CMP Journal 2025-11-17
Statistics
Nature Physics: 1
Physical Review Letters: 2
arXiv: 52
Nature Physics
Effective bands and band-like electron transport in amorphous solids
Original Paper | Electronic properties and materials | 2025-11-16 19:00 EST
Matthew Jankousky, Dimitar Pashov, João H. Mazo, Ross E. Larsen, Vladimir Dobrosavljević, Mark van Schilfgaarde, Vladan Stevanović
The localization of electrons caused by atomic disorder is a well-known phenomenon. However, under which circumstances electrons remain delocalized and retain band-like characteristics even when the crystal structure is completely absent, as found in certain amorphous solids, is less well understood. Here, to probe this phenomenon, we develop a fully first-principles description of the electronic structure and charge transport in amorphous materials, which combines a representation of the amorphous state as a composite (ensemble) of local environments and the state-of-the-art many-body electronic structure methods. Using amorphous In2O3 as an example, we demonstrate the accuracy of our approach in reproducing the band-like nature of the conduction electrons as well as their disorder-limited mobility. Our approach reveals the physical origins responsible for the electron delocalization and survival of the band dispersions despite the absence of long-range order.
Electronic properties and materials, Electronic structure
Physical Review Letters
Fully Relativistic Treatment of Extreme Mass-Ratio Inspirals in Collisionless Environments
Article | Cosmology, Astrophysics, and Gravitation | 2025-11-17 05:00 EST
Rodrigo Vicente, Theophanes K. Karydas, and Gianfranco Bertone
Future mHz gravitational wave interferometers will precisely probe massive black hole environments, such as accretion disks, cold dark matter overdensities, and clouds of ultralight bosons, as long as we can accurately model the dephasing they induce on the waveform of extreme mass-ratio inspirals (…
Phys. Rev. Lett. 135, 211401 (2025)
Cosmology, Astrophysics, and Gravitation
Hidden Permutation Symmetry of Squared Amplitudes in Aharony-Bergman-Jafferis-Maldacena Theory
Article | Particles and Fields | 2025-11-17 05:00 EST
Song He (何颂), Canxin Shi (施灿欣), Yichao Tang (唐一朝), and Yao-Qi Zhang (张耀奇)
We define the "squared amplitudes" in planar Aharony-Bergman-Jafferis-Maldacena theory, analogous to those in super-Yang-Mills (SYM) theory. Surprisingly, the -point -loop integrands with fixed are unified in a single generating function. Similar to the SYM four-point half-Bogomol'nyi-Pr…
Phys. Rev. Lett. 135, 211601 (2025)
Particles and Fields
arXiv
Solid-angle based nearest-neighbor algorithm adapted for systems with low coordination number
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-17 20:00 EST
Alptuğ Ulugöl, Frank Smallenburg, Laura Filion
Nearest-neighbor identification is central to the analysis of local structure in condensed matter systems. The solid-angle-based nearest-neighbor (SANN) algorithm is widely used offering a parameter-free and computationally efficient alternative to cutoff- or Voronoi-based methods. Unfortunately, however, in systems with low coordination numbers, SANN tends to identify many particles as neighbors that are outside the nearest neighbor shell. Here, we propose a solution to this problem. Specifically, we propose a geometric modification, the ``inscribed circle modification’’, that resolves systematic overcounting in low-coordination lattices without introducing free parameters. We benchmark the modified algorithm (mSANN) against Voronoi and the original SANN algorithm in crystalline, quasicrystalline, and heterogeneous systems, and demonstrate that it provides robust and low-cost neighbor identification across both two and three dimensions.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
13 pages, 12 figures
Raman fingerprint of high-temperature superconductivity in compressed hydrides
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-17 20:00 EST
Philip Dalladay-Simpson, Guglielmo Marchese, Zi-Yu Cao, Paolo Barone, Lara Benfatto, Gaston Garbarino, Francesco Mauri, Federico Aiace Gorelli
The discovery of high-temperature superconductivity in hydrogen-rich compounds under extreme pressures has prompted great excitement, intense research, but also debate over the past decade. Electrical transport has been the primary diagnostic tool for identifying superconductivity in these systems, whereas complementary probes, including magnetic, spectroscopic, tunnelling and ultrafast methods, remain mostly qualitative due to experimental constraints and sample heterogeneity. Recent concerns over their reliability have fuelled controversy, leading to scepticism and pointing out the need for alternative, quantitative approaches. In this study, we acquired unprecedented high-quality Raman spectra of hexagonal LaH10 at approximately 145 GPa and low temperatures, in conjunction with electrical transport measurements. Upon cooling, we observe a drop of resistivity and simultaneous remarkable variations of phonon frequencies and linewidths. These effects are interpreted and perfectly reproduced by the Migdal-Eliashberg theory, providing a definitive proof of phonon-mediated superconductivity and enabling a quantitative determination of the superconducting energy gap. Our results establish Raman spectroscopy as a robust, contact-free probe with micrometric resolution for studying high temperature superconductivity, opening a powerful route to its discovery and characterization.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Paramagnetic Phases of Strongly Correlated Ultracold Fermions Coupled to an Optical Cavity
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-11-17 20:00 EST
Renan da Silva Souza, Youjiang Xu, Walter Hofstetter
We numerically study a gas of two-component fermions coupled to a transversely pumped optical cavity and confined to a two-dimensional static square optical lattice. In the dispersive regime, the steady state of the system is described by an extended Hubbard Hamiltonian with cavity-mediated long-range interactions. Using real-space dynamical mean-field theory (RDMFT), we investigate the formation of the (superradiant) checkerboard density-wave phase both at quarter and half filling. We focus on the paramagnetic phase assuming sufficiently high temperatures such that no magnetic long-range order develops. At quarter filling, we find a reentrant homogeneous Fermi liquid to density wave phase transition with increasing temperature, which is due to the higher entropy of the ordered phase. At half filling, in addition to the Fermi liquid to Mott insulator phase transition, marked by a vanishing quasiparticle residue at the Fermi level, we identify the transition into a density-wave phase. Due to perfect Fermi surface nesting at half filling, we find that arbitrarily small long-range interactions destabilize the system towards the density-wave phase in the absence of short-range interactions. By varying short- and long-range interactions at a fixed low temperature, we obtain the full phase diagram and identify a region of coexistence between the homogeneous Fermi liquid and Mott insulating phase with the density-wave phase. In this region, we determine the thermodynamic phase transition by comparing the energies of the different RDMFT solutions.
Quantum Gases (cond-mat.quant-gas)
Anyonic Chern insulator in graphene induced by surface electromagnon vacuum fluctuations
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Xinle Cheng, Emil Viñas Boström, Frank Y. Gao, Edoardo Baldini, Dante M. Kennes, Angel Rubio
Sub-wavelength cavities have emerged as a promising platform to realize strong light-matter coupling in condensed matter systems. Previous studies are limited to dielectric sub-wavelength cavities, which preserve time-reversal symmetry. Here, we lift this constraint by proposing a cavity system based on magneto-electric materials, which host surface electromagnons with non-orthogonal electric field and magnetic field components. The quantum fluctuations of the surface electromagnons drive a nearby graphene monolayer into an anyonic Chern insulator, characterized by anyonic quasi-particles and a topological gap that decays polynomially with the graphene-substrate distance. Our work opens a path to controllably break time-reversal symmetry and induce exotic quantum states through cavity vacuum fluctuations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
High Mobility Multiple-Channel AlScN/GaN Heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Aias Asteris, Thai-Son Nguyen, Chuan F.C. Chang, Chandrashekhar Savant, Pierce Lonergan, Huili Grace Xing, Debdeep Jena
Aluminum scandium nitride (AlScN) is a promising barrier material for gallium nitride (GaN)-based transistors for the next generation of radio-frequency electronic devices. In this work, we examine the transport properties of two dimensional electron gases (2DEGs) in single- and multi-channel AlScN/GaN heterostructures grown by molecular beam epitaxy, and demonstrate the lowest sheet resistance among AlScN-based systems reported to date. Assorted schemes of GaN/AlN interlayers are first introduced in single-channel structures between AlScN and GaN to improve conductivity, increasing electron mobility up to $ 1370$ cm$ ^{2}$ /V$ \cdot$ s at 300 K and $ 4160$ cm$ ^{2}$ /V$ \cdot$ s at 77 K, reducing the sheet resistance down to 170 $ \Omega/\square$ and 70 $ \Omega/\square$ respectively. These improvements are then leveraged in multi-channel heterostructures, reaching sheet resistances of 65 $ \Omega/\square$ for three channels and 45 $ \Omega/\square$ for five channels at 300 K, further reduced to 21 $ \Omega/\square$ and 13 $ \Omega/\square$ at 2 K, respectively, confirming the presence of multiple 2DEGs. Structural characterization indicates pseudomorphic growth with smooth surfaces, while partial barrier relaxation and surface roughening are observed at high scandium content, with no impact on mobility. This first demonstration of ultra-low sheet resistance multi-channel AlScN/GaN heterostructures places AlScN on par with state-of-the-art multi-channel Al(In)N/GaN systems, showcasing its capacity to advance existing and enable new high-speed, high-power electronic devices.
