CMP Journal 2025-09-23
Statistics
Nature: 1
Nature Materials: 1
Nature Physics: 1
Physical Review Letters: 20
arXiv: 101
Nature
A multimodal robotic platform for multi-element electrocatalyst discovery
Original Paper | Electrocatalysis | 2025-09-22 20:00 EDT
Zhen Zhang, Zhichu Ren, Chia-Wei Hsu, Weibin Chen, Zhang-Wei Hong, Chi-Feng Lee, Aubrey Penn, Hongbin Xu, Daniel J. Zheng, Shuhan Miao, Yimeng Huang, Yifan Gao, Weiyin Chen, Hugh Smith, Yaoshen Niu, Yunsheng Tian, Ying-Rui Lu, Yu-Cheng Shao, Sipei Li, Hsiao-Tsu Wang, Iwnetim I. Abate, Pulkit Agrawal, Yang Shao-Horn, Ju Li
One of the goals of ‘AI for Science’ is to discover customized materials through real-world experiments. Pioneering advances have been achieved in computational predictions and the automation of materials synthesis1-7. Yet, most materials experimentation remains constrained to using unimodal active learning (AL) approaches, relying on a single data stream. The potential of AI to interpret experimental complexity remains largely untapped8,9. Here we present Copilot for Real-world Experimental Scientists (CRESt), a platform that integrates large multimodal models (LMMs, incorporating chemical compositions, text embeddings, and microstructural images) with Knowledge-Assisted Bayesian Optimization (KABO) and robotic automation. CRESt employs knowledge-embedding-based search space reduction and adaptive exploration-exploitation strategy to accelerate materials design, high-throughput synthesis and characterization, and electrochemical performance optimization. CRESt allows monitoring with cameras and vision-language-model-driven hypothesis generation to diagnose and correct experimental anomalies. Applied to electrochemical formate oxidation, CRESt explored over 900 catalyst chemistries and 3500 electrochemical tests within 3 months, identifying a state-of-the-art catalyst in the octonary chemical space (Pd-Pt-Cu-Au-Ir-Ce-Nb-Cr) which exhibits a 9.3-fold improvement in cost-specific performance.
Electrocatalysis, Fuel cells
Nature Materials
Stabilized perovskite phases enabling efficient perovskite/perovskite/silicon triple-junction solar cells
Original Paper | Electronic devices | 2025-09-22 20:00 EDT
Fuzong Xu, Erkan Aydin, Ilhan Yavuz, Caner Deger, Esma Ugur, Jiang Liu, Xuechun Zhang, Arsalan Razzaq, Lujia Xu, Marco Marengo, Badri Vishal, Adi Prasetio, Anand Subbiah, Anil Pininti, Thomas Allen, Stefaan De Wolf
Perovskite/perovskite/silicon triple-junction solar cells offer notable potential for high power output at low cost, yet their development is hindered by the phase instability of perovskites, which limits both device reproducibility and performance. The ~1.50-eV formamidinium lead triiodide (FAPbI3)-based middle layer degrades during subsequent fabrication steps, and the ~2.0-eV bromide-rich top layer suffers from light-induced phase segregation. Here we address these challenges by introducing ammonium propionic acid to enhance the phase stability in both perovskite layers. This strategy raises the phase transition energy barrier and suppresses vacancy defect formation through additional bonding with lattice cations. These improvements mitigate phase instabilities and enhance the power conversion efficiency of devices based on the modified perovskite films. As a result, perovskite/perovskite/silicon triple-junction solar cells achieve a power conversion efficiency of 28.7% on a 1-cm2 aperture area, with substantially improved reproducibility.
Electronic devices, Solar cells
Nature Physics
Universal anyon tunnelling in a chiral Luttinger liquid
Original Paper | Matter waves and particle beams | 2025-09-22 20:00 EDT
Ramon Guerrero-Suarez, Adithya Suresh, Tanmay Maiti, Shuang Liang, James Nakamura, Geoffrey Gardner, Claudio Chamon, Michael Manfra
The edge modes of fractional quantum Hall liquids are described by chiral Luttinger liquid theory. Despite many years of experimental investigation, fractional quantum Hall edge modes are not fully understood, and clear discrepancies between experimental observations and detailed predictions of chiral Luttinger liquid theory remain. Here we report the measurements of tunnelling conductance between counterpropagating edge modes at a filling factor of 1/3 across a quantum point contact. We present evidence for the tunnelling of anyons through an incompressible liquid that exhibits universal scaling behaviour with respect to temperature, source-drain bias and barrier transmission, as originally proposed by prior theoretical work. For large transmission through the quantum point contact, we measured the tunnelling exponent (\bar{g}=0.333\pm 0.005) averaged over 29 independent datasets, consistent with the scaling dimension of 1/6 for a Laughlin quasiparticle at the edge. When combined with the measurements of the fractional charge and the recently observed anyonic statistical angle, the measured tunnelling exponent fully characterizes the topological order of the primary Laughlin state at the filling factor of 1/3.
Matter waves and particle beams, Quantum Hall
Physical Review Letters
Trotterization is Substantially Efficient for Low-Energy States
Article | Quantum Information, Science, and Technology | 2025-09-23 06:00 EDT
Kaoru Mizuta and Tomotaka Kuwahara
Trotterization is one of the central approaches for simulating quantum many-body dynamics on quantum computers or tensor networks. In addition to its simple implementation, recent studies have revealed that its error and cost can be reduced if the initial state is closed in the low-energy subspace. …
Phys. Rev. Lett. 135, 130602 (2025)
Quantum Information, Science, and Technology
Quantum-Optimal Frequency Estimation of Stochastic ac Fields
Article | Quantum Information, Science, and Technology | 2025-09-23 06:00 EDT
Anirban Dey, Sara Mouradian, Cosmo Lupo, and Zixin Huang
Resolving frequencies in a time-dependent field is classically limited by the measurement bandwidth. Using tools from quantum metrology and quantum control may overcome this limit, yet the full advantage afforded by entanglement so far remains elusive. Here we map the problem of frequency measuremen…
Phys. Rev. Lett. 135, 130802 (2025)
Quantum Information, Science, and Technology
Unraveling Dicke Superradiant Decay with Separable Coherent Spin States
Article | Atomic, Molecular, and Optical Physics | 2025-09-23 06:00 EDT
P. Rosario, L. O. R. Solak, A. Cidrim, R. Bachelard, and J. Schachenmayer
Scientists have shown that entanglement plays no role in a form of collective light emission called Dicke superradiance, settling a long-standing debate.
Phys. Rev. Lett. 135, 133602 (2025)
Atomic, Molecular, and Optical Physics
Toward Chaotic Group Velocity Hopping of an On-Chip Dissipative Kerr Soliton
Article | Atomic, Molecular, and Optical Physics | 2025-09-23 06:00 EDT
Grégory Moille, Sashank Kaushik Sridhar, Pradyoth Shandilya, Avik Dutt, Curtis Menyuk, and Kartik Srinivasan
Chaos enables randomness-based applications, particularly in photonic systems. Integrated optical frequency combs (microcombs) have previously been observed in either chaotic modulation instability or stable, low-noise dissipative Kerr soliton (DKS) regimes. In this Letter, we demonstrate a new micr…
Phys. Rev. Lett. 135, 133802 (2025)
Atomic, Molecular, and Optical Physics
Revealing Band-Hybrid Cooper Pairs on the Surface of a Superconductor with Spin-Orbit Coupling
Article | Condensed Matter and Materials | 2025-09-23 06:00 EDT
Javier Zaldívar, Jon Ortuzar, Miguel Alvarado, Stefano Trivini, Julie Baumard, Carmen Rubio-Verdú, Edwin Herrera, Hermann Suderow, Alfredo Levy Yeyati, F. Sebastian Bergeret, and Jose Ignacio Pascual
Most superconductors exhibit spin-singlet pairing within a single band. In multiband systems with strong spin-orbit coupling, more exotic scenarios can emerge, including Cooper pairs between bands with distinct symmetries. Here, we present evidence of the formation of Cooper pairs between spin-nonde…
Phys. Rev. Lett. 135, 136201 (2025)
Condensed Matter and Materials
Brillouin Platycosms and Topological Phases
Article | Condensed Matter and Materials | 2025-09-23 06:00 EDT
Chen Zhang, Peiyuan Wang, Junkun Lyu, and Y. X. Zhao
There exist ten distinct closed flat 3D manifolds, known as "platycosms," that hold significance in mathematics and have been postulated as potential geometric models for our Universe. In this Letter, we demonstrate their manifestation as universes of Bloch particles, namely as momentum-space units …
Phys. Rev. Lett. 135, 136601 (2025)
Condensed Matter and Materials
Universal Bounds for Quantum Metrology in the Presence of Correlated Noise
Article | Quantum Information, Science, and Technology | 2025-09-22 06:00 EDT
Stanisław Kurdziałek, Francesco Albarelli, and Rafał Demkowicz-Dobrzański
We derive fundamental bounds for general quantum metrological models involving both temporal or spatial correlations (mathematically described by quantum combs), which may be effectively computed in the limit of a large number of probes or sensing channels involved. Although the bounds are not guara…
Phys. Rev. Lett. 135, 130801 (2025)
Quantum Information, Science, and Technology
Emergence of Unitarity and Locality from Hidden Zeros at One-Loop Order
Article | Particles and Fields | 2025-09-22 06:00 EDT
Jeffrey V. Backus and Laurentiu Rodina
Recent investigations into the geometric structure of scattering amplitudes have revealed the surprising existence of "hidden zeros": secret kinematic loci where tree-level amplitudes in theory, the nonlinear sigma model (NLSM), and Yang-Mills theory vanish. In this Letter, we propose the ext…
Phys. Rev. Lett. 135, 131601 (2025)
Particles and Fields
Search for a Dark Higgs Boson Produced in Association with Inelastic Dark Matter at the Belle II Experiment
Article | Particles and Fields | 2025-09-22 06:00 EDT
I. Adachi et al. (The Belle II Collaboration)
A search for a dark Higgs boson produced in association with inelastic dark matter results in significant new bounds on the scenario.
Phys. Rev. Lett. 135, 131801 (2025)
Particles and Fields
Muon-Decay Parameters from COHERENT
Article | Particles and Fields | 2025-09-22 06:00 EDT
Víctor Bresó-Pla, Sergio Cruz-Alzaga, Martín González-Alonso, and Suraj Prakash
We demonstrate that measurements of coherent elastic neutrino-nucleus scattering at spallation sources are valuable probes of muon-decay physics. Using COHERENT data we derive the first direct constraint on the Michel parameters governing the energy distribution. We also discuss future sensitivi…
Phys. Rev. Lett. 135, 131802 (2025)
Particles and Fields
QCD Theory Meets Information Theory
Article | Particles and Fields | 2025-09-22 06:00 EDT
Benoît Assi, Stefan Höche, Kyle Lee, and Jesse Thaler
We present a novel technique to incorporate precision calculations from quantum chromodynamics into fully differential particle-level Monte Carlo simulations. By minimizing an information-theoretic quantity subject to constraints, our reweighted Monte Carlo incorporates systematic uncertainties abse…
Phys. Rev. Lett. 135, 131901 (2025)
Particles and Fields
Precision Measurement of Spin-Dependent Dipolar Splitting in $^{6}\mathrm{Li}$ $p$-Wave Feshbach Resonances
Article | Atomic, Molecular, and Optical Physics | 2025-09-22 06:00 EDT
Shuai Peng, Sijia Peng, Lijun Ren, Shaokun Liu, Bin Liu, Jiaming Li, and Le Luo
The magnetic dipolar splitting of a -wave Feshbach resonance is governed by the spin-orbital configuration of the valence electrons in the triplet molecular state. We perform high-resolution trap-loss spectroscopy on ultracold atoms to resolve this splitting with sub-milligauss precision. By co…
Phys. Rev. Lett. 135, 133401 (2025)
Atomic, Molecular, and Optical Physics
Spontaneous Emission Decay and Excitation in Photonic Time Crystals
Article | Atomic, Molecular, and Optical Physics | 2025-09-22 06:00 EDT
Jagang Park, Kyungmin Lee, Ruo-Yang Zhang, Hee-Chul Park, Jung-Wan Ryu, Gil Young Cho, Min Yeul Lee, Zhaoqing Zhang, Namkyoo Park, Wonju Jeon, Jonghwa Shin, C. T. Chan, and Bumki Min
A material whose dielectric properties vary in time could produce exotic light-emission phenomena in a nearby atom, theorists predict.
Phys. Rev. Lett. 135, 133801 (2025)
Atomic, Molecular, and Optical Physics
Turbulence without Walls: Whither the Zeroth Law of Turbulence?
Article | Physics of Fluids, Earth & Planetary Science, and Climate | 2025-09-22 06:00 EDT
Kartik P. Iyer, Theodore D. Drivas, Gregory L. Eyink, and Katepalli R. Sreenivasan
Direct numerical simulations of incompressible homogeneous and isotropic turbulence in a periodic box show that the mean dissipation rate of the kinetic energy approaches zero as the Reynolds number goes to infinity, violating the classical zeroth law of turbulence but compatible with the Kolmogorov 4/5 law.
Phys. Rev. Lett. 135, 134001 (2025)
Physics of Fluids, Earth & Planetary Science, and Climate
New Pathway to Impact Ionization in a Photoexcited One-Dimensional Ionic Hubbard Model
Article | Condensed Matter and Materials | 2025-09-22 06:00 EDT
Zhenyu Cheng, Li Yang, Xiang Hu, Hantao Lu, Zhongbing Huang, and Liang Du
Using the time-dependent Lanczos method, we study the nonequilibrium dynamics of the half-filled one-dimensional ionic Hubbard model, deep within the Mott insulating regime, under the influence of a transient laser pulse. In equilibrium, increasing the staggered potential in the Mott regime reduces …
Phys. Rev. Lett. 135, 136501 (2025)
Condensed Matter and Materials
Robust Triple-q Magnetic Order with Trainable Spin Vorticity in ${\mathrm{Na}}{2}{\mathrm{Co}}{2}{\mathrm{TeO}}_{6}$
Article | Condensed Matter and Materials | 2025-09-22 06:00 EDT
Xianghong Jin, Mengqiao Geng, Fabio Orlandi, Dmitry Khalyavin, Pascal Manuel, Yang Liu, and Yuan Li
Recent studies suggest that the candidate Kitaev magnet possesses novel triple- magnetic order instead of conventional single- zigzag order. Here we present dedicated experiments in a search for distinct properties expected of the triple- order, namely, insensitivity of the magnetic Br…
Phys. Rev. Lett. 135, 136701 (2025)
Condensed Matter and Materials
Large Magnetoresistance in an Electrically Tunable van der Waals Antiferromagnet
Article | Condensed Matter and Materials | 2025-09-22 06:00 EDT
Chung-Tao Chou, Eugene Park, Josep Ingla-Aynes, Julian Klein, Kseniia Mosina, Jagadeesh S. Moodera, Zdenek Sofer, Frances M. Ross, and Luqiao Liu
The interplay between magnetic order and electronic band structure in antiferromagnets has garnered increasing interest due to its potential for spintronic applications. While magnetic transitions have been shown to induce substantial band structure modifications in optical measurements, their influ…
Phys. Rev. Lett. 135, 136702 (2025)
Condensed Matter and Materials
Super-Resolved Anomalous Diffusion: Deciphering the Joint Distribution of Anomalous Exponent and Diffusion Coefficient
Article | Statistical Physics; Classical, Nonlinear, and Complex Systems | 2025-09-22 06:00 EDT
Yann Lanoiselée, Gianni Pagnini, and Agnieszka Wyłomańska
The molecular motion in heterogeneous media displays anomalous diffusion by the mean-squared displacement . Motivated by experiments reporting populations of the anomalous diffusion parameters and , we aim to disentangle their respective contributions to the observed variability when …
Phys. Rev. Lett. 135, 137101 (2025)
Statistical Physics; Classical, Nonlinear, and Complex Systems
Entropic Modulation of Divalent Cation Transport
Article | Polymers, Chemical Physics, Soft Matter, and Biological Physics | 2025-09-22 06:00 EDT
Yechan Noh, Demian Riccardi, and Alex Smolyanitsky
Aqueous cations permeate subnanoscale pores by crossing free energy barriers dominated by competing enthalpic contributions from transiently decreased ion-solvent and increased ion-pore electrostatic interactions. This commonly accepted view is rooted in the studies of monovalent cation transport. D…
Phys. Rev. Lett. 135, 138001 (2025)
Polymers, Chemical Physics, Soft Matter, and Biological Physics
Efficient Microcanonical Histogram Analysis and Application to Peptide Aggregation
Article | Polymers, Chemical Physics, Soft Matter, and Biological Physics | 2025-09-22 06:00 EDT
Michael Bachmann
A new, general method for identifying and classifying phase transitions is applied to the aggregation transition in GNNQQNY heptapeptides.
Phys. Rev. Lett. 135, 138401 (2025)
Polymers, Chemical Physics, Soft Matter, and Biological Physics
arXiv
Facile Synthesis and On-Chip Color Tuning of CsPbBr${3}$@CsPbBr${3-x}$TFA$_{x}$ Nanoplatelets via Ion Engineering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Sana Khan, Saeed Goudarzi, Stephan Schäffer, Lars Sonneveld, Bart Macco, Ke Ran, Naho Kurahashi, Peter Haring Bolívar, Bruno Ehrler, Thomas Riedl, Gerhard Müller-Newen, Surendra. B. Anantharaman, Maryam Mohammadi, Max. C. Lemme
Metal halide perovskites (MHPs) have emerged as attractive optoelectronic materials because of high fluorescence quantum yield, broad color tunability, and excellent color purity. However, the ionic nature of MHPs makes them susceptible to polar solvents, leading to defect-induced nonradiative recombination and photoluminescence (PL) quenching. Here, we present a combined in-synthesis ($ \textit{in situ}$ ) and post-synthesis ion engineering to suppress nonradiative recombination and integrate multicolor MHP arrays on-chip through a perovskite-compatible photolithography process and $ \textit{in situ}$ vapor-phase anion exchange. CsPbBr$ _{3}$ @CsPbBr$ _{3-x}$ TFA$ _{x}$ nanoplatelets were grown on-chip via a single-step solution process incorporating trifluoroacetate (TFA$ ^{-}$ ) pseudohalides. X-ray photoelectron spectroscopy revealed that TFA$ ^{-}$ passivate uncoordinated Pb$ ^{2+}$ ions on nanoplatelet surface and suppresses the formation of metallic lead (Pb$ ^{0}$ ). This decreases the non-radiative recombination centers and yields a PL peak at 520 nm with a linewidth of 14.56$ % \pm$ 0.5 nm. The nanoplatelets were patterned via a top-down photolithography process and selectively masked with a PMMA/Al$ _{2}$ O$ _{3}$ stack to enable vapor-phase anion exchange. The PL peak shifted in the unmasked regions from 520 nm to 413 nm, resulting in distinct green and blue emission arrays. Our method enables the scalable fabrication of highly luminescent, two-color MHP arrays with tailored optical properties, advancing their integration into next-generation optoelectronic devices.
