully understood. Here, we use molecular dynamics simulations to characterize nanoscale dynamic heterogeneity in miscible blends of polyethylene oxide (PEO) and polymethyl methacrylate (PMMA) as a function of both temperature and blend composition. Probed over timescales of 100~ps, local PMMA segmental dynamics in blends align with neat PMMA when normalized by $ T_\text{g}$ , whereas PEO exhibits enhanced mobility caused by free-volume effects. The effects of dynamical coupling are found to be asymmetric between the extent of enhancement to PMMA and suppression of PEO dynamics based on analysis of local environment composition within blends. Asymmetric effects in the melt state are also identified over longer timescales according to a Rouse mode analysis over larger sub-chains for each species. These results provide fundamental insights into how dynamic heterogeneity manifests at the nanoscale, across conditions and compositions in miscible polymer blends. They establish a foundation for exploring whether such asymmetries are generalizable and how dynamic heterogeneity can be tuned through temperature, composition, and morphology.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
35 pages, 4 figures
Thermodynamics of multiple Maxwell demons
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-17 20:00 EDT
In many assembly line processes like metabolic and signaling networks in biological systems, the products of the first enzyme is the reactant for the next enzyme in the network. Working of multiple machines leads to efficient utilization of resources. Motivated by this, we investigate if multiple Maxwell demons lead to more efficient information processing. We study the phase space of multiple demons acting on an information tape based on the model of Mandal and Jarzynski [1, 2]. Their model is analytically solvable and the phase space of the device has three regions: engine, where work is delivered by writing information to the tape, erasure, where work is performed on the device to erase information on the tape, and dud, when work is performed and at the same time the information is written to the tape. For identical demons, we find that the erasure region increases at the expense of the dud region while the information engine region does not change appreciably. The efficiency of the multiple demon device increases with the number of demons in the device and saturates to the equilibrium (maximum) efficiency even at short cycle times for very large number of demons. By investigating a device with nonidentical demons acting on a tape, we identify the demon parameters that control the different regions of the phase space. Our model is well suited to study information processing in assembly line systems.
Statistical Mechanics (cond-mat.stat-mech)
Eur. Phys. J. B 95, 131 (2022)
Synthesis and anisotropic magnetism of singlecrystalline GdPt2Si2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-17 20:00 EDT
Gustavo Gomes Vasques, Mateus Dutra, Pedro Caetano Sabino, Juliana Gonçalves Dias, Julian Andrés Munévar Cagigas, Adriano Reinaldo Viçoto Benvenho, Marcos A. Avila
Single crystals of GdPt$ _2$ Si$ _2$ were grown using the Sn flux method, crystallizing in the CaBe$ _2$ Ge$ 2$ -type tetragonal structure with space group $ P4/nmm$ . Electrical resistivity, specific heat, and magnetization data revealed the presence of a double magnetic transition with $ T_N \approx 8.4$ K and $ T_0 \approx 6.8$ ~K. Analysis of the specific heat data suggest amplitude-modulated and equal-moment antiferromagnetic orderings, respectively. Field-induced magnetization and magnetic susceptibility data show a metamagnetic transition in the $ H \parallel a$ direction at 2K, as well as the suppression of the magnetic transition located at $ T_0$ with increasing external magnetic field. Electron Spin Resonance (ESR) shows the Gd$ ^{3+}$ resonance followed by a small second resonance. Peak-to-peak linewidth ($ \Delta H{pp}$ ) analysis reveals slight broadening at $ T \sim 120$ ~K, indicating an increase in magnetic fluctuations at high temperatures. Ferromagnetic (FM) local polarization at high temperatures is also observed through the $ g$ -factor analysis, which shows a notable positive shift ($ \Delta g$ ). Our results establish the fundamental physical properties of this material to aid in further understanding of the magnetism in the RPt$ _2$ Si$ _2$ series and related non-centrosymmetric systems.
Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 7 figures, accepted in Physica B (2025)
β-Ga2O3-Based Heterojunctions: Exploring Growth Orientations and Alloying Effect
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Mohamed Abdelilah Fadla, Khushabu Agrawal, Paolo La Torraca, Myrta Grüning, Karim Cherkaoui, Lorenzo Stella
We investigate the effects of alloying and growth orientation on the properties of the ultra-wide bandgap semiconductor \beta-Ga2O3 and pseudomorphic AlGaO alloy heterojunctions. Band offsets are computed from first principles using density functional theory (DFT) with the Heyd-Scuseria-Ernzerhof hybrid functional for different Al concentrations and four growth orientations, namely (100)B, (010), (001)B, and ($ \bar{2}$ 01). Significant variations are found and ascribed to the strained pseudomorphic alloys. The values of the band offsets are fed into technology computer-aided design (TCAD) models of Schottky barrier diodes (SBD). I-V and C-V characteristics from the TCAD models show reasonable agreement with recent experimental measurements in the forward bias region. Discrepancies in the negative bias region are expected due to the ideality of the Schottky junctions considered in this study. Our findings underscore the importance of growth orientation and strain in modelling of \beta-Ga2O3-based SBD.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Approximate Excited-State Potential Energy Surfaces for Defects in Solids
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Mark E. Turiansky, John L. Lyons
A description of electron-phonon coupling at a defect or impurity is essential to characterizing and harnessing its functionality for a particular application. Electron-phonon coupling limits the amount of useful light produced by a single-photon emitter and can destroy the efficiency of optoelectronic devices by enabling defects to act as recombination centers. Information on atomic relaxations in the excited state of the center is needed to assess electron-phonon coupling but may be inaccessible due to failed convergence or computational expense. Here we develop an approximation technique to quantify electron-phonon coupling using only the forces of the excited state evaluated in the equilibrium geometry of the ground state. The approximations are benchmarked on well-studied defect systems, namely C$ _{\rm N}$ in GaN, the nitrogen-vacancy center in diamond, and the carbon dimer in h-BN. We demonstrate that the zero-phonon line energy can be approximated with just a single mode, while the Huang-Rhys factor converges by including displacements up to the second nearest neighbors. This work also provides important insight into the success of the widely utilized one-dimensional accepting-mode approximation, specifically demonstrating that the accepting-mode Huang-Rhys factor is a strict upper bound on the full multidimensional Huang-Rhys factor.
Materials Science (cond-mat.mtrl-sci)
Kinetics of Amorphous Defect Phases Measured Through Ultrafast Nanocalorimetry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
W. Streit Cunningham, Tianjiao Lei, Hannah C. Howard, Timothy J Rupert, Daniel S. Gianola
Recognition of the role of extended defects on local phase transitions has led to the conceptualization of the defect phase, localized thermodynamically stable interfacial states that have since been applied in a myriad of material systems to realize significant enhancements in material properties. Here, we explore the kinetics of grain boundary confined amorphous defect phases, utilizing the high temperature and scanning rates afforded by ultrafast differential scanning calorimetry to apply targeted annealing/quenching treatments at high rates capable of capturing the kinetic behavior. Four Al-based nanocrystalline alloys, including two binary systems, Al-Ni and Al-Y, and two ternary systems, Al-Mg-Y and Al-Ni-Y, are selected to probe the materials design space (enthalpy of mixing, enthalpy of segregation, chemical complexity) for amorphous defect phase formation and stability, with correlative transmission electron microscopy applied to link phase evolution and grain stability to nanocalorimetry signatures. A series of targeted isothermal annealing heat treatments is utilized to construct a Time-Temperature-Transformation curve for the Al-Ni system, from which a critical cooling rate of 2,400 °C/s was determined for the grain boundary confined disordered-to-ordered transition. Finally, a thermal profile consisting of 1,000 repeated annealing sequences was created to explore the recovery of the amorphous defect phase following sequential annealing treatments, with results indicating remarkable microstructural stability after annealing at temperatures above 90% of the melting temperature. This work contributes to a deeper understanding of grain boundary localized thermodynamics and kinetics, with potential implications for the design and optimization of advanced materials with enhanced stability and performance.
Materials Science (cond-mat.mtrl-sci)
46 pages, 12 figures
Ultrafast dynamics of quantum matter driven by time-energy entangled photons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
Giovanni Citeroni, Marco Polini, Michael Dapolito, D. N. Basov, Giacomo Mazza
We study the dynamics of quantum matter interacting with time-energy entangled photons. We consider the stimulation of a collective mode of a two-dimensional material by means of one of the two partners of a time-energy entangled pair of photons. Using an exactly solvable model, we analyze the out-of-equilibrium properties of both light and matter degrees of freedom, and show how entanglement in the incident photons deeply modifies relevant time scales of the light-matter interaction process. We find that entanglement strongly suppresses the delay between the transmission and absorption events, which become synchronous in the limit of strongly entangled wave packets. By comparing numerical simulations with analytic modeling, we trace back this behavior to the representation of entangled wave packets in terms of a superposition of multiple train pulses containing an increasing number of ultrashort non-entangled packets. As a result, we show that the entangled driving allows the creation of a matter excitation on a time scale shorter than the temporal width of the pulse. Eventually, by analyzing temporal correlations of the excited matter degrees of freedom, we show that driving with entangled photons imprints characteristic temporal correlations of time-energy entangled modes in the matter degree of freedom.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
21 pages, 13 figures
Chirality across scales in tissue dynamics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Sihan Chen, Doruk Efe Gökmen, Michel Fruchart, Miriam Krumbein, Pascal Silberzan, Victor Yashunsky, Vincenzo Vitelli
Chiral processes that lack mirror symmetry pervade nature from enantioselective molecular interactions to the asymmetric development of organisms. An outstanding challenge at the interface between physics and biology consists in bridging the multiple scales between microscopic and macroscopic chirality. Here, we combine theory, experiments and modern inference algorithms to study a paradigmatic example of dynamic chirality transfer across scales: the generation of tissue-scale flows from subcellular forces. The distinctive properties of our microscopic graph model and the corresponding coarse-grained viscoelasticity are that (i) net cell proliferation is spatially inhomogeneous and (ii) cellular dynamics cannot be expressed as an energy gradient. To overcome the general challenge of inferring microscopic model parameters from noisy high-dimensional data, we develop a nudged automatic differentiation algorithm (NADA) that can handle large fluctuations in cell positions observed in single tissue snapshots. This data-calibrated microscopic model quantitatively captures proliferation-driven tissue flows observed at large scales in our experiments on fibroblastoma cell cultures. Beyond chirality, our inference algorithm can be used to extract interpretable graph models from limited amounts of noisy data of living and inanimate cellular systems such as networks of convection cells and flowing foams.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Clustering and emergent hyperuniformity by breaking microswimmer shape and actuation symmetries
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Anson G. Thambi, William E. Uspal
Hydrodynamic interactions driven by particle activity are ubiquitous in active colloidal systems. Although these interactions are strongly influenced by the interfacial actuation mechanism and geometry of the swimming particles, theoretical understanding of how these microscopic design parameters govern collective dynamics remains limited. Here, we investigate the collective dynamics of oblate spheroidal microswimmers. Using an approximate kinetic theory and corroborating boundary element method calculations, we demonstrate that breaking symmetries in both particle shape and interfacial actuation enables the emergence of dynamically stable immotile n-particle clusters. At larger scales, the clustering process drives the system into a dynamically arrested absorbing state characterized by disordered class I hyperuniform structures. Our analysis highlights the essential role of cluster-sourced long-range flows in establishing this long-range order. Overall, our findings reveal a robust, purely hydrodynamic mechanism for hierarchical self-organization in active matter systems, providing a novel strategy for engineering multifunctional hyperuniform materials.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Main text: 14 pages, 5 figures. Supplementary material: 14 pages, 7 figures
Trion formation and ordering in the attractive SU(3) Fermi-Hubbard model
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
Jonathan Stepp, Eduardo Ibarra-García-Padilla, Richard T. Scalettar, Kaden R. A. Hazzard
Recent advances in microwave shielding have increased the stability and control of large numbers of polar molecules, allowing for the first realization of a molecular Bose-Einstein condensate. Remarkably, it was also recently realized that shielded polar molecules exhibit an SU(N) symmetry among their hyperfine states, opening the door to SU(N) systems with larger N, bosonic particle statistics, and tunable interactions – both repulsive and attractive. Motivated by these results, we have studied the SU(3) attractive Fermi-Hubbard model (FHM) on a square lattice. Using the Determinant Quantum Monte Carlo (DQMC) method, we explore the finite-temperature phase diagram and provide evidence for three distinct regions – a three-component Fermi liquid (FL) region, a “trion” liquid (TL) region, and an ordered Charge Density Wave (CDW) phase. The CDW phase is stable at finite temperature (in contrast to the SU(2) CDW), while the FL to TL crossover appears to point to a quantum phase transition at zero temperature. Our method extends straightforwardly to larger N and is sign-problem free for even values of N. With these results, we demonstrate the potential physics enabled by using polar molecules as a quantum simulation platform for the attractive SU(N) FHM.
Quantum Gases (cond-mat.quant-gas)
7 pages, 3 figures, 5 pages of supplemental material (with 3 supplemental figures)
Fundamentals and Advances in Transverse Thermoelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Hiroto Adachi, Fuyuki Ando, Takamasa Hirai, Rajkumar Modak, Matthew Grayson, Ken-ichi Uchida
Transverse thermoelectric effects interconvert charge and heat currents in orthogonal directions due to the breaking of either time-reversal symmetry or structural symmetry, enabling simple and versatile thermal energy harvesting and solid-state cooling within single materials. In comparison to the complex module structures required for the conventional Seebeck and Peltier effects, the transverse thermoelectric effects provide the complete device structures, potentially resolving the fundamental issue of multi-module degradation of thermoelectric conversion performance. This review article provides an overview of all currently known transverse thermoelectric conversion phenomena and principles, as well as their characteristics, and reclassifies them in a unified manner. The performance of the transverse thermoelectric generator, refrigerator, and active cooler is formulated, showing that thermal boundary conditions play an essential role to discuss their behaviors. Examples of recent application research and material development in transverse thermoelectrics are also introduced, followed by a discussion of future prospects.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
31 pages, 11 figures, 1 Table
Multi-state detection and spatial addressing in a microscope for ultracold molecules
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
Jonathan M. Mortlock, Adarsh P. Raghuram, Benjamin P. Maddox, Philip D. Gregory, Simon L. Cornish
Precise measurement of the particle number, spatial distribution and internal state is fundamental to all proposed experiments with ultracold molecules both in bulk gases and optical lattices. Here, we demonstrate in-situ detection of individual molecules in a bulk sample of 87Rb133Cs molecules. Extending techniques from atomic quantum gas microscopy, we pin the molecules in a deep two-dimensional optical lattice and, following dissociation, collect fluorescence from the constituent atoms using a high-numerical-aperture objective. This enables detection of individual molecules up to the resolution of the sub-micron lattice spacing. Our approach provides direct access to the density distribution of small samples of molecules, allowing us to obtain precise measurements of density-dependent collisional losses. Further, by mapping two internal states of the molecule to different atomic species, we demonstrate simultaneous detection of the position and rotational state of individual molecules. Finally, we implement local addressing of the sample using a focused beam to induce a spatially-dependent light shift on the rotational transitions of the molecules.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
On the extremal spectral properties of random graphs
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-06-17 20:00 EDT
C. T Martínez Martínez, J. A. Méndez Bermúdez
In this work, we study some statistical properties of the extreme eigenstates of the randomly-weighted adjacency matrices of random graphs. We focus on two random graph models: Erdős-Rényi (ER) graphs and random geometric graphs (RGGs). Indeed, the adjacency matrices of both graph models are diluted versions of the Gaussian Orthogonal Ensemble (GOE) of random matrix theory (RMT), such that a transition from the Poisson Ensemble (PE) and the GOE is observed by increasing the graph average degree $ \langle k \rangle$ . First, we write down expressions for the spectral density in terms of $ \langle k \rangle$ for the regimes below and above the percolation threshold. Then, we show that the distributions of both, the largest $ \lambda_1$ and second-largest $ \lambda_2$ eigenvalues approach the Tracy-Widom distribution of type 1 for $ \langle k \rangle \gg 1$ , while $ \langle \lambda_1 \rangle = \sqrt{2\langle k \rangle}$ . Additionally, we demonstrate that the distributions of the normalized distance between $ \lambda_1$ and $ \lambda_2$ , the distribution of the ratio between higher consecutive eigenvalues spacings, as well as the distributions of the inverse participation ratios of the extreme eigenstates display a clear PE–to–GOE transition as a function of $ \langle k \rangle$ , so any of these distributions can be effectively used to probe the delocalization transition of the graph models without the need of the full spectrum.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
Extracting Composition-Dependent Diffusion Coefficients Over a Very Large Composition Range in NiCoFeCrMn High Entropy Alloy Following Strategic Design of Diffusion Couples and Physics Informed Neural Network Numerical Method
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Suman Sadhu, Saswata Bhattacharyya, Aloke Paul
Estimating composition dependent diffusion coefficients in multicomponent alloys was a longstanding challenge due to limitations in experimental methods. In this study, we have first demonstrated a strategic design of producing only three diffusion couples to estimate all types, that is tracer, intrinsic, and interdiffusion coefficients at the Kirkendall marker planes. This establishes a systematic variation of diffusion coefficients with composition in a very wide composition range of the NiCoFeCrMn system in comparison to the data available on impurity diffusion coefficients in pure elements and tracer diffusion coefficients at the equiatomic composition estimated by the radiotracer method. Following, a physics-informed Neural Network based numerical inverse method is developed to extract composition-dependent diffusivities over the whole composition range of the diffusion couples.