Materials Science (cond-mat.mtrl-sci)
10 pages, 10 figures
Mechanistic Transition from Screw to Edge Dislocation Glide Enhances High-Temperature Strength in Refractory Complex Concentrated Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Tamanna Zakia, Ayeman Nahin, Dunji Yu, Jacob Pustelnik, Juntan Li, Mason Kincheloe, Lia Amalia, Yan Chen, Peter K. Liaw, Haixuan Xu, Mingwei Zhang
The strength of body-centered cubic materials is traditionally known to be governed by screw dislocations. However, recent findings reveal that in certain refractory complex concentrated alloys, edge dislocations can instead control strength. This work integrates high-temperature mechanical testing, in-situ neutron scattering during heating and tension, scanning transmission electron microscopy, and molecular dynamics simulations to uncover the mechanism behind this behavior. In the Nb-Ta-Ti-V system, increasing the V content, due to its smaller atomic size, induces substantial atomic misfit that raises the glide barrier for edge dislocations relative to screw dislocations. This effect drives a gradual transition from screw to edge dislocation-controlled deformation, leading to markedly enhanced strength at elevated temperatures.
Materials Science (cond-mat.mtrl-sci)
Lead-Free Europium Halide Perovskite Nanoplatelets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Sebastian Fernández, Divine Mbachu, Manchen Hu, Han Cui, William Michaels, Pournima Narayanan, Tyler K. Colenbrander, Qi Zhou, Da Lin, Ona Segura Lecina, Guosong Hong, Daniel N. Congreve
Metal halide perovskites possess desirable optical, material, and electrical properties which have had substantial impact on next-generation optoelectronics. However, given the toxicity of lead, alternative lead-free perovskite semiconductors are needed. By fully replacing lead with rare-earth elements, one can simultaneously address toxicity concerns and achieve comparable optoelectronic performance. Here, we demonstrate the synthesis of two-dimensional europium halide perovskite nanoplatelets governed by the formula $ \mathrm{L_{2}EuX_{4}}$ where L is an organic ligand and X is a halide anion. The structure, morphology, and composition of the nanoplatelets are confirmed by XRD, AFM, and XPS. Deep blue-emitting $ \mathrm{PEA_{2}EuBr_{4}}$ perovskite nanoplatelets are synthesized in both the solution- and solid-states with photoluminescence emission centered at 446 nm and CIE color coordinates of (0.1515, 0.0327) and (0.1515, 0.0342), respectively. Additionally, near-ultraviolet $ \mathrm{PEA_{2}EuCl_{4}}$ perovskite nanoplatelets are synthesized in both the solution- and solid-states with photoluminescence emission centered at 400 nm and 401 nm, respectively. Overall, europium halide perovskite nanoplatelets offer a lead-free alternative for deep blue, violet, and near-ultraviolet light emission $ \unicode{x2013}$ charting new pathways for optoelectronics in this energy regime.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Parametric resonance in a spin-1/2 chain: dynamical effects of nontrivial topology
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Mahmoud T. Elewa, M. I. Dykman
Resonant parametric modulation is a major tool of studying magnetic systems. For a spin-1/2 chain in a strong magnetic field, the resulting excitations can be mapped on fermionic excitations in the Kitaev chain. We show that the response to the modulation turn-on allows one to reveal dynamical aspects of the nontrivial topology of the periodic chain. In the topological regime, depending on how fast the turn-on is, the system displays the absence of spatial magnetization correlations or their increase with the increasing detuning of the modulation from resonance. The transition between the topological and trivial regimes is controlled by the modulation frequency.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Impact of Nitrogen Atom Clusters and Vacancy Defects on Graphene: A Molecular Dynamics Investigation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Indranil Rudra, Md. Moktadir Billah Tahmid, Jahid Emon, Mohammad Jane Alam Khan
Graphene’s exceptional mechanical properties are crucial for its integration into advanced technological applications. However, real-world synthesis and functionalization processes introduce structural modifications that can compromise its mechanical integrity. Nitrogen doping, while beneficial for electronic property tuning, often results in atomic clustering rather than uniform distribution, while concurrent vacancy defect formation represents another common structural alteration during processing. This study systematically investigates the comparative effects of nitrogen atom clusters and equivalent sized vacancy defects on the mechanical behavior of graphene sheets through molecular dynamics simulations. The Nitrogen clustering significantly degraded mechanical performance almost similarly to random doping. In comparison, systems with equivalent-sized vacancy defects showed higher stiffness and lower ductility than those with clusters. The study revealed distinct failure mechanisms between doped and defective configurations, with nitrogen clusters showing modified crack propagation patterns while vacancies acted as pronounced stress concentrators, leading to premature failure. However, this study also showed that defect morphology critically influences mechanical properties. These findings provide important insights for optimizing graphene synthesis and processing protocols, highlighting the differential mechanical risks associated with dopant clustering versus vacancy formation. The results inform defect-tolerant design strategies for graphene-based nanoelectronics, composites, and sensors, where mechanical reliability is paramount for device performance and longevity.
Materials Science (cond-mat.mtrl-sci)
Manuscript under review at Scientific Reports. 15 pages, 5 figures
Probing universal imaginary-time relaxation critical dynamics with infinite projected entangled pair states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-17 20:00 EST
He-Yu Lin, Shuai Yin, Z. Y. Xie, Zhong-Yi Lu
We investigate the imaginary-time relaxation critical dynamics of the two-dimensional transverse-field Ising model using infinite projected entangled pair states (iPEPS) with the full-update strategy. Simulating directly in the thermodynamic limit, we explore the relaxation process near the critical point with two types of initial states: a fully polarized state and a product state with a small magnetization. For the fully polarized state, the magnetization shows a power law scaling $ M\propto \tau^{-\beta/(\nu z)}$ in the imaginary-time evolution, from which both the critical point and critical exponent can be determined with high accuracy. For the nearly paramagnetic state, the relaxation process exhibits a behavior of $ M\propto \tau^\theta$ with $ \theta=0.1958$ being the critical initial-slip exponent, which is in good agreement with that obtained from the dynamic scaling of the self-correlation in quantum Monte Carlo method. These universal features emerge well before the system converges to the ground state, demonstrating the efficiency of imaginary-time evolution for probing quantum criticality. Our results demonstrate that iPEPS can serve as a robust and scalable method for studying dynamical critical phenomena in two-dimensional quantum many-body systems.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
8 pages, 5 figures
Ripple-assisted adsorption of noble gases on graphene at room temperature
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Weilin Liu, Xianlei Huang, Li-Guo Dou, Qianglong Fang, Ang Li, Guowen Yuan, Yongjie Xu, Zhenjia Zhou, Jun Li, Yu Jiang, Zichong Huang, Zihao Fu, Peng-Xiang Hou, Chang Liu, Jinlan Wang, Wu Zhou, Ming-Gang Ju, Shao-Chun Li, Hui-Ming Cheng, Libo Gao
Controllable gas adsorption is critical for both scientific and industrial fields, and high-capacity adsorption of gases on solid surfaces provides a significant promise due to its high-safety and low-energy consumption. However, the adsorption of nonpolar gases, particularly noble gases, poses a considerable challenge under atmospheric pressure and room temperature (RT). Here, we theoretically simulate and experimentally realize the stable adsorption of noble gases like xenon (Xe), krypton (Kr), argon (Ar), and helium (He) on highly rippled graphene at RT. The elemental characteristics of adsorbed Xe are confirmed by electron energy loss spectroscopy and X-ray photoelectron spectroscopy. The adsorbed gas atoms are crystalized with periodic arrangements. These adsorbed noble gases on graphene exhibit high stability at RT and can be completely desorbed at approximately 350 °C without damaging the intrinsic lattice of graphene. The structural and physical properties of graphene are significantly influenced by the adsorbed gas, and they fully recover after desorption. Additionally, this controllable adsorption could be generalized to other layered adsorbents such as NbSe2, MoS2 and carbon nanotubes. We anticipate that this ripple-assisted adsorption will not only re-define the theoretical framework of gas adsorption, but also accelerate advancements in gas storage and separation technologies, as well as enhance the applications in catalysis, surface modification, and other related fields.