Materials Science (cond-mat.mtrl-sci)
38 pages
Asymptotically exact solution of the non-Hermitian disordered interacting Hatano-Nelson chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Valéria M. Mattiello, Victor L. Quito, Eduardo Miranda
We present an asymptotically exact solution of a paradigmatic non-Hermitian model: the disordered interacting fermionic Hatano-Nelson model, or equivalently, the non-Hermitian spin-1/2 XXZ model. We use a renormalization group method suited for disordered systems and show that non-Hermitian couplings are relevant perturbations to the Hermitian model, which ultimately leads to a quantum-to-classical crossover. The ground state of the model consists of a collection of strongly coupled pairs of spins of arbitrary size at random positions which, unlike the Hermitian case, do not form singlets, but a mixture of the singlet and the $ M=0$ triplet state. As a result, the magnetic susceptibility in the $ x,y$ -directions becomes negative and diverges at a finite small temperature. Additionally, in sharp contrast to the $ \ln(L)$ increase observed in disordered Hermitian chains, the entanglement entropy of a partition of size $ L$ saturates for large $ L$ , as the strongly coupled pairs become classical and stop contributing at large length scales.
Strongly Correlated Electrons (cond-mat.str-el), Disordered Systems and Neural Networks (cond-mat.dis-nn)
6 pages, 3 figures. Includes Supplemental Material (8 pages, 3 figures)
Berry Trashcan With Short Range Attraction:Exact $p_x+i p_y$ Superconductivity in Rhombohedral Graphene
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-23 20:00 EDT
Ming-Rui Li, Yves H. Kwan, Hong Yao, B. Andrei Bernevig
We show the presence of analytic $ p_x + i p_y$ superconducting ground states in the Berry Trashcan – a minimal model of rhombohedral graphene valid for $ n \ge 4$ layers – under short-range attractive interactions. We demonstrate that the model, whose dispersion consists of a flat bottom surrounded by steep walls of prohibitive kinetic energy, serves as a building block to understand superconductivity in the moiré-free limit. We find that the ground-state chirality has a ``ferromagnetic’’ coupling to that of the uniform Berry curvature of the model, and compare the analytically obtained binding energies, excitation spectra and off-diagonal long-range order (ODLRO) with numerical exact diagonalization results. We show that the analytic structure of this model is that of a restricted spectrum generating algebra (RSGA), initially developed for quantum scars, and build a variety of other exact (but contrived) models with exact chiral superconductivity based on a method developed in Ref.[1]. However, under short range attraction, we show that the Berry Trashcan is the optimal and only realistic point in the class of GMP-like algebras to host a chiral superconductor state. A toy model in 1D and its related physics is also investigated. Our results reveal that chiral superconductivity is natural under attractive interactions in the Berry trashcan model of rhombohedral graphene in displacement field, although we make no claim about the origin of the attraction.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
5.5 pages, 5 figures in the main text, 57 pages, 16 figures in the Appendix
Supersonic flow and hydraulic jump in an electronic de Laval nozzle
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Johannes Geurs, Tatiana A. Webb, Yinjie Guo, Itai Keren, Jack H. Farrell, Jikai Xu, Kenji Watanabe, Takashi Taniguchi, Dmitri N. Basov, James Hone, Andrew Lucas, Abhay Pasupathy, Cory R. Dean
In very clean solid-state systems, where carrier-carrier interactions dominate over any other scattering mechanisms, the flow of electrons can be described within a hydrodynamic framework. In these cases, analogues of viscous fluid phenomena have been experimentally observed. However, experimental studies of electron hydrodynamics have so far been limited to the low velocity, linear response regime. At velocities approaching the speed of sound, the electronic fluid is expected to exhibit compressible behaviour where nonlinear effects and discontinuities such as shocks and choked flow have long been predicted. This compressible regime remains unexplored in electronic systems, despite its promise of strongly nonlinear flow phenomena. Here, we demonstrate compressible electron flow in bilayer graphene through an electronic de Laval nozzle, a structure that accelerates charge carriers past the electronic speed of sound, until they slow down suddenly in a shock. Discontinuities in transport measurements and local flattening of potential in Kelvin probe measurements are consistent with a viscous electron shock front and the presence of supersonic electron flow, and are not consistent with Ohmic or ballistic flow. Breaking the sound barrier in electron liquids opens the door for novel, intrinsically nonlinear electronic devices beyond the paradigm of incompressible flow.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Fractional topological insulators at odd-integer filling: Phase diagram of two-valley quantum Hall model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Sahana Das, Glenn Wagner, Titus Neupert
The fractional quantum Hall effect has recently been shown to exist in heterostructures of van der Waals materials without an externally applied magnetic field, e.g. in twisted bilayers of MoTe$ _2$ . These fractional Chern insulators break time-reversal symmetry spontaneously through polarization of the electron spins in a quantum spin Hall insulator band structure with flat bands. This prompts the question, which states could be realized if the spins remain unpolarized or polarize partially. Specifically, the possibility of time-reversal symmetric topological order arises. Here, we study this problem for odd integer filling of the bands, specifically focusing on vanishing and half valley polarization. Short of reliable microscopic models for small twist angles around $ 2.1^\circ$ , we study the idealized situation of two Landau levels with opposite chirality, the two-valley quantum Hall model. Using exact diagonalization, we identify different phases arising in this model by tuning the interaction. In the physically relevant regime, the system initially exhibits phase-separated or valley-polarized states, which eventually transition into paired states by reducing onsite Coulomb repulsion.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10+4 pages, 8+7 figures
Spin and Orbital Rashba response in ferroelectric polarized PtSe$_2$/MoSe$_2$/LiNbO$_3$ heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Armando Pezo, Sylvain Massabeau, Filip Miljević, Jing Li, Fatima Ibrahim, Matthieu Jamet, Mairbek Chshiev, Jean-Marie George, Henri Jaffrès
Recent studies using Terahertz Time-Domain Spectroscopy (THz-TDS) with spintronic emitters as a source have revealed distinct signatures of the Rashba effect. This effect, which arises from the breaking of inversion symmetry in low-dimensional materials, has been recently investigated in CoFeB/PtSe$ _2$ /MoSe$ _2$ /LiNbO$ _3$ -based heterostructures [S. Massabeau et al., APL Mater. 13, 041102, 2025 ]. The observed phenomena are at the source of the generated THz far-field emission, typically through mechanisms such as spin-to-charge conversion triggered by the absorption of ultrafast optical pulses. In this work, we employ first-principles simulations to quantify the Rashba effect at PtSe$ _2$ /MoSe$ _2$ /LiNbO$ _3$ interfaces, expanding the traditional understanding of spin transport by incorporating the orbital degree of freedom. Moreover, we quantify the degree of control on the THz emission depending on the polarization direction of LiNbO$ _3$ . In order to achieve this, we analyze the accumulation of both spin and orbital components using linear response theory, revealing distinct behaviors. These findings are crucial for a deeper understanding of the physical processes governing angular momentum-to-charge conversion and THz emission. Moreover, they may provide broader insights into various experimental outcomes, including those related to spin-orbit torque.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Observation of mirror-odd and mirror-even spin texture in ultra-thin epitaxially-strained RuO2 films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Yichen Zhang, Seung Gyo Jeong, Luca Buiarelli, Seungjun Lee, Yucheng Guo, Jiaqin Wen, Hang Li, Sreejith Nair, In Hyeok Choi, Zheng Ren, Ziqin Yue, Alexei Fedorov, Sung-Kwan Mo, Junichiro Kono, Jong Seok Lee, Tony Low, Turan Birol, Rafael M. Fernandes, Milan Radovic, Bharat Jalan, Ming Yi
Recently, rutile RuO$ _2$ has attracted renewed interest due to expectations of prominent altermagnetic spin-splitting. However, accumulating experimental evidence suggests that in its bulk and thick-film forms, RuO$ _2$ does not display any form of magnetic ordering. Despite this, the spin structure of RuO$ _2$ remains largely unexplored in the ultra-thin limit, where substrate-imposed epitaxial strain can be substantial. Here, we employ spin-resolved angle-resolved photoemission spectroscopy, supported by ab-initio calculations, to reveal the electronic structure of 2.7~nm-thick epitaxial RuO$ _2$ heterostructures. We observe an unconventional spin texture characterized by the coexistence of mirror-even and mirror-odd momentum-dependent components. A comprehensive symmetry analysis rules out nonmagnetic origins of this spin texture. These findings suggest an emergent non-relativistic spin structure enabled by epitaxial strain in the ultra-thin limit, marking a distinct departure from the behavior of relaxed or bulk RuO$ _2$ . Our work opens new perspectives for exploring symmetry-breaking mechanisms and spin textures in oxide heterostructures.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
45 pages, 5 figures, 1 table
Fast momentum-selective transport of Bose-Einstein condensates via controlled non-adiabatic dynamics in optical lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-23 20:00 EDT
Raja Chamakhi, Dana Codruta Marinica, Naceur Gaaloul, Eric Charron, Mourad Telmini
We present a detailed numerical study of a protocol for momentum-selective transport of a Bose-Einstein condensate (BEC) in a one-dimensional optical lattice, achieving narrow momentum distributions through controlled non-adiabatic dynamics. The protocol consists of non-adiabatic loading into the lattice, coherent acceleration using a symmetric trapezoidal acceleration profile, and non-adiabatic release into free space. Using the time-dependent Gross-Pitaevskii equation, we simulate the full sequence and analyze the role of non-adiabatic excitations on the final momentum distribution. We identify the intra-site breathing dynamics as the dominant mechanism governing spectral purity under fast loading conditions. By tracking the condensate’s spatial width during the evolution, we demonstrate a direct correlation with the final momentum spread. A variational model based on a Gaussian ansatz quantitatively reproduces the observed dynamics and provides physical insight into the breathing mechanism. Our results reveal the existence of magic times, i.e. specific loading or acceleration durations synchronized with the breathing oscillation period, where quasi-monochromatic momentum distributions can be achieved even with loading times as short as 100 $ \mu$ s, offering a route to coherent transport that is faster than adiabatic protocols. This approach is particularly relevant for quantum sensors operating under stringent timing constraints.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
The physics of superconductor-ferromagnet hybrid structures
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-23 20:00 EDT
A. A. Golubov, S. V. Bakurskiy, M. Yu. Kupriyanov, T. Karabassov, A. S. Vasenko, A. S. Sidorenko
In this review, we summarize the theoretical foundations underlying a variety of phenomena in superconductor-ferromagnet (SF) hybrid structures, with a focus on recent advances in several key areas. These include: (i) the fundamental understanding of proximity effects in SF-based systems; (ii) spin-valve effects in SF and SFS Josephson junctions; and (iii) the design and realization of superconducting memory elements, particularly in SIsF-type Josephson junctions. We also discuss the experimental progress in fabricating and characterizing spin-valve structures. Our discussion is restricted to junctions incorporating weak, homogeneous metallic ferromagnets with collinear magnetization directions, where the essential physical mechanisms can be analyzed within a relatively tractable theoretical framework.
Superconductivity (cond-mat.supr-con)
Superconducting Dome in Ionic Liquid Gated Homoepitaxial Strontium Titanate Thin Films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-23 20:00 EDT
Sushant Padhye, Jin Yue, Shivasheesh Varshney, Bharat Jalan, David Goldhaber-Gordon, Evgeny Mikheev
In this work, we patterned a two-dimensional electron gas (2DEG) on the surface of a SrTiO$ _3$ thin film grown homoepitaxially on SrTiO$ _3$ by hybrid molecular beam epitaxy (hMBE). We explored the superconducting dome in this material system by tuning electron density with ionic liquid gating. We found superconducting transitions up to 503 mK near an optimal electron density of approximately 3 $ \times$ 10$ ^{13}$ cm$ ^{-2}$ . This is a meaningful increase from the typical optimal transition near 350 mK in similar 2DEGs on SrTiO$ _3$ single crystal substrate surfaces. Systematic tuning of 2DEG electron density revealed a consistent BCS scaling between superconducting critical temperature, coherence length, and electron mean free path. Substantial variation of transition width across the dome was described by a paraconductivity model combining Aslamazov-Larkin and Maki-Thompson contributions.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
From Coated to Uncoated: Scanning Electron Microscopy Corrections to Estimate True Surface Pore Size in Nanoporous Membranes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Sima Zeinali Danalou, Dian Yu, Niher R. Sarker, Hooman Chamani, Jane Y. Howe, Patrick C. Lee, Jay R. Werber
Scanning electron microscopy (SEM) is the premier method for characterizing the nanoscale surface pores in ultrafiltration (UF) membranes and the support layers of reverse osmosis (RO) membranes. Based on SEM, the conventional understanding is that membranes typically have low surface porosities of <10%. We hypothesized that high acceleration voltage during SEM imaging and sputter metal coatings required for SEM have led to systematic underestimations of porosity and pore size. We showed that imaging a commercial UF membrane at 1, 5, and 10 kV reduced measured porosity from 10.3% (1 kV) to 6.3% (10 kV), while increasing Pt coating thickness from 1.5 to 5 nm lowered porosity by 54% for the UF membrane (12.9% to 5.8%) and 46% for an RO support (13.1% to 7.0%). To account for coating thickness, we developed a digital correction method that simulates pore dilation, enabling the pore structure to be estimated for uncoated membranes. Dilation yielded uncoated porosity values of 23% for the UF membrane and 20% for the RO support, about 3-fold greater than values observed with a 4 nm coating. Mean pore diameters were 2-fold greater for the UF membrane and 1.5-fold greater for the RO support. Critically, dilation-derived pore-size distributions agreed with low-flux dextran-retention data fitted with the Bungay-Brenner model. Our results suggest that surface porosities and pore sizes of nanoporous membranes are much larger than previously understood, with major implications for structure/transport relationships. For future nanoscale pore analysis of membranes (and other nanoporous materials), we recommend low acceleration voltage (1 kV), minimal coatings (1-2 nm), and digital dilation to account for coating artifacts
Materials Science (cond-mat.mtrl-sci), Computer Vision and Pattern Recognition (cs.CV), Applied Physics (physics.app-ph), Chemical Physics (physics.chem-ph), Instrumentation and Detectors (physics.ins-det)
Joint commensuration in moiré charge-order superlattices drives shear topological defects
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Kyoung Hun Oh, Yifan Su, Honglie Ning, B. Q. Lv, Alfred Zong, Dong Wu, Qiaomei Liu, Gyeongbo Kang, Hyeongi Choi, Hyun-Woo J. Kim, Seunghyeok Ha, Jaehwon Kim, Suchismita Sarker, Jacob P. C. Ruff, Xiaozhe Shen, Duan Luo, Stephen Weathersby, Patrick Kramer, Xinxin Cheng, Dongsung Choi, Doron Azoury, Masataka Mogi, B. J. Kim, N. L. Wang, Hoyoung Jang, Nuh Gedik
The advent of two-dimensional moiré systems has revolutionized the exploration of phenomena arising from strong correlations and nontrivial band topology. Recently, a moiré superstructure formed by two coexisting charge density wave (CDW) orders with slightly mismatched wavevectors has been realized. These incommensurate CDWs can collectively exhibit commensurability, resulting in the jointly commensurate CDW (JC-CDW). This JC-CDW hosts phenomena including electronic anisotropy and phase-modulated hysteresis, and holds promise for non-volatile optoelectronic memory devices. Realizing such functionality requires understanding how the spatial periodicity, coherence, and amplitude of this order evolve under perturbations. Here, we address these questions using time- and momentum-resolved techniques to probe light-induced dynamics in EuTe$ _4$ . Our time-resolved diffraction results show that under intense photoexcitation, the JC-CDW wavevector and coherence length remain locked along the CDW direction, indicating preserved moiré periodicity while the moiré potential depth is suppressed. This robustness governs the configuration of the photoexcited JC-CDW and leads to the formation of previously underexplored shear-type topological defects. Furthermore, we developed an approach to simultaneously track the temporal evolution of the amplitude and phase of a CDW by following two diffraction peaks corresponding to one order, with findings verified by time-resolved photoemission and electron diffraction. This methodology enables reconstruction of the momentum- and time-resolved evolution of the JC-CDW and direct visualization of shear-type topological defect formation. These findings not only highlight the unique robustness of JC-CDWs out of equilibrium, but also establish a platform for optical moiré engineering and manipulation of quantum materials through topological defect control.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
24 pages, 4 figures
Gate-tunable chiral spin mode in WSe2/WS2 moiré superlattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Zhexu Shan, Wenjian Su, Kenji Watanabe, Takashi Taniguchi, Shiyao Zhu, Yuanfeng Xu, Yanhao Tang
The interplay between many-body and spin-orbit effects (SOC) can lead to novel phenomena in solids. Chiral spin modes (CSM) are collective spin excitations that arise from such interplay and connect states with opposite chirality, which, however, have been rarely observed. Here, we report a gate-tunable CSM that occurs between conduction SOC-split minibands in near-0°-twisted WSe2/WS2 bilayers. This mode manifests as a sharp resonance with giant Raman efficiency in the pseudovector-symmetry channel of the Raman spectra. By varying fillings, the CSM transitions from chiral spin exciton to excitonic polaron. The spin-flip nature is directly confirmed by the Zeeman effect. Moreover, the filling dependence compellingly evidences a charge-transfer insulator at filling of one. Our results demonstrate transition-metal-dichalcogenides moiré superlattices as a fertile platform for exploring exotic low-lying collective excitations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Prediction of Li3Fe8B8 compound with rapid one-dimensional ion diffusion channels
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Shiya Chen, Paul Oftedahl, Zhen Zhang, Zepeng Wu, Junjie Jiang, Vladimir Antropov, Julia V. Zaikina, Shunqing Wu, Kai-Ming Ho, Yang Sun
Using a computational crystal structure search in the Li-Fe-B ternary system, we predict a stable phase of Li3Fe8B8, featuring 1D channels that enable rapid Li-ion transport. Ab initio molecular dynamics simulations show that the Li-ion diffusion coefficient in Li3Fe8B8 surpasses that of common electrode and conductive additive materials by several orders of magnitude. The high diffusion in Li3Fe8B8 can be explained by the Frenkel-Kontorova model, which describes an incommensurate state between the Li diffusion chain and the periodic potential field caused by the FeB backbone structure. The favorable lithium-ion diffusivity and mechanical properties of Li3Fe8B8 make it a promising conductive additive for battery materials. Its itinerant ferromagnetism also offers a platform for exploring correlated-electron magnetism and spin-dependent phenomena.