Materials Science (cond-mat.mtrl-sci)
Hydrogen response to high-density dislocations in bulk perovskite oxide SrTiO3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Xufei Fang, Lars Dörrer, Svetlana Korneychuk, Maria Vrellou, Alexander Welle, Stefan Wagner, Astrid Pundt, Harald Schmidt, Christoph Kirchlechner
Hydrogen plays an increasingly important role in green energy technologies. For instance, proton-conducting oxides with high performance for fuel cell components or electrolysers need to be developed. However, this requires a fundamental understanding of hydrogen-defects interactions. While point defects and grain boundaries in oxides have been extensively studied, the role of dislocations as line defects remains less understood, primarily due to the challenge for effective dislocation engineering in brittle oxides. In this work, we demonstrate the impact of dislocations in bulk single-crystal perovskite oxide SrTiO3 on hydrogen uptake and diffusion using deuterium as tracer. Dislocations with a high density up to ~10 to the power of 14 per square meter were mechanically introduced at room temperature. Exposing this dislocation-rich and the reference regions (with a dislocation density of ~10 to the power of 10 per square meter) to deuterium at 400 °C for 1h, followed by secondary ion mass spectrometry measurements, we observed a ~100 times increase in deuterium incorporation in the dislocation-rich region. The result suggests that dislocations in oxides can act as an effective reservoir for deuterium. This proof-of-concept brings new insights into the emerging hydrogen-dislocation interactions in functional oxides.
Materials Science (cond-mat.mtrl-sci)
Bio-inspired learning algorithm for time series using Loewner equation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-17 20:00 EDT
Though the relationship between the theoretical statistical physics and machine learning techniques has been a well-discussed topic, the studies on the mechanism of learning inspired by the biological system are still developing. In this study, we investigate the application methods of Loewner equation to the learning algorithm particularly focusing on its statistical-mechanical aspects. We suggest two simple methods of learning of one-dimensional time series based on the unique encoding property of the discrete Loewner evolution. The first one is the Gaussian process (GP) regression using the normality of the distribution of Loewner driving force corresponding to the curve composed from the time series. The second one is the fluctuation-dissipation relation (FDR) for the time series, which is derived from the Loewner theory, measuring the sensitivity of the nonlinear dynamics under the small perturbation. These methods were numerically tested dealing with the neuronal dynamics generated by the leaky integrate-and-fire model. In addition, we discuss the similarity between the mapping mechanism of the present method and the structure of biological information processing from a point of view of self-organization system theory.
Statistical Mechanics (cond-mat.stat-mech), Chaotic Dynamics (nlin.CD)
Impact of in-plane disorders on the thermal conductivity of AgCrSe$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Shota Izumi, Yui Ishii, Jinfeng Zhu, Tsunemasa Sakamoto, Shintaro Kobayashi, Shogo Kawaguchi, Jie Ma, Shigeo Mori
Superionic conductors have recently attracted renewed attention for their use as thermoelectric materials due to their extremely low lattice thermal conductivity. Of central interest is why the superionic conductors exhibit such low thermal conductivity, and competing mechanisms have been proposed thus far. In this study, we investigate the effects of Cu and Au substitution for Ag site on the crystal structure and thermal properties of AgCrSe$ _2$ , which exhibits superionic conduction of Ag ions. We show that Au substitution significantly reduces the lattice thermal conductivity of AgCrSe$ _2$ . Powder structure analysis using synchrotron x-ray diffraction reveals that Au substitution increases the anisotropic atomic displacement parameter of Ag ions along the $ a$ and $ b$ axes. This result indicates that the amplitude of in-plane vibrations is enhanced, which is attributed to increased anharmonicity in the potential energy around Ag ions. The enhanced vibrational amplitude also suggests a reduction in the force constants between Ag ions. Consequently, the enhanced anharmonicity not only shortens the phonon lifetime ($ \tau$ ) by increasing phonon-phonon scattering, but also increases the number of low-energy phonons, which further contributes to the reduction of $ \tau$ . This anharmonicity mechanism is applicable to other superionic conductors exhibiting ultra-low thermal conductivity, promoting their widespread use as thermoelectric materials.
Materials Science (cond-mat.mtrl-sci)
9 pages, 6 figures
Distinguishing features of longitudinal magnetoconductivity for a Rarita-Schwinger-Weyl node
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
The band-degeneracy points in the Brillouin zones of chiral crystals exist in multiple avatars, with the high-symmetry points being able to host multifold nodes of distinct characters. A class of such crystals, assisted by the spin-orbit coupling, harbours fourfold degeneracy in the form of Rarita-Schwinger-Weyl node (RSWN) at the $ \Gamma$ -point. Our aim is to explore the nature of longitudinal magnetoconductivity, arising from applying collinear electric and magnetic fields, for such systems. Adjusting the chemical potential to lie near the intrinsic energy-location of the RSWN, the multifold nature of the RSWN is revealed by an interplay of intraband and interband scatterings, which would not arise in twofold degeneracies like the conventional Weyl nodes. The current study fills up the much-needed gap in obtaining the linear response from an exact computation, rather than the insufficient relaxation-time approximation employed earlier.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
we have reviewed the Boltzmann formalism for the ease of readability, although the framework is the same as used in arXiv:2505.19636 and arXiv:2506.07913
Uniaxial stress tuning of interfacial thermal conductance in cubic BAs/4H-SiC heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Lei Zhang, Fei Tian, Ke Chen, Zhongbo Yan, Kun Cao
Understanding interfacial thermal transport is essential for improving thermal management in high-speed power electronic devices, where the efficient removal of excess heat is a critical challenge. In this study, a machine learning interatomic potential with near first-principles accuracy was employed to investigate the interfacial thermal conductance (ITC) between [111]-oriented cubic boron arsenide (cBAs) and [0001]-oriented 4H silicon carbide (4H-SiC), as well as its dependence on uniaxial stress. Among all possible bonding configurations at the cBAs(111)/4H-SiC(0001) interface, the B-C bonded interface was identified as the most energetically favorable. Non-equilibrium molecular dynamics simulations revealed that, under ambient conditions (300 K and 0 GPa), the ITC of the B-C interface reaches 353 $ \pm$ 6 MW m$ ^{-2}$ K$ ^{-1}$ , and increases monotonically to 460 $ \pm$ 3 MW m$ ^{-2}$ K$ ^{-1}$ under a uniaxial stress of 25 GPa perpendicular to the interface. For comparison, the As-C bonded interface exhibits a lower ITC, increasing from 233 $ \pm$ 7 to 318 $ \pm$ 6 MW m$ ^{-2}$ K$ ^{-1}$ over the same stress range. These results demonstrate that proper interfacial bonding and moderate uniaxial stress can significantly enhance thermal transport across the cBAs(111)/4H-SiC(0001) heterointerface, offering valuable insight for thermal design in next-generation power electronics.
Materials Science (cond-mat.mtrl-sci)
Néel vector controlled exceptional contours in $p$-wave magnet-ferromagnet junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
Md Afsar Reja, Awadhesh Narayan
Non-Hermitian systems can host exceptional degeneracies where not only the eigenvalues, but also the corresponding eigenvectors coalesce. Recently, $ p$ -wave magnets have been introduced, which are characterized by their unusual odd parity. In this work, we propose the emergence of non-Hermitian degeneracies at the interface of $ p$ -wave magnets and ferromagnets. We demonstrate that this setup offers a remarkable tunability allowing realization of exceptional lines and rings, which can be controlled via the orientation of the $ p$ -wave Néel vector. We present the origin of these exceptional contours based on symmetry, and characterize them using phase rigidity. Our works puts forward a versatile platform to realize controllable non-Hermitian degeneracies at odd parity magnetic interfaces.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 3 figures, Comments are welcome!
Unconventional superconductivity in a non-centrosymmetric $α$-Mn alloy NbTaOs$_{2}$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
R. K. Kushwaha, Arushi, S. Jangid, P. K. Meena, R. Stewart, A. D. Hillier, R. P. Singh
Non-centrosymmetric superconductors have emerged as a fascinating avenue for exploring unconventional superconductivity. Their broken inversion and time-reversal symmetries make them prime candidates for realizing the intrinsic superconducting diode effect (SDE). In this work, we synthesize the ternary non-centrosymmetric $ \alpha$ -Mn alloy NbTaOs$ _{2}$ and conduct a comprehensive investigation of its superconducting properties through resistivity, magnetization, specific heat and muon spin rotation/relaxation ($ \mu$ SR) techniques. Our transverse field-$ \mu$ SR and specific heat results provide evidence of a moderately coupled, fully-gaped superconducting state. Zero field-$ \mu$ SR measurements reveal a subtle increase in the relaxation rate below the transition temperature, suggesting time reversal symmetry breaking in the superconducting ground state of NbTaOs$ _{2}$ .
Superconductivity (cond-mat.supr-con)
10 pages, 6 figures
Tunable corner states in topological insulators with long-range hoppings and diverse shapes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
In this work, we develop a theoretical framework for the control of corner modes in higher-order topological insulators (HOTIs) featuring long-range hoppings and diverse geometries, enabling precise tunability of their spatial positions. First, we demonstrate that the locations of corner states can be finely tuned by varying long-range hoppings in a circular HOTI, as revealed by a detailed edge theory analysis and the condition of vanishing Dirac mass. Moreover, we show that long-range hoppings along different directions (e.g., $ x$ and $ y$ ) have distinct effects on the positioning of corner states. Second, we investigate HOTIs with various polygonal geometries and find that the presence and location of corner modes depend sensitively on the shape. In particular, a corner hosts a localized mode if the Dirac masses of its two adjacent edges have opposite signs, while no corner mode emerges if the masses share the same sign. Our findings offer a versatile approach for the controlled manipulation of corner modes in HOTIs, opening new avenues for the design and implementation of higher-order topological materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 4 figures
Defect-Mediated Pairing and Dissociation of Strongly Correlated Electrons in Low Dimensional Lattices: The Quantum Taxi Effect
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-17 20:00 EDT
We study the quantum dynamics of a strongly correlated electron pair in a one-dimensional lattice, focusing on the occurrence of local dissociation/pairing mechanisms induced by a site energy defect. To this end, we simulate the time evolution of two interacting electrons on a finite-size chain governed by an extended Hubbard Hamiltonian including on-site Coulomb repulsion $ U $ and nearest-neighbor interaction $ V$ , along with single-electron hopping $ J$ . By introducing a local site energy defect with amplitude $ \Delta $ , we show that a transition between spatially paired/dissociated electrons can occur in the vicinity of this site. Such mechanisms arise in a strongly correlated regime with non-zero nearest neighbor Coulomb interactions and under the conditions $ (U \sim V \sim \Delta) \gg J$ . To rationalize these phenomena, we reformulate the two-electron dynamics of the original Hubbard chain as an effective single-particle problem on a two-dimensional network. Within this framework, we show that the pairing/dissociation dynamics are driven by resonances between two distinct families of two-electron eigenstates: $ (i)$ states with two spatially well-separated electrons with one located at the site defect, and $ (ii)$ states with locally bound electron located away from the defect. At resonance, these states hybridize, allowing transitions from locally paired to dissociated electrons (and vice versa) in the vicinity of the defect. These results provide new insights into exotic pairing phenomena in strongly correlated electronic systems and may have implications for the design of tunable many-body states in low-dimensional quantum materials.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Information fusion strategy integrating pre-trained language model and contrastive learning for materials knowledge mining
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Yongqian Peng, Zhouran Zhang, Longhui Zhang, Fengyuan Zhao, Yahao Li, Yicong Ye, Shuxin Bai
Machine learning has revolutionized materials design, yet predicting complex properties like alloy ductility remains challenging due to the influence of processing conditions and microstructural features that resist quantification through traditional reductionist approaches. Here, we present an innovative information fusion architecture that integrates domain-specific texts from materials science literature with quantitative physical descriptors to overcome these limitations. Our framework employs MatSciBERT for advanced textual comprehension and incorporates contrastive learning to automatically extract implicit knowledge regarding processing parameters and microstructural characteristics. Through rigorous ablation studies and comparative experiments, the model demonstrates superior performance, achieving coefficient of determination (R2) values of 0.849 and 0.680 on titanium alloy validation set and refractory multi-principal-element alloy test set. This systematic approach provides a holistic framework for property prediction in complex material systems where quantitative descriptors are incomplete and establishes a foundation for knowledge-guided materials design and informatics-driven materials discovery.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Half-integer thermal conductance in the absence of Majorana mode
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
Ujjal Roy, Sourav Manna, Souvik Chakraborty, Kenji Watanabe, Takashi Taniguchi, Ankur Das, Moshe Goldstein, Yuval Gefen, Anindya Das
Considering a range of candidate quantum phases of matter, half-integer thermal conductance ($ \kappa_{\text{th}}$ ) is believed to be an unambiguous evidence of non-Abelian states. It has been long known that such half-integer values arise due to the presence of Majorana edge modes, representing a significant step towards topological quantum computing platforms. Here we break this long-standing paradigm, reporting a comprehensive theoretical and experimental study where half-integer two-terminal thermal conductance plateau is realized employing Abelian phases. Our proposed setup features a confined geometry of bilayer graphene, interfacing distinct particle-like and hole-like integer quantum Hall states. Each segment of the device exhibits full charge and thermal equilibration. Our approach is amenable to generalization to other quantum Hall platforms, and may give rise to other values of fractional (electrical and thermal) quantized transport. Our study demonstrates that the observation of robust non-integer values of thermal conductance can arise as a manifestation of mundane equilibration dynamics as opposed to underlying non-trivial topology.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Exact Renormalization Relation and Binding Energies for Three Identical Bosons
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
In the low-energy limit, non-relativistic particles with short-range interactions exhibit universal behavior that is largely independent of microscopic details. This universality is typically described by effective field theory, in which the two-body interaction is renormalized to a single parameter-the scattering length. For systems of identical bosons, the three-body problem reveals the Efimov effect, a novel phenomenon proposed that necessitates the introduction of an additional three-body parameter. However, the exact relation between this three-body parameter, the coupling constants in the effective field theory, and the binding energies of Efimov states remains unresolved. In this Letter, we address this question through a comprehensive analysis of the Skorniakov-Ter-Martirosian equation with a finite cutoff. We establish an exact renormalization relation for the three-body parameter and determine its connection to the energies of Efimov bound states. These results are validated through high-precision numerical simulations. We expect our findings to be of fundamental interest across various fields, including atomic, nuclear, condensed matter, and particle physics, and to have broad applications in both few-body and many-body physics.