Materials Science (cond-mat.mtrl-sci)
Kapitza-Dirac interference of Higgs waves in superconductors
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-17 20:00 EST
Daemo Kang, Tien-Tien Yeh, Takahiro Morimoto, Alexander V. Balatsky
We present a novel framework for controlling Higgs mode and vortex dynamics in superconductors using structured light. We propose a phenomenon analog of the Kapitza-Dirac effect in superconductors, where Higgs waves scatter off light-induced vortex lattices, generating interference patterns akin to matter wave diffraction. We also find that the vortices enable the linear coupling of Higgs mode to the electromagnetic field. This interplay between light-engineered Higgs excitations and emergent vortex textures opens a pathway to probe nonequilibrium superconductivity with unprecedented spatial and temporal resolution. Our results bridge quantum optics and condensed matter physics, offering new examples of quantum printing where one uses structured light to manipulate the collective modes in correlated quantum fluids.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
Effect of doping on hot-carrier thermal breakdown in perforated graphene metasurfaces
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
M. Ryzhii, V. Ryzhii, C. Tang, T. Otsuji, M. S. Shur
We examine the robustness of the S-shaped current-voltage characteristics associated with hot-carrier-induced electrical breakdown in perforated graphene metasurfaces (PGMs) as a function of doping. The perforation of the graphene layer forms interdigital arrays of graphene microribbons (GMRs) interconnected by graphene nanoribbon (GNR) bridges. These GNR constrictions act as energy barriers for electrons and holes emitted from the GMRs and govern the inter-GMR thermionic current under an applied bias voltage. The doping and the voltage bias establish distinct electron and hole populations in adjacent GMRs. Peltier heating of these carriers within the GMRs increases their effective temperatures, thereby enhancing the inter-GMR current. The resulting positive feedback between carrier heating and current amplification can trigger an electrothermal breakdown, transforming a superlinear current-voltage dependence into an S-shaped characteristic exhibiting negative differential resistance. The degree of electron-hole asymmetry significantly influences this positive feedback and strongly modifies the overall current-voltage response. These results provide a framework for optimizing PGM-based devices employing GMR/GNR architectures, including voltage-controlled fast switches, incandescent emitters, and terahertz bolometric detectors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Mastering Rheology: A Strategic and practical guide for empowering all users
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-17 20:00 EST
Rheology, the study of flow, plays a vital role in diverse industries such as pharmaceuticals, cosmetics and food. In this work, we provide a comprehensive introduction to fundamental rheological experiments and offer a strategic approach to understand the rheological behavior of any soft condensed material. We emphasize the importance of design of a good rheological experiment, input parameter and analysis of the obtained output parameter. Through the standard design of the experiment and systematic conduction of rheological experiments, we can estimate a broad range of rheological parameters such as viscosity, modulus, stability, yield stress, nonlinear behavior of the material. Furthermore, we also discuss methods for detecting and good practices for reducing some of the common experimental errors that may arise. We also present a comprehensive range of advanced rheological characterization techniques that can be pursued to gain deeper insights into the mechanical behavior and structural evolution of soft materials. Through this work, we attempt to make rheology more accessible to researchers from various domains to incorporate rheology into their characterization study and enable them to confidently navigate rheological studies and contribute to material development.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Industrial & Engineering Chemistry Research Vol 64, Issue 42, 2025
Nearly semi-elliptic relation between the minimal conductivity and Hall conductivity in unpaired Dirac fermions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Bo Fu, Kai-Zhi Bai, Shi-Hao Bi, Shun-Qing Shen
Electric conductivities may reveal the topological and magnetic properties of band structures in solids, especially for two-dimensional unpaired Dirac fermions. In this work, we evaluate the longitudinal and Hall conductivity for unpaired Dirac fermions in the framework of the self-consistent Born approximation and find a nearly semi-elliptic relation between the minimal conductivity and Hall conductivities in the Dirac fermions. Near the charge neutrality point, disorder may drive a metal-insulator transition, and enhance the longitudinal conductivity. For the massless case, the minimal conductivity $ \sigma_{xx}^\ast$ coexists with the half-quantized Hall conductivity $ e^2/2h$ , forming an indicator for the parity anomalous semimetal. The relation signals a disorder-induced metallic phase that bridges two topologically distinct insulating phases, and agrees with the recent experimental observation in magnetic topological insulators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 4 figures. Comments are welcomed
Sliding of cylindrical shell into a rigid hole
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-17 20:00 EST
Yukiho Matsumoto, Keisuke Yoshida, Tomohiko G. Sano
Fitting two different materials is a versatile methodology in manufacturing complex structures. One of the canonical models for fitting is the snap-fit model, in which flexible materials and rigid structures are assembled by pushing their interlocking components together. The assembly via snap-fit is often accompanied by large deformations of flexible structures and abrupt force drops, highlighting the role of elasticity, geometry, and contact friction. Despite several model studies revealing fundamental mechanics for snap-fit, the current snap-fit design relies on prototyping and empirical rules. In this paper, we analyze a snap-fit model in which a naturally curved beam slips into a rigid hole. We construct an analytical model based on the theory of elastica with contact friction and demonstrate that its predictions are in excellent quantitative agreement with both simulations and experiments. We find three distinct sliding modes: Folding, Pinning, and Unfolding. The classification is systematically organized in a phase diagram based on the geometric parameters of the shells and the hole. Our study complements existing approaches by providing a predictive framework for contact-based structures that involve friction, elasticity, and geometry, and sheds light on a unified understanding of the interactions between an elastic and a rigid body.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
10 pages, 4 figures
Hopfions in the Lee-Huang-Yang superfluids
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-11-17 20:00 EST
Liangwei Dong, Mingjing Fan, Boris A. Malomed, Yaroslav V. Kartashov
It is known that, under appropriate conditions, mean-field interactions can be canceled in binary BEC, leading to the formation of the Lee-Huang-Yang (LHY) superfluid, in which the nonlinearity is solely represented by the quartic LHY term. In this work we systematically investigate the existence, stability and evolution of hopfion states in this species of quantum matter. They are characterized by two independent topological winding numbers: inner twist $ s$ of the vortex-ring core and overall vorticity $ m$ . The interplay between the LHY self-repulsion and a trapping harmonic-oscillator potential results in stability of the hopfions with $ s = 1$ and $ m$ ranging from $ 0$ to $ 4$ . The hopfions exhibit distinct topological phase distributions along the vertical axis and the radial direction in the horizontal plane. Their effective radius and peak density increase with the chemical potential, along with expansion of the vortex-ring core. Although the instability domain of the hopfion modes broadens with the increase of $ m$ , stable hopfions persist in a wide range of the chemical potential, up to $ m=4$ , at least, provided that the norm exceeds a certain threshold value. The predictions are experimentally accessible in currently used BEC setups.
Quantum Gases (cond-mat.quant-gas)
8 pages, 5 figures, to be published in Chaos, Solitons & Fractals
Chiral active gyrator: Memory induced direction reversal of rotational motion
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-17 20:00 EST
We theoretically explore the dynamics of a chiral active Ornstein Uhlenbeck particle confined in a two-dimensional anisotropic harmonic trap. The particle is driven by chirality and is coupled to two orthogonal heat baths, potentially at two different temperatures. Using both analytical approach and numerical simulation, we explore the rotational dynamics of the particle in both viscous and viscoelastic environments. While the particle is suspended in a viscoelastic bath, characterized by a finite memory time scale, we interestingly observe that even in the absence of a temperature gradient, the angular momentum changes its sign as a function of the memory timescale, reflecting the direction reversal of rotational motion of the particle, and it is solely due to the interplay between memory and chirality. This direction reversal is a distinct memory-induced phenomenon and does not occur in the viscous limit. Moreover, increasing (or decreasing) the temperature gradient shifts the magnitude of the angular momentum further into the negative (or positive) direction, selecting a unique direction of rotation for the particle throughout the activity-memory parameter space. However, in the viscous limit, the direction reversal of the rotational motion is still possible but occurs only across a neutral line in parameter space, along which the contributions from both chirality and thermal anisotropy to the net angular momentum exactly cancel. These results highlight a distinct mechanism for directional control in active systems, with memory enabling reversal phenomena unique to viscoelastic media.