Materials Science (cond-mat.mtrl-sci)
Positive magnetoconductance in SrVO3 double quantum wells with a magnetic EuTiO3 barrier
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
N. Takahara, K. S. Takahashi, Y. Tokura, M. Kawasaki
Controlling Mott insulator states has been a long-standing topic in condensed matter physics. Among various controlling parameters, two-dimensional (2D) confinement in epitaxial heterostructures has been demonstrated to convert the correlated metallic nature of SrVO3 into a Mott insulator by reducing the quantum well thickness. Here, we fabricate double quantum well (DQW) structures of SrVO3 with a magnetic barrier of EuTiO3 to tune the hybridization of wave functions by a magnetic field. A significant positive magnetoconductance is observed for DQWs with barriers thinner than 2 nm, while DQWs with thicker barriers do not show such large positive magnetoconductance, instead behaving as a parallel circuit of two single QWs. The observed positive magnetoconductance is accounted in terms of enhanced hybridization of V 3d orbitals across the EuTiO3 barrier under a magnetic field, where the barrier height is reduced by the Zeeman splitting of Ti 3d bands in forced ferromagnetic ordering of localized 4f electrons on Eu2+sites.
Strongly Correlated Electrons (cond-mat.str-el)
Universality Classes of delocalization-localization transitions in Chiral Symplectic Class
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-09-23 20:00 EDT
Shiyin Kuang, Tong Wang, Zhenyu Xiao, Pengwei Zhao, Ryuichi Shindou
By a simulation study of three-dimensional (3D) and two-dimensional (2D) disordered lattice models in the chiral symplectic class, we show that one-dimensional (1D) weak topology universally induces an intermediate quasi-localized (QL) phase between metal and Anderson-localized phases, in which the localization length of wave functions is divergent only along the spatial direction associated with the weak topological index. Our numerical evaluation of the critical exponents of the metal-to-QL transition and the Anderson transition (in the absence of the weak topology) demonstrates that they belong to different universality classes. We also confirm that the critical exponents of these two transitions in the chiral symplectic class significantly differ from those in the chiral unitary and chiral orthogonal classes, highlighting the impact of Kramers time-reversal symmetry on quantum critical behavior.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 4 figures, 2 tables
Bulk-edge coulping induced by a moving impurity
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
More physics at the boundaries of a topological lattice remains to be explored for future applications of topological edge states. This work investigates the stability of topological edge states in the presence of a moving impurity. By modeling the impurity as a moving Gaussian on-site potential at the boundary of a two-dimensional (2D) lattice, we show that a moving impurity may cause significant modifications to edge transport, a feature markedly different from the expected robustness of edge transport against a static impurity. We further identify an interesting mechanism to explain the bulk-edge coupling using a co-moving frame, where the density of the bulk states and the degeneracy between the edge states and the bulk become key elements. The physical insights developed in this work are validated across multiple systems, including Chern insulators, quantum spin Hall insulators, and Floquet Chern insulators. Results presented in this work are complementary to our current understanding of the robustness of topological edge transport.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
Pure hydrodynamic instabilities in active jets of “puller” microalgae
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Isabelle Eisenmann, Marco Vona, Nicolas Desprat, Takuji Ishikawa, Eric Lauga, Raphaël Jeanneret
Active fluids can develop spontaneous flow instabilities and complex patterns. However, spatio-temporal control of active particles has remained challenging, despite its relevance in biological and applied contexts. Here, we harnessed phototaxis to steer millions of swimming ``puller” Chlamydomonas reinhardtii algae to create active jets and control both pearling and buckling instabilities through the preferential orientation of the cells. Our experiments, supported by a full analytical model and simulations, confirm long-standing predictions that self-generated flows can lead to jet destabilization. Our results further indicate that pullers can behave analogously to pushers when their orientation is properly tuned, and demonstrate how light enables efficient control of active fluids.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Accepted for publication in Physical Review Letters
Hydrodynamic Instabilities of Active Jets
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Marco Vona, Isabelle Eisenmann, Nicolas Desprat, Raphaël Jeanneret, Takuji Ishikawa, Eric Lauga
Using a combination of theory, experiments, and numerical simulations, we investigate the stability of coherent structures in a suspension of strongly aligned active swimmers. We show that a dilute jet of pullers undergoes a pearling instability, while a jet of pushers exhibits a helical (or, in two dimensions, zigzag) instability. We further characterise the nonlinear evolution of these instabilities, deriving exact and approximate solutions for the spreading and mutual attraction of puller clusters, as well as the wavelength coarsening of the helical instability. Our theoretical predictions closely match the experimentally observed wavelengths, timescales, and flow fields in suspensions of photophobic algae, as well as results from direct numerical simulations. These findings reveal the intrinsic instability mechanisms of aligned active suspensions and demonstrate that coherent structures can be destabilised by the flows they generate.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Accepted for publication in Physical Review Fluids
Dynamics of bright solitons in spin-orbit coupled Bose-Einstein condensates under the influence of optical and Rabi-coupling lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-23 20:00 EDT
Sumaita Sultana, Sk Siddik, Golam Ali Sekh
We consider coupled matter-wave bright solitons in spatial coherence spin-orbit coupled Bose-Einstein condensates in optical and Rabi-coupling lattice potentials and find an effective potential for separation of coupled matter-wave solitons. We show that the Rabi lattice significantly affects the potential near the region of overlap between the solitons. We study the effects of Rabi lattice on the dynamics of solitons for different initial overlap and that the dynamics is controlled by the interplay between the Rabi lattice and inter-component interaction. We investigate that, by tuning the Rabi lattice strength, one can realize localize, periodic and splitting dynamics of the total density profile of the coupled solitons.
Quantum Gases (cond-mat.quant-gas)
6 pages and 8 figures
International Journal of Modern Physics B (2025)
Investigating the influence of hydrophobicity and electrostatics on the particle-scale dynamics and rheology of dense microgel suspensions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Sayantan Chanda, Chandeshwar Misra, Ranjini Bandyopadhyay
Colloidal microgel particles such as poly(N-isopropylacrylamide) (PNIPAM) undergo a reversible volume phase transition at a volume phase transition temperature, VPTT, in aqueous media. Although the particles shrink in size as the temperature is raised beyond the VPTT, Romeo et al. [Adv. Mater. 2010, 22, 3441-3445] had previously shown that dense aqueous PNIPAM suspensions transform from one viscoelastic solid-like phase to another, with an intermediate viscoelastic liquid-like phase near the VPTT, due to a change in the inter-particle interaction from hydrophilic to hydrophobic. Here, we show using a combination of experimental techniques that particle hydrophobicity can be significant even below the VPTT and can result in the emergence of attractive gel-like phases. We achieve this by incorporating polar salts such as sodium chloride and potassium chloride, or non-polar additives such as sucrose, to the aqueous medium. Above the VPTT, we observe that suspension rigidity is the highest in the presence of polar salts because of the combined effects of ionic and hydrophobic attractions. In the presence of non-dissociating sucrose, in contrast, the inter-microgel interaction remains hydrophobic across the VPTT. Such easy tunability of interactions by incorporating commonly available chemicals into the suspension medium opens up new avenues for the synthesis of novel metamaterials.
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
47 pages including supplementary information, 8 figures
Thermal History Asymmetry and Dissipation in Dense Colloidal Microgel Glasses
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Sonali Vasant Kawale, Yogesh M Joshi, Ranjini Bandyopadhyay
Microstructurally arrested matter, from molecular glasses to soft glassy materials, can retain a memory of their thermal or mechanical (shear) histories. Their history-dependent and nonlinear microstructural recoveries have been studied within the Kovacs framework. Here, we applied the temperature ramps of varying magnitudes to dense colloidal suspensions of thermoresponsive, deformable and compressible microgel particles should serve as an effective strategy to probe the nonlinear path-dependent structural recovery of these systems. We synthesised Poly (N-isopropylacrylamide) (PNIPAM) microgel particles using the free radical precipitation polymerisation method. Using oscillatory rheology, we studied the relaxations of the viscoelastic moduli of dense PNIPAM suspensions that were heated and cooled at various temperature ramp rates. Path-dependent structural recovery was quantified by studying the asymmetric approach of the suspension elastic modulus toward the final temperature during the heating and cooling temperature ramps. The loss modulus peaks, observed at the times of initiation and termination of the temperature ramps, were understood to arise from energy dissipation due to microgel rearrangement events and found to be inversely correlated with the asymmetry in the elastic response. Our work highlights the important role of energy dissipation through microgel rearrangements in eliminating path-dependent asymmetries in the storage moduli of dense PNIPAM glasses subjected to thermal shocks. By tuning the applied temperature ramp rate and particle packing density, therefore, asymmetric storage modulus relaxations in dense systems can be modulated via adjustments of the accessible free volume.
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
34 pages including supplementary material, 6 figures
Much ado about MOFs: Metal-Organic-Frameworks as Quantum Materials
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Natalia Drichko, V. Sara Thoi, N. Peter Armitage
Metal-organic frameworks (MOFs) are a highly tunable class of crystalline materials where metal atoms or clusters are connected by organic linkers. They offer a versatile platform for exploring quantum phenomena such as entangled magnetism, superconductivity, and topology. Particularly for magnetism, their modular chemistry enables extensive control over magnetic interactions, spin magnitudes, lattice geometries, and even light-responsiveness, making them a uniquely adaptable platform. However, despite their promise, their low-temperature behavior and magnetic properties remain largely unexplored and represent an underappreciated opportunity in quantum materials research. With potential applications ranging from quantum computation to energy transfer, we believe that MOFs and particularly {\it magnetic} MOFs offer a vast and largely untapped frontier for transformative discoveries and high-impact quantum materials research.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
The Su-Schrieffer-Heeger model on a one-dimensional lattice: Analytical wave functions of topological edge states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
The one-dimensional Su-Schrieffer-Heeger (SSH) model is a prototype model in the field of topological condensed matter physics, and the existence and characteristics of its topological edge states are crucial for revealing the topological essence of low-dimensional systems. This paper focuses on the analytical wave functions of topological edge states in the SSH model, systematically sorting out the fundamentals of model construction. Based on the tight-binding approximation, it derives the matrix form of the SSH model Hamiltonian and the band structureand clarifies the role of chiral symmetry in the classification of topological phases. By solving the Schrodinger equation of the finite-length lattice, the mathematical expression of the analytical wave function of topological edge states is fully derived, verifying its localized feature of exponential decay. Moreover, it quantitatively analyzes the influence laws of lattice parameters (hopping integrals, lattice constants), electron-electron interactions, and external field perturbations on the wave function amplitude, decay coefficient, and energy. Furthermore, it establishes the quantitative correlation between the analytical wave function and electronic transport (conductivity) as well as optical properties (light absorption coefficient), and discusses its application prospects in the design of topological qubits and the development of new topological materials. The research results provide theoretical support for an in-depth understanding of the physical essence of low-dimensional topological states and lay a foundation for the performance optimization of topology-related devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), General Topology (math.GN)
Melting point depression of charge density wave in 1T-TiSe$_2$ due to size effects
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Saif Siddique, Mehrdad T. Kiani, Omri Lesser, Stephen D. Funni, Nishkarsh Agarwal, Maya Gates, Miti Shah, William Millsaps, Suk Hyun Sung, Noah Schnitzer, Lopa Bhatt, David A. Muller, Robert Hovden, Ismail El Baggari, Eun-Ah Kim, Judy J. Cha
Classical nucleation theory predicts size-dependent nucleation and melting due to surface and confinement effects at the nanoscale. In correlated electronic states, observation of size-dependent nucleation and melting is rarely reported, likely due to the extremely small length scales necessary to observe such effects for electronic states. Here, using 1T-TiSe$ _2$ nanoflakes as a prototypical two-dimensional (2D) charge density wave (CDW) system, we perform in-situ cryogenic electron microscopy with temperature down to 20 K and observe size-dependent nucleation and melting of CDWs. Specifically, we observe a melting point depression of CDW for 1T-TiSe$ _2$ flakes with lateral sizes less than 100 nm. By fitting experimental data to a Ginzburg-Landau model, we estimate a zero-temperature correlation length of 10–50 nm, which matches the reported CDW domain size for 1T-TiSe$ _2$ . As the flake size approaches the correlation length, the divergence of the CDW correlation length near the transition is cut off by the finite flake size, limiting long-range order and thereby lowering the transition temperature. For very small flakes whose size is close to the correlation length, we also observe absence of CDWs, as predicted by the model. We thus show that an electronic phase transition follows classical nucleation theory.
Materials Science (cond-mat.mtrl-sci)
Ductile fracture of HDPE thin films: failure mechanisms and tuning of fracture properties by bonding a rubber layer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Rahul G. Ramachandran, Zachary Kushnir, Deepak Langhe, Sachin S. Velankar, Spandan Maiti
High-density polyethylene (HDPE) thin films, while inherently ductile, exhibit poor flaw tolerance. Our experiments show that they fail prematurely not at the point of maximum stretch, but at the boundary of a necked region or notch-tip plastic zone. This study investigates this counter-intuitive failure mechanism and demonstrates how an elastomeric interlayer can mitigate it to enhance toughness. Through a combined experimental (uniaxial, center-notched, pure shear tests) and computational approach, we analyze freestanding HDPE and HDPE-SEPS-HDPE trilayer laminates. Finite element simulations reveal that failure in free-standing HDPE is not governed by a maximum stretch criterion. Instead, it is driven by ductile damage, modeled using a damage parameter that depends on stress-triaxiality and plastic strain. This damage localizes initially at the notch or neck center, but migrates into a “hotspot” at the neck/plastic zone boundary, matching the observed crack initiation site. The addition of a soft SEPS interlayer fundamentally alters this behavior by suppressing the ductile damage, causing the failure mechanism to switch from being damage-driven at the neck/plastic zone boundary to being stretch-driven at the notch tip. This switch enhances flaw tolerance and stretchability by relocating and delaying fracture initiation in both defect-free and notched geometries. This work exposes the failure mechanism in HDPE thin films and provides a mechanistically-grounded framework for toughening ductile polymers by manipulating the competition between damage and stretch localization.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft)
$Δ_T$ Noise as a Robust Diagnostic for Chiral, Helical and Trivial Edge Modes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Sachiraj Mishra, Colin Benjamin
In this article we demonstrate that $ \Delta_T$ noise provides a sensitive, practical probe for distinguishing chiral edge modes from topological helical and trivial (non-topological) helical edge transport. Measured under zero-current conditions, $ \Delta_T$ noise reveals contrasts that conventional conductance measurements typically miss. Crucially, $ \Delta_T$ requires no external energy input in the form of an applied voltage bias, yet encodes the same intrinsic information that shot noise yields in the zero-temperature, finite-bias limit, without the distorting effects of Joule heating. This absence of bias-induced heating makes $ \Delta_T$ noise both more precise and more reliable than conventional shot-noise approaches. Moreover, the diagnostic power of $ \Delta_T$ noise persists at finite frequencies $ \omega$ too. The frequency-dependent signal $ \Delta_{T}(\omega)$ exhibits distinctive spectral signatures (including sign changes) that further enhance its utility as an experimentally accessible fingerprint of edge-mode topology.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
21 pages, 13 figures
Low-Noise Nanoscale Vortex Sensor for Out-of-Plane Magnetic Field Detection
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Ajay Jha, Alvaro Palomino, Stéphane Auffret, Hélène Béa, Ricardo C. Sousa, Liliana D. Buda-Prejbeanu, Bernard Dieny
This study investigates a vortex sensor based on a nanoscale (sub-100 nm) magnetic tunnel junction (MTJ) with a strong shape anisotropy, designed for sensitivity to the out-of-plane magnetic field component ($ H_z$ ). The sensor comprises a free layer with a vortex configuration and a perpendicularly magnetized reference layer, which provides a reproducible and linear response when excited by a perpendicular magnetic field. Experimental measurements and micromagnetic simulations were combined to systematically assess the influence of structural parameters, specifically aspect ratio and defect landscape, on key sensor performance metrics, including dynamic range, sensitivity, and detectivity. The out-of-plane vortex sensor demonstrates a significantly improved dynamic range exceeding 200 mT, compared to the 40-80 mT typical of conventional in-plane vortex sensors. Frequency-dependent noise measurements reveal that the sensor exhibits low intrinsic noise, along with improved detectivity and resolution. This performance is ascribed to the field-dependent expansion and contraction of the vortex core, which reduces Barkhausen-type noise caused by defect-induced pinning potentials. Moreover, the sub-100,nm lateral dimensions of the sensor enable scalable array integration, providing further enhancements in noise and detectivity through collective averaging. These results underscore the potential of this sensor architecture for advanced magnetic field sensing applications requiring a wide dynamic range and high measurement accuracy at the same time.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
pyRMG: A Python Framework for High-Throughput, Large-Cell Real-Space MultiGrid DFT Calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
R. J. Morelock, S. Bagchi, E. L. Briggs, W. Lu, J. Bernholc, P. Ganesh
Computational materials science has evolved toward materials informatics, where large datasets of complex, multispecies compounds are generated and evaluated using density functional theory (DFT). Materials genome projects mine these datasets for candidates with breakthrough properties, but existing databases remain limited to compounds with relatively small unit cells due to computational cost. Exascale computers now provide the power to simulate larger and more chemically realistic systems, but fully realizing this potential requires DFT codes that can efficiently scale to thousands of processors. Our real-space multigrid (RMG) DFT code’s grid-decomposition approach scales nearly linearly with the number of GPUs, even for simulations exceeding thousands of atoms. This scalability makes RMG a compelling tool for high-throughput DFT studies of materials that would otherwise be bottlenecked in other codes (for example, by global Fast Fourier Transforms in plane-wave DFT). In this work, we present pyRMG, a Python package designed to streamline the setup and execution of RMG DFT calculations. Built on the pymatgen and ASE Python packages, pyRMG automates input generation and convergence checking, and integrates with modern job schedulers (e.g., Flux) on leadership-class platforms such as Frontier and Perlmutter. We demonstrate pyRMG for a high-throughput study of interfacial strain and twist-angle effects in lattice-matched, 2D Bi$ _2$ Se$ _3$ /NbSe$ _2$ heterostructures, which form large, anisotropic supercells. Our results link strain and twist angle to material informatics properties, including stability and band gap, and show that pyRMG can initialize and converge challenging RMG-based workflows with limited user intervention.
Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
39 pages, 5 figures
A simple time coarse graining method for molecular dynamics simulations of liquids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Maxime Martin, Levi Pereon, Quoc Tuan Truong, Victor Teboul
Considering molecular dynamic simulations as a stochastic method, we investigate the possibility of time coarse graining the simulations. Similarly to Boltzmann inversion method in spatial coarse graining, which begins with a free energy called potential of mean force, we test the effect of a generalized potential of mean force that uses the distinct part of the Van Hove correlation function with a characteristic time different from zero. We show that the method is approximately equivalent to replace the hard core of the original potential by a smooth harmonic function. We then compare the results of simulations using the modified potential and the original one. Results show that this simple modification of the potential, namely replacing the short range wall with a smooth quadratic law, leads to a shift in the time step resulting in the same dynamics than the original potential function but with a much larger time step.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
A facilitation-induced fluidization transition in supercooled water triggered by a few active molecules
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Quoc Tuan Truong, Victor Teboul
Using an activation mechanism reproducing facilitation, a dynamic phase transition triggered by a few active molecules was recently found in a supercooled model liquid. Prompted by this finding we investigate the presence of a similar transition in supercooled water. We find the presence of the phase transition in water despite the numerous anomalies of water, suggesting universality of the transition. The transition appears at constant temperature, being only induced by the motion of a small percentage of active molecules and the system cooperativity. We observe that cooperative motions strongly increase at the transition and do not disappear when the medium viscosity drops. An increase of temperature is needed to make the cooperative motions disappear, suggesting a connection to the kinetic energy to potential energy ratio instead of the medium viscosity.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Tunneling magnetoresistance in a junction made of $X$-wave magnets with $X=p,d,f,g,i$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
We investigate the tunneling magnetoresistance (TMR) of a bilayer system made of $ X$ -wave magnets with $ X=p,d,f,g,i$ , where $ X=d,g,i$ corresponds to altermagnets. A universal analytic formula is derived for the TMR ratio. It is proportional to $ \left\vert J\right\vert /\left( N_{X}\Gamma \right) $ for small $ \Gamma $ , where $ N_{X}$ is the number of the nodes of the $ X$ -wave magnet, $ J$ is the strength of the $ X$ -wave magnet, and $ \Gamma $ is the self-energy. It is contrasted with the TMR ratio made of ferromagnets, where it is proportional to $ J^{2}/\Gamma ^{2}$ for small $ \Gamma $ . Therefore, the TMR ratio is larger in ferromagnets for $ \left\vert J\right\vert >\Gamma $ . However, the $ X$ -wave magnets are expected to achieve high-speed and ultra-dense memory owing to the zero net magnetization.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
7 figures, 11 figures
The exact relation between the entanglement entropies of the $XY$ and quantum Ising chains with free and fixed boundary conditions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
The entanglement entropies of $ XY$ chains and quantum Ising chains (QICs) with fixed boundary conditions are studied here. Three kinds of boundary conditions (BCs) are considered: fixed up–up or down–down (the spins at both ends are aligned in the same direction), fixed up–down or down–up (the spins at the two ends are aligned in opposite directions), and fixed–free (the spin at one end is aligned, and the other end is free). It is shown that i) the entanglement entropy of an $ XY$ chain with a fixed–free BC is the sum of those of QICs with a fixed–free BC and with a free–free BC; ii) the entanglement entropy of an $ XY$ chain with a fixed up–up boundary condition is the sum of those of QICs with a fixed up–up BC and with a free–free BC; and iii) the entanglement entropy of an $ XY$ chain with a fixed up–down BC is the sum of that of a QIC with a fixed up–up BC and that of the first excited state of a QIC with a free–free BC.
Statistical Mechanics (cond-mat.stat-mech)
Selective photocatalyitic CO2 reduction to acetic acid on chiral mesostructured ZnIn2S4
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Yongping Cui, Yuanbo Li, Zhi-qiang Wang, Lu Han, Xueli Wang, Jinquan Chen, Aokun Liu, Lu Yu, Changlin Tian, Xue-qing Gong, Wanning Zhang, Yuxi Fang
Acetic acid, an important industrial chemical, is a key target for CO2 reduction due to its dual role in carbon utilization and chemical feedstock this http URL acetic acid can be produced by prhotocatalytic CO2 redcution. Among other multicarbon products, it is typically a low-yieleded product due to competing reaction pathways and inefficient C-C coupling. Herein, we report a chiral mesostructured ZnIn2S4 photocatalyst that achieves a remarkable acetic acid yield of 962 umolg-1h-1 with a high selectivity of 97.3%. The yield is ten times higher than the current highest reported value, while attaining state-of-the-art selectivity. The remarkable The remarkable productivity arises from synergistic cooperation between chiral structure and sulfur (S) sites of CMZI. Chirality-induced spin polarization in CMZI stabilizes the key triplet OCCO intermediate, significantly promoting C-C coupling efficiency. Theoretical calculations reveal that the S sites on (102) crystal facets of ZnIn2S4 exhibit thermodynamic and kinetic preferences for acetic acid formation. This work offers critical insights into catalytic strategies for CO2 reduction that could enable the synthesis and scalable production of various multicarbon products.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
9 pages, 4 figures
Spin Seebeck effect in two-sublattice ferrimagnets in the vicinity of $T_{\rm C}$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Hayato Fukushima, Masanori Ichioka, Hiroto Adachi
Spin Seebeck effect refers to the magnonic thermal spin injection from a magnet into the adjacent heavy metal. A ferrimagnetic insulator yttrium iron garnet (YIG) is the material most studied for the spin Seebeck effect. Here, to account for a convex downward temperature dependence of the spin Seebeck effect observed in YIG/Pt system near the Curie temperature $ T_{\rm C}$ , we develop Ginzburg-Landau theory of the spin Seebeck effect in two-sublattice ferrimagnets. We find that only when we take into account the ``Néel coupling’’, i.e., interfacial exchange coupling between the Néel order parameter of YIG and spin accumulation of Pt, the convex downward temperature dependence is explained. The present result sheds light on the importance of the Néel coupling in ferrimagnetic spintronics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Accepted for publication in Phys. Rev. B
Spin PN Junctions: Giant Magnetoresistance, Tunable Circular Polarization, and Spin Zener Filter
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
We demonstrate that spin PN junctions-magnetic semiconductor homojunctions with spin splitting-induced band offsets-fundamentally redefine carrier transport via spin-dependent recom bination probabilities. By integrating this mechanism into the Shockley model, we predict
a near 100 enhancement in magnetoresistance sensitivity under small forward bias, where exponen tial modulation of recombination lifetimes by magnetic fields amplifies resistance changes.
Angular momentum conservation enables magnetically tunable circularly polarized luminescence:
exclusive conduction-band or valence-band splitting in both neutral regions achieves near-half po larization, while global splitting degrades emission coherence. Furthermore, we propose
a “spin Zener filter” exploiting 1eV valence band splitting in (Ga, Mn)As, where spin-dependent
barrier heights generate near 100% spin-polarized tunneling currents within a voltage-selective win dow. These results establish spin PN junctions as a universal design paradigm for magnetically
amplified electronics, polarization-programmable optoelectronics, and voltage-gated spin injection
without ferromagnetic contacts.
Materials Science (cond-mat.mtrl-sci)
11 pages, 4 figures, 2 tables
Nonadiabatic H-Atom Scattering Channels on Ge(111) Elucidated by the Hierarchical Equations of Motion
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Xiaohan Dan, Zhuoran Long, Tianyin Qiu, Jan Paul Menzel, Qiang Shi, Victor Batista
Atomic and molecular scattering at semiconductor interfaces plays a central role in surface chemistry and catalysis, yet predictive simulations remain challenging due to strong nonadiabatic effects causing the breakdown of the Born-Oppenheimer approximation. Here, we present fully quantum simulations of H-atom scattering from the Ge(111)c(2x8) rest site using the hierarchical equations of motion (HEOM) with matrix product states (MPS). The system is modeled by mapping a density functional theory (DFT) potential energy surface onto a Newns-Anderson Hamiltonian. Our simulations reproduce the experimentally observed bimodal kinetic energy distributions, capturing both elastic and energy-loss channels. By systematically examining atom-surface coupling, incident energy, and isotope substitution, we identify the strong-coupling regime required to recover the experimental energy-loss profile. This regime suppresses the elastic peak, implying additional site-specific scattering channels in the observed elastic peak. Deuterium substitution further produces a subtle shift in the energy-loss peak, consistent with experiment. These results establish HEOM as a rigorous framework for quantum surface scattering, capable of capturing nonadiabatic dynamics beyond electronic friction and perturbative approaches.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Radio-Frequency Detection of Fabry-Pérot Interference and Quantum Capacitance in Long-Channel Three-Dimensional Dirac Semimetal Cd3As2 Nanowires
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Sung Jin An, Jisu Kim, Myung-Chul Jung, Kidong Park, Jeunghee Park, Seung-Bo Shim, Hakseong Kim, Zhuo Bin Siu, Mansoor B. A. Jalil, Christian Schönenberger, Nojoon Myoung, Jungpil Seo, Minkyung Jung
We demonstrate phase-coherent transport in suspended long-channel Cd3As2 nanowire devices using both direct current (DC) transport and radio-frequency (RF) reflectometry measurements. By integrating Cd3As2 nanowires with on-chip superconducting LC resonators, we achieve sensitive detection of both resistance and quantum capacitance variations. In a long-channel device (L ~ 1.8 {\mu}m), clear Fabry-Pérot (FP) interference patterns are observed in both DC and RF measurements, provide strong evidence for ballistic electron transport. RF reflectometry reveals gate-dependent modulations of the resonance frequency, arising from quantum capacitance oscillations induced by changes in the density of states and FP interference. These oscillations exhibit a quasi-periodic structure that closely correlates with the FP patterns in DC transport measurements. In another device of a Cd3As2 nanowire Josephson junction (L ~ 730 nm, superconducting Al contacts), FP interference patterns are too weak to be resolved in DC conductance but are detectable using RF reflectometry. These results demonstrate the high quality of our Cd3As2 nanowires and the versatility of RF reflectometry, establishing their potential for applications in topological quantum devices, such as Andreev qubits or gatemon architectures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Thermoelectric properties of Lead halide Janus layers – A theoretical investigation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
A.E. Sudheer, M Vallinayagam, G Tejaswini, A Kumar, M Posselt, C Kamal, M Zschornak, D Murali
Thermoelectric materials offer a promising route for efficient heat-to-power conversion. In search of materials functional at high and low operating temperatures, we investigate the thermoelectric properties of two-dimensional lead halide Janus layers (JLs) using density functional theory. The electronegativity difference between halides in JLs significantly modulates the electronic structure, particularly the strong Pb-F bonding in PbIF JLs leads to pronounced band curvature and a unique direct bandgap. Estimated through three-phonon interactions, the lattice thermal conductivity is intrinsically low, primarily due to acoustic phonon contributions and suppressed optical phonon transport. The thermoelectric coefficients are enhanced with carrier doping, resulting in figures of merit as high as 8.94 at room temperature and upto 36.31 at elevated temperatures. These findings establish two-dimensional lead halide Janus layers as exceptional candidates for thermoelectric conversion, and the insights into their elemental and electronic characteristics offer a valuable basis for the future design of high-performance lead-based thermoelectric materials.
Materials Science (cond-mat.mtrl-sci)
Antiferromagnetic nonreciprocity of light emission in CuB$_2$O$_4$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
A. R. Nurmukhametov, D. R. Yakovlev, V. Yu. Ivanov, D. Kudlacik, M. V. Eremin, R. V. Pisarev, M. Bayer
Nonreciprocity of light emission, when the radiation intensity differs for two opposite propagation directions, is a rare phenomenon in solids because it requires a violation of the crystal symmetry with respect to time-reversal. Such violation via time-reversal symmetry breaking can occur either due to an applied magnetic field or due to a magnetic ordering. We perform a detailed theoretical and experimental study of the photoluminescence (PL) nonreciprocity in the noncentrosymmetric tetragonal antiferromagnet CuB$ _2$ O$ _4$ , where this effect reaches 80% below the Néel phase transition temperature of $ T_N = 20$ ~K. The effect is observed for three sets of extremely narrow exciton and exciton-magnon PL lines, associated with Frenkel excitons on the Cu$ ^{2+}$ ions in the magnetic $ 4b$ subsystem. A strong manifestation of the nonreciprocity of emission is found in certain geometries for the commensurate antiferromagnetic phase, as well as in other phases with incommensurate spin ordering. In accordance with the magnetic symmetry of CuB$ _2$ O$ _4$ , the nonreciprocity of emission is observed for light propagation along certain directions within the easy (001) plane. A rigorous quantum-mechanical analysis of the wave functions of the initial and final states of the Cu$ ^{2+}$ ions responsible for the PL is performed for various experimental geometries of the crystallographic axes and the applied magnetic field. The analysis confirms that the nonreciprocity of emission from Frenkel excitons in CuB$ _2$ O$ _4$ is due to the interference of magnetic-dipole and electric-dipole transitions of antiferromagnetically ordered $ 4b$ spins of the Cu$ ^{2+}$ ions, in good agreement with the experimental data.
Materials Science (cond-mat.mtrl-sci)
Magnetic Frustration in CuYbSe$_2$: an Yb-Based Triangular Lattice Selenide
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Barkha Khattar, Anzar Ali, Masahiko Isobe, Yogesh Singh
The Yb based triangular lattice delafossites $ A$ Yb$ X_2$ ($ A$ = alkali metal, $ X$ = O, S, Se) have recently been studied as quantum spin liquid candidates. We report the synthesis of powders and single crystals of CuYbSe$ _2$ with a perfect triangular lattice of Yb$ ^{3+}$ moments. Magnetic susceptibility and heat capacity measurements reveal no evidence of long-range magnetic ordering down to $ 1.8$ ~K in spite of a significant antiferromagnetic exchange between Yb$ ^{3+}$ moments, suggesting a frustrated magnetic system. Electrical resistivity measurements indicate insulating behavior, consistent with the localized nature of magnetic moments. Heat capacity reveals that CuYbSe$ _2$ can be treated as an effective spin $ S = 1/2$ triangular lattice antiferromagnet below $ \sim 50$ ~K. Magnetic susceptibility measurements on single crystals reveals weak magnetic anisotropy. These properties position CuYbSe$ _2$ as a promising candidate for a quantum spin liquid state and as a new platform for exploring exotic magnetic ground states in triangular lattice systems.
Strongly Correlated Electrons (cond-mat.str-el)
Growth of rhombohedral boron nitride crystals using an iron flux
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
W. Desrat, M. Moret, J. Plo, T. Michel, A. Ibanez, P. Valvin, V. Jacques, I. Philip-Robert, G. Cassabois, B. Gil
We report the growth of high quality rhombohedral boron nitride (rBN) crystals by the iron flux method at atmospheric pressure. In contrast to the lamellar structure of standard hexagonal boron nitride (hBN) covering the metal ingot, the current synthetized BN shell is composed of many triangular bulk crystallites, of submillimeter size, predominantly in the rhombohedral phase, with only weak traces of hBN detected by high resolution X-ray diffraction. The low-temperature photoluminescence emission confirms the excellent quality of the rhombohedral stacking with unprecedented width for all phonon replicas at the band edge. The Raman spectra are characterized by the absence of any low-energy modes at $ \sim50$ cm$ ^{-1}$ , the presence of an extended band around $ 800$ cm$ ^{-1}$ and an asymmetric high energy mode at $ 1366$ cm$ ^{-1}$ . These observations are in very good agreement with the phonon dispersion calculated for the rhombohedral primitive cell with $ C_{3v}$ symmetry.