Quantum Gases (cond-mat.quant-gas), Nuclear Theory (nucl-th)
6 pages + supplementary material
Exciton condensation of composite fermions in double layer quantum Hall systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-17 20:00 EDT
Xiang-Jian Hou, Lei Wang, Ying-Hai Wu
We study fractional quantum Hall states in double layer systems that can be interpreted as exciton condensates of composite fermions. An electron in one layer is dressed by two fluxes from the same layer and two fluxes from the other layer to become composite fermions that form effective Landau levels. It is found that two types of composite fermion exciton condensates could occur. In the first type ones, all effective levels are partially occupied and excitonic correlations are present between composite fermions in the same effective level. In the second type ones, composite fermions in the topmost effective levels of the two layers form exciton condensate whereas those in lower effective levels are independent. The electric transport signatures of these states are analyzed. We demonstrate using numerical calculations that some composite fermion exciton condensates can be realized in microscopic models that are relevant for graphene and transition metal dichalcogenides. For a fixed total filling factor, an exciton condensate may only be realized when the electron densities in the two layers belong to a certain range. It is possible that two types of states appear at the same total filling factor in different ranges. These results shed light on recent experimental observations and also suggest some promising future directions.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 5 figures
Tailored ordering enables high-capacity cathode materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Tzu-chen Liu, Adolfo Salgado-Casanova, So Yubuchi, Bianca Baldassarri, Muratahan Aykol, Jun Yoshida, Hisatsugu Yamasaki, Yizhou Zhu, Steven B. Torrisi, Christopher Wolverton
Newly designed Li-ion battery cathode materials with high capacity and greater flexibility in chemical composition will be critical for the growing electric vehicles market. Cathode structures with cation disorder were once considered suboptimal, but recent demonstrations have highlighted their potential in Li$ _{1+x}$ M$ _{1-x}$ O$ _{2}$ chemistries with a wide range of metal combinations M. By relaxing the strict requirements of maintaining ordered Li diffusion pathways, countless multi-metal compositions in LiMO$ _2$ may become viable, aiding the quest for high-capacity cobalt-free cathodes. A challenge presented by this freedom in composition space is designing compositions which possess specific, tailored types of both long- and short-range orderings, which can ensure both phase stability and Li diffusion. However, the combinatorial complexity associated with local cation environments impedes the development of general design guidelines for favorable orderings. Here we propose ordering design frameworks from computational ordering descriptors, which in tandem with low-cost heuristics and elemental statistics can be used to simultaneously achieve compositions that possess favorable phase stability as well as configurations amenable to Li diffusion. Utilizing this computational framework, validated through multiple successful synthesis and characterization experiments, we not only demonstrate the design of LiCr$ _{0.75}$ Fe$ _{0.25}$ O$ _2$ , showcasing initial charge capacity of 234 mAhg$ ^{-1}$ and 320 mAhg$ ^{-1}$ in its 20% Li-excess variant Li$ _{1.2}$ Cr$ _{0.6}$ Fe$ _{0.2}$ O$ _2$ , but also present the elemental ordering statistics for 32 elements, informed by one of the most extensive first-principles studies of ordering tendencies known to us.
Materials Science (cond-mat.mtrl-sci)
Language Models Enable Data-Augmented Synthesis Planning for Inorganic Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Thorben Prein, Elton Pan, Janik Jehkul, Steffen Weinmann, Elsa A. Olivetti, Jennifer L. M. Rupp
Inorganic synthesis planning currently relies primarily on heuristic approaches or machine-learning models trained on limited datasets, which constrains its generality. We demonstrate that language models, without task-specific fine-tuning, can recall synthesis conditions. Off-the-shelf models, such as GPT-4.1, Gemini 2.0 Flash and Llama 4 Maverick, achieve a Top-1 precursor-prediction accuracy of up to 53.8 % and a Top-5 performance of 66.1 % on a held-out set of 1,000 reactions. They also predict calcination and sintering temperatures with mean absolute errors below 126 °C, matching specialized regression methods. Ensembling these language models further enhances predictive accuracy and reduces inference cost per prediction by up to 70 %. We subsequently employ language models to generate 28,548 synthetic reaction recipes, which we combine with literature-mined examples to pretrain a transformer-based model, SyntMTE. After fine-tuning on the combined dataset, SyntMTE reduces mean-absolute error in sintering temperature prediction to 73 °C and in calcination temperature to 98 °C. This strategy improves models by up to 8.7 % compared with baselines trained exclusively on experimental data. Finally, in a case study on Li7La3Zr2O12 solid-state electrolytes, we demonstrate that SyntMTE reproduces the experimentally observed dopant-dependent sintering trends. Our hybrid workflow enables scalable, data-efficient inorganic synthesis planning.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Machine Learning (stat.ML)
Nanodroplets Condensation on Solid Surfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Matteo Teodori, Dario Abbondanza, Mirko Gallo, Carlo Massimo Casciola
This paper deals with the condensation of liquid droplets on hydrophobic and hydrophilic surfaces. A stochastic mesoscale model based on the theory of fluctuating hydrodynamics and the thermodynamics of a diffuse interface approach shows how direct simulation of the vapour-liquid transition from the nucleation process to droplet hydrodynamics can be achieved. Such simulations explain the role of wettability in filmwise and dropwise condensation regimes and the main limitations of classical nucleation theory.
Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
Inferring Grain Size Distributions from Magnetic Hysteresis in M-type Hexaferrites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Masoud Ataei, Mohammad Jafar Molaei, Abolghasem Ataie
We develop a stochastic-dynamic framework to infer latent grain size distribution from magnetic hysteresis data in M-type hexaferrite materials, offering an alternative to imaging-based characterization. A stochastic nucleation-growth process yields a Modified Lognormal Power-law grain size distribution. This is combined with Brown’s relation to obtain a coercivity probability distribution, which is embedded within a dynamic magnetization model. A key feature is the joint estimation of microstructural parameters, including the critical grain radius, through inverse optimization of full hysteresis loops. Experimental validation on hydrothermally synthesized strontium hexaferrite subjected to nitrogen treatment and recalcination reveals interpretable trajectories of nucleation, growth, and structural memory encoded in the magnetic response.
Materials Science (cond-mat.mtrl-sci), Data Analysis, Statistics and Probability (physics.data-an), Applications (stat.AP)
First-Passage Observables of $d$-dimensional Confined Jump Processes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-17 20:00 EDT
Jérémie Klinger, Olivier Bénichou, Raphaël Voituriez
First-passage observables (FPO) are central to understanding stochastic processes in confined domains, with applications spanning chemical reaction kinetics, foraging behavior, and molecular transport. While extensive analytical results exist for continuous processes, discrete jump processes – crucial for describing empirically observed dynamics – remain largely unexplored in this context. This paper presents a comprehensive framework to systematically evaluate FPO for $ d$ -dimensional confined isotropic jump processes, capturing both geometric and dynamical observables. Leveraging the connection between jump processes and their continuous counterparts, we address the limitations of continuous approximations in capturing discrete effects, particularly near absorbing boundaries. Our method unifies FPO calculations across edge and bulk regimes, providing explicit asymptotic expressions for key observables, such as splitting probabilities, harmonic measures, and first-passage time distributions in complex geometries. We illustrate our approach with paradigmatic examples, including eccentric splitting probabilities in two-dimensional disks and mean exit times for heavy-tailed processes. These results underscore the broad applicability of our framework to diverse physical systems, offering novel insights into the interplay between discrete dynamics and confining geometries.
Statistical Mechanics (cond-mat.stat-mech)
Main text - 13 pages, 9 figures SM - 6 pages
Machine learning potentials for modeling alloys across compositions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Killian Sheriff, Daniel Xiao, Yifan Cao, Lewis R. Owen, Rodrigo Freitas
Materials properties depend strongly on chemical composition, i.e., the relative amounts of each chemical element. Changes in composition lead to entirely different chemical arrangements, which vary in complexity from perfectly ordered (i.e., stoichiometric compounds) to completely disordered (i.e., solid solutions). Accurately capturing this range of chemical arrangements remains a major challenge, limiting the predictive accuracy of machine learning potentials (MLPs) in materials modeling. Here, we combine information theory and machine learning to optimize the sampling of chemical motifs and design MLPs that effectively capture the behavior of metallic alloys across their entire compositional and structural landscape. The effectiveness of this approach is demonstrated by predicting the compositional dependence of various material properties - including stacking-fault energies, short-range order, heat capacities, and phase diagrams - for the AuPt and CuAu binary alloys, the ternary CrCoNi, and the TiTaVW high-entropy alloy. Extensive comparison against experimental data demonstrates the robustness of this approach in enabling materials modeling with high physical fidelity.
Materials Science (cond-mat.mtrl-sci)
12 pages, 9 figures
Statistical Description of Fermi System over a Surface in a Uniform External Field
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-17 20:00 EDT
A statistical approach to the description of the thermodynamic properties of the Fermi particle system occupying a half-space over a plane of finite size in a uniform external field is proposed. The number of particles per unit area is assumed to be arbitrary, in particular, small. General formulas are obtained for entropy, energy, thermodynamic potential, heat capacities under various conditions and the distribution of the particle number density over the surface. In the continuum limit of a large surface area, the temperature dependences of heat capacities and density distribution are calculated. The cases of gravitational and electric fields are considered.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
15 pages, 6 figures
Finding Some Impossibility of Flat-Folding of Given Origami Crease Pattern by Graphical Representation
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-06-17 20:00 EDT
Flat-foldability problem of origami is the problem to determine whether a given crease pattern drawn on a piece of paper is possible to fold without any penetration or intrusion of a polygon into any connections among them. It is known from the results of Bern and Hayes and following studies that determining whether an origami diagram which constitute of polygons in general shapes can be flat-folded is an NP-hard problem. In this manuscript, on determining the flat foldability of unsigned crease patterns that satisfy the necessary conditions imposed by the Kawasaki-Justin theorem for all interior vertices, we introduce a graph representation based on an arrangement of polygons whose contours are consist of creases, allowing overlapping of the polygons. On the graphical representation, a method is proposed to efficiently detect the conditions for flat-folding inability by using the properties of the cycle basis. We also demonstrate the above method using an example of a fold that is already known to be impossible to flat-fold.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
6 pages, 4figures
Collective Interference Phonon Spin Manifested in Infrared Circular Dichroism
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Yizhou Liu, Yu-Tao Tan, Dapeng Liu, Jie Ren
The classical field description of phonon spin" relies on the invariance of a continuous elastic field under infinitesimal rotation. However, a local medium element” in the continuous field may contain large numbers of vibrational particles at microscopic level, like for complex lattices with many atoms in a unit cell. We find this causes the phonon spin in real materials no longer a simple sum of each atom rotation, but a collective interference of many particles, since phonons are phase-coherent vibrational modes across unit cells. We demonstrate the many-particle-interference phonon spin manifested as the dipole moment rotating (DMR) of charge-polarized unit cell, by deriving the infrared circular dichroism (ICD) with phonon-photon interaction in complex lattices. We compare the DMR with the local atom rotation without interference, and exemplify their distinct ICD spectrum in a chiral lattice model and two realistic chiral materials. Detectable ICD measurements are proposed in $ \alpha$ -quartz with Weyl phonon at Gamma point. Our study underlies the important role of many-particle-interference and uncovers a deeper insight of phonon spin in real materials with complex lattices.
Materials Science (cond-mat.mtrl-sci)
16 pages, 6 figures
Interface-controlled antiferromagnetic tunnel junctions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Liu Yang, Yuan-Yuan Jiang, Xiao-Yan Guo, Shu-Hui Zhang, Rui-Chun Xiao, Wen-Jian Lu, Lan Wang, Yu-Ping Sun, Evgeny Y. Tsymbal, Ding-Fu Shao
Magnetic tunnel junctions (MTJs) are the key building blocks of high-performance spintronic devices. While conventional MTJs rely on ferromagnetic (FM) materials, employing antiferromagnetic (AFM) compounds can significantly increase operation speed and packing density. Current prototypes of AFM tunnel junctions (AFMTJs) exploit antiferromagnets either as spin-filter insulating barriers or as metal electrodes supporting bulk spin-dependent currents. Here, we highlight a largely overlooked AFMTJ prototype, where bulk-spin-degenerate electrodes with an A-type AFM stacking form magnetically uncompensated interfaces, enabling spin-polarized tunneling currents and a sizable tunneling magnetoresistance (TMR) effect. Using first-principles quantum-transport calculations and the van der Waals (vdW) metal Fe$ _{4}$ GeTe$ _{2}$ as a representative A-type AFM electrode, we demonstrate a large negative TMR arising solely from the alignment of interfacial magnetic moments. This prototype of AFMTJs can also be realized with various non-vdW A-type AFM metals that support roughness-insensitive surface magnetization. Beyond TMR, AFMTJs based on A-type antiferromagnets allow convenient switching of the Néel vector, opening a new paradigm for AFM spintronics that leverages spin-dependent properties at AFM interfaces.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Newton in press
Superconductivity and inhomogeneous charge-ordered state in the two-Dimensional Hubbard model – Off-Diagonal Wave Function Monte Carlo Studies of Hubbard Model IV
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-17 20:00 EDT
We investigate the ground-state properties of the two-dimensional Hubbard model, based on the off-diagonal wave function variational Monte Carlo method. We use an optimized wave function that is improved from an initial one-body wave function by multiplying by multiple correlation operators that are given by the form of exp($ -S$ )-type where $ S$ is a suitable operator. We examine the inhomogeneous ground state at near 1/8 doping in the strongly correlated region where the on-site Coulomb interaction is larger than the bandwidth. The $ d$ -wave superconductivity with a spatially oscillating gap function can coexist with the charge ordering in the ground state without magnetic ordering, and superconducting condensation energy increases by this coexistence. We also show the $ d$ -wave pair correlation function as a function of lattice sites. The correlation function indicates that the long-range superconducting order indeed exists, and also that the strong electron correlation suppresses the pair correlation function.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 21 figures
Optimizing optical properties of bilayer PtSe$_2$: the role of twist angle and hydrostatic pressure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Paulina Jureczko, Zbigniew Dendzik, Marcin Kurpas
Two-dimensional van der Waals materials offer exceptional tunability in their electronic properties. In this paper, we explore how twisting and hydrostatic pressure can be leveraged to engineer the electronic and optical characteristics of bilayer PtSe$ _2$ . Using state-of-the-art first-principles density functional methods, we calculate the electronic band structure and the imaginary part of the dielectric function across multiple twist angles and pressure values. We find, that at the twist angle $ \theta=13.17^\circ$ , bilayer PtSe$ _2$ , which is intrinsically an indirect semiconductor, transforms into a direct-gap semiconductor. Moreover, we demonstrate that hydrostatic out-of-plane pressure boosts near-infrared optical activity, further expanding the functional potential of PtSe$ _2$ bilayers. The demonstrated high tunability of electronic and optical properties by twisting and pressure opens new application directions of PtSe$ _2$ in optoelectronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 4 figures
Layer Pseudospin Superconductivity in Twisted MoTe$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
Jin-Xin Hu, Akito Daido, Zi-Ting Sun, Ying-Ming Xie, K. T. Law
Recent experiments have observed signatures of spin-valley-polarized unconventional superconductivity in twisted bilayer MoTe$ _2$ (tMoTe$ _2$ ). Here, we explore the rich physics of superconducting tMoTe$ _2$ , enabled by its unique layer-pseudospin structure. Within a minimal two-orbital layer-pseudospin model framework, both interlayer and intralayer Cooper pairings can be effectively visualized using a layer-space Bloch sphere representation. Remarkably, we find that interlayer pairing prevails in the spin-valley-polarized state, whereas intralayer pairing dominates in the spin-valley-unpolarized state. Strikingly, we further predict that for spin-valley-polarized intravalley superconducting state, experimentally feasible weak displacement fields can stabilize finite-momentum pairings at low temperatures. Additionally, in-plane magnetic fields, which break three-fold rotational symmetry, induce field-direction-dependent finite-momentum pairing states, leading to a versatile momentum-selection phase diagram. Our work highlights the crucial role of layer pseudospin in tMoTe$ _2$ ‘s unconventional superconductivity and demonstrates its unique tunability via external fields.