Soft Condensed Matter (cond-mat.soft)
14 pages, 8 figures
Intrinsic structure of relaxor ferroelectrics from first principles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Xinyu Xu, Kehan Cai, Pinchen Xie
We hybridize swap Monte Carlo and geometric relaxation to determine the intrinsic compositional structure (CS) of lead magnesium niobate (PMN) relaxor. We verify the stability of a Nb-rich sublattice in PMN, as prescribed by the prevailing random-site model. But ions in the complementary sublattice are not randomly mixed. The majority of Nb ions collapse into a dominant Nb cluster which percolates the lattice with a mesh-like geometry that prevents large space charges. Subsequent molecular dynamics simulations predict a pair distribution function agreeing with neutron scattering experiments. Analysis of dipolar structures in the Nb cluster sheds light on the unique dielectric property of PMN.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)
Ergodic properties of occupation times in heterogeneous media
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-17 20:00 EST
Vicenç Méndez, Rosa Flaquer-Galmés
We investigate the ergodic properties of Brownian motion in heterogeneous media through the statistics of occupation times. Using the Feynman-Kac formalism, we derive analytical expressions for the distributions, moments, and ergodicity breaking parameters of occupation times in two models with spatially varying diffusion coefficient: a piecewise-constant profile and a power-law profile. In the piecewise model, the half occupation time and the occupation time within an interval follow asymmetric arcsine and half-Gaussian distributions, respectively, indicating non-ergodic behavior. For the power-law case, the corresponding distributions are the Lamperti and Mittag-Leffler. In both models, we identify a transition from non-ergodic to ergodic dynamics as the exponent vary. Numerical simulations fully corroborate the analytical results, demonstrating the effectiveness of the Feynman-Kac approach for quantifying ergodicity in heterogeneous diffusion processes.
Statistical Mechanics (cond-mat.stat-mech)
Emergent Synchronization and Defect Dynamics in Confined Chiral Active Suspensions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-17 20:00 EST
Zaiyi Shen, Leilei Wang, Shishuang Zhang, Chenlu Li, Kaili Xie, Xu Zheng, Juho S. Lintuvuori
Hydrodynamic interactions can generate rich emergent structures in active matter systems. Using large-scale hydrodynamic simulations, we demonstrate that hydrodynamic coupling alone can drive spontaneous self-organization across a hierarchy of spatial and temporal scales in confined suspensions of torque-driven particles at moderate Reynolds numbers. Spinners first self-assemble into dimers, which crystallize into a hexatic lattice and subsequently undergo a collective tilting instability. The resulting tilted dimers rotate and synchronize through hydrodynamic repulsion, which can be tuned by the Reynolds number. Upon synchronization, the polar director develops splay and bend deformations and nucleates topological defects with charges of $ \pm1$ . These defects induce long-wavelength concentration gradients and drive crystal vortex dynamics spanning hundreds of particle diameters. Our results reveal a purely hydrodynamic route to synchronization and defect-mediated dynamics in chiral active matter, without explicit alignment rules or interparticle forces.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Optical conductivity of layered topological semimetal TaNiTe$_5$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-17 20:00 EST
Jakov Budić, Serena Nasrallah, D. Santos-Cottin, A. Pulkkinen, J. Minár, P. Sačer, B. Gudac, V. Despoja, N. Barišić, C. C. Homes, Ana Akrap, Mario Novak
We present an infrared spectroscopy study of the layered topological semimetal TaNiTe$ _5$ , a material with a quasi-one-dimensional structure and strong in-plane anisotropy. Despite its structural features, infrared reflectivity and electronic transport measurements along the $ a$ and $ c$ crystallographic axes show metallic behavior without evidence of reduced dimensionality. Optical conductivity reveals an anisotropic but conventional metallic response with low scattering rates and a single sharp infrared-active phonon mode at $ 396$ cm$ ^{-1}$ ($ 49$ meV). Ab initio calculations closely match the experimental optical data and confirm a three-dimensional electronic structure. Our results demonstrate that TaNiTe$ _5$ behaves as a three-dimensional anisotropic semimetal in its electronic and optical properties.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Data at this https URL
Non-Gaussianity-induced enhanced target-finding dynamics of confined colloids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-17 20:00 EST
Guirec de Tournemire (LOMA), Nicolas Fares (LOMA), Yacine Amarouchene (LOMA), Thomas Salez (LOMA)
The encounter of diffusing entities underlies a wide range of natural phenomena. The dynamics of these first-passage processes are strongly influenced by the geometry of the system, for example through confining boundaries. Confinement, which alters the diffusion of microscopic particles through both conservative and hydrodynamic interactions, emerges as a key ingredient for modeling realistic environments. In this Letter, we investigate the impact of confinement on the first-passage statistics of a diffusing particle. This diffusive motion is probed, with nanometric precision, by combining \textit{state-of-the-art} holographic microscopy with advanced statistical inference methods. Our experimental and numerical results provide a comprehensive understanding of this process, which is governed by the coupling between gravitational, screened electrostatic and hydrodynamic forces, as well as thermal fluctuations. We further show that confinement can either slow down or enhance the typical first-passage kinetics, depending on the experimental parameters and considered direction of space. In particular, the observed boost in wall-normal target-finding efficiency appears to be a direct consequence of the non-Gaussian displacement distribution induced by the near-surface effects, and the associated increased probability of large displacements. As the latter are rare events, our findings may be of relevance to rationalize confined chemical reactions, or biological \textit{winners-take-all} stochastic processes near boundaries.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Classical Physics (physics.class-ph)
Optical Properties of Superconducting K${0.8}$Fe${1.7}$(Se${0.73}$S${0.27}$)$_2$ Single Crystals
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-17 20:00 EST
Andrei Muratov (1), Yevgeny Rakhmanov (1 and 2), Andrei Shilov (1), Igor Morozov (2), Yurii Aleshchenko (1) ((1) P.N. Lebedev Physical Institute of RAS, Moscow, Russia, (2) Lomonosov Moscow State University, Department of Chemistry, Moscow, Russia)
The optical properties of the superconducting K$ _{0.8}$ Fe$ _{1.7}$ (Se$ _{0.73}$ S$ _{0.27}$ )$ _2$ single crystals with a critical temperature $ T_c\approx 26$ K have been measured in the {\it ab} plane in a wide frequency range using both infrared Fourier-transform spectroscopy and spectroscopic ellipsometry at temperatures of 4–300 K. The normal-state reflectance of K$ _{0.8}$ Fe$ _{1.7}$ (Se$ _{0.73}$ S$ _{0.27}$ )$ _2$ is analyzed using a Drude-Lorentz model with one Drude component. The temperature dependences of the plasma frequency, optical conductivity, scattering rate, and dc resistivity of the Drude contribution in the normal state are presented. In the superconducting state, we observe a signature of the superconducting gap opening at $ 2\Delta $ (5K) = 11.8meV. An abrupt decrease in the low-frequency dielectric permittivity $ \varepsilon _1(\omega )$ at $ T < T_c$ also evidences the formation of the superconducting condensate. The superconducting plasma frequency $ \omega _{pl,s} = (213\pm 5)$ ~cm$ ^{-1}$ and the magnetic penetration depth $ \lambda =(7.5\pm 0.2)$ ~$ \mu $ m at $ T=5$ ~K are determined.