Materials Science (cond-mat.mtrl-sci)
Influence of carbon dioxide and water concentration on terbium thin films produced by Molecular Plating
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Ernst Artes, Primiana Cavallo, Tobias Häger, Carl-Christian Meyer, Christoph Mokry, Dennis Renisch, Jörg Runke, Evgenia Schaffner, Alice Seibert, Christina Trautmann, Christoph E. Düllmann
Terbium and thulium thin films were produced by Molecular Plating under controlled conditions to elucidate a possible influence of water and carbon dioxide present in the plating solution. Platings were made in a glovebox with variable concentration of residual water and \ce{CO2} in a controlled inert atmosphere to study the impact on the quality of the produced thin films and on deposition yields. The morphology of the thin films was analyzed by scanning electron microscopy. The deposition yield was determined by neutron activation analysis at the research reactor TRIGA Mainz. Chemical analysis of the deposited layers was conducted using a combination of infrared, Raman and X-ray photoelectron spectroscopy. The Raman and IR spectra reveal the formation of hydroxides, oxides and carbonates. Water in the plating solution affects the quality of the thin films when its concentration exceeds 1 vol.-%. The presence of \ce{CO2} leads to an increased carbonate content, which negatively influences the film quality
Materials Science (cond-mat.mtrl-sci)
Radiochim. Acta 2025; aop
Emergent Ising symmetry and supercritical fluids
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
The symmetry of Ising model questions any single crossover scenario for supercritical fluids. In this work, we firstly study a pair of thermodynamic crossovers $ L^\pm$ analytically for the Van der Waals class fluids. We uncover an emergent $ Z_2$ symmetry in addition to the universal scalings in the scaling regime for this class fluids. By using the self-reciprocal property between coexistenct phases, we further establish that under suitable conditions, the Ising symmetry generally emerges in the scaling regime for a general universality class. As a consequence, the thermodynamic crossovers $ L^\pm$ generally exhibit an emergent $ Z_2$ symmetry in the scaling regime. This partly resolves the symmetry puzzle raised by the Ising model. The results also imply that the physical importance of the Ising model in critical phenomenon is far beyond the scope of magentic transitions.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
Comments are welcome
$\texttt{DiffSyn}$: A Generative Diffusion Approach to Materials Synthesis Planning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Elton Pan, Soonhyoung Kwon, Sulin Liu, Mingrou Xie, Alexander J. Hoffman, Yifei Duan, Thorben Prein, Killian Sheriff, Yuriy Roman-Leshkov, Manuel Moliner, Rafael Gomez-Bombarelli, Elsa Olivetti
The synthesis of crystalline materials, such as zeolites, remains a significant challenge due to a high-dimensional synthesis space, intricate structure-synthesis relationships and time-consuming experiments. Considering the one-to-many relationship between structure and synthesis, we propose $ \texttt{DiffSyn}$ , a generative diffusion model trained on over 23,000 synthesis recipes spanning 50 years of literature. $ \texttt{DiffSyn}$ generates probable synthesis routes conditioned on a desired zeolite structure and an organic template. $ \texttt{DiffSyn}$ achieves state-of-the-art performance by capturing the multi-modal nature of structure-synthesis relationships. We apply $ \texttt{DiffSyn}$ to differentiate among competing phases and generate optimal synthesis routes. As a proof of concept, we synthesize a UFI material using $ \texttt{DiffSyn}$ -generated synthesis routes. These routes, rationalized by density functional theory binding energies, resulted in the successful synthesis of a UFI material with a high Si/Al$ _{\text{ICP}}$ of 19.0, which is expected to improve thermal stability and is higher than that of any previously recorded.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI), Machine Learning (cs.LG)
Efficient simulation of a pair of dissipative qubits antiferromagnetically coupled
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
Francesco G. Capone, Giulio De Filippis, Vittorio Cataudella, Antonio de Candia
We investigate the efficiency of different quantum Monte Carlo simulations of a pair of antiferromagnetically coupled qubits in an Ohmic dissipative environment. Using a Trotter-Suzuky decomposition and integrating out the degrees of freedom of the thermal bath, the model maps onto a frustrated long-range double-chain Ising lattice. We prove that: i) due to frustration, the conventional Swendsen-Wang approach to cluster dynamics turns out to suffer from a severe inefficiency, stemming from the mismatch between spin correlations and cluster connectivity; ii) the Kandel-Domany approach is extremely effective in the study of dissipative quantum qubits. We partition the double-chain into different types of plaquettes and minimize the weight of graphs containing antiferromagnetic bonds by using both analytic and numerical approaches. Monte Carlo simulation results show that long range'' plaquette decompositions are more efficient than the local’’ ones, especially for high levels of dissipation.
Statistical Mechanics (cond-mat.stat-mech)
10 pages, 7 figures
Third-order quantum phase transitions of bosonic non-Abelian fractional quantum Hall states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Kai-Wen Huang, Xiang-Jian Hou, Ying-Hai Wu
We study phase transitions in bilayer and trilayer bosonic quantum Hall systems. In the absence of interlayer tunneling and interaction, each layer is chosen to have filling factor $ \nu=1/2$ or $ 1$ to realize the Laughlin state or the Moore-Read state. By tuning interlayer tunneling and/or interaction, multiple phases can be generated. In the absence of interlayer interaction, three phase transitions appear when interlayer tunneling becomes sufficiently strong: (1) from two decoupled $ \nu=1/2$ Laughlin states to the Moore-Read state in bilayer systems; (2) from one $ \nu=1/2$ Laughlin state plus one $ \nu=1$ Moore-Read state to the Read-Rezayi $ \mathbb{Z}{3}$ state in bilayer systems; (3) from three decoupled $ \nu=1/2$ Laughlin states to the Read-Rezayi $ \mathbb{Z}{3}$ state in trilayer systems. Numerical calculations suggest that these transitions are third-order ones. We propose non-Abelian Chern-Simons-Higgs theory to describe them. If both interlayer tunneling and interaction are present, one-component or multi-component composite fermion liquids and Jain states can be realized. This leads to intricate phase diagrams that host multiple phase transitions and possibly exotic critical points.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas)
10 pages, 7 figures
Probing the quantum metric of 3D topological insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Giacomo Sala, Emanuele Longo, Maria Teresa Mercaldo, Stefano Gariglio, Mario Cuoco, Roberto Mantovan, Carmine Ortix, Andrea D. Caviglia
The surface states of 3D topological insulators possess geometric structures that imprint distinctive signatures on electronic transport. A prime example is the Berry curvature, which controls electric frequency doubling via a higher order moment, called Berry curvature triple. In addition to the Berry curvature, topological surface states are expected to exhibit a nontrivial quantum metric, which plays a key role in governing nonlinear magnetotransport. However, its manifestation has yet to be experimentally observed in 3D topological insulators. Here, we provide evidence for a nonlinear response activated by the quantum metric of the topological surface states of Sb$ _2$ Te$ _3$ . We measure a time-reversal odd, nonlinear magnetoresistance that is independent of temperature and disorder below 30 K and is thus of intrinsic geometrical origin. Our measurements demonstrate the existence of quantum geometry-induced transport in topological phases of matter and provide strategies for designing novel functionalities in topological devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Quantum sensing of arbitrary magnetic signals with molecular spins
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
M. Lanza, C. Bonizzoni, O. Mironova, F. Santanni, A. Nicolini, A. Ghirri, A. Cornia, M. Affronte
Molecular spins offer a promising platform for quantum sensing, particularly in organic, supramolecular or biological environments. Detection of periodic magnetic fields has been demonstrated with molecular spins ($ S$ = 1/2) using manipulation protocols synchronized with the probed field. In this work, we develop two quantum sensing protocols that enable discrimination between different time-dependent magnetic field signals, without synchronization. These are based on the Hahn echo sequence and have been tested on VO(TPP) and $ \text{VOPt(SCOPh)}_4$ molecular spins embedded in a superconducting YBCO microwave resonator. We report a magnetic field sensitivity up to a few $ 10^{-7} T \text{Hz}^{-\frac{1}{2}}$ (with lower bounds approaching $ 10^{-8} T \text{Hz}^{-\frac{1}{2}}$ ) for signals with duration of a few microseconds. Under the given conditions, the minimum signal area that can be measured is in the $ 10^{-10}$ T s range, suggesting a potential trade-off between minimum measurable field and the required signal duration and memory time.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 5 figures
Arrested phase separation and chiral symmetry breaking in active dumbbells under shear
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Lucio Mauro Carenza, Giuseppe Negro, Pasquale Digregorio, Antonio Suma, Giuseppe Gonnella
Through molecular dynamics simulations, we investigate the phase separation and aggregation dynamics of active dumbbell particles in two-dimensions subjected to shear.
We find that the growth of the phase-separated region is arrested when shear is applied, with the average clusters size plateauing towards a value $ R_s$ that remains constant over time. While activity enhances the resilience of clusters against shear-induced breakup, $ R_s$ decreases with growing shear rate $ \dot\gamma$ , with an intermediate regime where $ R_s\propto \dot\gamma^{-1}$ . We find that clusters in the stationary state are progressively less polarized and increasingly elongated with increasing shear. At the same time, we find a breaking in chiral symmetry of both rotation direction and internal organization of clusters: typically, dumbbells point towards the cluster center with a small non-zero angle, such that the active torque opposes the shear torque, with cluster’s angular velocity well captured by a simplified analytical model. We argue this conformation makes clusters more stable against shear.
Soft Condensed Matter (cond-mat.soft)
THz electrodynamics and superconducting energy scales of ZrN thin films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-23 20:00 EDT
Ozan Saritas, Frederik Bolle, Yayi Lin, Martin Dressel, Roman Potjan, Marcus Wislicenus, Andre Reck, Marc Scheffler
The terahertz (THz) properties of ZrN thin films grown with CMOS-techniques on industry-standard 300 mm silicon wafers are investigated in order to explore their superconducting behavior. The films have thicknesses ranging from 18 to 48 nm, and their critical temperatures Tc are between 5 and 7.3 K. We probe the real and imaginary parts of the complex dynamical conductivity sigma in the frequency range from 100 - 540 GHz (0.4 - 2.2 meV) and as a function of temperature. The experiments provide direct access to the low-energy electrodynamics and key materials parameters such as superconducting energy gap and superfluid density. Our findings indicate that ZrN is a weakly coupled BCS-type superconductor with a gap-to-Tc ratio of approximately 3.4 in the thick film limit. For thinner films, this coupling ratio increases up to 4.0, departing from the BCS prediction. The results establish large-scale ZrN thin films as promising material for high-frequency superconducting applications.
Superconductivity (cond-mat.supr-con)
7 pages, 5 figures
Gauge-invariant absolute quantification of electric and magnetic multipole densities in crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Electric and magnetic multipole densities in crystalline solids, including the familiar electric dipole density in ferroelectrics and the magnetic dipole density in ferromagnets, are of central importance for our understanding of ordered phases in matter. However, determining the magnitude of these quantities has proven to be conceptually and technically difficult. Here we present a universally applicable approach, based on projection operators, that yields gauge-invariant absolute measures for all types of electric and magnetic order in crystals. We demonstrate the utility of the general theory using concrete examples of electric and magnetic multipole order in variants of lonsdaleite and diamond structures. Besides the magnetic dipole density in ferromagnets, we also consider, e.g., the magnetic octupole density in altermagnets. The robust method developed in this work lends itself to be incorporated into the suite of computational materials-science tools. The multipole densities can be used as thermodynamic state variables including Landau order parameters.
Materials Science (cond-mat.mtrl-sci)
5 pages, 3 figures
Viscoelastic properties of tumor spheroids revealed by a microfluidic compression device and a modified power law model
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Mrinal Pandey, Bangguo Zhu, Kaitlyn Roach, Young Joon Suh, Jeffrey E Segall, Chung-Yuen Hui, Mingming Wu
Clinically, palpation is one of the important diagnostic methods to assess tumor malignancy. In laboratory research, it is well accepted that the bulk stiffness of the tumor and the surrounding tissue is closely correlated with the malignant state of the tumor. Here, we postulate that, in addition to tumor stiffness, tumor viscoelasticity - the fact that tumor tissue takes time to bounce back after compression, can also be used to evaluate the tumor malignancy state. In this work, we characterized the viscoelastic properties of breast tumor spheroids using a recently developed microfluidic compression device and a theoretical power law model. Breast tumor cells at varying malignant levels; a non-tumorigenic epithelial (MCF10A), moderately malignant tumor (MCF7) and triple negative metastatic tumor (MDA-MB-231) cells were used. Spheroids embedded within a 3D extracellular matrix were periodically compressed, and their strain responses were recorded using microscopic imaging. Our results revealed that the measured strain relaxation curves can be successfully described by a modified power law model, demonstrated that non-tumorigenic tumor spheroids were more elastic, exhibited shorter relaxation time and less plasticity than those of tumorigenic spheroids. Together, these results highlight that viscoelastic properties in addition to bulk stiffness of the tumor spheroids can serve as a complementary mechanical biomarker of tumor malignancy and demonstrate the validity of a modified power law model for the mechanical characterization of a living tissue.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
This manuscript contains 14 pages, 4 figures, along with a Supplementary Information
Universal Scaling Functions of the Gr{ü}neisen Ratio near Quantum Critical Points
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Xuan Zhou, Enze Lv, Wei Li, Yang Qi
The Grüneisen ratio, defined as $ \Gamma_g \equiv (1/T) (\partial T/\partial g)_S$ , serves as a highly sensitive probe for detecting quantum critical points (QCPs) driven by an external feild $ g$ and for characterizing the magnetocaloric effect (MCE). Near a QCP, the Grüneisen ratio displays a universal divergence which is governed by a universality-class-dependent scaling function stemming from the scale invariance. In this work, we systematically investigate the universal scaling functions of Grüneisen ratio in both one-dimensional (1D) and two-dimensional (2D) quantum spin systems, including the transverse-field Ising model, the spin-1/2 Heisenberg model, the quantum $ q$ -state Potts model ($ q=3,4$ ) and the $ J_1$ -$ J_2$ columnar dimer model. Our approach employs the thermal tensor-network method for infinite-size 1D systems and the stochastic series expansion quantum Monte Carlo (SSE QMC) simulations for 2D systems, enabling precise calculations of the Grüneisen ratio near QCPs. Through data collapse analysis, we extract the corresponding scaling functions, which establish quantitative frameworks to interpret magnetocaloric experiments and guide the development of ultralow-temperature refrigeration.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
12 pages, 6 figures
Protection of metal interfaces against hydrogen-assisted cracking
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Guillaume Hachet, Shaolou Wei, Ali Tehranchi, Xizhen Dong, Jérémy Lestang, Aochen Zhang, Binhan Sun, Stefan Zaefferer, Baptiste Gault, Dirk Ponge, Dierk Raabe
Enabling a hydrogen economy requires the development of materials resistant to hydrogen embrittlement (HE). More than 100 years of research have led to several mechanisms and models describing how hydrogen interacts with lattice defects and leads to mechanical property degradation. However, solutions to protect materials from hydrogen are still scarce. Here, we investigate the role of interstitial solutes in protecting critical crystalline defects sensitive to hydrogen. Ab initio calculations show that boron and carbon in solid solutions at grain boundaries can efficiently prevent hydrogen segregation. We then realized this interface protection concept on martensitic steel, a material strongly prone to HE, by doping the most sensitive interfaces with different concentrations of boron and carbon. This segregation, in addition to stress relaxations, critically reduced the hydrogen ingress by half, leading to an unprecedented resistance against HE. This tailored interstitial segregation strategy can be extended to other metallic materials susceptible to hydrogen-induced interfacial failure
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Pre-print
Interplay of interlayer distance and in-plane lattice relaxations in encapsulated twisted bilayers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Encapsulation protects functional layers, ensuring structural stability and improving the quality of assembled van der Waals heterostructures. Here, we develop a model that describes lattice relaxation in twisted bilayers accounting for encapsulation effects, incorporated via a single parameter characterizing rigidity of encapsulation material interfaces. By analysing the twist-angle dependence of weak-to-strong lattice relaxation transition in twisted transition metal dichalcogenide bilayers, we show that increasing interface rigidity raises the crossover twist angle between the two relaxation regimes. Furthermore, tuning this rigidity parameter allows to achieve a good agreement with existing experimental results.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Magnetically Enhanced Thermoelectric Effect Driven by Martensitic Transformation in the Weak Itinerant Ferromagnet Co$_2$NbSn
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Takumi Kihara, Xiao Xu, Yuki Ogi, Yoshiya Adachi, Tufan Roy, Ryuji Matsuura, Takeshi Kanomata
We investigated the magnetic and thermoelectric properties of the full Heusler alloy Co$ _2$ NbSn, which exhibits a martensitic transformation at 240 K. Magnetization measurements reveal weak itinerant ferromagnetism in the martensitic phase, which is well described by Takahashi’s spin fluctuation theory. The characteristic spin fluctuation parameters were estimated to be T_0 = 1.0$ \times$ 10^3 K and T_A = 7.2$ \times$ 10^3 K. Seebeck coefficient measurements under magnetic fields up to 9 T show complex temperature and field dependence, which we decomposed into electron diffusion, spin fluctuation drag, and magnon drag components. A significant magnon-drag contribution was identified in both austenite and martensitic phases. Remarkably, this contribution is strongly enhanced in the martensitic phase compared to the austenite phase, despite a smaller magnetic moment. These findings provide evidence for robust low-energy spin excitations and highlight the potential of martensitic transformation in enhancing the thermoelectric performance of itinerant ferromagnetic alloys.
Materials Science (cond-mat.mtrl-sci)
18 pages, 8 figures
The nuts and bolts of gauge invariance of heat transport
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
In this work I revisit the notion of gauge invariance in thermal transport and show, in the simplest and most general possibile terms, why heat conductivity is unaffected by the specific choice of energy density. I provide the minimal and general conditions under which any two energy densities, though differing locally, lead to the same heat conductivity within the Green-Kubo framework. The relevance of gauge invariance in heat-transport simulations performed with machine-trained neural-network potentials is also briefly highlighted.
Statistical Mechanics (cond-mat.stat-mech)
4 pages, 1 figure
Dynamics of $\mathrm{CP}^{N-1}$ skyrmions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Seungho Lee, Hyojae Jeon, Jung Hoon Han
We derive several exact results for the dynamics of CP$ ^{N-1}$ skyrmions with arbitrary $ N$ . Fractonic continuity equation is shown to hold for arbitrary CP$ ^{N-1}$ fluid implying the conservation of the topological charge and the dipole moment. Inclusion of the Gilbert damping modifies the continuity equation, resulting in the violation of the dipole moment conservation but not of the topological charge. Thiele’s equation for the CP$ ^{N-1}$ skyrmion follows from the modified continuity equation. The Girvin-MacDonald-Platzman (GMP) algebra in the long-wavelength limit is derived for arbitrary CP$ ^{N-1}$ fluid. In the case of CP$ ^2$ skyrmions, we identify two kinds of energetically stable skyrmions in which the quadrupolar moments or the ferromagnetic moments are dominant. In the latter case, one can associate a nonzero CP$ ^1$ charge equal to half the CP$ ^2$ skyrmion charge and argue that the topological Hall effect of electrons should exist due to their coupling to the ferromagnetic part of the CP$ ^2$ texture.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 1 figure
Coarsening dynamics for spiral and nonspiral waves in active Potts models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
This study examines the domain-growth dynamics of $ q$ -state active Potts models ($ q = 3$ –$ 8$ ) under the cyclically symmetric conditions using Monte Carlo simulations on square and hexagonal lattices. By imposing active cyclic flipping of states, finite-length waves emerge in the long-term limit. This study focuses on coarsening dynamics from an initially random mixture of states to these moving-domain states. When spiral waves appear in the final state, the correlation length follows the Lifshitz–Allen–Cahn (LAC) law ($ \propto t^{1/2}$ ) until saturation is observed at the characteristic wavelength. By contrast, in the case of nonspiral waves, the growth rate is raised prior to the saturation, leading to a transient increase in the coarsening exponent. Moreover, the mean cluster size exhibits a similar form of transient increase under most of the conditions. In factorized symmetry modes at $ q=6$ , domains composed of two or three states similarly follow the LAC law. Finally, this study confirmed that the choice of lattice type (square or hexagonal) and update scheme (Metropolis or Glauber) does not alter the dynamic behavior.