Superconductivity (cond-mat.supr-con)
10 pages, 5 figures
Structure-Dynamics Correlation and Its Link to Fragility and Dynamic Heterogeneity
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Mohit Sharma, Srikanth Sastry, Sarika Maitra Bhattacharyya
Understanding the connection between structure, dynamics, and fragility (the rate at which relaxation times grow with decreasing temperature) is central to unraveling the glass transition. Fragility is often linked to dynamic heterogeneity, and thus it is commonly assumed that if structure influences dynamics, more fragile systems should exhibit stronger structure–dynamics correlations. In this study, we test the generality of this assumption using three model systems: Lennard-Jones (LJ) and Weeks–Chandler–Andersen, where fragility is tuned via density, and a modified LJ (q, p) system, where potential softness is changed to vary fragility. We employ a structural order parameter derived from the mean–field caging potential and analyze energy barriers at both macroscopic and microscopic levels. While the macroscopic slope of the energy barrier, suitably defined, correlates with fragility, no consistent correlation is found for the microscopic energy barriers. Instead, the latter shows a strong correlation with an independently computed structure–dynamics measure obtained from isoconfigurational ensemble. Surprisingly, the two systems with the highest structure–dynamics correlation, LJ at rho = 1.1 and the (8, 5) model, are respectively the least and most fragile within their classes. These systems exhibit broad mobility distributions, bimodal displacement profiles, and high non-Gaussian parameters, all indicative of dynamic heterogeneity. However, their dynamic susceptibilities remain low, suggesting a decoupling between spatial correlation and temporal heterogeneity. Both systems lie in the enthalpy-dominated regime and are near the spinodal, suggesting mechanical instability as a source of heterogeneity. These findings challenge the conventional linkage among fragility, heterogeneity, and structure–dynamics correlation.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Statistical Mechanics (cond-mat.stat-mech)
17 pages, 63 figures
Electric Field Control of Spin Orbit Coupling and Circular Photogalvanic Effect in a True Ferrielectric Crystal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Yunlin Lei, Xinyu Yang, Shouyu Wang, Daliang Zhang, Zitao Wang, Jiayou Zhang, Yihao Yang, Chuanshou Wang, Tianqi Xiao, Yinxin Bai, Junjiang Tian, Congcong Chen, Yu Han, Shuai Dong, Junling Wang
Materials possessing long range ordering of magnetic spins or electric dipoles have been the focus of condensed matter research. Among them, ferri-systems with two sublattices of unequal/noncollinear spins or electric dipoles are expected to combine the properties of ferro- and antiferro-systems, but lack experimental observations in single phase materials. This is particularly true for the ferrielectric system, since the electric dipoles usually can be redefined to incorporate the two sublattices into one, making it indistinguishable from ferroelectric. This raises doubts about whether or not ferrielectricity can be considered as an independent ferroic order. Here we report the observation of true ferrielectric behaviors in a hybrid single crystal (MV)[SbBr5] (MV2+ = N,N’-dimethyl-4,4’-bipyridinium or methylviologen), where the two electric dipole sublattices switch asynchronously, thus cannot be reduced to ferroelectric by redefining the unit cell. Furthermore, the complex dipole configuration imparts circularly polarized light sensitivity to the system. An electric field can modulate the non-collinear dipole sublattices and even induce a transition from ferrielectric to ferroelectric state, thereby tuning the helicity-dependent photocurrent. This study opens a new paradigm for the study of true irreducible ferrielectricity (a new class of polar system) and provides an effective approach to the electric field control of spin-orbit coupling and circular photogalvanic effect.
Materials Science (cond-mat.mtrl-sci)
Large Scale Manufacture of Phase Pure Two-Dimensional Metallic MoS2 Nanosheets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Ziwei Jeffrey Yang, Zhuangnan Li, James Moloney, Leyi Loh, John Walmsley, Jiahang Li, Lixin Liu, Han Zang, Han Yan, Soumya Sarkar, Yan Wang, Manish Chhowalla
Metallic monolayered [or two - dimensional (2D)] MoS2 nanosheets show tremendous promise for energy storage and catalysis applications. However, state-of-the-art chemical exfoliation methods require > 48 hours to produce milligrams of metallic 2D MoS2. Further, chemically exfoliated MoS2 nanosheets are a mixture of metallic (1T or 1T prime 50% to 70%) and semiconducting (2H 30% to 50%) phases. Here, we demonstrate large-scale and rapid (>600 grams per hour) production of purely metallic phase 2D MoS2 (and WS2, MoSe2) nanosheets using microwave irradiation. Atomic resolution imaging shows 1T or 1T prime metallic phase in basal plane - consistent with close to 100% metallic phase concentration measured by X-ray photoelectron spectroscopy. The high 1T phase concentration results in the highest exchange current density of 0.175 plus-minus 0.03 mA cm-2 and among the lowest Tafel slopes (39 - 43 mV dec-1) measured to date for the hydrogen evolution reaction. In supercapacitors and lithium-sulfur pouch cell batteries, record-high volumetric capacitance of 753 plus-minus 3.6 F cm-3 and specific capacity of 1245 plus-minus 16 mAh g-1 (at exceptionally low electrolyte to sulfur ratio = 2 microlitre g-1), respectively, are obtained. Our method provides a practical pathway for producing high quality purely metallic phase 2D materials for high performance energy devices.
Materials Science (cond-mat.mtrl-sci)
DFT-based insight into finite-temperature properties of ferroelectric perovskites with lone-pair: the case of CsGeX$_3$ (X=Cl, Br, I)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Ravi Kashikar, S. Lisenkov, I. Ponomareva
Ferroelectrics remain in the focus of scientific attention for decades owing to their fundamental and practical appeal. Recently, ferroelectricity has been demonstrated in semiconducting halide perovskites, offering both a rare combination of ferroelectricity and semiconductivity in the same material and a possible alternative to the prevailing perovskite oxide ferroelectrics. We propose a route to simulating such materials at finite temperatures capable of reproducing key experimental and first-principle data, such as Curie temperature, phase transition sequence, spontaneous polarization, and soft mode frequencies. The key methodological finding is the superior performance of hybrid exchange correlation functionals in parametrization of effective Hamiltonians for ferroelectrics with lone pair. The parametrization for effective Hamiltonians for CsGeX$ _3$ , (X=Cl, Br, I) is reported. The application of methodology to study polarization reversal in CsGeX$ _3$ , allows for the development of a ``minimalistic” model for polarization reversal in ferroelectrics that provides an insight into the mechanisms of polarization reversal and its key features, such as the relationship between the coercive field, temperature, and AC field frequency. Importantly, the model reveals the origin of the well-known and ever-puzzling overestimation of coercive fields in computations. Furthermore, we report a variety of finite-temperature properties of CsGeX$ _3$ , ferroelectrics, such as dielectric susceptibility, pyroelectric coefficients, and energy storage density, which reveal that these halide perovskites possess properties comparable to their oxide counterparts. We believe that our work provides significant methodological advancements, deepens fundamental understanding of ferroelectrics, and reveals the potential of halide perovskite ferroelectrics.
Materials Science (cond-mat.mtrl-sci)
Symplectic Spin-Lattice Dynamics with Machine-Learning Potentials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Accurate atomic-scale simulations of magnetic materials require precise handling of coupled spin-lattice degrees of freedom. Traditional spin-lattice dynamics (SLD), employing Newtonian equation for lattice evolution and the Landau-Lifshitz-Gilbert (LLG) equation for spins, encounters severe limitations with machine-learning potentials, including poor energy conservation and excessive computational costs due to non-symplectic integration. In this work, we propose TSPIN, a unified Nosé-Hoover Chain-based method overcoming these issues. By extending the classical Lagrangian with explicit spin kinetic terms and thermostat variables, we derive symplectic Hamiltonian formulations suitable for NVE, NVT, and NPT ensembles. The method integrates spin and lattice dynamics simultaneously, ensuring robust energy conservation and significantly reducing computational cost. Benchmarks against analytical harmonic spin-lattice models confirm its accuracy, and application to FCC iron using a DeepSPIN MLP demonstrates superior numerical stability and near-linear computational scaling compared to the conventional LLG method. Thus, TSPIN provides a powerful, broadly applicable framework for efficiently simulating complex spin-lattice phenomena and multi-degree-of-freedom systems at large scales.
Materials Science (cond-mat.mtrl-sci)
Information dynamics, natural computing and Maxwell’s demon in two skyrmions system
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
Yoshishige Suzuki, Hiroki Mori, Soma Miki, Kota Emoto, Ryo Ishikawa, Eiiti Tamura, Hikaru Nomura, Minori Goto
The probabilistic information flow and natural computational capability of a system with two magnetic skyrmions at room temperature have been experimentally evaluated. Based on this evaluation, an all-solid-state built-in Maxwell’s demon operating at room temperature is also proposed. Probabilistic behavior has gained attention for its potential to enable unconventional computing paradigms. However, information propagation and computation in such systems are more complex than in conventional computers, making their visualization essential. In this study, a two-skyrmion system confined within a square potential well at thermal equilibrium was analyzed using information thermodynamics. Transfer entropy and the time derivative of mutual information were employed to investigate the information propagation speed, the absence of a Maxwell’s demon in thermal equilibrium, and the system’s non-Markovian properties. Furthermore, it was demonstrated that the system exhibits a small but finite computational capability for the nonlinear XOR operation, potentially linked to hidden information in the non-Markovian system. Based on these experiments and analyses, an all-solid-state built-in Maxwell’s demon utilizing the two-skyrmion system and operating at room temperature is proposed.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
18 pages, 7 figures
Disorder by Design: Unveiling Local Structure and Functional Insights in High Entropy Oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
John P. Barber, William J. Deary, Andrew N. Titus, Gerald R. Bejger, Saeed S.I. Almishal, Christina M. Rost
High entropy oxides (HEOs) are a rapidly growing class of compositionally complex ceramics in which configurational disorder is engineered to unlock novel functionality. While average crystallographic symmetry is often retained, local structural and chemical disorder, including cation size and valence mismatch, oxygen sublattice distortions, and site-specific bonding, strongly governs ionic transport, redox behavior, magnetic ordering, and dielectric response. This review outlines how these modes of disorder manifest across key oxide families such as rock salt, spinel, fluorite, and perovskite. We highlight recent advances in spectroscopy, total scattering, and high-resolution microscopy enable multi-scale insight into short- and intermediate-range order. By integrating experimental observations with theoretical modeling of entropy and local energetics, we establish a framework linking structural heterogeneity to emergent properties. These insights not only deepen our fundamental understanding of disorder-property relationships but also offer a path toward rational design of tunable materials for catalysis, energy storage, electronics, and much more.
Materials Science (cond-mat.mtrl-sci)
30 pages, 9 figures, 2 tables
Assessing Vibrational Frequencies of CO Adsorbed on Cerium Oxide Surfaces Using SCAN and r2SCAN Functionals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Alexander Contreras-Payares, Pablo G. Lustemberg, M. Verónica Ganduglia-Pirovano
The vibrational frequency of carbon monoxide (CO) adsorbed on ceria-based catalysts serves as a sensitive probe for identifying exposed surface facets, provided that experimental reference data on well-defined single-crystal surfaces and reliable theoretical assignments are available. Previous studies have shown that the hybrid DFT approach using the HSE06 functional yields good agreement with experimental observations, whereas the generalized gradient approximation (GGA) with PBE+U does not. In this work, we assess the performance of different exchange-correlation functionals by comparing the meta-GGA functionals SCAN and r2SCAN meta-GGA functionals with HSE06 in predicting CO vibrational frequencies on cerium oxide surfaces. The meta-GGA functionals offer no significant improvement for oxidized CeO2(111) and CeO2(110) surfaces and fail to localize excess charge on the reduced surfaces. Adding a Hubbard U term improves charge localization, but the predicted vibrational frequencies still fall short of HSE06 accuracy. These limitations are attributed to the meta-GGA’s inability to adequately capture facet- and configuration-specific donation and back-donation effects, which influence the C-O bond length and CO force constant upon adsorption. Despite the higher computational cost when used with plane-wave basis sets, hybrid DFT remains essential for accurate interpretation of experimental results.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Optimisation of Activator Solutions for Geopolymer Synthesis: Thermochemical Stability, Sequencing, and Standardisation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Ramon Skane, Franca Jones, Arie van Riessen, Evan Jamieson, Xiao Sun, William D.A. Rickard
Geopolymers present a sustainable alternative to conventional binders, however, their commercial viability is hindered by a lack of standardised methods for preparing stabile activator solutions; alkaline feedstocks critical to geopolymer synthesis. This study presents a combined experimental and modelling approach to evaluate the thermochemical stability, solubility constraints, and silica speciation behaviour of sodium silicate-based activators. Using quantitative 29Si NMR analysis, thermodynamic stability and three-dimensional solubility modelling, this research identifies optimal preparation conditions that minimise irreversible precipitation risks and optimises mixing periods. Key findings indicate that higher solution temperatures associated with optimised activator solution preparation were found to enhance thermochemical stability and reactivity, while cooling increased viscosity and the likelihood of unstable solution behaviour, which may necessitate discarding. The order in which feedstocks are combined directly affects whether the solution becomes unstable, with an optimal sequence of water, alkali-hydroxide, soluble silicate found to ensure greater process reliability. A predictive model and accompanying visual tools enable practitioners to assess solution viability and define stability windows by quantifying initial and final/unstable periods and temperatures based on feedstock composition and solution temperature. These results contribute to improved reproducibility and quality control in geopolymer research and represent a step toward developing standard operating procedures for activator solution synthesis.