Superconductivity (cond-mat.supr-con)
11 pages, 5 figures, 1 table
Journal of Superconductivity and Novel Magnetism 38, 236 (2025)
Field-tunable partial antiferromagnetism, glassy spin dynamics, and magnetodielectric coupling in the quasi-one-dimensional spin-chain compound Ca3CoIrO6
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Priyanka Mahalle (1 and 2), A. Kumar (1 and 2), Kumar Bharti (3), Dipanshu Bansal (3), P. D. Babu (4), S. M. Yusuf (1 and 2) ((1) Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India, (2) Homi Bhabha National Institute, Anushaktinagar, Mumbai-400094, India, (3) Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India, (4) UGC-DAE Consortium for Scientific Research, Mumbai Centre, BARC Campus, Mumbai 400 085, India)
We report a comprehensive investigation of the quasi-one-dimensional spin-chain compound Ca3CoIrO6 (CCIO) using a combination of structural, magnetic, thermodynamic, transport, Raman, and dielectric measurements. Temperature-dependent neutron powder diffraction confirms the rhombohedral R-3c structure down to 5 K without any structural phase transition. DC magnetization, ac susceptibility, and relaxation measurements reveal a gradual evolution from a high-temperature paramagnetic-like state to a partially disordered antiferromagnetic (PDA) state below 100 K, accompanied by slow cluster-like spin dynamics followed by a freezing transition near 30 K. Isothermal magnetic hysteresis M(H) loops demonstrate partial chain freezing, while robust exchange bias is observed in field-cooled protocols, highlighting the interplay between PDA ordering and frozen spins. Resistivity and specific heat data indicate strong coupling between spin and charge degrees of freedom, accompanied by activated transport behavior. Raman spectroscopy identifies pronounced anomalies in phonon frequencies and linewidths across multiple magnetic regimes, reflecting strong spin-lattice coupling. Polarization-electric field (P-E) measurements reveal temperature-dependent crossovers from linear dielectric to weakly hysteretic behavior, consistent with short-range polar correlations driven by spin-lattice interactions. These findings establish CCIO as a prototypical quasi-one-dimensional frustrated spin-chain system where geometric frustration, spin-orbit coupling, and low-dimensionality generate field-tunable PDA order, glassy spin dynamics, exchange bias, and magnetodielectric coupling. These results provide new insights into frustration-driven phases in low-dimensional oxides and point towards potential multifunctional applications based on intrinsic magnetodielectric and exchange bias phenomena.
Materials Science (cond-mat.mtrl-sci)
32 pages, 19 figures, 2 tables
Tunable electronic band structure in WSSe van der Waals Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Meryem Bouaziz, Leonard Schue, Noeliarinala Felana Andriambelaza, Natalia Alyabyeva, Jean-Christophe Girard, Pavel Dudin, Fabian Cadiz, Jose Avila, Yannick Dappe, Cesar Gonzalez, Julien Chaste, Fabrice Oehler, Christine Giorgetti, Fausto Sirotti, Abdelkarim Ouerghi
The electronic structure of semiconducting 2D materials such as transition metal dichalcogenides (TMDs) is known to be tunable by its environment, from simple external fields applied with electrical contacts up to complex van der Waals heterostructure assemblies. However, conventional alloying from reference binary TMD compounds to composition-controlled ternary alloys also offers unexplored opportunities. In this work, we use nano-angle resolved photoemission spectroscopy (nano-ARPES) and density functional theory (DFT) calculations to study the structural and electronic properties of different alloy compositions of bulk WS2(1-x)Se2x. Our results demonstrate the continuous variation of the band structure and the progressive evolution of the valence band splitting at the K points from 420 to 520 meV in bulk WS2(1-x)Se2x. We also carried out scanning tunneling microscopy (STM) measurements and DFT to understand the possible S or Se substitutions variants in WS2(1-x)Se2x alloys, with different local atomic configurations. Our work opens up perspectives for the fine control of the band dispersion in van der Waals materials and demonstrate how the band structure can be tuned in bulk TMDs. The collected information can serve as a reference for future applications.
Materials Science (cond-mat.mtrl-sci)
PRB 2025
Nonequilibrium Thermodynamics of Associative Memory Continuous-Time Recurrent Neural Networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-11-17 20:00 EST
Miguel Aguilera, Daniele De Martino, Ivan Garashchuk, Dmitry Sinelshchikov
Continuous-Time Recurrent Neural Networks (CTRNNs) have been widely used for their capacity to model complex temporal behaviour. However, their internal dynamics often remain difficult to interpret. In this paper, we propose a new class of CTRNNs based on Hopfield-like associative memories with asymmetric couplings. This model combines the expressive power of associative memories with a tractable mathematical formalism to characterize fluctuations in nonequilibrium dynamics. We show that this mathematical description allows us to directly compute the evolution of its macroscopic observables (the encoded features), as well as the instantaneous entropy and entropy dissipation of the system, thereby offering a bridge between dynamical systems descriptions of low-dimensional observables and the statistical mechanics of large nonequilibrium networks. Our results suggest that these nonequilibrium associative CTRNNs can serve as more interpretable models for complex sequence-encoding networks.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Chaotic Dynamics (nlin.CD)
7 pages, 4 figures
Published in Proceedings of ALIFE2025 conference
Models for active particles: common features and differences
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-17 20:00 EST
Colin-Marius Koch, Michael Wilczek
Systems of active particles can show a large variety of collective behavior. In theory, two aspects determine the collective behavior: the model at the particle level and the parameter regime. While many studies consider a single model and study its parameter regime, here, we focus on the former aspect. Motivated by experiments that study dilute suspensions of Chlamydomonas reinhardtii in a self-generated oxygen gradient, we compare various models with external field-dependent motility to understand how the collective behavior changes between models. We vary the particle-particle interaction from no interactions to steric interactions, the particle shape from round disks to dumbbells, the self-propulsion mechanism from constant speed to rocking motion, and the particle’s center of mass from the geometric center to off-center. We find that changes in the model of the active agents can lead to similar statistics in the dilute regime and different collective behavior in the dense regime. We conclude that active particle models do not easily generalize for different real active agents, but instead require a clear understanding of the agents’ microscopic properties.
Soft Condensed Matter (cond-mat.soft)
submitted to Phys. Rev. E
Counterintuitive Potential-Barrier Affinity Effect
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Qiang Xu, Zhao Liu, Yanming Ma
Electron accumulation in interatomic regions is a fundamental quantum phenomenon dictating chemical bonding and material properties, yet its origin remains elusive across disciplines. Here, we report a counterintuitive quantum effect – potential-barrier affinity (PBA) – revealed by solving the Schrödinger equation for a crystalline potential. PBA effect drives significant interatomic electron accumulation when electron energy exceeds the barrier maximum. This effect essentially determines interatomic electron density patterns, governing microstructures and properties of condensed matters. Our theory overturns the traditional wisdom that the interstitial electron localization in electride requires potential-well constraints or hybrid orbitals, and it serves the fundamental mechanism underlying the formation of conventional chemical bonds. This work delivers a paradigm shift in understanding electron distribution and establishes a theoretical foundation for the microscopic design of material properties.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
8 pages, 4 figures
Topological Theory of Helium 4
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-17 20:00 EST
In this paper we attempt to construct the topological theory of superfluid helium $ 4$ in the framework of the (rigid) $ U(1)$ model in which the initial $ U(1)$ group is destroyed with appearance of (topologically nontrivial) domains separated by domain walls treated as step voltages between domains (e.g. with neighboring topological numbers). This can explain the superfluid properties in a helium $ 4$ specimen as well as the appearance of topologically nontrivial vortices therein.
Superconductivity (cond-mat.supr-con)
Comments wellcome
From LRO to Disorder via QLRO in Spatially Inhomogeneous Polar Flock
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-17 20:00 EST
Anish Kumar, Vivek Semwal, Shradha Mishra
We study the collective behavior of a polar flock in an inhomogeneous environment in two-dimensions. The inhomogeneity is modelled by introducing regions at random locations on the substrate with higher noise but accessible for the flock to move. Hence inside such regions the particles orientation get randomised. Such inhomogeneities are different from the physical disorder, which obstructs the space for the incoming particles. The study focuses on how the phase behavior of polar flock changes by tuning the packing fraction of inhomogeneity. As packing fraction increases, the system crosses over from long-range to quasi long range order and ultimately to a disordered phase, while the order disorder transition for flocking changes from discontinuous to continuous. The resultant phase behavior of polar flock patterns here is comparable to that exhibited in the presence of physical disorder.