Statistical Mechanics (cond-mat.stat-mech), Pattern Formation and Solitons (nlin.PS)
8 pages, 9 figures
Dimensionality effect on exceptional fermionic superfluidity with spin-dependent asymmetric hopping
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-23 20:00 EDT
Soma Takemori, Kazuki Yamamoto, Akihisa Koga
Non-Hermitian (NH) quantum systems host exceptional points (EPs), where eigenstates and eigenvalues coalesce, leading to unconventional many-body phenomena absent in Hermitian systems. While NH fermionic systems with complex interactions exhibit superfluid (SF) breakdown with EPs, spin-dependent asymmetric hopping can stabilize a NH superfluid (NH-SF) that coexists with EPs. In this work, we investigate the quasi-one-dimensional NH attractive Fermi-Hubbard model by using NH BCS theory. We demonstrate that, when the system is regarded as weakly-coupled chains, the exceptional SF phase becomes unstable and metastable (exceptional) SF state appears between the stable SF and normal states. In the one-dimensional limit, the exceptional SF disappear entirely and EPs only appear on the phase boundary between the normal and SF states. These results reveal how dimensional crossover governs the stability of the exceptional SF, providing the insights into the interplay between dimensionality and dissipation, with potential relevance for experimental implications in ultracold atoms.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
11 pages, 5 figures
Topical review: the nature of the ground state and possibility of a quantum spin liquid in 1T metal dichalcogenides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
C. J. Butler, M. Naritsuka, T. Hanaguri
The compounds 1T-TaX2 (X = S, Se) and 1T-NbSe2 have been considered as potential hosts of a quantum spin liquid phase. This is based on the widely held view that the Mott-Hubbard mechanism drives the insulating behaviour of its charge density wave ground state, resulting in localized spins, interacting antiferromagnetically, on a geometrically frustrated lattice. However this assumes layer-wise independent behaviour. A growing body of evidence shows not only that inter-layer interactions are very significant in 1T-TaS2, but also that they mediate some of its most interesting functional properties. Here we offer a perspective from the point of view of scanning tunnelling microscopy that helps to visualize the microscopic degrees of freedom of inter-layer interactions in bulk 1T-TaS2, and the associated impact on the local density-of-states, including the occurrence of multiple distinct insulating phases. We consider to what extent the bulk of 1T-TaS2, and its surface terminations can be considered as Mott insulating and whether, or where, quantum spin liquid behaviour might persist. To better understand the bulk behaviour we also draw insights from measurements on isolated monolayers of 1T-TaX2 and 1T-NbSe2, where the confounding complications of inter-layer interactions are absent. We highlight some outstanding questions raised by a comprehensive evaluation of the experimental results, and finally suggest future experiments that could address them.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
45 pages, 24 figures. Accepted for publication in Journal of Physics: Condensed Matter
Tracking four-dimensional atomic evolutions of single nanocatalysts throughout the life cycles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Jisheng Xie, Zhiheng Xie, Dijin Jiang, Shiyun Li, Yiheng Dai, Yao Zhang, Mufan Li, Jihan Zhou
Structural changes induced by chemical reactions critically determine the catalytic performance and mechanism. However, precise tracking of the three-dimensional (3D) atomic structural evolution of individual bimetallic nanocatalysts remains challenging. Here we develop four-dimensional electrocatalytic atomic-resolution electron tomography, a method for directly tracking 3D atomic rearrangements in identical nanoparticles by electrocatalytic reactions. Using Pd-Pt bimetallic nanoparticles as a model system, we capture the atomic evolution of single nanocatalysts throughout electrocatalytic cycles. We observe two stages of evolutions: surface reconstruction and atom leaching, which are corroborated with the voltage-dependent behaviors probed by in situ electrochemical transmission electron microscopy. We identify chemical short-range order at atomic level and further reveal anisotropic chemical redistributions across different crystallographic orientations. These findings highlight the necessity of incorporating 3D spatiotemporal and chemical evolutions into the rational design of functional nanocatalysts in the future.
Materials Science (cond-mat.mtrl-sci)
52 pages, 3 main figures, 29 SI figures
Predicting the Curie Temperature of Magnetic Materials with Machine Learning: Descriptor Engineering, Graph Neural Networks, and the Role of Curated Data
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Akram Abedi Orang, Mojtaba Alaei, Artem R. Oganov
Predicting the Curie temperature ($ T_\mathrm{C}$ ) of magnetic materials is crucial for advancing applications in data storage, spintronics, and sensors. We present a machine learning (ML) framework to predict $ T_{\mathrm{C}}$ using a curated dataset of 2,500 ferromagnetic compounds, employing two types of elemental descriptor-based features: one based on stoichiometry-weighted descriptors, and the other leveraging Graph Neural Networks (GNNs). CatBoost trained on the stoichiometry-weighted descriptors achieved an $ R^2$ score of 0.87, while the use of GNN-based representations led to a further improvement, with CatBoost reaching an $ R^2$ of 0.91, highlighting the effectiveness of graph-based feature learning. We also demonstrated that using an uncurated dataset available online leads to poor predictions, resulting in a low $ R^2$ score of 0.66 for the CatBoost model. We analyzed feature importance using tools such as Recursive Feature Elimination (RFE), which revealed that ionization energies are a key physicochemical factor influencing $ T_\mathrm{C}$ . Notably, the use of only the first 10 ionization energies as input features resulted in high predictive accuracy, with $ R^2$ scores of up to 0.85 for statistical models and 0.89 for the GNN-based approach. These results highlight that combining robust ML models with thoughtful feature engineering and high-quality data, can accelerate the discovery of magnetic materials. Our curated dataset is publicly available on GitHub.
Materials Science (cond-mat.mtrl-sci)
Electronic-correlation-assisted charge stripe order in a Kagome superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-23 20:00 EDT
Linwei Huai, Zhuying Wang, Huachen Rao, Yulei Han, Bo Liu, Shuikang Yu, Yunmei Zhang, Ruiqing Zang, Runqing Luan, Shuting Peng, Zhenhua Qiao, Zhenyu Wang, Junfeng He, Tao Wu, Xianhui Chen
A central mystery in high-temperature cuprate superconductors is the coexistence of multiple exotic orders, which is presumably associated with strong electronic correlation. The ongoing interest in this enigmatic phenomenon is further energized when similar electronic orders and states emerge and coexist in less correlated Kagome superconductors. Here, by utilizing angle-resolved photoemission spectroscopy (ARPES), nuclear magnetic resonance (NMR) spectroscopy, scanning tunneling microscopy (STM) and first-principles calculations, we reveal the sudden emergence of a distinct short-range charge stripe order in Sn-doped CsV$ _3$ Sb$ _5$ Kagome superconductors when the long-range $ 2 \times 2$ charge density wave order in pristine CsV$ _3$ Sb$ _5$ is suppressed. This short-range stripe order features a modulation vector of approximately 1/3 along one of the three lattice directions, induces remarkable quasiparticle scattering between the original quasi-1D Kagome-d-bands and their replica of folding, and clearly suppresses the electron density of states at the Fermi level. Our first-principles calculations reveal that $ 3 \times 1$ supermodulation represents a hidden secondary instability in pristine CsV$ _3$ Sb$ _5$ . This instability is further enhanced by in-plane chemical pressure induced by Sn substitution, and coupled to the electronic correlation, leading to a unique charge stripe order in the system. As such, our results reveal a new route toward emergent electronic orders via cooperative interactions between the lattice and electronic degrees of freedom.
Superconductivity (cond-mat.supr-con)
23 pages and 4 figures
Same-group element replacement enhances superconductivity in clathrate-like YH4
New Submission | Superconductivity (cond-mat.supr-con) | 2025-09-23 20:00 EDT
Xuejie Li, Yuzhou Hao, Yujie Liu, Xiaoying Wang, Turab Lookman, Jun Sun, Xiangdong Ding, Zhibin Gao
H3S, LaH10, and hydrogen-based compounds have garnered significant interest due to their high-temperature superconducting properties. However, the requirement for extremely high pressures limits their practical applications. In this study, YH4 is adopted as a base material, with partial substitution of Yttrium (Y) by Scandium (Sc), Lanthanum (La), and Zirconium (Zr). Pure YH4, stable at 120 GPa, exhibits a critical temperature (Tc) of 84-95 K. Substituting half of the Y atoms increases Tc to 124.43 K for (Y,Sc)H4 at 100 GPa but reduces it to 101.24 K for (Y,La)H4 at 120 GPa. In contrast, (Y,Zr)H4 at 200 GPa shows a further suppressed Tc of 69.55 K. The remarkable superconductivity in (Y,Sc)H4 might be related to its unique phonon dispersion without optical-acoustic gap, compressed Y-H bonds, and significant electron delocalization under pressure, collectively boosting electron-phonon interactions. Furthermore, the lowest optical phonons play a crucial role in the superconductivity of these materials. This work suggests that substituting Y with same-group metal elements is an effective strategy to enhance Tc in hydride superconductors.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Magnetic flux controlled current phase relationship in double Quantum Dot Josephson junction
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Yiyan Wang, Cong Li, Bing Dong
In this work, we study a Josephson junction with parallel-connected quantum dots (QDs) threaded by a magnetic flux in the central region. We discretize the superconducting (SC) electrode into three discrete energy levels and modify the tunneling coefficients to construct a finite-dimensional surrogate Hamiltonian. By directly diagonalizing this Hamiltonian, we compute the physical quantities of the system. Additionally, we employ a low-energy effective model to gain deeper physical insight. Our findings reveal that when only one QD exhibits Coulomb interaction, the system undergoes a phase transition between singlet and doublet states. The magnetic flux has a minor influence on the singlet state but significantly affects the doublet state. When both QDs have interactions, the system undergoes two phase transitions as the SC phase difference increases: the ground state evolves from a doublet to a singlet and finally into a triplet state at $ \phi = \pi$ . Increasing the magnetic flux suppresses the doublet and triplet phases, eventually stabilizing the singlet state. In this regime, enhancing the interaction strength does not induce a singlet-doublet transition but instead drives a transition between upper and lower singlet states, leading to a critical current peak as $ U$ increases. Finally, we examine the case where the tunneling coefficient $ \Gamma$ exceeds the SC pairing potential $ \Delta$ . Here, doublet states dominate, and the system only exhibits a phase transition between doublet and triplet states when $ \phi_B = 0$ . In the presence of a magnetic flux, the three states converge, resulting in a triple point in the ($ \phi$ , $ \phi_B$ ) parameter space.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
12 pages, 8 figures
Delta-Doped Diamond via in-situ Plasma-Distance Control
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Philip Schätzle, Felix Hoffmann, Sven Mägdefessel, Patrik Straňák, Lutz Kirste, Peter Knittel
We present an approach for the CVD growth of diamond, where the sample is placed in a defined distance from the reactor baseplate, to which the plasma couples. We observe two previously unknown growth regimes. In the first case, the sample is positioned within three to five millimeters of the plasma, leading to a decreased growth rate, compared to a position inside the plasma and, additionally, to an increased nitrogen incorporation, allowing the fabrication of delta-doped layers with a thickness below 30 nm. In another regime, where the sample is more than 10 mm away from the plasma, no growth is observed. Instead, we assume a deposition of nitrogen-rich species on the diamond surface, which is incorporated during the growth of the following layer. All fabricated layers show NV emission, where the intensity correlates with the nitrogen incorporation. The growth techniques could allow the fabrication of highly doped thin films for quantum sensing applications, as well as layers with low NV concentration, for quantum computing. The new approaches are applicable not only for nitrogen incorporation but also for other defects, for example, phosphorus, which could open up new avenues for diamond-based electronics.
Materials Science (cond-mat.mtrl-sci), Plasma Physics (physics.plasm-ph)
Measurements and scaling of X-ray total scattering from single crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
S. Gorfman, M. Eremenko, V. Krayzman, A. Bosak, P. Y. Zavalij, I. Levin
We present a measurement protocol and a data reduction workflow for obtaining single-crystal X-ray total-scattering datasets that capture both Bragg-peak and diffuse scattering intensities on an absolute (electrons2/atom) scale. We further demonstrate that the intensity scale factor derived from crystallographic refinements using Bragg peaks is in close agreement with that obtained by matching the scattering function, computed via spherical integration of the 3D total scattering signal, to the theoretical coherent baseline, calculated as the spherical average of the Debye-Waller factor. The latter approach can be applied to diffuse scattering without including Bragg peaks. Our results set the ground for structural refinements using large atomic configurations while simultaneously fitting Bragg intensities and diffuse scattering from a single crystal. Moreover, with the convergence between the two scaling methods, the Bragg and diffuse components can be obtained from the same total-scattering dataset, as achieved in this work, or measured independently.
Materials Science (cond-mat.mtrl-sci)
21 pages, 8 figures, 2 Appendices
Deciphering the dynamics of the light-induced phase transition in VO$_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
S. Mandal, P. Kumar, H. Y. Kim, Z. Pi, J. Xu, D. Chen, D. Kazenwadel, P. Baum, S. Meng, E. Goulielmakis
Vanadium dioxide (VO$ _2$ ) is central in the study of ultrafast photoinduced insulator-to-metal phase transitions in strongly correlated materials, and a primary candidate for next-generation light-driven devices. However, the physical mechanism underlying its phase transition remains unresolved. Here, we use single-cycle light transients to perform phase-resolved ultrafast spectroscopy on VO$ _2$ crystals. Our experiments reveal two processes: a structural transformation from the insulating monoclinic M1-VO$ _2$ phase to the excited metallic rutile R\ast-VO$ _2$ phase, followed by electron thermalization and relaxation dynamics intrinsic to the newly formed excited metallic phase.
Strongly Correlated Electrons (cond-mat.str-el), Optics (physics.optics)
The van der Waals Gap: a Hidden Showstopper in Semiconductor Device Scaling
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Continued miniaturization of transistors is critical for sustaining advances in computing performance, energy efficiency, and integration density. A central nanoscale challenge is controlling gate leakage through ultrathin dielectrics. In evaluating candidate insulators, permittivity and bandgap are often emphasized; however, interfaces between two-dimensional (2D) semiconductors and gate dielectrics typically form a van der Waals (vdW) gap whose electronic properties are underappreciated. Using first-principles calculations and analytical modeling supported by experiment, we find typical vdW gaps of about 1.4 Å with an effective dielectric constant near 2, which adds roughly 2.7 Å to the equivalent oxide thickness (EOT). The vdW gap serves as an additional tunneling barrier that can reduce gate leakage by one to two orders of magnitude, but it also introduces parasitic capacitance that can offset the benefits of high-k dielectrics. We introduce a dimensionless figure of merit that combines dielectric screening, tunneling suppression, and thickness-dependent permittivity of ultrathin oxides to predict the minimum achievable EOT for a target gate-leakage current in the presence of a vdW gap. Although some materials may benefit from vdW gaps, our results indicate they often impose severe constraints on further scaling. In particular, due to the vdW gap, most currently considered insulators are unlikely to scale to an EOT of 5 Å as targeted by the IRDS roadmap for future nodes. As a potential alternative, we examine ``zippered’’ structures in which quasi-covalent bonding between 2D layers eliminates the vdW gap while avoiding dangling bonds.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Linear Viscoelasticity of Dilute Solutions of Semiflexible Polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Amit Varakhedkar, P. Sunthar, J. Ravi Prakash
The linear viscoelastic response of dilute solutions of semiflexible polymers is studied using Brownian dynamics simulations of coarse-grained bead-spring chains. The springs obey the FENE-Fraenkel force law, a bending potential is used to capture chain stiffness and hydrodynamic interactions are included through the Rotne-Prager-Yamakawa tensor. By calculating the relaxation modulus following a step strain, we demonstrate that the bead-spring chain behaves like an inextensible semiflexible rod over a wide time window with an appropriate choice of spring stiffness and chain extensibility. In the absence of hydrodynamic interactions, our results agree with the existing theoretical predictions for the linear viscoelastic response of free-draining, inextensible, semiflexible rods in dilute solutions. It is shown that at intermediate times, the stress relaxation modulus exhibits power law behaviour, with the exponent ranging from $ (-1/2)$ for flexible chains to $ (-5/4)$ for highly rigid chains. At long times, rigid chains undergo orientational relaxation, while flexible chains exhibit Rouse relaxation. Hydrodynamic interactions are found to effect the behaviour at intermediate and long times, with the difference from free-draining behaviour increasing with increasing chain flexibility. Computations of the frequency dependence of loss and storage moduli are found to be in good agreement with experimental data for a wide variety of systems involving semiflexible polymers of varying stiffness across a broad frequency range.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
17 pages, 15 figures
Selective reflection of light in glassforming ternary liquid crystalline mixtures
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Aleksandra Deptuch, Zuzanna Zając, Marcin Piwowarczyk, Anna Drzewicz, Magdalena Urbańska, Ewa Juszyńska-Gałązka
Two ternary liquid crystalline mixtures are formulated and investigated by differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction, and broadband dielectric spectroscopy. Paraelectric smectic A\ast, ferroelectric smectic C\ast, and antiferroelectric smectic C$ _A$ \ast phases are detected. The glass of the smectic C$ _A$ \ast phase is formed at moderate cooling rates. One mixture shows a strong thermochromic effect in the smectic C$ _A$ \ast phase and selectively reflects blue light in the glassy state. Both mixtures reflect either green or red light in the smectic C\ast phase, depending on temperature treatment: whether the sample is cooled or heated, or at which rate the temperature changes.
Soft Condensed Matter (cond-mat.soft)
Emergent Composite Particles from the Universal Exact Identities in Quantum Many-Body Systems with Generic Bilinear Interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
A fundamental challenge in quantum many-body physics is to understand the universal properties of strongly correlated systems. In this work, we establish a universal and exact identity from the Dyson-Schwinger equations within the Keldysh-Schwinger field theory for systems with generic bilinear interactions. Our derivation demonstrates the emergence of composite particles as “elementary excitations”, whose Green’s functions definitively determine the original single-particle Green’s function. This universal relation uniquely identifies the composite particles governing correlations and rigorously connects their spectra to the observable single-particle spectrum. Thus, our exact identity reveals a new pathway toward a paradigm for understanding many-body correlated systems.
Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 1 figures
Melanin-Based Compounds as Low-Cost Sensors for Nitroaromatics: Theoretical Insights on Molecular Interactions and Optoelectronic Responses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Jo{ã}o Paulo Cachaneski-Lopes (UNESP, UPPA), Felipe Hawthorne (UFPR), Cristiano Woellner (UFPR), Toby Nelson, Roger Hiorns (UPPA), Carlos Graeff (UNESP), Didier Bégué (UPPA), Augusto Batagin-Neto (UNESP)
Nitroaromatic compounds (NACs) are used in various industrial applications including dyes, inks, herbicides, pharmaceuticals, and explosives. Due to their toxicity and environmental persistence, reliable detection and monitoring methods are required. Hybrid organic–inorganic structures have shown potential for NAC sensing; however, their complex synthesis, high processing costs, and limited reproducibility hinder practical implementation, highlighting the need for simpler and more accessible materials. In this study, we employed density functional theory (DFT)-based calculations to evaluate the electronic, optical, and reactive properties of two melanin-based oligomeric systems, aiming to assess their potential use as NAC detectors. Our results indicate the potential of these materials to detect a series of nitroaromatic compounds such as 2,4-DNP, 2,4-DNT, 2,6-DNT, TNP, and TNT by electrical and infrared optical measurements. Born–Oppenheimer molecular dynamics (BOMD) simulations reveal the thermal stability of the adsorption process, confirming effective substrate–analyte interaction under different temperature conditions. To the best of our knowledge, this compound has not been proposed for sensing applications. Its low cost and facile synthesis make it a promising candidate for the development of environmentally friendly organic NAC sensors.
Materials Science (cond-mat.mtrl-sci)
ACS Omega, 2025
Arbitrary number of thermally induced phase transitions in different universality classes in $XY$ models with higher-order terms
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
We propose generalized variants of the $ XY$ model capable of exhibiting an arbitrary number of phase transitions only by varying temperature. They are constructed by supplementing the magnetic coupling with $ n_t-1$ nematic terms of exponentially increasing order with the base $ q=2,3,4$ and $ 5$ , and increasing interaction strength. It is found that for $ q=2,3$ and $ 4$ with sufficiently large coupling strength of the final term, the models exhibit a number of phase transitions equal to the number of the terms in the generalized Hamiltonian. Starting from the paramagnetic phase, the system transitions through the cascade of $ n_t-1$ nematic phases of the orders $ q^{k}$ , $ k=n_t-1,n_t-2,\hdots,1$ , that are characterized by $ q^{k}$ preferential spin directions symmetrically disposed around the circle, to the ferromagnetic (FM) phase at the lowest temperatures. Besides the BKT transition from the paramagnetic phase, all the remaining transitions have a non-BKT nature: depending on the value of $ q$ they belong to either the Ising ($ q=2$ and $ 4$ ) or the three-states Potts ($ q=3$ ) universality class. For $ q=5$ , due to the interplay between different terms, the phase transitions between the ordered phases observed for $ q<5$ split into two and the number of the ordered phases increases to $ 2n_t-1$ . These phases are characterized by a domain structure with the gradually increasing short-range FM ordering within domains that extends to different kinds of FM ordering in the last two low-temperature phases. The respective transitions do not seem to obey any universality.
Statistical Mechanics (cond-mat.stat-mech)
21 pages, 10 figures
Design, synthesis, and physical properties of the intergrowth compound Eu$_2$CuZn$_2$As$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Xiyu Chen, Ziwen Wang, Wuzhang Yang, Jia-Yi Lu, Zhiyu Zhou, Shanshan Wang, Zhi Ren, Guang-Han Cao, Shuai Dong, Zhi-Cheng Wang
The rational combination of existing magnetic topological compounds presents a promising route for designing new topological materials. We report the synthesis and comprehensive characterization of the layered quaternary intergrowth compound Eu$ _2$ CuZn$ _2$ As$ _3$ , which combines structural units of two known magnetic topological materials, EuCuAs and EuZn$ _2$ As$ 2$ . Eu$ 2$ CuZn$ 2$ As$ 3$ exhibits an antiferromagnetic ground state with successive magnetic transitions: quasi-two-dimensional ordering at $ T\mathrm{M} = 29.3$ ,K, long-range antiferromagnetic ordering at $ T\mathrm{N} = 19$ ,K, and spin-reorientation at $ T\mathrm{SR} = 16.3$ ,K. The stepwise magnetic transitions manifest as plateau-like anomalies in the heat capacity. These transitions originate from multiple superexchange pathways and periodic variation of interplane Eu-Eu distances in the intergrowth structure. Charge transport shows a pronounced resistivity increase above $ T\mathrm{N}$ followed by minimal change below the ordering temperature. Magnetic fields rapidly suppress this resistivity rise, yielding significant negative magnetoresistance. Remarkably, Eu$ _2$ CuZn$ _2$ As$ _3$ inherits the nonlinear anomalous Hall effect characteristic of its parent compounds. Energy evaluations of collinear spin configurations reveal a lowest-energy state with ferromagnetic coupling between Eu planes in EuCuAs units while maintaining antiferromagnetic coupling within EuZn$ _2$ As$ _2$ units. The corresponding electronic structure displays potentially topologically nontrivial features. Our work demonstrates the efficacy of structural hybridization for discovering novel magnetic topological materials and establishes a general strategy for materials discovery.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Reduced fluctuations: Surprising effects of noise cross correlations in a coupled, driven model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
We elucidate how the strong coupling phases of a coupled driven model, originally proposed in S. Mukherjee, Phys. Rev. E 108, 024219 (2023), are affected by noise cross correlations in general dimensions $ d$ . This model has two dynamical variables, where one of the variables is autonomous being independent of the other, whereas the second one depends explicitly on the former. By employing model coupling theories, we study the strong coupling phase of model. We show that the scaling laws in the strong coupling phase of the second field depend strongly on the strength of the noise cross correlations: the roughness exponent of the second field varies continuously with the noise cross correlation amplitude. As the latter amplitude rises, the roughness exponent gradually decreases, suggestion a novel suppression of the fluctuations of the second field in the strong coupling phase by noise cross correlations. We discuss the phenomenological implications of our results.
Statistical Mechanics (cond-mat.stat-mech)
8 pages, 1 figure, preliminary version
Spin-Seebeck Signatures of Spin Chirality in Kagome Antiferromagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Feodor Svetlanov Konomaev, Mithuss Tharmalingam, Kjetil M. D. Hals
Non-collinear antiferromagnets (NCAFMs) are appealing for antiferromagnetic spintronics, as they combine the advantages of collinear antiferromagnets with novel emergent phenomena stemming from their complex spin structures. These phenomena are often associated with the intrinsic spin chirality, which characterizes the handedness of the ground-state spin configuration. Here, we investigate a kagome NCAFM interfaced with a normal metal and demonstrate that the ground-state vector spin chirality can be probed through measurements of the spin Seebeck effect (SSE). Starting from a microscopic spin Hamiltonian, we derive the corresponding bosonic Bogoliubov-de Gennes Hamiltonians for the two chiral configurations. Using linear response theory, we obtain a general expression for the spin current thermally pumped into the normal metal by the SSE. We show that a sizable in-plane spin current emerges exclusively in the negative-chiral state, providing a direct signature for real-time detection of chirality switching in kagome NCAFMs. In addition, we find a field-dependent out-of-plane spin current whose magnitude differs between the two chiralities by about 4%, reflecting their distinct magnon band structures.
Materials Science (cond-mat.mtrl-sci)
8 pages, 3 figures, submitted to Physical Review B
Characterizing the Structure of 3D DNA Origami in a Transmission Electron Microscope
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Alyna Ong, Christoph Hadlich, Taekyu Jeong, Darius Pohl, Iman Elbalasy, Ralf Seidel, Michael Mertig, Bernd Rellinghaus
DNA origami nanostructures provide programmable control over nanoscale geometry but remain challenging to image due to their low atomic number. Here, we systematically evaluate imaging strategies for both stained and unstained DNA origami deposited on carbon-coated TEM grids. Using Weber contrast as a quantitative metric, we compared different operating modes of (scanning) transmission electron microscopy, (S)TEM, in order to find optimum imaging conditions. STEM was consistently found to deliver the highest contrast, with optimal performance at a camera length of 600 mm towards the high angle annular dark field (HAADF) detector. As expected, the contrast was higher for the thicker three-dimensional nanotubes as compared to DNA 6-helix bundles (6HBs) due to the larger projected thickness of the former. The contrast was effectively enhanced by heavy metal staining with uranyl formate. Notably, 3D molds preserved their designated dimensions upon staining and also largely retained their structural integrity upon complexation with palladium, which also improved the visibility of the structures. These results establish STEM as the optimal approach for high-contrast imaging of DNA origami even of unstained samples and provide practical guidelines for sample preparation and imaging conditions that promote reliable structural visualization.
Materials Science (cond-mat.mtrl-sci)
18 pages, 6 figures, 2 supplementary figures
Topological Mechanics of Entangled Networks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Juntao Huang, Jiabin Liu, Shaoting Lin
Entangled networks are ubiquitous in tissues, polymers, and fabrics. However, their mechanics remain insufficiently understood due to the complexity of the topological constraints at the network level. Here, we develop a mathematical framework that models entangled networks as graphs, capturing topological constraints of entanglements. We prove that entanglements reduce system energy by enabling uniform tension along chains crossing entanglements and by redistributing stress through sliding. Under this framework, we study elasticity and fracture, validated by experiments on entangled fabrics and hydrogels. For elasticity, entanglements increase strength by enabling stress homogeneity in the network. For fracture, entanglements enhance toughness by mitigating stress concentration around crack tips. We discover counterintuitive physical laws governing crack-tip stretch during crack opening: stress deconcentration at small deformation, constitutive-law independence at intermediate deformation, and linear scaling at large deformation. This framework establishes fundamental principles of linking topology to mechanics of entangled networks and offers a foundational tool for designing reconfigurable materials.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Computational Physics (physics.comp-ph)
Breaking of Time-Reversal Symmetry and Onsager Reciprocity in Chiral Molecule Interfacd with an Environment
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Molecular closed shell structures are known to form spin-singlet configurations, resulting from the spin-exchange associated with electron-electron interactions. While the vanishing total spin-moment is an immanent property of the spin-singlet, the vanishing local moments is a result of fluctuations between degenerate spin-configurations. Here, it is demonstrated that the spin-configuration of a chiral molecule is enantiospecifically locked when coupled to an electron reservoir. The coupling opens up the molecular closed shell structure, which broadens the energy levels. Together with the molecular spin-orbit coupling, this dissipative coupling generates an effective spin-splitting of the molecular energy levels and facilitates stabilization of a chirality determined spin-configuration. Simultaneously, the charge molecular charge distribution is shown to depend linearly on the magnetization of the reservoir such that no linear response regime is established with respect to the external magnetization. Accordingly, the Onsager reciprocity theorem does not apply to a chiral molecule attached to a reservoir, hence, providing a theoretical foundation for the chirality induced spin selectivity effect.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 7 figures; submitted
Folding-unfolding transition of active polymer on the reconfiguration of bidirectional tangential active force
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
The role of active stress on the conformational dynamics of a polymer has drawn significant interest due to its potential applications in understanding the energy landscape of protein structures, buckling of biopolymers, genomic spatial organization, and their large scale coherent dynamics. We present a model of bidirectional active force that acts along the polymer’s tangent, with its direction stochastically reversing between head to tail and tail to head orientations. The active polymer shows a structural transition from a random coil like state to a compressed state with variations in the active force, directional (polarity) reversal rate, and their fraction. Furthermore, the polymer re-swells and stretches more than its passive limit for a large active force. The polymer’s radius of gyration follows the ideal chain-like scaling relation in both the compressed and swelled states. The bidirectional active force also drives dynamical transitions, where the effective diffusivity abruptly shifts from a linear to quadratic increase. Similarly, in the regime of large activity, the linear decrease of the longest relaxation time of the polymer changes to a power law behavior. We have shown that the active polymer’s conformational, relaxation, and diffusive behaviors display a transition from an active polar linear polymer model (APLP) to an active Brownian particle (ABP) polymer model with the increase in the fraction of the opposite polarity and their reconfiguration time.
Soft Condensed Matter (cond-mat.soft)
41 pages, 23 figures
Macromolecules, 2025
Role of Oxygen during Methane Oxidation on Pd$_1$/PdO$_1$@CeO$_2$ Surface: A Combined Density Functional Theory, Microkinetic, and Machine Learning Approach
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Shalini Tomar, Hojin Jeong, Joon Hwan Choi, Seung-Cheol Lee, Satadeep Bhattacharjee
This work explores the role of oxygen in industrial methane oxidation. Oxygen, a well-known oxidizing agent, drives CH$ _4$ conversion to CO$ _2$ and H$ _2$ O. We report how oxygen influences oxidation on single Pd and PdO clusters supported on CeO$ _2$ (111). Oxygen is introduced by (1) lattice O in PdO and (2) O$ _2$ adsorption on an isolated Pd atom, forming PdO$ _x$ clusters. Density-functional theory (DFT) mapped multiple reaction pathways on the Pd$ _1$ /PdO$ _1$ @CeO$ _2$ (111) surface; both Pd and PdO clusters were found to thermodynamically favour methane activation. The computed barrier for CH$ _4$ activation is 0.63 eV on PdO$ _1$ @CeO$ _2$ (111). A single Pd atom markedly accelerates O$ _2$ dissociation to PdO$ _2$ , and the presence of lattice oxygen lowers this barrier by 0.36 eV relative to an oxygen-deficient surface, enhancing catalytic efficiency. Reaction selectivity, coverage-dependent production rates, degree of rate control (DRC), and intrinsic turnover frequency (TOF) were quantified through steady-state microkinetic modelling. The simulations predict full conversion of CH$ _4$ to CO$ _2$ and H$ _2$ O above 600 K, whereas partial-oxidation intermediates dominate at lower temperature and high O coverage. Rate constants for all elementary steps were derived via the Sure Independence Screening and Sparsifying Operator (SISSO) symbolic-regression method, yielding a concise predictive expression based on charge, coordination number, and key Pd-O/C-H distances. These combined DFT-microkinetic-SISSO results clarify oxygen’s mechanistic participation and provide practical guidelines for designing Pd/CeO$ _2$ catalysts with improved activity toward methane oxidation, a reaction of pressing environmental and industrial importance.
Materials Science (cond-mat.mtrl-sci)
Strong Disorder Renormalization Group Method for Bond Disordered Antiferromagnetic Quantum Spin Chains with Long Range Interactions: Excited States and Finite Temperature Properties
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-09-23 20:00 EDT
We extend the recently introduced strong disorder renormalization group method in real space, well suited to study bond disordered antiferromagnetic power law coupled quantum spin chains, to study excited states, and finite temperature properties. First, we apply it to a short range coupled spin chain, which is defined by the model with power law interaction, keeping only interactions between adjacent spins. We show that the distribution of the absolute value of the couplings is the infinite randomness fixed point distribution. However, the sign of the couplings becomes distributed, and the number of negative couplings increases with temperature $ T.$ Next, we derive the Master equation for the power law long range interaction between all spins with power exponent $ \alpha$ . While the sign of the couplings is found to be distributed, the distribution of the coupling amplitude is given by the strong disorder distribution with finite width $ 2\alpha,$ with small corrections for $ \alpha >2$ . Resulting finite temperature properties of both short and power law long ranged spin systems are derived, including the magnetic susceptibility, concurrence and entanglement entropy.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
13 pages, 11 figures
How Realistic are Idealized Copper Surfaces? A Machine Learning Study of Rough Copper-Water Interfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Linus C. Erhard, Johannes Schörghuber, Aleix Comas-Vives, Georg K. H. Madsen
Copper is a highly promising catalyst for the electrochemical CO$ _2$ reduction reaction (CO2RR) since it is the only pure metal that can form highly added-value products such as ethylene and ethanol. Since the CO2RR takes place in aqueous solution, the detailed atomic structure of the water-copper interface is essential for unraveling the key reaction mechanisms. In this study, we investigate copper-water interfaces exhibiting nanometer-scale roughnesses. We introduce two molecular dynamics protocols to create rough copper surfaces, which are subsequently brought into contact with water. From these interfaces, we sample additional training configurations from machine-learning-interatomic-potential-driven molecular dynamics simulations containing hundreds of thousands of atoms. An active learning workflow is developed to identify regions with high spatially resolved uncertainty and convert them into DFT-feasible cells through a modified amorphous matrix embedding approach. Finally, we analyze the local environments at the interface using unsupervised machine-learning techniques. Unique environments emerge on the rough copper surfaces absent from model systems, including stacking-fault-induced configurations and undercoordinated corner atoms. Notably, corner atoms consistently feature chemisorbed water molecules in our simulations, indicating their potential importance in catalytic processes.
Materials Science (cond-mat.mtrl-sci)
The promise of high-resolution valence band RIXS at the actinide M$_{4,5}$-edges
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Martin Sundermann, Henrik Hahn, Denise S. Christovam, Maurits W. Haverkort, Roberto Caciuffo, Bernhard Keimer, Liu Hao Tjeng, Andrea Severing, Hlynur Gretarsson
Understanding the electronic structure of actinide materials is crucial for both fundamental research and nuclear applications. The partially filled 5f shells exhibit complex behavior due to strong correlations and ligand hybridization, requiring advanced spectroscopic techniques. Here, we report on the development and application of high-resolution valence-band resonant inelastic x-ray spectroscopy (VB-RIXS) experiments at the uranium M$ _{4,5}$ edges (3551 and 3725,eV). We present data of UO$ _2$ , a well-established model actinide compound. VB-RIXS is particularly well suited for probing the 5f-shell electronic structure, as it probes, in contrast to core-to-core RIXS, excitations without leaving a high-energy core hole in the final state. In VB-RIXS, we achieve energy resolutions of 50,meV (M$ _5$ ) and 90,meV (M$ _4$ ), enabling the resolution of multiplet excitations and crystal-field effects, as well as charge-transfer and fluorescence-like features with unprecedented clarity. As such, high resolution VB-RIXS offers direct insights into both low-energy, near ground-state properties and high-energy hybridization and covalency effects. Our results demonstrate the power of VB-RIXS as a versatile and powerful tool for probing the strongly correlated electronic structure of actinide materials, providing essential input for quantitative modeling and the validation of theoretical concepts.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 6 figures
Machine Learning Approach to Predict Curie Temperature in Binary Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Svitlana Ponomarova, Oleksandr Ponomarov, Yurii Koval
This study presents a machine learning approach to predict the Curie temperature in binary alloys, specifically focusing on the Fe-Pt, Fe-Ni, Fe-Pd, and Co-Pt compounds within a concentration range of 10 to 90 atomic percent. The optimal mathematical algorithm for this task is the Voting Ensemble algorithm, which combines the predictions from multiple individual models to produce a final prediction. The results are validated against classical methods for calculating Curie temperatures. The experimental findings indicate that factors such as external pressure, atomic ordering, and alloy composition have a significant influence on the Curie temperatures in all examined binary systems. These factors can be leveraged to design alloys with specific Curie temperatures. Moreover, the proposed features, feature analysis algorithms, and computational methods pave the way for advancements across various materials, including ternary alloys, bulk materials, and nanomaterials, inspiring innovation in the field.