Materials Science (cond-mat.mtrl-sci), Mathematical Physics (math-ph), Optimization and Control (math.OC), Applied Physics (physics.app-ph), Chemical Physics (physics.chem-ph)
Fragmentation of a trapped multiple-species bosonic mixture
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
We consider a multiple-species mixture of interacting bosons, $ N_1$ bosons of mass $ m_1$ , $ N_2$ bosons of mass $ m_2$ , and $ N_3$ bosons of mass $ m_3$ in a harmonic trap of frequency $ \omega$ . The corresponding intraspecies interaction strengths are $ \lambda_{11}$ , $ \lambda_{22}$ , and $ \lambda_{33}$ , and the interspecies interaction strengths are $ \lambda_{12}$ , $ \lambda_{13}$ , and $ \lambda_{23}$ . When the shape of all interactions are harmonic, this is the generic multiple-species harmonic-interaction model which is exactly solvable. We start by solving the many-particle Hamiltonian and concisely discussing the ground-state wavefunction and energy in explicit forms as functions of all parameters, the masses, numbers of particles, and the intraspecies and interspecies interaction strengths. We then move to compute explicitly the reduced one-particle density matrices for all the species and diagonalize them, thus generalizing the treatment in [J. Chem. Phys. {\bf 161}, 184307 (2024)]. The respective eigenvalues determine the degree of fragmentation of each species. As applications, we focus on aspects that do not appear for the respective single-species and two-species systems. For instance, placing a mixture of two kinds of bosons in a bath made by a third kind, and controlling the fragmentation of the former by coupling to the latter. Another example exploits the possibility of different connectivities (i.e., which species interacts with which species) in the mixture, and demonstrates how the fragmentation of species $ 3$ can be manipulated by the interaction between species $ 1$ and species $ 2$ , when species $ 3$ and $ 1$ do not interact with each other. We thereby highlight properties of fragmentation that only appear in the multiple-species mixture. Further applications are briefly discussed.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
25 pages, 2 figures
Kinetic theory of coupled binary-fluid-surfactant systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Alexandra J. Hardy, Samuel Cameron, Steven McDonald, Abdallah Daddi-Moussa-Ider, Elsen Tjhung
We derive a self-consistent hydrodynamic theory of coupled binary-fluid-surfactant systems from the underlying microscopic physics using Rayleigh’s variational principle. At the microscopic level, surfactant molecules are modelled as dumbbells that exert forces and torques on the fluid and interface while undergoing Brownian motion. We obtain the overdamped stochastic dynamics of these particles from a Rayleighian dissipation functional, which we then coarse-grain to derive a set of continuum equations governing the surfactant concentration, orientation, and the fluid density and velocity. This approach introduces a polarization field, representing the average orientation of surfactants, and yields a mesoscopic free energy functional from which all governing equations are consistently derived. The resulting model accurately captures key surfactant phenomena, including surface tension reduction and droplet stabilization, as confirmed by both perturbation theory and numerical simulations.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Flocking as a second-order phase transition in self-aligning active crystals
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Marco Musacchio, Alexander P. Antonov, Hartmut Löwen, Lorenzo Caprini
We study a two-dimensional crystal composed of active units governed by self-alignment. This mechanism induces a torque that aligns a particle’s orientation with its velocity and leads to a phase transition from a disordered to a flocking crystal. Here, we provide the first microscopic theory that analytically maps the crystal dynamics onto a Landau-Ginzburg model, in which the velocity-dependent effective free energy undergoes a transition from a single-well shape to a Mexican-hat profile. As confirmed by simulations, our theory quantitatively predicts the transition point and characteristic spatial velocity correlations. The continuous change of the order parameter and the diverging behavior of the analytically predicted correlation length imply that flocking in self-aligning active crystals is a second-order phase transition. These findings provide a theoretical foundation for the flocking phenomenon observed experimentally in active granular particles and migrating cells.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Quasiparticle Properties of Long-Range Impurities in a Bose Condensate
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
T. Alper Yoğurt, Matthew T. Eiles
An impurity immersed in a Bose condensate can form a quasiparticle known as a Bose polaron. When the impurity-boson interaction is short-ranged, the quasiparticle’s properties are universal, characterized - independent of the bath density $ n_0$ - by the impurity-boson scattering length $ a_{IB}$ . Long-ranged interactions - such as provided by Rydberg or ionic impurities - introduce an effective interaction range $ r_{\mathrm{eff}}$ , and boson-boson interactions provide a third length scale, the condensate coherence length $ \xi $ . These competing length scales raise the question of whether a universal description remains valid across different bath densities. In this study, we discuss the quasiparticle nature of long-range impurities and its dependence on the length scales $ n_0^{-1/3} $ , $ r_{\mathrm{eff}} $ , and $ \xi $ . We employ two complementary theories - the coherent state Ansatz and the perturbative Gross-Pitaevskii theory - which incorporate beyond-Fröhlich interactions. We derive an analytical expression for the beyond-Fröhlich effective mass for a contact interaction and numerically compute the effective mass for long-range impurities. We argue that the coupling parameter $ |a_{IB}| n_0^{1/3} $ remains the principal parameter governing the properties of the polaron. For weak $ (|a_{IB}| n_0^{1/3} \ll 1) $ and intermediate $ (|a_{IB}| n_0^{1/3} \simeq 1) $ values of the coupling parameter, long-range impurities in a BEC are well-described as quasiparticles with a finite quasiparticle weight and a well-defined effective mass. However, the quasiparticle weight becomes significantly suppressed as the effective impurity volume is occupied by an increasing number of bath particles $ (r_{\mathrm{eff}} n_0^{1/3} \gg 1) $ .
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph)
Monte Carlo simulations of crystal defects in open ensembles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Flynn Walsh, Babak Sadigh, Joseph T. McKeown, Timofey Frolov
Open materials systems are often inaccessible to conventional atomistic simulations, which add and remove atoms by creating high-energy defects that may be sampled with vanishing probability. This longstanding challenge motivates a new Hamiltonian Monte Carlo method that maps the grand canonical problem to a canonical system involving non-interacting fictitious particles. To trial deletions or insertions, a real or fictitious particle is selected according to an energy-based biasing scheme and gradually transformed over a microcanonical molecular dynamics trajectory. The method is validated, optimized, and used to compute point defect free energies that allow for arbitrary structures and interactions among multiple defects. Several grain boundaries are then equilibrated in a physically representative open ensemble, demonstrating a new approach to studying interface structures and their phase transitions.
Materials Science (cond-mat.mtrl-sci)
10 pages, 7 figures
The impact of parameter spread of high-temperature superconducting Josephson junctions on the performance of quantum-based voltage standards
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
Guanghong Wen, Yi Zhu, Yingxiang Zheng, Shuhe Cui, Ji Wang, Yanyun Ren, Hao Li, Guofeng Zhang, Lixing You
Quantum metrology based on Josephson junction array reproduces the most accurate desired voltage by far, therefore being introduced to provide voltage standards worldwide. In this work, we quantitatively analyzed the dependence of the first Shapiro step height of the junction array at 50 GHz on the parameter spread of 10,000 Josephson junctions by numerical simulation with resistively shunted junction model. The results indicate an upper limit spread of the critical current and resistance of the Josephson junctions. Specifically, to keep the maximum first Shapiro step above 0.88 mA, the critical current standard deviation, $ \sigma$ , should not exceed 25%, and for it to stay above 0.6 mA, the resistance standard deviation should not exceed 1.5%.
Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
Topological phase transitions in strained Lieb-Kagome lattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
W. P. Lima, T. F. O. Lara, J. P. G. Nascimento, J. Milton Pereira Jr., D. R. da Costa
Lieb and Kagome lattices exhibit two-dimensional topological insulator behavior with $ \mathbb{Z}_2$ topological classification when considering spin-orbit coupling. In this study, we used a general tight-binding Hamiltonian with a morphological control parameter $ \theta$ to describe the Lieb ($ \theta=\pi/2$ ), Kagome ($ \theta=2\pi/3$ ), and transition lattices ($ \pi/2<\theta<2\pi/3$ ) while considering intrinsic spin-orbit (ISO) coupling. We systematically investigated the effects of shear and uniaxial strains, applied along different crystallographic directions, on the electronic spectrum of these structures. Our findings reveal that these deformations can induce topological phase transitions by modifying the structural lattice angle associated with the interconversibility process between Lieb and Kagome, the amplitude of the strain, and the magnitude of the ISO coupling. These transitions are confirmed by the evolution of Berry curvature and by changes in the Chern number when the gap closes. Additionally, by analyzing hypothetical strain scenarios in which the hopping and ISO coupling parameters remain intentionally unchanged, our results demonstrated that the strain-induced phase transitions arise from changes in the hopping and ISO coupling parameters.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 10 figures
Implementing van der Waals forces for polytope particles in DEM simulations of clay
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Dominik Krengel, Jian Chen, Zhipeng Yu, Hans-Georg Matuttis, Takashi Matsushima
Clay minerals are non-spherical nano-scale particles that usually form flocculated, house-of-card like structures under the influence of inter-molecular forces. Numerical modeling of clays is still in its infancy as the required inter-particle forces are available only for spherical particles. A polytope approach would allow shape-accurate forces and torques while simultaneously being more performant. The Anandarajah solution provides an analytical formulation for van der Waals forces for cuboid particles but in its original form is not suitable for implementation in DEM simulations. In this work, we discuss the necessary changes for a functional implementation of the Anandarajah solution in a DEM simulation of rectangular particles and their extension to cuboid particles.
Soft Condensed Matter (cond-mat.soft)
4 pages, 5 figures, accepted for publication
Diagnosing 2D symmetry protected topological states via mixed state anomaly
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-17 20:00 EDT
Chao Xu, Yunlong Zang, Yixin Ma, Yingfei Gu, Shenghan Jiang
Symmetry-protected topological (SPT) phases are short-range entangled quantum states characterized by anomalous edge behavior, a manifestation of the bulk-boundary correspondence for topological phases. Moreover, the Li-Haldane conjecture posits that the entanglement spectrum exhibits the same anomaly as the physical edge spectrum, thereby serving as an entanglement-based fingerprint for identifying topological phases. In this work, we extend the entanglement-based diagnostic tools by demonstrating that the edge anomaly is manifested not only in the entanglement spectrum but also in the reduced density matrix itself, a phenomenon we refer to as the mixed state anomaly. Focusing on the two-dimensional $ \mathbb{Z}_2$ SPT phase, we show that this anomaly is subtly encoded in symmetry-twisted mixed states, leading to a topological contribution to the disorder parameter beyond the area law, as well as a spontaneous-symmetry-breaking type long-range order when time reversal symmetry is present.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
8+14 pages, 1 captioned figure, 1 table
First-passage and extreme value statistics for overdamped Brownian motion in a linear potential
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-17 20:00 EDT
We investigate the first-passage properties and extreme-value statistics of an overdamped Brownian particle confined by an external linear potential $ V(x)=\mu |x-x_0|$ , where $ \mu>0$ is the strength of the potential and $ x_0>0$ is the position of the lowest point of the potential, which coincides with the starting position of the particle. The Brownian motion terminates whenever the particle passes through the origin at a random time $ t_f$ . Our study reveals that the mean first-passage time $ \langle t_f \rangle$ exhibits a nonmonotonic behavior with respect to $ \mu$ , with a unique minimum occurring at an optimal value of $ \mu \simeq 1.24468D/x_0$ , where $ D$ is the diffusion constant of the Brownian particle. Moreover, we examine the distribution $ P(M|x_0)$ of the maximum displacement $ M$ during the first-passage process, as well as the statistics of the time $ t_m$ at which $ M$ is reached. Intriguingly, there exists another optimal $ \mu \simeq 1.24011 D/x_0$ that minimizes the mean time $ \langle t_m \rangle$ . All our analytical findings are corroborated through numerical simulations.
Statistical Mechanics (cond-mat.stat-mech)
8 pages, 4 figures
Physica A 672 (2025) 130673
Density-Independent Glassy Behavior in the High-Density Phase of Motility-Induced Phase Separation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Toranosuke Umemura, Issei Sakai, Takuma Akimoto
We investigate the nonequilibrium dynamics of active matter using a two-dimensional active Brownian particles model. In these systems, self-propelled particles undergo motility-induced phase separation (MIPS), spontaneously segregating into dense and dilute phases. We find that in the high-density phase, local particle mobility exhibits glassy behavior, with diffusivity remaining unchanged despite variations in the global system density. As global density increases further, the system undergoes a transition to a solid-like state through this glassy phase. These findings provide insights into nonequilibrium phase transitions in active matter, revealing a robust glassy phase en route to solidification, and may guide future studies in both synthetic and biological active systems.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
8 pages, 4 figures
Resonant dynamics of dipole-conserving Bose-Hubbard model with time-dependent tensor electric fields
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
Recently, tensor gauge fields and their coupling to fracton phases of matter have attracted more and more research interest, and a series of novel quantum phenomena arising from the coupling has been predicted. In this article, we propose a theoretical scheme to construct a time-dependent rank-2 tensor electric field by introducing a periodically driving quadratic potential in a dipole-conserving Bose-Hubbard model, and investigate the dynamics of dipole and fracton excitations when the drive frequency is resonant with the on-site interaction. We find that the dynamics are dominated by the splitting of large dipoles with the photon-assisted correlated tunneling and the movement of small dipoles, both of which can be well controlled by the drive amplitude. Our work provides a possible approach for engineering the dynamics of dipole-conserving quantum systems via tensor gauge fields.
Quantum Gases (cond-mat.quant-gas)
10 pages, 7 figures
Hydrogen bond symmetrization in high-pressure ice clathrates
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Lorenzo Monacelli, Maria Rescigno, Alasdair Nicholls, Umbertoluca Ranieri, Simone Di Cataldo, Livia Eleonora Bove
Hydrogen bond symmetrization is a fundamental pressure-induced transformation in which the distinction between donor and acceptor sites vanishes, resulting in a symmetric hydrogen-bond network. While extensively studied in pure ice, most notably during the ice VII to ice X transition, this phenomenon remains less well characterized in hydrogen hydrates. In this work, we investigate hydrogen bond symmetrization in the high-pressure phases of hydrogen hydrate (H2-H2O and H2-D2O) through a combined approach of Raman spectroscopy and first-principles quantum atomistic simulations. We focus on the C2 and C3 filled-ice phases, using both hydrogenated and deuterated water frameworks. Our results reveal that quantum fluctuations and the interaction between the encaged H2 molecules and the host lattice play a crucial role in driving the symmetrization process. Remarkably, we find that in both C2 and C3 phases, hydrogen bond symmetrization occurs via a continuous crossover at significantly lower pressures than in pure ice, without any change in the overall crystal symmetry. These findings provide new insight into the quantum-driven mechanisms of bond symmetrization in complex hydrogen-bonded systems under extreme conditions.
Materials Science (cond-mat.mtrl-sci)
8 pages, 6 figures
Ab initio functional-independent calculations of the clamped Pockels tensor of tetragonal barium titanate
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Virginie de Mestral, Lorenzo Bastonero, Michele Kotiuga, Marko Mladenovic, Nicola Marzari, Mathieu Luisier
We present an ab initio method to calculate the clamped Pockels tensor of ferroelectric materials from density-functional theory, the modern theory of polarization exploiting the electric-enthalpy functional, and automated first- and second-order finite-difference derivatives of the polarizations and the Hellmann-Feynman forces. Thanks to the functional-independent capabilities of our approach, we can determine the Pockels tensor of tetragonal barium titanate (BTO) beyond the local density approximation (LDA), with arbitrary exchange-correlation (XC) functionals, for example, PBEsol. The latter, together with RRKJ ultra-soft pseudo-potentials (PP) and a supercell exhibiting local titanium off-centering, enables us to stabilize the negative optical phonon modes encountered in tetragonal BTO when LDA and norm-conserving PP are combined. As a result, the correct value range of $ r_{51}$ , the largest experimental Pockels coefficient of BTO, is recovered. We also reveal that $ r_{51}$ increases with decreasing titanium off-centering for this material. The lessons learned from the structural, dielectric, and vibrational investigations of BTO will be essential to design next-generation electro-optical modulators based on the Pockels effect.
Materials Science (cond-mat.mtrl-sci)
28 pages, 8 figures
V. de Mestral, L. Bastonero, M. Kotiuga, M. Mladenovic, N. Marzari, and M. Luisier, Ab initio functional-independent calculations of the clamped pockels tensor of tetragonal barium titanate, Phys. Rev. B 111, 184306 (2025)
Backsolution: A Framework for Solving Inverse Problems via Automatic Differentiation
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-06-17 20:00 EDT
We present a simple yet powerful framework for solving inverse problems by leveraging automatic differentiation. Our method is broadly applicable whenever a smooth cost function can be defined near the true solution, and a numerical simulator is available. As a concrete example, we demonstrate that our method can accurately reconstruct the spatial profiles in a conductor from magnetotransport measurements. Even if the given data are insufficient to uniquely determine the profiles, the same framework enables effective reverse modeling. This method is general, flexible, and readily adaptable to a broad class of inverse problems across condensed matter physics and beyond.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Two-photon 3D printing of functional microstructures inside living cells
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Marusa Mur, Aljaz Kavcic, Uros Jagodic, Rok Podlipec, Matjaz Humar
3D printing has revolutionized numerous scientific fields and industries, with printing in biological systems emerging as a rapidly advancing area of research. However, its application to the subcellular level remains largely unexplored. Here, we demonstrate for the first time the fabrication of custom-shaped polymeric microstructures directly inside living cells using two-photon polymerization. A biocompatible photoresist is injected into live cells and selectively polymerized with a femtosecond laser. The unpolymerized photoresist is dissolved naturally within the cytoplasm, leaving behind stable intracellular structures with submicron resolution within live cells. We printed various shapes, including a $ 10 \mu m$ elephant, barcodes for cell tracking, diffraction gratings for remote readout, and microlasers. Our top-down intracellular biofabrication approach, combined with existing functional photoresists, could open new avenues for various applications, including intracellular sensing, biomechanical manipulation, bioelectronics, and targeted intracellular drug delivery. Moreover, these embedded structures could offer unprecedented control over the intracellular environment, enabling the engineering of cellular properties beyond those found in nature.