Soft Condensed Matter (cond-mat.soft)
Electronic and magnetic properties of light rare-earth cubic Laves compounds derived from XMCD experiments
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Vilde G. S. Lunde, Benedicte S. Ofstad, Øystein S. Fjellvåg, Philippe Ohresser, Anja O. Sjåstad, Bjørn C. Hauback, Christoph Frommen
This work presents electronic and magnetic properties of selected members in the cubic Laves phase series Nd1-xPrxCoNi and Ce0.25Pr0.75CoNi, together with the corresponding binary compositions (NdCo2, NdNi2, PrCo2, PrNi2, CeCo2, CeNi2), using soft x-ray absorption spectroscopy, x-ray magnetic circular dichroism (XMCD), density-functional theory, and crystal field multiplet calculations. All transition-metal moments saturate below 1 T, while the rare-earth moments do not saturate even at 5 T, consistent with van Vleck paramagnetic contributions and crystal field suppression. While the sum rules are widely used to extract element-specific magnetic moments from XMCD, we show that for 3d transition metals, their application requires accurate estimates of the number of unoccupied 3d states. We observe a finite magnetic moment on Ni, challenging the common assumption of its nonmagnetic character in Laves phases. The orbital magnetic moments were determined using the spin rules, while the spin moments were estimated from single-ion values from multiplet calculations, due to the invalidity of the spin sum rule for light rare-earth elements. The magnetic moments of Nd and Pr are found to be suppressed relative to their free-ion values, with multiplet theory indicating that this is due to crystal field effects. Our results confirm that Nd and Pr maintain localized 4f3 and 4f2 configurations, respectively, and that their element-specific magnetic moments are robust to rare-earth substitution. Ce, on the other hand, exhibits a tunable mixed-valent ground state with both magnetic 4f1 and nonmagnetic 4f0 components. The relative fraction of these states varies with the electronegativity of the surrounding 3d transition metals, revealing a pathway to tune Ce magnetism via composition. This work establishes a framework for accurately interpreting XMCD in light rare-earth-based intermetallics.
Materials Science (cond-mat.mtrl-sci)
Manuscript 11 pages, Supplemental 5 pages. Manuscript 7 figures, Supplemental 4 figures
Topological states and flat bands in exactly solvable decorated Cayley trees
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Wanda P. Duss, Askar Iliasov, Tomáš Bzdušek
We derive the full spectrum of decorated Cayley trees that constitute tree analogs of selected two-dimensional Euclidean lattices; namely of the Lieb, the double Lieb, the kagome, and the star lattice. The common feature of these Euclidean lattices is that their nearest-neighbor models give rise to flat energy bands interpretable through compact localized states. We find that the tree analogs exhibit similar flat or nearly flat energy bands at the corresponding energies. Interestingly, such flat bands in the decorated Cayley trees acquire an interpretation that is absent in their Euclidean counterparts: as edge states localized to the inner or the outer boundary of the tree branches. In particular, we establish an exact correspondence between the Lieb-Cayley tree and an ensemble of one-dimensional Su-Schrieffer-Heeger chains, which maps topological edge states on one side of the chains to flat-band states localized in the bulk of the tree, furnishing the flat energy band with a topological stability. Similar mapping to topological edge states or to states bound to edge defects in one-dimensional chains is shown for flat-band states in all the considered tree decorations. We finally show that the persistence of exact flat bands on infinite decorated trees (i.e., Bethe lattices) arises naturally from a covering interpretation of tree graphs. Our findings reveal a rich landscape of flat-band and topological phenomena in non-Euclidean systems, where geometry alone can generate and stabilize unconventional quantum states.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
29 pages, 24 figures + 8 pages of Supplemental Material
Multiple correlation lengths and type-1.5 superconductivity in $U(1)$ superconductors due to hidden competition between irreducible representations of nonlocal pairing
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-17 20:00 EST
Anton Talkachov, Paul Leask, Egor Babaev
A fundamental characteristic of a superconducting state is the coherence length $ \xi$ . Multicomponent superconductors, particularly ones breaking multiple symmetries, are characterized by multiple coherence lengths. Here we show that even, nominally $ single$ -component superconductors under certain conditions are characterized by multiple coherence lengths. We consider nearest-neighbor pairing interactions on a square lattice that leads to $ s$ -wave and $ d$ -wave representations of link superconducting order parameter. We show that even if the subdominant order parameter is completely suppressed in the ground state, it results in multiple correlation lengths with nontrivial hierarchy, resulting in important physical consequences in inhomogeneous solutions. Under certain conditions, this leads to type-1.5 superconductivity, where magnetic field penetration length falls between two coherence lengths, leading to vortex clustering in an external magnetic field.
Superconductivity (cond-mat.supr-con)
5 pages, 4 figures (Supplementary 11 pages, 4 figures)
Orbital Accumulation Induced by Chiral Phonons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Tetsuya Sato, Takeo Kato, Aurelien Manchon
We theoretically investigate orbital accumulation driven by chiral phonons via orbital-dependent electron-lattice coupling. We derive a formula for the orbital accumulation induced by classical lattice dynamics or nonequilibrium phonons, using the Berry curvature, linear response theory, and the nonequilibrium Green’s function method. We show that chiral phonons primarily couple to orbital quadrupole moments and that static orbital dipole accumulation can be generated in the second-order of lattice displacement. Our study provides a useful method for generating orbital accumulation without using spin-orbit interaction.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
20 pages, 4 figures
Impact of spin-orbit coupling and Zeeman interaction on the subharmonic gap structure due to multiple Andreev reflections in nanoscopic Josephson junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
D. Kuiri, J. H. Correa, A. Biborski, M. P. Nowak
Multiple Andreev reflections in voltage-biased Josephson junctions give rise to the subharmonic gap structure in the conductance, which is widely used to characterize transport properties and estimate the induced gap in the junctions. Here we theoretically investigate the evolution of the subharmonic gap structure in spinful Josephson junctions. Spin mixing introduced by the spin-orbit coupling opens avoided crossings in the dispersion relation of the leads, which, as we demonstrate, subsequently results in pronounced multiple Andreev reflection features in the conductance traces. We analyze how these features evolve under an external magnetic field and explain that their visibility in conductance is governed by the spin polarization of the bands.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Interpretable descriptors enable prediction of hydrogen-based superconductors at moderate pressures
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-17 20:00 EST
Jiawei Chen, Junhao Peng, Yanwei Liang, Renhai Wang, Huafeng Dong, Wei Zhang
Room temperature superconductivity remains elusive, and hydrogen-base compounds despite remarkable transition temperatures(Tc) typically require extreme pressures that hinder application. To accelerate discovery under moderate pressures, an interpretable framework based on symbolic regression is developed to predict Tc in hydrogen-based superconductors. A key descriptor is an integrated density of states (IDOS) within 1 eV of the Fermi level (EF), which exhibits greater robustness than conventional single-point DOS features. The resulting analytic model links electronic-structure characteristics to superconducting performance, achieves high accuracy (RMSEtrain = 20.15 K), and generalizes well to external datasets. By relying solely on electronic structure calculations, the approach greatly accelerates materials screening. Guided by this model, four hydrogen-based candidates are identified and validated via calculation: Na2GaCuH6 with Tc =42.04 K at ambient pressure (exceeding MgB2), and NaCaH12, NaSrH12, and KSrH12 with Tc up to 162.35 K, 86.32 K, and 55.13 K at 100 GPa, 25 GPa, and 25 GPa, respectively. Beyond rapid screening, the interpretable form clarifies how hydrogen-projected electronic weight near EF and related features govern Tc in hydrides, offering a mechanism-aware route to stabilize high-Tc phases at reduced pressures.