Materials Science (cond-mat.mtrl-sci)
The Open Catalyst 2025 (OC25) Dataset and Models for Solid-Liquid Interfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Sushree Jagriti Sahoo, Mikael Maraschin, Daniel S. Levine, Zachary Ulissi, C. Lawrence Zitnick, Joel B Varley, Joseph A. Gauthier, Nitish Govindarajan, Muhammed Shuaibi
Catalysis at solid-liquid interfaces plays a central role in the advancement of energy storage and sustainable chemical production technologies. By enabling accurate, long-time scale simulations, machine learning (ML) models have the potential to accelerate the discovery of (electro)catalysts. While prior Open Catalyst datasets (OC20 and OC22) have advanced the field by providing large-scale density functional theory (DFT) data of adsorbates on surfaces at solid-gas interfaces, they do not capture the critical role of solvent and electrolyte effects at solid-liquid interfaces. To bridge this gap, we introduce the Open Catalyst 2025 (OC25) dataset, consisting of 7,801,261 calculations across 1,511,270 unique explicit solvent environments. OC25 constitutes the largest and most diverse solid-liquid interface dataset that is currently available and provides configurational and elemental diversity: spanning 88 elements, commonly used solvents/ions, varying solvent layers, and off-equilibrium sampling. State-of-the-art models trained on the OC25 dataset exhibit energy, force, and solvation energy errors as low as 0.1 eV, 0.015 eV/Å, and 0.04 eV, respectively; significantly lower than than the recently released Universal Models for Atoms (UMA-OC20). Additionally, we discuss the impact of the quality of DFT-calculated forces on model training and performance. The dataset and accompanying baseline models are made openly available for the community. We anticipate the dataset to facilitate large length-scale and long-timescale simulations of catalytic transformations at solid-liquid interfaces, advancing molecular-level insights into functional interfaces and enabling the discovery of next-generation energy storage and conversion technologies.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Direct identification of local doping effects in Barium-hexaferrite by electron vortex beams
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Darius Pohl, Hitoshi Makino, Arthur Ernst, Devendra Singh Negi, Sebastian Schneider, Rolf Erni, Jan Rusz
We demonstrate atomic-scale mapping of local magnetic moments and doping effects in Ti-doped barium hexaferrite (BaFe11TiO19) using atom-sized electron vortex beams (EVBs) with controlled orbital angular momentum (OAM) in a scanning transmission electron microscope. By measuring electron energy loss magnetic circular dichroism (EMCD) at the Fe-L2,3 edges, we directly resolve the spatial distribution of antiparallel-aligned magnetic sublattices and quantify the impact of non-magnetic Ti4+ substitution. The EMCD signal, detected from single atomic Fe columns, reveals a marked reduction and sign reversal in the magnetic moment at Ti-rich 4f2 sites, corroborated by inelastic scattering simulations and density functional theory calculations that indicate induced Fe2+ formation and modified exchange interactions. Our results show that EVBs enable direct, element-specific, and atomically resolved magnetic characterization, opening new avenues for investigating local magnetic phenomena and dopant effects in nano-structured magnetic materials, such as those used in spintronic devices. This method paves the way for detailed studies of complex spin textures, magnetic interfaces, and dynamic processes at the atomic scale.
Materials Science (cond-mat.mtrl-sci)
Random functions as data compressors for machine learning of molecular processes
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Jayashrita Debnath, Gerhard Hummer
Machine learning (ML) is rapidly transforming the way molecular dynamics simulations are performed and analyzed, from materials modeling to studies of protein folding and function. ML algorithms are often employed to learn low-dimensional representations of conformational landscapes and to cluster trajectories into relevant metastable states. Most of these algorithms require selecting a small number of features that describe the problem of interest. Although deep neural networks can tackle large numbers of input features, the training costs increase with input size, which makes the selection of a subset of features mandatory for most problems of practical interest. Here, we show that random nonlinear projections can be used to compress large feature spaces and make computations faster without substantial loss of information. We describe an efficient way to produce random projections and then exemplify the general procedure for protein folding. For our test cases NTL9 and the double-norleucin variant of the villin headpiece, we find that random compression retains the core static and dynamic information of the original high dimensional feature space and makes trajectory analysis more robust.
Soft Condensed Matter (cond-mat.soft), Machine Learning (cs.LG)
MIM-Diode-Like Rectification in Lateral 1T/1H/1T-MoS$_2$ Homojunctions via Interfacial Dipole Engineering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Elias Eckmann, Ersoy Şaşıoğlu, Nicki F. Hinsche, Ingrid Mertig
Lateral two-dimensional (2D) tunnel diodes that reproduce metal-insulator-metal (MIM)-diode-like rectification without using dissimilar contacts are attractive for scalable nanoelectronics. MoS$ _2$ can exist in both the semiconducting 1H phase and the metallic 1T phase, enabling phase-engineered homojunctions within a single material. First-principles electronic structure and quantum transport calculations show that phase-engineered 1T/1H/1T–MoS$ _2$ homojunctions exhibit pronounced MIM-diode-like rectification originating from interfacial charge transfer at asymmetric 1T/1H interfaces. The charge transfer establishes interface dipole steps that impose a built-in potential drop across the 1H barrier, thereby generating a trapezoidal tunnel barrier at zero bias. In contrast, symmetric 1T/1H interfaces do not form interface dipoles and show no rectification. To clarify the microscopic origin, a lateral graphene/hexagonal-boron-nitride/graphene junction is analyzed as a minimal MIM diode analogue with a simple interface and well-defined barrier, confirming that interface-induced dipoles, rather than work-function difference, enable the effect. The mechanism operates entirely within a single monolayer material system and does not rely on out-of-plane stacking, highlighting compatibility with phase patterning in 2D semiconductors. These results establish lateral 1T/1H/1T–MoS$ _2$ as a fully 2D, single-material platform for MIM-diode-like rectification and position interface-dipole engineering as a general strategy for ultrathin in-plane diodes, high-frequency detectors, and energy-harvesting tunnel devices.
Materials Science (cond-mat.mtrl-sci)
Supplemental information included
Microsecond-scale sucrose conformational dynamics in aqueous solution via molecular dynamics methods
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-09-23 20:00 EDT
Vladimir Deshchenya, Kirill Gerke, Nikolay Kondratyuk
Molecular dynamics methods have proven their applicability for the reproduction and prediction of molecular conformations during the last decades. However, most of works considered dilute solutions and relatively short trajectories that limit insights into conformational dynamics. In this study, we investigate the conformational dynamics of sucrose in aqueous solution using microsecond-scale molecular dynamics simulations. For the most of the calculations we use the OPLS-AA/1.14\astCM1A-LBCC force field, but we also utilize OPLS-AA/1.14\astCM1A and GLYCAM06 for the comparison. We focused on the glycosidic linkage conformers and their lifetimes, glucopyranose and fructofuranose ring puckering. Our findings indicate that the $ ^1\mathrm{C}_4$ glucopyranose ring conformation can stabilize the sucrose conformer, appeared only in the GLYCAM06 and OPLS-AA/1.14\astCM1A force fields. All the results are strengthened by comparison with the available experimental data on NMR J-coupling constants and ultrasonic spectra.
Soft Condensed Matter (cond-mat.soft)
J. Chem. Phys. 163, 044502 (2025)
When is nonreciprocity relevant?
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
Giulia Garcia Lorenzana, David Martin, Yael Avni, Daniel S. Seara, Michel Fruchart, Giulio Biroli, Vincenzo Vitelli
Nonreciprocal interactions are widely observed in nonequilibrium systems, from biological or sociological dynamics to open quantum systems. Despite the ubiquity of nonreciprocity, its impact on phase transitions is not fully understood. In this work, we derive criteria to perturbatively assess whether nonreciprocity changes the universality class of pairs of asymmetrically coupled systems undergoing a phase transition. These simple criteria are stated in terms of the unperturbed critical exponents, in the spirit of the Harris criterion for disordered systems, and agree with numerical simulations. Beyond nonreciprocity, our approach provides guidelines for assessing how dynamical phase transitions are affected by perturbations.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn)
5 pages, 2 figures + supplementary material
Optimal local basis truncation of lattice quantum many-body systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-09-23 20:00 EDT
Peter Majcen, Giovanni Cataldi, Pietro Silvi, Simone Montangero
We show how to optimally reduce the local Hilbert basis of lattice quantum many-body (QMB) Hamiltonians. The basis truncation exploits the most relevant eigenvalues of the estimated single-site reduced density matrix (RDM). It is accurate and numerically stable across different model phases, even close to quantum phase transitions. We apply this procedure to different models, such as the Sine-Gordon model, the $ \varphi^{4}$ theory, and lattice gauge theories, namely Abelian $ \mathrm{U}(1)$ and non-Abelian $ \mathrm{SU}(2)$ , in one and two spatial dimensions. Our results reduce state-of-the-art estimates of computational resources for classical and quantum simulations.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), High Energy Physics - Lattice (hep-lat), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
15 pages, 10 figures
Microsecond-Pulsed Nanocalorimetry: A Scalable Approach for Ultrasensitive Heat Capacity Measurements
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Hugo Gómez-Torres, Manel Molina-Ruiz, Simone Privitera, Enric Menéndez, Llibertat Abad, Jordi Sort, Olivier Bourgeois, Javier Rodriguez-Viejo, Aitor Lopeandia
We introduce a nanocalorimetric technique based on microsecond-pulsed heating (\mu s-PHnC) that enables high-sensitivity, quasi-isothermal heat capacity measurements on nanoscale samples. Such resolution is critical for exploring thermodynamic signatures in low-dimensional materials, where conventional techniques fall short. By confining thermal excitation to microsecond timescales, this approach minimizes lateral heat diffusion, reduces heat capacity addenda to below 10^{-9} J K^{-1}, and achieves noise densities as low as 75 pJ K^{-1} Hz^{-1/2} mm^{-2}, unlocking precise thermodynamic characterization of subnanogram samples in areas as small as 30 x 30 \mu m^{2}. The method delivers exceptional temperature homogeneity, as demonstrated by resolving sharp phase transitions, such as the antiferromagnetic transition in ultrathin CoO films, with unprecedented clarity. Its quasi-static operation is inherently compatible with external stimuli, including magnetic and electric fields, thereby expanding its utility for in-operando thermodynamic studies. This advancement establishes a robust and scalable platform for probing thermal phenomena in nanostructured and low-dimensional materials, significantly broadening the scope of nanocalorimetry.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
23 pages, 10 figures
Two-dimensional percolation model with long-range interaction
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-09-23 20:00 EDT
Ziyu Liu, Tianning Xiao, Zhijie Fan, Youjin Deng
We perform large-scale simulations of the two-dimensional long-range bond percolation model with algebraically decaying percolation probabilities $ \sim 1/r^{2+\sigma}$ , using both conventional ensemble and event-based ensemble methods for system sizes up to $ L=16384$ . We accurately determine the critical points, the universal values of several dimensionless quantities, and the corresponding critical exponents. Our results provide compelling evidence that the system undergoes a crossover from short-range to long-range universality at $ \sigma = 2$ , in contradiction to Sak’s criterion. Notably, we observe a pronounced jump in the universal values and critical exponents at $ \sigma = 2$ , a feature absent from previous studies.
Statistical Mechanics (cond-mat.stat-mech)
Tuning Magnetic and Electronic Properties of Double Perovskite La$2$CoIr${1-x}$Ti$_x$O$_6$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-09-23 20:00 EDT
Sromona Nandi, Vineeta Yadav, Sheetal, C. S. Yadav, Bikash Das, Subhadeep Datta, Kapildeb Dolui, Rudra Sekhar Manna
The La$ _2$ CoIr$ _{1-x}$ Ti$ _x$ O$ _6$ double perovskite series serves as an effective platform for investigating the evolution of magnetic and electronic properties as a function of chemical pressure (doping) or hydrostatic pressure due to the interplay between the electrons correlation and spin-orbit coupling. In this study, the substitution of nonmagnetic Ti$ ^{4+}$ at the magnetic Ir$ ^{4+}$ -site leads to a systematic decrease in unit cell volume keeping the monoclinic symmetry throughout, reflecting the effect of chemical pressure along with a gradual suppression of magnetic interactions. The parent compound ($ x =$ 0) exhibits a ferromagnetic-like state with a Curie temperature of 92 K, which continuously evolves into an antiferromagnetic ground state upon full Ti substitution ($ x =$ 1) with a Neel temperature of 14.6 K. Isothermal magnetization measurements reveal a hysteresis behavior with step-like feature at zero field, indicative of a noncollinear magnetic ordering. Additionally, the enhancement of magnetization under hydrostatic pressure on La$ _2$ CoIrO$ _6$ suggests the presence of piezomagnetic behavior. Thermal expansion measurements on La$ _2$ CoIrO$ _6$ highlight a coupling between spin and lattice degrees of freedom. The pressure dependence of the transition temperature in the zero-pressure limit, calculated using Ehrenfest’s relation, shows good agreement with magnetization data under applied this http URL-principles density functional theory (DFT) calculations preformed for $ x =$ 0, 0.5 and 1, further reveal that strong SOC associated with Ir plays a decisive role in shaping the electronic band structure, with the insulating gap progressively widening as Ti content increases from 0.28 eV ($ x =$ 0), 0.44 eV ($ x =$ 0.5), and 1.01 eV ($ x =$ 1). The magnetic moment decreased more than 50% for $ x =$ 0.5, showing the decrease in magnetic exchange pathways.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 8 figures
Exploring molecular supersolidity via exact and mean-field theories: single microwave shielding
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-23 20:00 EDT
Tiziano Arnone Cardinale, Thomas Bland, Stephanie M. Reimann
Ultracold polar molecules with microwave shielding provide a powerful platform for exploring quantum many-body physics with strong, anisotropic interactions. We develop an extended Gross-Pitaevskii framework for bosonic molecules under single microwave shielding, incorporating effective interactions and quantum fluctuations, and benchmark it against exact Quantum Monte Carlo simulations. In the regime of positive scattering lengths, our approach captures superfluid, supersolid, and droplet phases with excellent accuracy. We show that elliptic microwave polarization induces direction-dependent superfluidity - absent in cylindrically symmetric systems - enabling tunable anisotropy and potential applications in directional quantum sensing. A quasi-1D theory reveals that roton softening and instabilities can be controlled via ellipticity, consistent with recent experiments. Furthermore, we find that the nature of the superfluid-to-supersolid transition is strongly influenced by the ellipticity: the transition is sharp at low ellipticity and continuous at higher values. This tunability offers a potential route for low entropy preparation of molecular supersolids via adiabatic ramps. While double shielding is often used experimentally, our results demonstrate that single-shielded molecules already offer rich, controllable behavior, laying the groundwork for future studies with more complex shielding schemes.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
16 pages, 10 figures
Pseudogap in a Fermi-Hubbard quantum simulator
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-09-23 20:00 EDT
Lev Haldar Kendrick, Anant Kale, Youqi Gang, Alexander Dennisovich Deters, Martin Lebrat, Aaron W. Young, Markus Greiner
Understanding doped Mott insulators is a fundamental goal in condensed matter physics, with relevance to cuprate superconductors and other quantum materials. The doped Hubbard model minimally describes such systems, and has explicated some of their complex behavior. However, many open questions remain concerning the anomalous metallic states which emerge at low temperatures and intermediate doping and which, in cuprates, give rise to high-temperature superconductivity upon cooling. Here we observe a crossover between a normal metal and a pseudogapped metal in the Hubbard model by performing thermodynamic and spectroscopic measurements in a cold atom quantum simulator, leveraging a recent several-fold reduction in experimentally achievable temperatures. Measurements of the compressibility show a maximum versus doping that develops upon cooling, signaling an inflection point in the equation of state. We track this maximum versus interaction strength, revealing a line of thermodynamic anomalies in the phase diagram that separates an underdoped from an overdoped metal at large interactions. Lattice modulation spectroscopy shows a loss of spectral weight at low energies in the underdoped regime which is non-uniform in the Brillouin zone, indicating the formation of a pseudogap. We use this signal to establish a pseudogap phase diagram as a function of interactions and doping. Our results experimentally demonstrate the existence of a pseudogapped metal in the Hubbard model, partially characterize the pseudogap regime, and suggest a link between the pseudogap and charge order which can be probed in future work. Furthermore, this work demonstrates the utility of quantum simulation in addressing frontier problems in correlated electron physics.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
7+20 pages, 4+10 figures
Electronic structure and optical signatures of highly-doped graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-09-23 20:00 EDT
Saúl Antonio Herrera-González, Guillermo Parra-Martínez, Francisco Guinea, Jose Angel Silva-Guillén, Pierre A. Pantaleón, Gerardo G. Naumis
Heavily doping graphene by intercalation can raise its Fermi level near an extended van Hove singularity, potentially inducing correlated electronic phases. Intercalation also modifies the band structure: dopants may hybridize with carbon orbitals and order into $ \sqrt{3}\times\sqrt{3}$ or $ 2\times2$ superstructures, introducing periodic potentials that fold the graphene $ \pi$ bands. Angle-resolved photoemission spectroscopy further shows a pronounced flattening of the conduction band near the M points, producing higher-order van Hove singularities. These effects depend strongly on the dopant species and substrate, with implications for both many-body physics and transport. We construct effective tight-binding models that incorporate dopant ordering, carbon-dopant hybridization, and $ \pi$ -band renormalization. Model parameters are obtained from density functional theory and reproduce dispersions observed in photoemission experiments. Using these models, we compute the optical conductivity and identify characteristic signatures associated with dopant ordering and hybridization. Our results provide a framework to interpret experimental spectra and to probe the superlattice symmetry of highly doped monolayer graphene.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)