Soft Condensed Matter (cond-mat.soft)
Penta-twinned gold nanoparticles under pressure: a comprehensive study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Camino Martín-Sáncheza, Ana Sánchez-Iglesias, José Antonio Barreda-Argüeso, Jean-Paul Itié, Paul Chauvigne, Luis M. Liz-Marzán, Fernando Rodríguez
We report on the high-pressure optical and mechanical properties of penta-twinned gold nanoparticles (PT-AuNPs) of different geometries: decahedra, rods and bipyramids. Our results show that, unlike single-crystal (SC-AuNPs), PT-AuNPs preserve both their non-cubic crystal structures and their overall morphology up to 30 GPa. This structural integrity under compression is related to an enhanced mechanical resilience of PT-AuNPs, despite exhibiting bulk moduli comparable to those of SC-AuNPs. Notwithstanding, comparable pressure-induced localized surface plasmon resonance redshifts - for all nanoparticle geometries - were observed. Our analysis indicates that these shifts are primarily caused by changes in the refractive index of the surrounding medium, with electron density compression playing a minor role, contrasting with the behavior in SC-AuNPs, where electron density compression has a greater influence.
Materials Science (cond-mat.mtrl-sci)
15 pages, 5 figures
Emergent quantum field theories on curved spacetimes in spinor Bose-Einstein condensates: from scalar to Proca fields
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
Simon Brunner, Christian F. Schmidt, Stefan Floerchinger
We consider excitations of a spin-1 Bose-Einstein-condensate (BEC) in the vicinity of different mean-field configurations and derive mappings to emergent relativistic scalar field theories minimally coupled to curved acoustic spacetimes. The quantum fields are typically identified with Nambu-Goldstone bosons, such that the structure of the analogue quantum field theories on curved spacetimes depends on the (spontaneous) symmetry breaking pattern of the respective ground-state. The emergent spacetime geometries are independent of each other and exhibit bi-metricity in the polar and antiferromagnetic phase, whereas one has tri-metricity in the ferromagnetic phase. Compared to scalar BECs, the spinor degrees of freedom allow to investigate massive vector and scalar fields where the former is a spin-nematic rotation mode in the polar phase which can be cast into a Proca field that is minimally coupled to a curved spacetime that emerges on length scales larger than the spin-healing length. Finally, we specify the Zeeman couplings and the condensate trap to be spacetime-dependent such that a cosmological FLRW-metric can be achieved. This work enables a pathway towards quantum-simulating cosmological particle production of Proca quanta via quenching the quadratic Zeeman-coefficient or via magnetic field ramps, which both result in the creation of spin-nematic squeezed states.
Quantum Gases (cond-mat.quant-gas), General Relativity and Quantum Cosmology (gr-qc), High Energy Physics - Theory (hep-th)
12 pages (main text), 1 table. Comments are welcome
Non-reciprocal interactions reshape cells in a model for symbiosis
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Maitane Muñoz-Basagoiti, Michael Wassermair, Miguel Amaral, Buzz Baum, Anđela Šarić
The shape of a cell influences and it is influenced by interactions with its neighbouring partners. Here, we introduce a coarse-grained model of non-reciprocal interactions between single-cell organisms to study emergent morphologies during symbiotic association. We show that the cell membrane can be remodelled into branched protrusions, invaginations, transient blebs and other dynamical phases that depend on the number of interacting partners, the asymmetry, and the magnitude of partnership activity. Our model finds a dynamical feedback between the local deformation of the membrane and its driving force, leading to morphologies not accessible to reciprocal systems.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Computational Physics (physics.comp-ph)
6 pages, 5 figures, supplementary information
Inferring Material Parameters from Current-Voltage Curves in Organic Solar Cells via Neural-Network-Based Surrogate Models
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Eunchi Kim, Paula Hartnagel, Barbara Urbano, Leonard Christen, Thomas Kirchartz
Machine learning has emerged as a promising approach for estimating material parameters in solar cells. Traditional methods for parameter extraction often rely on time-consuming numerical simulations that fail to capture the full complexity of the parameter space and discard valuable information from suboptimal simulations. In this study, we introduce a novel workflow for parameter estimation in organic solar cells based on a combination of numerical simulations and neural networks. The workflow begins with the selection of an appropriate experimental dataset, followed by the definition of a device model that accurately describes the experiment. To reduce computational complexity, the number of variable parameters is carefully selected, and reasonable ranges are set for each parameter. Instead of directly fitting the experimental data using a numerical model, a neural network was trained on a large dataset of simulated results, allowing for efficient exploration of the high-dimensional parameter space. This approach not only accelerates the parameter estimation process but also provides valuable insights into the likelihood and uncertainty of the estimated parameters. We demonstrate the effectiveness of this method on organic solar cells based on the PBDB-TF-T1:BTP-4F-12 material system, demonstrating the potential of machine learning for rapid and comprehensive characterization of emerging photovoltaic materials.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
21 pages, 11 figures
Tuning the Viscosity and Jamming Point in Dense Active non-Brownian Suspensions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Using numerical simulations, we study the rheological response of dense non-Brownian suspensions containing active particles. The active particles are modelled as run-and-tumble particles with three controlling parameters: the fraction of active particles in the system, an active force applied to the particles, and a persistence time after which the direction of the active force changes randomly. Our simulations reveal that the presence of activity can reduce the viscosity (by an order of magnitude) by decreasing the number of frictional contacts, which also shifts the jamming point to a higher volume fraction. Moreover, the microscopic structure of force chains in the presence of activity is qualitatively different from that in the passive system, showing reduced anisotropy. We also find that while the presence of activity drives the system away from jamming by preventing the formation of force chains, unjamming an already jammed state by breaking existing force chains requires a higher activity strength. Finally, we propose a new constitutive law to describe the rheology of dense active non-Brownian suspensions.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Computing and compressing local vertex functions in imaginary and real frequencies from the multipoint numerical renormalization group using quantics tensor cross interpolation
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-17 20:00 EDT
Markus Frankenbach, Marc Ritter, Mathias Pelz, Nepomuk Ritz, Jan von Delft, Anxiang Ge
The multipoint numerical renormalization group (mpNRG) is a powerful impurity solver that provides accurate spectral data useful for computing local, dynamic correlation functions in imaginary or real frequencies non-perturbatively across a wide range of interactions and temperatures. It gives access to a local, non-perturbative four-point vertex in imaginary and real frequencies, which can be used as input for subsequent computations such as diagrammatic extensions of dynamical mean–field theory. However, computing and manipulating the real-frequency four-point vertex on large, dense grids quickly becomes numerically challenging when the density and/or the extent of the frequency grid is increased. In this paper, we compute four-point vertices in a strongly compressed quantics tensor train format using quantics tensor cross interpolation, starting from discrete partial spectral functions obtained from mpNRG. This enables evaluations of the vertex on frequency grids with resolutions far beyond the reach of previous implementations. We benchmark this approach on the four-point vertex of the single-impurity Anderson model across a wide range of physical parameters, both in its full form and its asymptotic decomposition. For imaginary frequencies, the full vertex can be represented to an accuracy on the order of $ 2\cdot 10^{-3}$ with maximum bond dimensions not exceeding 120. The more complex full real-frequency vertex requires maximum bond dimensions not exceeding 170 for an accuracy of $ \lesssim 2%$ . Our work marks another step toward tensor-train-based diagrammatic calculations for correlated electronic lattice models starting from a local, non-perturbative mpNRG vertex.
Strongly Correlated Electrons (cond-mat.str-el)
19 pages, 12 figures, 5 tables
Tunneling conductance in superconducting junctions with $p$-wave unconventional magnets breaking time-reversal symmetry
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
Yuri Fukaya, Keiji Yada, Yukio Tanaka
A new type of magnet called $ p$ -wave unconventional magnet is proposed, stimulated by the discovery of altermagnet. We study the tunneling conductance of $ p$ -wave unconventional magnet/superconductor junctions by adopting the effective Hamiltonian of $ p$ -wave unconventional magnets with time-reversal symmetry breaking, suggested in Ref [arXiv: 2309.01607 (2024)]. The tunneling conductance shows an asymmetric behavior with respect to bias voltage in the helical $ p$ -wave superconductor junctions. It is caused by the lack of helical edge states contributing to the charge conductance owing to the momentum-dependent spin-split feature of the Fermi surface in $ p$ -wave unconventional magnets. In chiral $ d$ and $ p$ -wave superconductor junctions, the resulting spin-resolved tunneling conductance takes a different value for spin sectors due to the time-reversal symmetry breaking in superconductors. Our results qualitatively reproduce the results based on the simplified Hamiltonian in Ref [J.\ Phys.\ Soc.\ Jpn.\ \textbf{93}, 114703 (2024)], where only the odd function of the exchange coupling of $ p$ -wave unconventional magnets is taken into account, which gives the shift of the Fermi surface and preserves the time-reversal symmetry similar to the spin-orbit coupling.
Superconductivity (cond-mat.supr-con)
15 pages, 10 figures
Statistical analysis of electron-induced switching of a spin-crossover complex
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
Jonas Fußangel, Björn Sothmann, Sven Johannsen, Sascha Ossinger, Felix Tuczek, Richard Berndt, Jürgen König, Manuel Gruber
Spin-crossover complexes exhibit two stable configurations with distinct spin states. The investigation of these molecules using low-temperature scanning tunneling microscopy has opened new perspectives for understanding the associated switching mechanisms at the single-molecule level. While the role of tunneling electrons in driving the spin-state switching has been clearly evidenced, the underlying microscopic mechanism is not completely understood. In this study, we investigate the electron-induced switching of [Fe(H$ _2$ B(pz)(pypz))$ _2$ ] (pz = pyrazole, pypz = pyridylpyrazole) adsorbed on Ag(111). The current time traces show transitions between two current levels corresponding to the two spin states. We extract switching rates from these traces by analyzing waiting-time distributions. Their sample-voltage dependence can be explained within a simple model in which the switching is triggered by a transient charging of the molecule. The comparison between experimental data and theoretical modeling provides estimates for the energies of the lowest unoccupied molecular orbitals, which were so far experimentally inaccessible. Overall, our approach offers new insights into the electron-induced switching mechanism and predicts enhanced switching rates upon electronic decoupling of the molecule from the metallic substrate, for example by introducing an ultrathin insulating layer.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Uncovering the nanoscopic phase behavior of ternary solutions in the presence of electrolytes: from pre-Ouzo to Ouzo region
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
Mingbo Li, Rushi Lai, Yadi Tian, Yawen Gao, Benlong Wang, Chao Sun
In this work, we report a comprehensive study of how electrolyte addition governs the structure and stability of surfactant-free microemulsions in a trans-anethol/ethanol/water system. The universal structural response has been validated, spanning the full range of solution dispersed-phase structurings, from sub-10 nm W/O reverse-aggregates to O/W mesoscopic droplets (100 nm) and classical Ouzo droplets (1 {\mu}m). Experimental results reveal that there is a threshold for electrolyte levels above which oil-in-water nanodroplet coalescence and phase separation are triggered: screening of electrical double layers and “salting out” of hydrophobic components drives hydrotrope into fewer, larger droplets. The total oil volume sequestered in the dispersed phase remains essentially constant, indicating oil redistribution rather than dissolution. In contrast, water-in-oil nanodroplets in a predominantly organic medium display near-complete insensitivity to ionic strength, owing to low dielectric screening and tight interfacial packing that exclude substantial ion uptake. Finally, addition of high salt to Ouzo droplets accelerates their collapse: large droplets fuse and sediment, leaving only residual nanostructures and confirming electrolyte-driven phase demixing. This insight offers clear guidelines for designing additive-free emulsions with tailored lifetimes and nanostructure architectures across pharmaceutical, food, and materials applications.
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
Crystal field tuned spin-flip luminescence in NiPS3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Léonard Schue, Nashra Pistawala, Hebatalla Elnaggar, Yannick Klein, Christophe Bellin, Johan Biscaras, Fausto Sirotti, Yves Lassailly, Fabian Cadiz, Luminita Harnagea, Abhay Shukla
Layered magnetic materials potentially hold the key to future applications based on optical control and manipulation of magnetism. NiPS3, a prototype member of this family, is antiferromagnetic below 155 K and exhibits sharp photoluminescence associated to a transition between a triplet ground state and a singlet excited state. The nature of the luminescent transition is a matter of current debate and so is an eventual fundamental link of this excitation to magnetism. Here we provide answers through experiments and calculations. We fabricate samples with metal and ligand substitutions which alter the Neel transition temperature and measure the effects of these changes on the temperature dependent photoluminescence. We perform crystal field and charge transfer multiplet calculations to explain the origin of the excitation and identify the effects of the magnetic ground state on its properties. These measurements and calculations provide a comprehensive explanation for the observed properties and a template for finding similar materials exhibiting spin-flip luminescence.
Materials Science (cond-mat.mtrl-sci)
Role of topotactic hydrogen in Superconductivity of Infinite-layer Nickelate NdNiO$_{2}$: A first-principles and variational Monte Carlo study
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
Manoj Gupta, Arun Kumar Maurya, Amal Medhi, Tanusri Saha Dasgupta
Employing combination of first-principles calculations, low-energy model construction, and variational Monte Carlo solution of the ab-initio derived Hubbard model, we study the effect of hydrogenation in the electronic structure and superconducting properties of infinite-layer nickelate, NdNiO$ 2$ . We find that the introduction of hydrogen at the apical oxygen vacancy position strongly influences the Wannier function corresponding to the effective interstitial orbital at the Ni site bound to the hydrogen. This results in the near disappearance of the electron pocket at the $ k_z$ = $ \pi$ Fermi surface, keeping that of $ k_z$ = 0 unchanged, compared to the dehydrogenated case. The two-band model thus remains valid even in the presence of H. The calculated superconducting order parameters both in absence and presence of H, show a two-hump superconductivity arising the two overlapping domes, one arising from $ d{x^{2}-y^{2}}$ and another arising from interstitial orbital degree of freedom. Hydrogenation strengthens the latter, marginally affecting the former.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
*Equal contribution first author
2D MXene-Based Photocatalysts for Efficient Water Splitting and Hydrogen Evolution: A brief review
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
C. B. Subba, Prasad Mattipally, J. Sivakumar, A. Laref, A. Yvaz, D. P. Rai, Z. Pachuau
Photocatalytic water splitting offers a viable and sustainable method for hydrogen production. MXenes, a class of 2D transition-metal carbides/nitrides, have emerged as potential photocatalysts and co-catalysts due to their tunable electronic properties, high conductivity, and surface functionality. This review explores recent advances in MXene-based photocatalysts for hydrogen production, discussing their synthesis, electronic structures, and photocatalytic mechanisms. The key challenges, including stability issues, charge recombination, and bandgap optimisation, are critically analysed. Finally, future research directions are outlined to improve MXene-based systems for large-scale hydrogen production.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Self-consistent Hartree-Fock-Bogoliubov approach for bosons: self-eliminating divergence and pure pair condensate
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
M. Bulakhov, A. S. Peletminskii
We investigate the thermodynamic properties of an interacting Bose gas with a condensate within the energy-functional formulation of the Hartree-Fock-Bogoliubov approach. For a contact interaction, we derive a self-consistent solution to the HFB equations that intrinsically eliminates divergence. This solution characterizes the equilibrium state featuring a condensate of correlated pairs of particles. We analyze the temperature dependence of key thermodynamic quantities such as condensate density, chemical potential, entropy, pressure, specific heat capacity at constant volume, and isothermal compressibility and compare them with predictions from the Popov approximation. Our results reveal a first-order phase transition between the normal state and the degenerate state, accompanied by an increased transition temperature relative to the ideal Bose gas. Analysis of the compressibility indicates that a pure pair condensate is unstable, and the stable equilibrium corresponds to a mixture of single-particle and pair condensates.