Superconductivity (cond-mat.supr-con), Computational Physics (physics.comp-ph)
6 pages, 4 figures
Scaling of free cumulants in closed system-bath setups
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-17 20:00 EST
Merlin Füllgraf, Jochen Gemmer, Jiaozi Wang
The Eigenstate Thermalization Hypothesis (ETH) has been established as a cornerstone for understanding thermalization in quantum many-body systems. Recently, there has been growing interest in the full ETH, which extends the framework of the conventional ETH and postulates a smooth function to describe the multi-point correlations among matrix elements. Within this framework, free cumulants play a central role, and most previous studies have primarily focused on closed systems. In this paper, we extend the analysis to a system-bath setup, considering both an idealized case with a random-matrix bath and a more realistic scenario where the bath is modeled as a defect Ising chain. In both cases, we uncover a universal scaling of microcanonical free cumulants of system observables with respect to the interaction strength. Furthermore we establish a connection between this scaling behavior and the thermalization dynamics of the thermal free cumulants of corresponding observables.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
15 pages, 6 figures
Fokker-Planck approach for thermal fluctuations in antiferromagnetic systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
E. Martello, G. A. Falci, E. Paladino, F. M. D. Pellegrino
We develop a Fokker-Planck approach to describe the dynamics of staggered magnetization and thermal fluctuations in a two-dimensional antiferromagnetic system with uniaxial anisotropy. Beginning with a classical model for the antiferromagnetic system, we incorporate a Landau-Lifshitz-Gilbert equation augmented by Langevin fields to account for thermal fluctuations, and we derive the Fokker-Planck equation governing the probability distribution function of the spin configuration. Employing the mean-field approximation, we derive the equations of motion for the spin polarization and the two-time spin-spin correlation functions. The methodology is applied to the study of spin-wave dynamics and to the formulation of a phenomenological model for resistance fluctuations in two-dimensional antiferromagnetic semiconductors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
20 pages, 4 figures
Wiener-Hopf factorization and non-Hermitian topology for Amoeba formulation in one-dimensional multiband systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
The non-Hermitian skin effect (NHSE), characterized by the extensive localization of bulk modes at the boundaries, has attracted significant attention as a hallmark feature of non-Hermitian topology. This localization invalidates the conventional Bloch band theory, necessitating an analysis under open boundary conditions even in the thermodynamic limit. The Amoeba formulation addresses this challenge by computing the spectral potential rather than the spectrum itself. Based on the (strong) Szegö limit theorem and its topological generalization, this approach reduces the evaluation of the potential to an optimization problem involving the Ronkin function. However, while the generalized Szegö limit theorem is formally applicable in arbitrary dimensions, its implementation is limited to single-band systems, and its applicability to multiband systems remains unclear. In this paper, we establish the Wiener-Hopf factorization (WHF) of the non-Bloch Hamiltonian as a powerful framework, providing a unified and rigorous foundation for Amoeba analysis in multiband systems. By combining the WHF with Hermitian doubling, we first elucidate the applicability criteria for the generalized Szegö limit theorem in multiband systems. We then show that the WHF provides the natural mathematical origin for the symmetry-decomposed Ronkin function in symmetry class AII$ ^\dagger$ , leading to a rigorous proof of the generalized Szegö limit theorem for these systems and opening a path toward systematic generalizations to other symmetry classes.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
21 pages, 13 figures
Interlinking helical spin textures in nanopatterned chiral magnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Luke Alexander Turnbull, Max Thomas Birch, Marisel Di Pietro Martínez, Rikako Yamamoto, Jeffrey Neethirajan, Marina Raboni Ferreira, Elina Zhakina, Hayden Jeffrey Binger, Young-Gwan Choi, Rachid Belkhou, Simone Finizio, Markus Weigand, Dieter Suess, Daniel Alexander Mayoh, Geetha Balakrishnan, Claas Abert, Sebastian Wintz, Claire Donnelly
Nanoscale topologically non-trivial magnetization configurations generate significant interest due to both the fundamental properties of their knotted structures and their potential applications in ultra-efficient computing devices. While such textures have been widely studied in two dimensions, three-dimensional (3D) systems can yield more complex configurations, resulting in richer topologies and dynamic behaviors. However, reliably nucleating these 3D textures has proven challenging, and so far, 3D configurations such as vortex rings and hopfions can often only be observed forming spontaneously in relatively uncontrolled manners. Here, we demonstrate that through the 3D nanopatterning of chiral single crystal helimagnets into nano-tori, the controlled formation of a magnetic double helix can be achieved. This surface-localized topological state is stabilized by the interplay of intrinsic exchange interactions of the single crystal with the extrinsic emergent effects of the patterned geometry. These double helices host magnetic defects akin to supercoiling in circular DNA and climbing vines. We expect this study to serve as a foundation for future research combining single crystal systems with 3D nanopatterning, offering a new degree of control over emergent phenomena in nanoscale magnets and wider quantum material systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Relaxation to an Ideal Chern Band through Coupling to a Markovian Bath
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
We propose a microscopic, weak-coupling mechanism by which generic Chern bands relax toward ideal bands. We consider coupling interacting electrons to a Caldeira-Leggett like Ohmic bosonic bath. Using the Born-Markov approximation, Slater determinant states of a Chern band under Hartree-Fock approximation evolve toward Slater determinant states corresponding to an ideal Chern band. We validate our proposal by performing numerical simulation of a massive Dirac model, showing that the Berry curvature and quantum metric indeed co-evolve to saturate the trace condition. Our proposal provides a concrete dissipative route to realize ideal Chern bands, a fundamental building block for the stabilization of fractional Chern insulators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), Mathematical Physics (math-ph)
18 pages (including Appendix), 3 figures
Metavalent Bonding-Induced Phonon Hardening and Giant Anharmonicity in BeO
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Xuejie Li, Yuzhou Hao, Yujie Liu, Shengying Yue, Xiaolong Yang, Turab Lookman, Xiangdong Ding, Jun Sun, Zhibin Gao
The search for materials with intrinsically low thermal conductivity ($ \kappa_L$ ) is critical for energy applications, yet conventional descriptors often fail to capture the complex interplay between bonding and lattice dynamics. Here, first-principles calculations are used to contrast the thermal transport in covalent zincblende (zb) and metavalent rocksalt (rs) BeO. We find that the metavalent bonding in rs-BeO enhances lattice anharmonicity, activating multi-phonon scattering channels and suppressing phonon transport. This results in an ultralow $ \kappa_L$ of 24 W m$ ^{-1}$ K$ ^{-1}$ at 300 K, starkly contrasting with the zb phase (357 W m$ ^{-1}$ K$ ^{-1}$ ). Accurately modeling such strongly anharmonic systems requires explicit inclusion of temperature-dependent phonon renormalization and four-phonon scattering. These contributions, negligible in zb-BeO, are essential for high-precision calculations of the severely suppressed $ \kappa_L$ in rs-BeO. Finally, we identify three key indicators to guide the discovery of metavalently bonded, incipient-metallic materials: (i) an NaCl-type crystal structure, (ii) large Grüneisen parameters ($ \textgreater$ 2), and (iii) a breakdown of the Lyddane-Sachs-Teller relation. These findings provide microscopic insight into thermal transport suppression by metavalent bonding and offer a predictive framework for identifying promising thermoelectrics and phase-change materials.
Materials Science (cond-mat.mtrl-sci)
ARPES signatures of trions in van der Waals materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Giuseppe Meneghini, Maja Löwe, Raul Perea-Causin, Jan Philipp Bange, Wiebke Bennecke, Marcel Reutzel, Stefan Mathias, Ermin Malic
Angle-resolved photoemission spectroscopy (ARPES) has recently emerged as a direct probe of excitonic correlations in two-dimensional semiconductors, resolving their dispersion and dynamics in energy-momentum space, including dark exciton states inaccessible to optical techniques. However, the ARPES fingerprint of charged excitons (trions), which plays a key role in all doped and gated 2D material systems, has remained unknown so far. We present a first theoretical analysis of trion signatures in monolayer transition-metal dichalcogenides, highlighting how the additional charge carrier modifies the spectral position and shape relative to neutral excitons in ARPES spectra. Interestingly, we further predict that mass-imbalanced trions yield a characteristic double-peak structure, clearly separated in energy and line shape from neutral excitons. The predicted temperature dependence of these features offers guidance for experimental investigations aimed at identifying trionic states, thereby establishing a framework for ARPES studies of many-body Coulomb complexes in doped two-dimensional semiconductors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Theoretical study of orbital torque: Dependence on ferromagnet species and nonmagnetic layer thickness
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
The manipulation of magnetization in ferromagnetic metals (FMs) through orbital torque (OT) has emerged as a promising route for energy-efficient magnetic devices without relying on heavy metals. While Ti and Cu are among the most extensively studied light nonmagnetic metals (NMs) for OT devices, theoretical calculations of the resulting torque have remained limited. Here, we present a systematic and quantitative theoretical study of current-induced torques in Ti/FM and Cu/FM (FM = Co, Ni) bilayers using semi-realistic tight-binding models derived from ab initio electronic structures. We find that the torque in Ti/FM is larger for Ni than for Co, but this trend does not necessarily hold in Cu/FM, revealing that the FM dependence of OT is not universal but varies with the orbital current source. Moreover, the dependence of OT on NM thickness clearly indicates its NM bulk origin in both Ti- and Cu-based systems. Notwithstanding, the quantitative characteristics of OT cannot be explained by a simplified picture based on the individual bulk properties of the NM or FM layers. These results provide microscopic insight and practical guidance for designing light-metal-based orbitronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 5 figures
Visible and Terahertz Nonlinear Responses in the Topological Noble Metal Dichalcogenide PdTe2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
George J. de Coster, Lucas Lafeta, Stefan Heiserer, Cormac Ó Coileáin, Zdenek Sofer, Achim Hartschuh, Georg S. Duesberg, Paul Seifert
Nonlinear processes can offer pathways to next-generation sensors and frequency mixing devices to overcome modern imaging, detection, and communication challenges. In this article, we report on strong second and third-order nonlinear optical responses in visible and terahertz (THz) light in single crystals of the noble metal dichalcogenide PdTe2. We find that buried conduction and valence topological surface states of PdTe2 lead to resonant enhancement of optical second-harmonic generation. On the other hand, although the nonlinear responses obtained with THz excitation are not close to this resonance, they can be clearly observed in reflection geometry, even in the presence of broadband excitation, where optical filters are not necessary to observe the odd-order higher harmonic gain. By carefully considering the radiative photocurrent framework of stimulated THz emission, we are able to extract fingerprints of both second- and third-order processes in the THz regime, and show that PdTe2 is a promising material candidate for radio frequency rectification, frequency mixing, and beam focusing.