Quantum Gases (cond-mat.quant-gas)
14 pages, 5 figures
Sodium induced beneficial effects in wide bandgap Cu(In,Ga)S2 solar cell with 15.7% efficiency
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Arivazhagan Valluvar Oli, Kulwinder Kaur, Michele Melchiorre, Aubin Jean-Claude Mireille Prot, Sevan Gharabeiki, Yucheng Hu, Gunnar Kusch, Adam Hultqvist, Tobias Törndahl, Wolfram Hempel, Wolfram Witte, Rachel A. Oliver, Susanne Siebentritt
This study underscores the pivotal role of sodium (Na) supply in optimizing the optoelectronic properties of wide bandgap (~1.6 eV) Cu(In,Ga)S2 (CIGS) thin film absorbers for high efficiency solar cells. Our findings demonstrate that the synergistic use of Na from the glass substrate, in conjunction with in-situ sodium fluoride (NaF) co-evaporation, significantly enhances the structural and optoelectronic properties of the CIGS. CIGS grown under either Na-deficient or excess conditions exhibits inferior microstructural and optoelectronic properties, whereas an optimal Na supply leads to enhanced photovoltaic performance. Optimal Na incorporation minimizes vertical gallium fluctuations and improves the grain size and crystallinity. An absolute 1 sun calibrated photoluminescence (PL) measurement reveals a substantial suppression of bulk defects and a reduction in non-radiative losses, resulting in a high quasi-fermi level splitting ({\Delta}EF) of 1.07 eV, 93 meV higher than in Na-deficient CIGS with the same bandgap. Optimal Na supply further increases excited carrier decay time, as revealed from time-resolved PL, and hole doping density. Cross-sectional hyperspectral cathodoluminescence mapping reveals that optimal Na supply significantly reduces defect density near the surface, thereby effectively translating {\Delta}EF to open-circuit voltage (VOC). As a result, a champion wide bandgap CIGS solar cell with a cadmium-free ZnSnO buffer layer achieved an impressive VOC of 971 meV and an active area power conversion efficiency of 15.7%, highlighting its potential for advancing tandem photovoltaic technologies with stable inorganic top cell.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Excitations and dynamical structure factor of $J_1-J_2$ spin-$3/2$ and spin-$5/2$ Heisenberg spin chains
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-17 20:00 EDT
Aman Sharma, Mithilesh Nayak, Natalia Chepiga, Frédéric Mila
We study the dynamical structure factor of the frustrated spin-$ 3/2$ $ J_1$ -$ J_2$ Heisenberg chains, with particular focus on the partially dimerized phase that emerges between two Kosterlitz-Thouless transitions. Using a valence bond solid ansatz corroborated by density matrix renormalization group simulations, we investigate the nature of magnon and spinon excitations through the single-mode approximation. We show that the magnon develops an incommensurate dispersion at $ J_2 \approx 0.32J_1$ , while the spinons, viewed as domain walls between degenerate valence bond solid states, become incommensurate at $ J_2 \approx 0.4J_1$ beyond the Lifshitz point ($ J_2 \approx 0.388J_1$ ). The dynamical structure factor exhibits rich spectral features shaped by the interplay between these excitations, with magnons appearing as resonances embedded in the spinon continuum. The spinon gap shows a nonmonotonic behavior, reaching a peak near the center of the partially dimerized phase and closing at the boundaries, suggesting the appearance of a floating phase as a result of the condensation of incommensurate spinons. Comparative analysis with the spin-$ 5/2$ case confirms the universality of these phenomena across half-integer higher-spin systems. Our results provide detailed insight into how fractionalization and incommensurate condensation govern the spectral properties of frustrated spin chains, offering a unified picture across different spin magnitudes.
Strongly Correlated Electrons (cond-mat.str-el)
From Brittle to Ductile and Back: Reentrant Fracture Transition in Disordered Two-Phase Solids
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-17 20:00 EDT
Subrat Senapati, Anuradha Banerjee, R Rajesh
Fracture processes in multi-phase solids are inherently complex due to multiple competing mechanisms. Here, we investigate the elastic and fracture behaviour of two-phase solids, comprising a fragile phase and a tough phase using a disordered spring network model. The macroscopic response is found to depend on the failure strain mismatch, the elastic modulus ratio, as well as the relative composition of the constituent phases. As the proportion of the tough phase increases, the system undergoes a reentrant phase transition in fracture behaviour: from brittle to ductile-like and back to brittle. These transitions are identified through both avalanche statistics and cluster size characteristics of broken springs. Notably, the avalanche exponent associated with the majority phase changes universality class during the brittle to ductile transition. Analysis of time evolution of cluster characteristics reveals distinct growth mechanisms in the two regimes. In the brittle regime, dominant clusters rapidly absorb other large clusters, keeping the total number of clusters nearly constant. In contrast, the ductile regime is characterised by more gradual coalescence, leading to a decrease in the total number of clusters over time while their average size increases. We provide a physical interpretation of the mechanisms underlying the observed switch in fracture behaviour.
Statistical Mechanics (cond-mat.stat-mech)
Continuing the discussion on “The inconvenient truth about flocks” by Chen et al
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-17 20:00 EDT
We hereby reply concisely and hopefully clearly to the ongoing claims of incorrectness made by Chen et al. about our work on two-dimensional flocks.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
2 pages. Reply to arXiv:2505.21602
Electronic Correlations Control Interlayer Coupling and Magnetic Transition in MnBi$_2$Te$_4$/MnBr$_3$ Heterostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Yuanhao Zhu, Xixi Yuan, Ying Zhao, Jin Zhang, Zijing Ding, Huixia Fu
Bulk MnBi$ _2$ Te$ _4$ (MBT) is an intrinsic antiferromagnetic topological insulator. However, its low Néel temperature of $ \sim 25,\mathrm{K}$ severely restricts its practical applications. Here, we propose a van der Waals heterostructure composed of monolayer MBT (ML-MBT) and monolayer MnBr$ 3$ , an intrinsic Chern insulator possessing a high Curie temperature ($ T\mathrm{C} \sim 200,\mathrm{K}$ ). By employing density functional theory calculations and Monte Carlo simulations, we demonstrate that interfacing ML-MBT with MnBr$ 3$ significantly enhances the $ T\mathrm{C}$ of ML-MBT by a factor of four to five. Electronic correlations characterized by the Hubbard parameter $ U_2$ for Mn-$ d$ orbitals in MnBr$ _3$ play a crucial role in governing magnetic coupling within the system. At a moderate correlation strength of $ U_2 = 3.0,\mathrm{eV}$ , slight structural distortions in MnBr$ _3$ break intralayer symmetry, enabling robust interlayer ferromagnetic coupling and yielding a single, unified magnetic transition. Increasing $ U_2$ reduces these structural distortions, weakens interlayer coupling, and induces two distinct magnetic transitions, indicating interlayer magnetic decoupling. Thus, the MBT/MnBr$ _3$ heterostructure offers a novel approach for controlling magnetic order and enhancing the performance of spintronic devices.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
A first-principles investigation of altermagnetism in CrSb2 under applied pressure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
R. Tamang, Shivraj Gurung, Shalika Ram Bhandari, Matthew J. Stitz, Ganesh Pokharel, Keshav Shrestha, D. P. Rai
In this study, we employed first-principles density functional theory (DFT) calculations within the GGA+U framework to explore the electronic and magnetic properties of CrSb2 under varying hydrostatic pressures. CrSb2 exhibits non-relativistic spin splitting (NRSS) of around 0.5 eV around the Fermi level and the d-wave symmetric Fermi surface. Our magnetic susceptibility measurements further confirm the collinear antiferromagnetic (AFM) ground state in CrSb2 , a prerequisite for altermagnetism. The presence of collinear AFM and spin-band splitting without the application of spin-orbit coupling (SOC) supports CrSb2 as a potential contender for altermagnet. With increasing pressure, we have observed an intricate evolution of spin splitting in the valence and conduction bands, governed by changes in orbital contributions. The observation of the structural phase transition above 10 GPa is in qualitative agreement with the previous experimental findings. Our results not only support the classification of CrSb2 as an altermagnetic candidate but also provide critical insight into the role of pressure in tuning its spin-dependent electronic structure.
Materials Science (cond-mat.mtrl-sci)
On the diffusion of hard sphere fluids in disordered porous media: New extended Enskog theory description
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-17 20:00 EDT
M. F. Holovko, M. Ya. Korvatska
We proposed a new extended version of Enskog theory for the description of the self-diffusion coefficient of a colloidal hard-sphere fluid adsorbed in a matrix of disordered hard-sphere obstacles. In a considered approach instead of contact values of the fluid-fluid and fluid-matrix pair distribution functions, we introduced by input the new functions that include the dependence on the fraction of the volume free from matrix particles and from fluid particles trapped by matrix particles. It is shown that the introduction of this free volume fraction by the Fermi-like distribution leads to the best agreement between theoretical predictions and computer simulation results [Chang R., Jagannathan K., Yethiraj A., Phys. Rev. E, 2004, 69, 051101].
Soft Condensed Matter (cond-mat.soft)
8 pages, 2 figures
Nonlinear bulk photocurrent probe Z2 topological phase transition
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Debasis Dutta, Raihan Ahammed, Yingdong Wei, Xiaokai Pan, Xiaoshuang Chen, Lin Wang, Amit Agarwal
Detecting topological phase transitions in bulk is challenging due to the limitations of surface sensitive probes like ARPES. Here, we demonstrate that nonlinear bulk photocurrents, specifically shift and injection currents, serve as effective probes of Z_2 topological transitions. These photocurrents show a robust polarity reversal across the Z_2 phase transition, offering a direct optical signature that distinguishes strong topological phases from weak or trivial ones. This effect originates from a reorganization of key band geometric quantities, the Berry curvature and shift vector, on time-reversal-invariant momentum planes. Using a low energy Dirac model, we trace this behaviour to a band inversion in the time-reversal-invariant momentum plane that drives the topological transition. We validate these findings through tight-binding model for Bi_2Te_3 and first-principles calculations for ZrTe_5 and BiTeI, where the topological phase can be tuned by pressure or temperature. Our results establish nonlinear photocurrent as a sensitive and broadly applicable probe of Z_2 topological phase transitions.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 6 figures, 61 references. We will appreciate any comments of suggestions on this work
On the ambient conditions crystal structure of AgSbTe2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Baihong Sun, Sergei Grazhdannikov, Muhamed Dawod, Lunhua He, Jiazheng Hao, Thomas Meier, Yansun Yao, Yaron Amouyal, Elissaios Stavrou
We present a combined X-ray and neutron diffraction, Raman spectroscopy, and 121Sb NMR studies of AgSbTe2, supported by first-principles calculations aiming to elucidate its crystal structure. While diffraction methods cannot unambiguously resolve the structure, Raman and NMR data, together with electric field gradient calculations, strongly support the rhombohedral R-3m phase. Moreover, the agreement between experimental and calculated Raman spectra further corroborates this result, resolving the 60-year sold debate about the exact crystal structure of the AgSbTe2 compound.
Materials Science (cond-mat.mtrl-sci)
Extrinsic Dopants as Growth Modifiers in Cu-Cr-O delafossites: A Study of Incorporation Limits and Film Properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Marco Moreira, Yves Fleming, Patrick Grysan, Christele Vergne, Adrian Marie Philippe, Petru Lunca-Popa
Cu-Cr-O delafossite thin films were grown by metal-organic chemical vapor deposition with various extrinsic dopants (Al, Mg, Mn, Sc, Y, and Zn) targeted at 5 at % to investigate how such doping influences their structure and properties. X-ray photoelectron spectroscopy revealed that the actual dopant incorporation is well below the nominal 5 %, with only Al and Sc present above detection. An off-stoichiometric Cu-Cr-O composition is determined, with no secondary phases detected. Transmission electron microscopy indicates that films grown on c-plane sapphire are epitaxial near the substrate interface but relax into a polycrystalline structure beyond 20 nm, while films on silicon are polycrystalline throughout. All films show high p-type conductivity (on the order of 10-10^2 Scm-1) attributable to the excess oxygen, with no significant variation among different dopants. Optical transmission measurements indicate a slight red-shift (~20 nm) of the absorption edge for all doped films, likely arising from strain effects and subtle structural disorder introduced during growth. We discuss the influence of lattice strain (investigated by X-ray diffraction sin {\psi} squared measurements showing residual strain) and small polaron absorption behavior in these films. Despite limited incorporation of dopants, subtle structural and optical shifts suggest that dopant precursor chemistry and growth conditions play a significant role in influencing film stoichiometry and properties.
Materials Science (cond-mat.mtrl-sci)
Faceting transition in aluminum as a grain boundary phase transition
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Grain boundaries facet due to anisotropic grain boundary energies: While the faceted boundary has a larger area than the corresponding straight boundary, a significantly lower energy of the facets compared to a straight segment can drive the faceting. This picture is complicated by faceting/defaceting transitions where the free energy difference between the two states depends on the temperature. Here, we use atomistic computer simulations to show how such a transition in a $ \Sigma 3$ $ [11\overline{1}]$ tilt grain boundary in Al is in fact a grain boundary phase transition (also called complexion transition). This means that the faceted and defaceted boundaries are associated with different atomic structures, which have different thermodynamic stability ranges. At low temperatures, the grain boundary phase associated with faceting is stable, while at high temperatures the flat grain boundary phase is stable. We also report on our thorough tests of Al interatomic potentials for this purpose, which include comparisons to density-functional theory calculations. Our chosen potential performs well for our grain boundaries. As a consequence we were able to obtain results that align with previous experimental results.
Materials Science (cond-mat.mtrl-sci)
14 pages, 11 figures
Superconductivity with repulsion: a variational approach
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
Laura Fanfarillo, Yifu Cao, Chandan Setty, Sergio Caprara, Peter J. Hirschfeld
We revisit the stability of the superconducting state within mean-field theory in the presence of repulsive pairing interactions, focusing on multiband systems where such channels naturally arise. We show that, when repulsion is present, the self-consistent BCS solution appears as a saddle point of the conventional mean-field free energy, casting doubt on its physical stability. We show that this pathology is an artifact of using a non-variational functional. Recasting the problem with Bogoliubov’s variational principle restores a free energy that is bounded from below and places the BCS solution at a genuine minimum. Using a two-band toy model relevant to iron-based superconductors, we demonstrate the stability of the s$ _\pm$ state and clarify how projection schemes that rely only on the interaction matrix can misidentify the attractive eigenmode that drives pairing. Our results clarify the instability issue highlighted by Aase et al. and provide a consistent foundation for analyzing fluctuations in the presence of repulsive interactions.
Superconductivity (cond-mat.supr-con)
6 pages, 3 figures
Emergent topology in thin films of nodal line semimetals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
We investigate finite-size topological phases in thin films of nodal line semimetals (co-dimension 2) in three dimensions. By analyzing the hybridization of drumhead surface states, we demonstrate that such systems can transition into either a lower-dimensional nodal line state (co-dimension 1) or a fully gapped trivial phase. Additionally, we explore the hybridization of bulk states along the nodal loop when the system is finite in directions parallel to the loop’s plane. This generally results in a topologically nontrivial gap. In films finite along a single in-plane direction, a partial gap opens, giving rise to two-dimensional Weyl cones characterized by a one-dimensional $ \mathbb{Z}$ invariant. When the system is finite along both in-plane directions, a fully gapped phase appears, distinguished by a $ \mathbb{Z}$ invariant whose value increases with film thickness. We further discuss the bulk-boundary correspondence associated with these emergent topological phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 5 figures
Observation of many-body coherence in quasi-one-dimensional attractive Bose gases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
Hikaru Tamura, Sambit Banerjee, Rongjie Li, Panayotis Kevrekidis, Simeon I. Mistakidis, Chen-Lung Hung
Macroscopic coherence is an important feature of quantum many-body systems exhibiting collective behaviors, with examples ranging from atomic Bose-Einstein condensates, and quantum liquids to superconductors. Probing many-body coherence in a dynamically unstable regime, however, presents an intriguing and outstanding challenge in out-of-equilibrium quantum many-body physics. Here, we experimentally study the first- and second-order coherence of degenerate quasi-one-dimensional (1D) Bose gases quenched from repulsive to modulationally unstable attractive interaction regimes. The resulting dynamics, monitored by in-situ density and matter-wave interference imaging, reveals phase-coherent density wave evolutions arising from the interplay between noise-amplified density modulations and dispersive shock waves of broad interest within nonlinear physics. At longer times, the gases become phase-scrambled, exhibiting a finite correlation length. Interestingly, following an interaction quench back to the repulsive regime, we observe that quasi-long-range coherence can be spontaneously re-established. This captivating rephasing dynamics can be attributed to the nucleation and annihilation of density defects in the quasi-1D geometry. These results shed light on out-of-equilibrium phase coherence in quantum many-body systems in a regime where beyond mean-field effects may arise and theoretical approaches have not been well-established.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Searching for topological semi-complete bandgap in elastic truss lattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
Yiran Hao, Dong Liu, Liyou Luo, Jialu Mu, Hanyu Wang, Zibo Liu, Jensen Li, Zhihong Zhu, Qinghua Guo, Biao Yang
Gapless topological phases have attracted significant interest across both quantum and classical systems owing to their novel physics and promising applications. However, the search for ideal gapless topological nodes inside a clear bandgap is still lacking in elastic systems. The degenerate points are always hidden in the trivial bulk bands due to the intricate elastic modes involved. Here, we find a topological semi-complete bandgap in a three-dimensional elastic truss lattice by tuning a supporting rod, which exhibits a complete bandgap except for the inevitable topological degenerate points. Furthermore, we experimentally map the topological semi-complete bandgap and the inside nontrivial surface state arcs with a scanning laser vibrometer. The introduced scheme provides a systematic approach for the idealization of semi-complete bandgaps and thus may significantly advance the practical utility of topological phases in mechanical engineering domains.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Freestanding single-crystal superconducting electron-doped cuprate membrane
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
Shay Sandik, Bat-Chen Elshalem, Amram Azulay, Mye Waisbort, Amit Kohn, Beena Kalisky, Yoram Dagan
Thin films of cuprate superconductors are easier to control in terms of doping as compared to bulk samples. However, they require specific substrates to facilitate epitaxial growth. These substrates are often incompatible with materials used in electronic applications. Furthermore, it is challenging to separate the substrate’s properties from the material of interest. Here, we demonstrate the fabrication of an electron-doped cuprate membrane. We show that the membrane has a coherent crystal structure. Furthermore, the superconducting properties of the membrane post-liftoff closely resemble those of the thin films pre-lift-off, as revealed by a scanning superconducting quantum interference device (SQUID) microscope. Such membranes pave the way for designing new material properties and incorporating complex superconducting materials into typically incompatible electronic devices.
Superconductivity (cond-mat.supr-con)
Phys. Rev. Mater., 9, L021802 (2025)
Quantifying stored energy release in irradiated YBa$_2$Cu$_3$O$_7$ through molecular dynamics annealing simulations
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
Lauryn Kortman, Alexis Devitre, Charles Hirst
Over the lifetime of a fusion power plant, irradiation-induced defects will accumulate in the superconducting magnets compromising their ability to carry current without losses, generate high magnetic fields, and thus maintain plasma confinement. These defects also store potential energy within the crystalline lattice of materials, which can be released upon annealing. This phenomenon raises the question of whether the energy stored in defects may be sufficient to accelerate, or even trigger, a magnet quench? To provide an order of magnitude estimate, we used molecular dynamics simulations to generate defected YBCO supercells and conduct isothermal annealing simulations. Our results reveal that the maximum volumetric stored energy in a 4 mDPA defected single crystal of YBCO (240 $ J/cm^3$ ) is 30 times greater than the experimental minimum quench energy values for YBCO tapes (8.1 $ J/cm^3$ ). Our simulations also show that the amount of energy released increases as a function of annealing temperature or irradiation dose. This trend demonstrates that localized heating events in an irradiated fusion magnet have the potential to release significant amounts of defect energy. These findings underscore the critical need for experimental validation of the accumulation and release of defect stored energy, and highlight the importance of incorporating this contribution into quench detection systems, to enhance the operational safety of large-scale YBCO fusion magnets.
Superconductivity (cond-mat.supr-con)
19 pages, 5 figures
Anomalous Superfluid Density in Pair-Density-Wave Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-17 20:00 EDT
Ke Wang, Qijin Chen, Rufus Boyack, K. Levin
We study the superfluid density $ n_s(T)$ of pair-density-wave (PDW) superconductors; this determines where they are unstable and establishes signatures of their unusual order. Here we compute $ n_s(T)$ for the 2D unidirectional PDW superconducting phases that emerge from a microscopic model (with nearest neighbor attraction). With gapped and gapless bands in the Bogoliubov quasiparticle dispersion, this theory provides self-consistently determined wavevectors (\mathbf{Q}) for the spatially modulated pairing. We report a negative $ n_s$ for a significant fraction of the purportedly physical phase diagram. Independent of the microscopic model, we can generally understand that the implied instability in these superconductors arises from the variationally large (|\mathbf{Q}|). In the stable regime, the finite-temperature superfluid density (n_s(T)) displays unusual temperature dependences originating from the gapless Bogoliubov bands which reflect Van Hove-singularity-induced Sommerfeld contributions. These gapless bands, as well as the negative contributions from the Higgs mode, additionally lead to an anomalously small (highly anisotropic) superfluid density. This will then yield an unexpectedly large finite-frequency weight in the optical conductivity.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 4 figures
Viscosity, breakdown of Stokes-Einstein relation and dynamical heterogeneity in supercooled liquid Ge 2 Sb 2 Te 5 from simulations with a neural network potential
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-06-17 20:00 EDT
Simone Marcorini, Rocco Pomodoro, Omar Abou El Kheir, Marco Bernasconi
Phase change materials are exploited in non-volatile electronic memories and photonic devices that rely on a fast and reversible transformation between the amorphous and crystalline phase upon heating. The recrystallization of the amorphous phase at the operation conditions of the memories occurs in the supercooled liquid phase above the glass transition temperature $ T_g$ . The dynamics of the supercooled liquid is thus of great relevance for the operation of the devices and, close to $ T_g$ , also for the structural relaxations of the glass that affect the performances of the memories. Information on the atomic dynamics is provided by the diffusion coefficient ($ D$ ) and by the viscosity ($ \eta$ ) which are, however, both difficult to be measured experimentally at the operation conditions of the devices due to the fast crystallization. In this work, we leverage a machine learning interatomic potential for the flagship phase change compound compound Ge$ _2$ Sb$ _2$ Te$ _5$ to compute $ \eta$ , $ D$ and the $ \alpha$ -relaxation time in a wide temperature range from 1200 K to about 100 K above $ T_g$ . Large scale molecular dynamics simulations allowed quantifying the fragility of the liquid and the occurrence of a breakdown of the Stokes-Einstein relation between $ \eta$ and $ D$ in the supercooled phase. Isoconfigurational analysis provided a visualization of the emergence of dynamical heterogeneities responsible for the breakdown of the Stokes-Einstein relation. The analysis revealed that the regions of most mobile atoms are related to the presence of Ge atoms with particular local environments.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
Significant role of first-principles electron-phonon coupling in the electronic and thermoelectric properties of LiZnAs and ScAgC semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Vinod Kumar Solet, Sudhir K. Pandey
The half-Heusler (hH) compounds are currently considered promising thermoelectric (TE) materials due to their favorable thermopower and electrical conductivity. Accurate estimates of these properties are therefore highly desirable and require a detailed understanding of the microscopic mechanisms that govern transport. To enable such estimations, we carry out comprehensive first-principles computations of one of the primary factors limiting carrier transport, namely the electron-phonon ($ e-ph$ ) interaction, in representative hH semiconductors such as LiZnAs and ScAgC. Our study first investigates the $ e-ph$ renormalization of electronic dispersion based on the non-adiabatic Allen-Heine-Cardona theory. We then solve the Boltzmann transport equation (BTE) under multiple relaxation-time approximations (RTAs) to evaluate the carrier transport properties. Phonon-limited electron and hole mobilities are comparatively assessed using the linearized self-energy and momentum RTAs (SERTA and MRTA), and the exact or iterative BTE (IBTE) solutions within $ e-ph$ coupling. Electrical transport coefficients for TE performance are also comparatively analyzed under the constant RTA (CRTA), SERTA, and MRTA schemes. The lattice thermal conductivity, determined from phonon-phonon interaction, is further reduced through nanostructuring techniques. The bulk LiZnAs (ScAgC) compound achieves the highest figure of merit ($ zT$ ) of 1.05 (0.78) at 900 K with an electron doping concentration of 10$ ^{18}$ (10$ ^{19}$ ) cm$ ^{-3}$ under the MRTA scheme. This value significantly increases to 1.53 (1.0) for a 20 nm nanostructured sample. The remarkably high $ zT$ achieved through inherently present phonon-induced electron scattering and the grain-boundary effect in semiconductors opens a promising path for discovering highly efficient and accurate hH materials for TE technology.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), Strongly Correlated Electrons (cond-mat.str-el), Applied Physics (physics.app-ph)
11 pages, 8 figures
Observing the Birth of Rydberg Exciton Fermi Polarons on a Moire Fermi Sea
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-17 20:00 EDT
Eric A. Arsenault, Gillian E. Minarik, Jiaqi Cai, Minhao He, Yiliu Li, Takashi Taniguchi, Kenji Watanabe, Dmitri Basov, Matthew Yankowitz, Xiaodong Xu, X.-Y. Zhu
The optical spectra of two-dimensional (2D) semiconductors are dominated by tightly bound excitons and trions. In the low doping limit, trions are often described as three-body quasiparticles consisting of two electrons and one hole or vice versa. However, trions are more rigorously understood as quasiparticles arising from the interaction between an exciton and excitation of the Fermi sea - referred to as exciton Fermi polaron. Here we employ pump-probe spectroscopy to directly observe the formation of exciton Fermi polarons in a model system composed of a WSe2 monolayer adjacent to twisted bilayer graphene (tBLG). Following the pump-injection of Rydberg excitons in WSe2, a time-delayed probe pulse tracks the development of Rydberg exciton Fermi polarons as interactions with localized carriers in the tBLG moire superlattice evolve. Both the exciton Fermi polaron relaxation rate and binding energy are found to increase with electron or hole density. Our findings provide insight into the optical response of fundamental excitations in 2D Van der Waals systems and reveal how many-body interactions give rise to emergent quasiparticles.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 4 figures, 11 pages appendix
Photomagnetic-Chiral Anisotropy mediated by Chirality-Driven Asymmetric Spin Splitting
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Tianwei Ouyang, Hang Su, Wanning Zhang, Yingying Duan, Yuxi Fang, Shunai Che, Yizhou Liu
Photo-magnetic effects (PMEs), intrinsic to transition metals, arises from the interaction between light-induced angu-lar momentum and electronic spin. These effects are suppressed in noble metals with high symmetry and electron density. Introducing chiral structures can induce photomagnetic-chiral anisotropy (PM-ChA) of metals by linking chirality and spin dynamics. However, a theoretical explain remains elusive. Here, we investigated the mechanism of PM-ChA in tetrahelix-stacked chiral nanostructured gold chains (CNACs) using first-principles calculations. Non-equilibrium Green’s function calculations reveal that chiral potentials enhance spin channel asymmetry by amplify-ing spin-orbit coupling (SOC)-induced spin splitting. Real-time time-dependent density functional theory simulations further identify SOC as the bridge connecting chiral spintronics to PME, where chirality-driven spin flips from asymmetric geometries generate opposing photomagnetic fields in materials of different handedness. These findings are consistent with experimental observations in chiral nanostructured gold films and provide a theoretical instruction for design metallic spintronic devices.
Materials Science (cond-mat.mtrl-sci)
19 pages, 16 figures
Dimer-projection contact and the clock shift of a unitary Fermi gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-17 20:00 EDT
Kevin G. S. Xie, Colin J. Dale, Kiera Pond Grehan, Maggie Fen Wang, Tilman Enss, Paul S. Julienne, Zhenhua Yu, Joseph H. Thywissen
The time evolution of the contact parameter provides key insights into correlation dynamics in ultracold gases. However, most contact measurements to date have focused on equilibrium systems or slow, global dynamics. Here, we demonstrate that projecting a unitary Fermi gas onto a low-lying dimer state enables rapid probing of the contact. Using $ ^{40}$ K near a broad s-wave Feshbach resonance, we compare the strength of the dimer-projection feature to the strength of the high-frequency tail of radio-frequency spectroscopy. By tuning the correlation strength through temperature, we find that the dimer signal scales proportionally with the contact parameter, in agreement with coupled-channels calculations. Our measurements enable us to constrain the clock shift of the unitary Fermi gas, to which the dimer feature is the dominant contributor. We observe deviations from universal predictions due to finite-range and multichannel effects. Our results establish new universal contact relations and shed light on the structure of the clock shift in strongly interacting Fermi gases. The demonstrated ability to resolve short-range correlations on timescales shorter than the inverse Fermi energy opens new avenues for studying contact correlators, hydrodynamic attractors, and quantum critical behavior.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph)
13 pages, 5 figures
Catalogue of chiral phonon materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-17 20:00 EDT
Yue Yang, Zhenyu Xiao, Yu Mao, Zhanghuan Li, Zhenyang Wang, Tianqi Deng, Yanhao Tang, Zhi-Da Song, Yuan Li, Huiqiu Yuan, Ming Shi, Yuanfeng Xu
Chiral phonons, circularly polarized lattice vibrations carrying intrinsic angular momentum, offer unprecedented opportunities for controlling heat flow, manipulating quantum states through spin-phonon coupling, and realizing exotic transport phenomena. Despite their fundamental importance, a universal framework for identifying and classifying these elusive excitations has remained out of reach. Here, we address this challenge by establishing a comprehensive symmetry-based theory that systematically classifies the helicity and the velocity-angular momentum tensor underlying phonon magnetization in thermal transport across all 230 crystallographic space groups. Our approach, grounded in fundamental representations of phononic angular momentum, reveals three distinct classes of crystals: achiral crystals with vanishing angular momentum, chiral crystals with s-wave helicity, and achiral crystals exhibiting higher-order helicity patterns beyond the s-wave. By performing high-throughput computations and symmetry analysis of the dynamical matrices for 11614 crystalline compounds, we identified 2738 materials exhibiting chiral phonon modes and shortlisted the 170 most promising candidates for future experimental investigation. These results are compiled into an open-access Chiral Phonon Materials Database website, enabling rapid screening for materials with desired chiral phonon properties. Our theoretical framework transcends phonons–it provides a universal paradigm for classifying chiral excitations in crystalline lattices, from magnons to electronic quasiparticles.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
163 pages, 4+173 figures. The Chiral Phonon Materials Database can be accessed at this https URL
Compact representation and long-time extrapolation of real-time data for quantum systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-17 20:00 EDT
Andre Erpenbeck, Yuanran Zhu, Yang Yu, Lei Zhang, Richard Gerum, Olga Goulko, Chao Yang, Guy Cohen, Emanuel Gull
Representing real-time data as a sum of complex exponentials provides a compact form that enables both denoising and extrapolation. As a fully data-driven method, the Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm is agnostic to the underlying physical equations, making it broadly applicable to various observables and experimental or numerical setups. In this work, we consider applications of the ESPRIT algorithm primarily to extend real-time dynamical data from simulations of quantum systems. We evaluate ESPRIT’s performance in the presence of noise and compare it to other extrapolation methods. We demonstrate its ability to extract information from short-time dynamics to reliably predict long-time behavior and determine the minimum time interval required for accurate results. We discuss how this insight can be leveraged in numerical methods that propagate quantum systems in time, and show how ESPRIT can predict infinite-time values of dynamical observables, offering a purely data-driven approach to characterizing quantum phases.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)