Materials Science (cond-mat.mtrl-sci)
10 pages, 6 figures
RF-Squad: A radiofrequency simulator for quantum dot arrays
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Tara Murphy, Katarina Brlec, Giovanni Oakes, Lorenzo Peri, Henning Sirringhaus, Henry Moss, M. Fernando Gonzalez Zalba, David Wise
Spins in semiconductor quantum dots offer a scalable approach to quantum computing; however, precise control and efficient readout of large quantum dot arrays remain challenging, mainly due to the hyperdimensional voltage space required for tuning multiple gates per dot. To automate this process, large datasets are required for testing and training autotuning algorithms. To address the demand for such large datasets, we introduce RF-Squad, a physics-based simulator designed to realistically replicate radiofrequency (RF) reflectometry measurements of quantum dot arrays, with the ability to go beyond the Constant Interaction Model (CIM) and simulate physical phenomena such as tunnel coupling, tunnel rates, and quantum confinement. Implemented in JAX, an accelerated linear algebra library, RF-Squad achieves high computational speed, enabling the simulation of a 100x100 pixel charge stability diagram of a double quantum dot (DQD) in 52.1 $ \pm$ 0.2 milliseconds at the CIM level. Using optimization algorithms, combined with it’s layered architecture, RF-Squad allows users to balance physical accuracy with computational speed, scaling from simple to highly detailed models.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
The Interoperability Challenge in DFT Workflows Across Implementations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
S. K. Steensen, T. S. Thakur, M. Dillenz, J. M. Carlsson, C. R. C. Rego, E. Flores, H. Hajiyani, F. Hanke, J. M. G. Lastra, W. Wenzel, N. Marzari, T. Vegge, G. Pizzi, I. E. Castelli
Interoperability and cross-validation remains a significant challenge in the computational materials discovery community. In this context, we introduce a common input/output standard designed for internal translation by various workflow managers (AiiDA, PerQueue, Pipeline Pilot, and SimStack) to produce results in a unified schema. This standard aims to enable engine-agnostic workflow execution across multiple density functional theory (DFT) codes, including CASTEP, GPAW, Quantum ESPRESSO, and VASP. As a demonstration, we have implemented a workflow to calculate the open-circuit voltage across several battery cathode materials using the proposed universal input/output schema. We analyze and resolve the challenges of reconciling energetics computed by different DFT engines and document the code-specific idiosyncrasies that make straightforward comparisons difficult. Motivated by these challenges, we outline general design principles for robust automated DFT workflows. This work represents a practical step towards more reproducible and interoperable workflows for high-throughput materials screening, while highlighting challenges of aligning electronic properties, especially for non-pristine structures.
Materials Science (cond-mat.mtrl-sci)
STEM EBIC as a Quantitative Probe of Semiconductor Devices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-17 20:00 EST
Sebastian Schneider, Sebastian Beckert, René Hammer, Markus König, Grigore Moldovan, Darius Pohl
Electron beam-induced current (EBIC) imaging in the scanning transmission electron microscope (STEM), STEM-EBIC, provides direct access to carrier transport at the nanoscale. While well established in bulk SEM geometries, its application to thin TEM lamellae remains largely unexplored. Here, we present a systematic STEM-EBIC study of silicon photodiode lamellae prepared by gallium and xenon focused ion beam (FIB) milling. We directly visualize the p-n junctions in thin cross sections and extract effective diffusion lengths for electrons and holes as a function of local thickness. The values are orders of magnitude smaller than those obtained by SEM-EBIC on bulk silicon, reflecting pronounced surface recombination and FIB-induced surface modifications. Current-voltage measurements further reveal severe deviations from the expected diode-like behavior, which we attribute to ohmic metal-semiconductor contacts in the emasurement setup. Our analysis establishes STEM-EBIC as a quantitative probe of carrier transport in nanoscale devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Stable Quantum Vortices in Lee-Huang-Yang Dipolar Superfluids
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-11-17 20:00 EST
S. Sabari, R. Radha, Lauro Tomio, B. A. Malomed
The nucleation and dynamics of vortices in the quasi-two-dimensional rotating dipolar Bose-Einstein condensate are explored by taking into account the Lee-Huang-Yang (LHY) correction to the mean-field (MF) theory. Assuming approximate cancellation of the MF interactions, we focus on the formation of a pure LHY superfluid. The effect of rotational frequency $ \Omega $ is investigated numerically by determining the corresponding number of stable vortices in the superfluid, together with the respective energy per particle $ E$ and chemical potential $ \mu $ . The LHY superfluid provides a deep minimum of $ E$ and $ \mu $ , indicating that it is a remarkably robust state of quantum matter. By fixing the LHY interaction strength, an exact single-vortex critical frequency is found, along with the respective chemical potential. A notable feature, observed when creating the LHY superfluid with fewer than five vortices, which is understood as being due to the superfluid’s nonlinearity and trapping aspect ratio, is the large frequency ranges admitting the production of two and four vortices, as compared to the small frequency ranges to obtain one and three vortices.
Quantum Gases (cond-mat.quant-gas)
13 pages, 11 figuea
Coherent-state path integrals in quantum thermodynamics
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-11-17 20:00 EST
Luca Salasnich, Cesare Vianello
In these notes, we elucidate some subtle aspects of coherent-state path integrals, focusing on their application to the equilibrium thermodynamics of quantum many-particle systems. These subtleties emerge when evaluating path integrals in the continuum, either in imaginary time or in Matsubara-frequency space. Our central message is that, when handled with due care, the path integral yields results identical to those obtained from the canonical Hamiltonian approach. We illustrate this through a pedagogical treatment of several paradigmatic systems: the bosonic and fermionic harmonic oscillators, the single-site Bose-Hubbard and Hubbard models, the weakly-interacting Bose gas with contact and finite-range interactions, and the BCS superconductor with contact and finite-range interactions.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Superconductivity (cond-mat.supr-con)
Lecture notes, 42 pages
Human-AI collaborative autonomous synthesis with pulsed laser deposition for remote epitaxy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-17 20:00 EST
Asraful Haque, Daniel T. Yimam, Jawad Chowdhury, Ralph Bulanadi, Ivan Vlassiouk, John Lasseter, Sujoy Ghosh, Christopher M. Rouleau, Kai Xiao, Yongtao Liu, Eva Zarkadoula, Rama K. Vasudevan, Sumner B. Harris
Autonomous laboratories typically rely on data-driven decision-making, occasionally with human-in-the-loop oversight to inject domain expertise. Fully leveraging AI agents, however, requires tightly coupled, collaborative workflows spanning hypothesis generation, experimental planning, execution, and interpretation. To address this, we develop and deploy a human-AI collaborative (HAIC) workflow that integrates large language models for hypothesis generation and analysis, with collaborative policy updates driving autonomous pulsed laser deposition (PLD) experiments for remote epitaxy of BaTiO$ _3$ /graphene. HAIC accelerated the hypothesis formation and experimental design and efficiently mapped the growth space to graphene-damage. In situ Raman spectroscopy reveals that chemistry drives degradation while the highest energy plume components seed defects, identifying a low-O$ _2$ pressure low-temperature synthesis window that preserves graphene but is incompatible with optimal BaTiO$ _3$ growth. Thus, we show a two-step Ar/O$ _2$ deposition is required to exfoliate ferroelectric BaTiO$ _3$ while maintaining a monolayer graphene interlayer. HAIC stages human insight with AI reasoning between autonomous batches to drive rapid scientific progress, providing an evolution to many existing human-in-the-loop autonomous workflows.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI)