Materials Science
Photoelectron Spectroscopy Study of U-Te Thin Films: A Unified Perspective of Hybridization Effects across Compositions
E. A. Tereshina-Chitrova, S. G. Alex, O. Koloskova et al. (+6 more)
Uranium tellurides span
magnetic and superconducting ground states, yet systematic electronic-structure information across the U-Te series remains scarce. In this study, we perform photoemission measurements on freshly prepared UxTey thin films covering the range of bulk stoichiometries under ultra-high
vacuum (10^-9 Pa), enabling clean surfaces and compositions matching bulk phases, including the celebrated UTe2. X-ray and ultraviolet photoelectron spectroscopy (XPS/UPS) reveal consistent
evolution of the U 4f and Te 3d core levels and valence states across the series, in good agreement with the limited bulk data. Supported by uniform ab initio calculations for all U-Te compounds, we identify systematic trends in U-Te hybridization and charge-transfer effects across the series. These results establish thin-film photoemission as a reliable route for mapping electronic-structure trends in tellurides of heavy elements with diverse electronic ground states.
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All authors E. A. Tereshina-Chitrova, S. G. Alex, O. Koloskova, L. Havela, L. Horak, O. Romanyuk, F. Huber, T. Gouder, M. Divis
Superconductivity
Spin-density-wave transition in monolayer-trilayer La3Ni2O7 single crystals
Mingxin Zhang, Jie Dou, Di Peng et al. (+17 more)
The recent discovery of high-temperature superconductivity in pressurized Ruddlesden-Popper nickelates stimulated intense research into their correlated electron physics. Establishing the diversity of ground states across different Ruddlesden-Popper phases is crucial for elucidating the superconducting mechanisms in these nickelates. Motivated by the recent report of superconductivity in hybrid 1212-type La5Ni3O11, we synthesized and investigated the long-range-ordered hybrid 1313-type La3Ni2O7. In contrast to its
bilayer counterpart, the 1313-type La3Ni2O7 exhibits characteristic semiconducting behavior at ambient pressure, displaying a distinct anomaly at 170 K. This behavior is consistently evidenced by measurements of both
magnetic susceptibility and specific heat.
Nuclear magnetic resonance spectroscopy unambiguously indicates a
spin-density-wave transition occurring at 170 K. High-pressure electrical transport measurements demonstrate the induction of metallization under pressure, yet reveal no discernible traces of superconductivity up to 65 GPa. Our findings establish hybrid 1313-type La3Ni2O7 as a new member of the Ruddlesden-Popper nickelate family exhibiting a distinct
spin-density-wave transition, and offers a new platform for investigating the interplay among
crystal structure, electronic orders, and superconductivity in hybrid nickelates.
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All authors Mingxin Zhang, Jie Dou, Di Peng, Cuiying Pei, Qi Wang, Yi Zhao, Chao Xiong, Shuo Li, Jun Luo, Juefei Wu, Lingxiao Zhao, Qing Zhang, Jie Yang, Yulin Chen, Jinkui Zhao, Wenge Yang, Hanjie Guo, Qiaoshi Zeng, Rui Zhou, Yanpeng Qi
Superconductivity
Weakly anisotropic superconductivity of Pr4Ni3O10 single crystals
Cuiying Pei, Yang Shen, Di Peng et al. (+17 more)
Since the discovery of high-temperature superconductivity, studying the upper critical field and its anisotropy has been crucial for understanding superconducting mechanism and guiding applications. Here we perform in situ high-pressure angular-dependent electrical transport measurements on Pr4Ni3O10 single
crystals using a custom diamond anvil
cell (DAC) rotator and confirming its anisotropic superconductivity. The anisotropy parameter is approximately 1.6, decreasing with increasing temperature and approaches 1 near Tc. Comparing effective mass anisotropy and inter-block distance in cuprates and iron-based
superconductors (FeSCs) reveals that Pr4Ni3O10 single
crystals superconductors are consistent with a two-band model, where intralayer
quantum confinement within the unit
cell induces interlayer coherence, thereby leading to three-dimensional (3D) superconductivity. This study not only establishes the existence of anisotropic superconductivity in bulk Ruddlesden-Popper nickelates, but also provide critical insight into the role of dimensionality in high-temperature superconductivity.
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All authors Cuiying Pei, Yang Shen, Di Peng, Mingxin Zhang, Yi Zhao, Xiangzhuo Xing, Qi Wang, Juefei Wu, Junjie Wang, Lingxiao Zhao, Zhenfang Xing, Yulin Chen, Jinkui Zhao, Wenge Yang, Xiaobing Liu, Zhixiang Shi, Hanjie Guo, Qiaoshi Zeng, Guang-Ming Zhang, Yanpeng Qi
Disordered Systems and Neural Networks
Polychronous Wave Computing: Timing-Native Address Selection in Spiking Networks
Natalila G. Berloff
Spike timing offers a combinatorial address space, suggesting that timing-based spiking inference can be executed as lookup and routing rather than as dense multiply–accumulate. Yet most neuromorphic and photonic systems still digitize events into timestamps, bins, or rates and then perform selection in clocked logic. We introduce Polychronous Wave Computing (PWC), a timing-native address-selection primitive that maps relative spike latencies directly to a discrete output route in the wave domain. Spike times are phase-encoded in a rotating frame and processed by a programmable multiport interferometer that evaluates K template correlations in parallel; a driven–dissipative winner-take-all stage then performs a physical argmax, emitting a one-hot output port. We derive the operating envelope imposed by phase wrapping and mutual coherence, and collapse timing jitter, static phase mismatch, and dephasing into a single effective phase-noise budget whose induced winner–runner-up margin predicts boundary-first failures and provides an intensity-only calibration target. Simulations show that nonlinear competition improves routing fidelity compared with noisy linear intensity readout, and that hardware-in-the-loop phase tuning rescues a temporal-order gate from 55.9% to 97.2% accuracy under strong static mismatch. PWC provides a fast routing coprocessor for LUT-style spiking networks and sparse top-1 gates (e.g., mixture-of-experts routing) across polaritonic, photonic, and oscillator platforms.
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Strongly Correlated Electrons
SCF framework, HF stability and RPA correlation for Jordan-Wigner-transformed spin Hamiltonians on arbitrary coupling topologies
Shadan Ghassemi Tabrizi, Thomas M. Henderson, Thomas D. Kühne et al. (+1 more)
Mapping
spins to
fermions via the Jordan-Wigner (JW) transformation can render mean-field (Hartree-Fock, HF) descriptions effective for strongly correlated
spin systems. As established in recent work, the application of such approaches is not limited by the nonlocal structure of JW strings or by site ordering, because string operators can be absorbed into Thouless rotations of a Slater determinant, and the variational optimization of a
unitary Lie-Algebraic similarity transformation removes any ordering dependence. Leveraging these ideas, we develop a self-consistent field (SCF) scheme that expresses the mean-field energy as a functional of the single-particle density
matrix, providing an alternative to gradient-based optimization of Thouless parameters. We derive the analytic orbital Hessian to diagnose HF stability and compute ground-state correlation energy through the random-phase approximation (RPA).
Benchmark results for the XXZ and J1-J2 model on one- and two-dimensional
lattices demonstrate that RPA significantly improves mean-field accuracy.
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All authors Shadan Ghassemi Tabrizi, Thomas M. Henderson, Thomas D. Kühne, Gustavo E. Scuseria
Superconductivity
Synthesizing Strong-Coupling Kohn-Luttinger Superconductivity in 2D Van der Waals materials
Shi-Cong Mo, Hongyi Yu and Wéi Wú
The Kohn-Luttinger (KL) mechanism of pairing, which describes superconductivity emergent from repulsive interactions, typically yields Cooper pairs at high angular-momentum ($\ell > 0$) and extremely low transition temperatures ($T_c$). Here, we reveal an inter-layer s-wave ($\ell=0$) KL superconductivity with greatly elevated $T_c$ in a multi-layer Hubbard model, which prototypes stacked two-dimensional (2D) electrons in layered van der Waals materials. By employing determinant
quantum Monte Carlo and dynamical mean-field theory simulations, we show that a strong pairing attraction $V^{*}$, without the mediation of collective modes, can emerge between inter-layer electrons in the system. As inter-layer repulsion $U$ increases, $V^{*}$ evolves from a conventional KL relation of $V^{*} \propto -U^2$, to a linear strong-coupling scaling of $V^{*} \propto -U$, resulting in enhanced superconductivity at large $U$. This strong-coupling KL pairing is robust against changes in
lattice geometries and dimensionalities, and it can persist, in the presence of a large remnant Coulomb repulsion $U^{*}$ between pairing electrons. Using ab initio calculations, we propose a few 2D layered van der Waals materials that can potentially realize and control this unconventional superconductivity.
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Superconductivity
Coexistence of stripe order and superconductivity in NaAlSi
Ruixia Zhong, Qi Wang, Zhongzheng Yang et al. (+4 more)
Here, we report a scanning tunneling microscopy study on an s-wave
superconductor NaAlSi, revealing the coexistence of stripe order and superconductivity. This stripe order manifests as a unidirectional spatial charge modulation with a commensurate period of four times the
lattice constant. This modulation undergoes a phase shift in the differential conductance maps under opposite bias voltages, while its period remains approximately constant over an energy range of $\pm$50 meV. These features suggest that this stripe is likely a static charge order. Furthermore, we find that the stripe order imposes a periodic modulation on the intensity of the superconducting coherence peaks. This work provides new perspectives on the intricate interplay between stripe order and s-wave superconductivity.
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All authors Ruixia Zhong, Qi Wang, Zhongzheng Yang, Fanbang Zheng, Wenhui Li, Yanpeng Qi, Shichao Yan
Soft Condensed Matter
Griffiths-like region explains the dynamic anomaly in metallic glass-forming liquids
Lin Ma, Xiaodong Yang, Xinjia Zhou et al. (+2 more)
Complex fluids such as water exhibits many anomalous phenomena, and research suggests these properties are closely tied to critical fluctuations near the
liquid-
liquid phase transition critical point (LLCP). However, whether a similar LLCP exists in metallic glass-forming
liquids, which are notable for their high atomic coordination, remains an open question. Although dynamic anomalies such as the breakdown of the Stokes-Einstein (SE) relation have often been attributed to dynamic heterogeneity or structural changes, relatively few studies have analyzed these anomalies from a thermodynamic-fluctuation perspective. This gap probably stems from the challenges in detecting density-driven phase transitions in such systems. Here, we use numerical simulations to explore the thermodynamic mechanisms behind dynamic anomalies in a prototypical metallic glass-forming melt. We observe substantial thermodynamic fluctuations near a particular region, which likely corresponds to a frustration state of
liquid, vapor, and glass. These fluctuations may contribute to the violation of the SE relation. Our findings offer a fresh Griffiths-like perspective on the dynamic anomalies seen in supercooled metallic
liquids, and shed new light on their underlying mechanisms.
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All authors Lin Ma, Xiaodong Yang, Xinjia Zhou, Gang Sun, Zhen Wei Wu
Statistical Mechanics · Cross-listed from quant-ph
Failure of the mean-field Hartree approximation for a bosonic many-body system with non-Hermitian Hamiltonian
Matias Ginzburg, Simone Rademacher and Giacomo De Palma
Mean-field Hartree theory is a central tool for reducing many-body dynamics to an effective one-particle
evolution. This approximation has been employed when the
Hamiltonian governing the many-body dynamics is not Hermitian. Indeed, non-Hermitian
Hamiltonians model particle gain/loss or the
evolution of open
quantum systems between consecutive
quantum jumps. Furthermore, the validity of the Hartree approximation for generic non-Hermitian
Hamiltonians lies at the basis of a
quantum algorithm for nonlinear differential equations. In this work, we show that this approximation can fail. First, we consider the most general bosonic mean-field
Hamiltonian with two-body interactions and we prove that, for non-Hermitian
Hamiltonian, the Hartree equation does not capture the correct second time derivative of the one-particle marginal state at $t=0$ in the thermodynamic limit. Then, we analytically solve a model of $N$ bosonic
qubits with a purely anti-Hermitian
Hamiltonian, compute the limit for $N\to\infty$ of the one-particle marginal state and show that it does not agree with the solution of the non-Hermitian Hartree equation. We further show that there exists an initial condition such that the exact one-particle marginal state undergoes a finite-time transition to a mixed state, a phenomenon that is completely absent in the case of Hermitian
Hamiltonians. Finally, we simulate a non-Hermitian
Hamiltonian with real spectrum and show that, also in this case, there are initial conditions for which the Hartree equation does not reproduce the correct one-particle marginal state in the limit $N\to\infty$. Our findings challenge the validity of the mean-field Hartree approximation for non-Hermitian
Hamiltonians, and call for additional conditions for the validity of the mean-field regime to model the dynamics of particle gain and loss and the open-system dynamics in bosonic many-body systems.
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Materials Science
Phase Transitions in Low-Dimensional Layered Double Perovskites: The Role of the Organic Moieties
Beatriz Martín-García, Davide Spirito, Giulia Biffi et al. (+3 more)
Halide double perovskites are an interesting alternative to Pb-containing counterparts as active materials in optoelectronic devices. Low-dimensional double perovskites are fabricated by introducing large organic cations, resulting in organic/inorganic architectures with one or more inorganic octahedral layers separated by organic cations. Here, we synthesize layered double perovskites based on 3D Cs2AgBiBr6 that consist of double (2L) or single (1L) inorganic octahedral layers, using ammonium cations of different size and chemical structure. Temperature-dependent Raman spectroscopy reveals phase transition signatures in both inorganic
lattice and organic moieties by detecting variations in their vibrational modes. Changes in the conformational arrangement of the organic cations to an ordered state coincide with a phase transition in the 1L systems with the shortest ammonium moieties. Significant changes of photoluminescence intensity observed around the transition temperature suggest that optical properties may be deeply affected by the octahedral tilts emerging at the phase transition.
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All authors Beatriz Martín-García, Davide Spirito, Giulia Biffi, Sergey Artyukhin, Francesco Bonaccorso, Roman Krahne
Mesoscale and Nanoscale Physics
Topological Charges, Fermi Arcs, and Surface States of $K_4$ Crystal
Shoya Yoshida, Katsuhiro Takahashi and Katsunori Wakabayashi
We investigate the topological electronic properties of the $K_4$
crystal by constructing a tight-binding model. The bulk band structure hosts Weyl nodes with higher and conventional chiralities ($\chi = \pm 2$ and $\chi = \pm 1$) located at high-
symmetry points in the Brillouin zone. Through analytical evaluation of the Berry
curvature, we identify the positions and chiralities of these Weyl nodes. Furthermore, slab calculations for the (001) surface reveal
Fermi arcs that connect Weyl nodes of opposite chirality, including those linking $\chi = \pm 2$ nodes with pairs of $\chi = \mp 1$ nodes. These results demonstrate that the $K_4$
crystal is a spinless Weyl semimetal featuring topologically protected surface states originating from multiple types of Weyl nodes.
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Materials Science
Visual Luminescence Thermometry Enabled by Phase-Transition-Activated Cross Relaxation of Tb3+ Ions
L. Marciniak and M. Szymczak
The development of visual luminescent thermometers capable of exhibiting pronounced color changes in response to temperature variations requires the rational design of phosphors with high spectrally selective thermal sensitivity. In this work, we present a strategy based on phase-transition-induced activation of cross-relaxation processes in LiYO2:Tb3+. The monoclinic-to-tetragonal structural phase transition modifies the point
symmetry of Tb3+ ions in the host
lattice, enhances the Stark effect, and enables energetic resonance required for efficient cross relaxation. Consequently, emission originating from the 5D3 excited state is rapidly quenched relative to that from the 5D4 level above approximately 300 K, resulting in a distinct temperature-dependent color change of the emitted light from blue to green. This mechanism yields exceptionally high chromaticity-coordinate-based sensitivities, reaching SRx,max = 0.40% K-1 and SRy,max=0.72% K-1 at 410 K. Furthermore, phase-transition-driven modifications of the Tb3+ emission spectral profile enable the realization of a multimode luminescent thermometer with a maximum relative sensitivity of SRmax=13% K-1. The practical applicability of this system is demonstrated through an ON-OFF luminescent thermal switch and fully filter-free, dynamic two-dimensional thermal imaging using the blue and green channels of a standard digital camera, enabling intuitive visualization, remote readout, and temperature mapping under dynamic conditions.
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Mesoscale and Nanoscale Physics
Theory of Correlated Hofstadter Spectrum in Magic-Angle Graphene
Chen Zhao, Zhaowen Miao, Zhen Ma et al. (+4 more)
The
magnetic-field-induced correlated Chern
insulator (CCI) states in magic-angle twisted
bilayer graphene (MATBG) have been intensively studied in experiments, but a simple and clear understanding of their origin is still lacking. Here, we propose a unified theoretical framework for the CCI states in MATBG that successfully explains most experimental observations. The key insight of our theory is that, due to the very narrow bandwidth of MATBG, correlation-enhanced valley and
spin Zeeman terms are critical for shaping the intricate Hofstadter spectrum, resulting in an interwoven,
flavor-resolved (
spin and valley) Hofstadter spectrum that can well describe the observed CCI states. Crucially, due to the Zeeman effect, the crossings between these
flavor-polarized Hofstadter spectra are
magnetic-field-dependent, causing certain CCI states to emerge only above a critical field. This is the main mechanism underlying the critical field phenomenon of the CCI states observed in experiments. Our theory provides a clear and unified physical picture for the correlated Hofstadter spectrum in MATBG.
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All authors Chen Zhao, Zhaowen Miao, Zhen Ma, Ying-Hai Wu, Ming Lu, Jin-Hua Gao, X. C. Xie
Materials Science
Machine learning interatomic potentials for solid-state precipitation
Lorenzo Piersante and Anirudh Raju Natarajan
Machine learning interatomic potentials (MLIPs) are routinely used to model diverse atomistic phenomena, yet parameterizing them to accurately capture solid-state phase transformations remains difficult. We present error metrics and data-generation schemes designed to streamline the parameterization of MLIPs for modeling precipitation in multi-component
alloys. We developed an
algorithm that enumerates symmetrically distinct transformation pathways connecting chemical decorations on different parent
crystal structures. Additionally, we introduce the weighted Kendall-$\tau$ coefficient and its semi-grand canonical generalization as metrics for quantifying MLIP accuracy in predicting low-temperature thermodynamics. We apply these approaches to parameterize an MLIP for a dilute Mg-Nd
alloy. The resulting potential reproduces the complex early-stage precipitation behavior observed in experiment. Large-scale atomistic simulations reveal competition between order-disorder and structural transformations. Furthermore, these results suggest a continuous transition between high-
symmetry hcp and bcc
crystal structures during aging heat treatments.
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Superconductivity
Correlation lengths of flat-band superconductivity from quantum geometry
S. S. Elden and M. Iskin
Flat-band
superconductors provide a regime in which kinetic energy is quenched, so that pairing is governed primarily by interactions and
quantum geometry. We investigate characteristic superconducting length scales in all-flat-band systems under the assumptions of time-reversal
symmetry and spatially-uniform pairing, focusing on the size of the lowest-lying two-body bound state, the average Cooper-pair size, and the zero-temperature coherence length in two-band Hubbard models. Using the Creutz ladder and the $\chi$
lattice as representative examples, we show that both the two-body bound-state size and the many-body Cooper-pair size remain finite and small in the weak-coupling limit, being controlled by the
quantum metric of the flat bands. By contrast, the coherence length exhibits qualitatively distinct behavior, diverging in the dilute limit and in the vicinity of insulating regimes. These results demonstrate that, in flat-band
superconductors, the pair size and the coherence length are fundamentally distinct physical quantities and highlight the central role of band geometry in shaping superconducting length scales when kinetic energy is quenched.
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Materials Science · Cross-listed from physics.optics
Dislocation Entropy: Temperature and Density Dependence
A. G. Sukharev
Laser hardening of metals occurs under the influence of a shock wave, which changes the distribution and density of one-dimensional defects - dislocations. There is a relationship between the density of dislocations, the grain size and the resistance of a single
crystal to shear loading. The mechanism of hardening processes continues to be intensively studied, and the dynamics of defects plays a central role here. In this paper, the dislocation
entropy is analyzed from a combinatorial point of view and from the point of view of a physical oscillator with a given energy reserve. Both contributions play an important role in describing the free energy of a one-dimensional ensemble of dislocations, and are necessary to take into account the dynamic processes inside the grain of a polycrystalline structure. Keywords:
Laser Shock Peening, statistical mechanics
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Statistical Mechanics
Classification of instabilities for the nonideal Brusselator model
Premashis Kumar, Massimiliano Esposito and Timur Aslyamov
We investigate a nonideal, thermodynamically consistent Brusselator reaction-
diffusion (RD) system that explicitly incorporates molecular interactions among species in both the
diffusion process and the underlying chemical reaction network. Within this framework, we systematically revisit the Cross-Hohenberg classification of instabilities to assess the feasibility and characteristics of the various types of instability arising from the interplay between entropic and energetic contributions. Our analysis demonstrates that only type I and type III instabilities (the Cross-Hohenberg classification) can occur in this system; Energetic contributions do not explicitly generate instabilities, but may implicitly control their occurrence through their influence on the fixed-point (steady-state) concentrations. In cases where instabilities of different types coexist, we show that the resulting patterns are highly sensitive to the relative strengths of the competing instabilities.
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Mesoscale and Nanoscale Physics
Giant Shubnikov-de Haas Oscillations with V-Shaped Minima in a High-Mobility Two-Dimensional Electron Gas: Experiment and Phenomenological Model
E. Yu. Zhdanov, M. V. Budantsev, D. I. Sarypov et al. (+3 more)
Giant Shubnikov-de Haas oscillations (SdHO) with V-shaped minima are experimentally studied in a high-mobility two-dimensional electron gas based on GaAs/AlGaAs
heterostructures. A phenomenological model with two parameters (transport momentum relaxation time $\tau_{\text{tr}}$ and
quantum scattering time $\tau_q$) is developed, accurately describing experimentally measured magnetoresistance over an unexpectedly wide range of
magnetic fields (up to 3.5 T) and temperatures (from 2 K to 15 K). The model combines: (i) a quasiclassical density of states with a
magnetic-field-dependent Gaussian broadening of Landau levels, (ii) a momentum relaxation time scaling with the density of states, and (iii) oscillations of the
Fermi level at a fixed electron density. This model reproduces V-shaped oscillation minima with zero-resistance points, a smooth background of positive magnetoresistance, and enables the extraction of $\tau_q$ and $\tau_{\text{tr}}$ even in microstructures where ballistic and viscous effects dominate at low fields. As expected, the temperature dependence reveals that $\tau_{\text{tr}}$ scales inversely with temperature due to acoustic
phonon scattering, while $\tau_q$ remains temperature-independent.
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All authors E. Yu. Zhdanov, M. V. Budantsev, D. I. Sarypov, D. A. Pokhabov, A. K. Bakarov, A. G. Pogosov
Materials Science
Water Phase Diagram from a General-Purpose Atomic Cluster Expansion Potential
Eslam Ibrahim, Yury Lysogorskiy, Ralf Drautz et al. (+1 more)
Water's phase diagram remains one of the most intricate and challenging
benchmarks in molecular modeling. In this study, we compute the phase diagram of water using an Atomic Cluster Expansion (ACE) potential trained on density-functional theory (DFT) calculations based on the revPBE-D3 exchange and correlation functional. We compute solid-
liquid chemical potential differences and melting points using biased coexistence simulations with the On-the-Fly Probability Enhanced Sampling (OPES) method. Starting from these points, we trace coexistence lines using Gibbs-Duhem integration. This combination of methods allows us to consistently map pressure-temperature phase boundaries and reconstruct the full phase diagram between approximately 100-500 K and 0-4 GPa. The stability regions of the main ice polymorphs (Ih, II, V, VI, and VII) are reproduced in close agreement with experiments. As in earlier studies based on DFT, ice III is metastable and there are systematic shifts of coexistence lines with respect to experimental results. Our results demonstrate the capability of our general-purpose ACE potential to capture the complex phase behavior of water across wide thermodynamic conditions.
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All authors Eslam Ibrahim, Yury Lysogorskiy, Ralf Drautz, Pablo Piaggi
Soft Condensed Matter
Multiscale Prediction of Polymer Relaxation Dynamics via Computational and Data-Driven Methods
Nguyen T. T. Duyen, Ngo T. Que and Anh D. Phan
We present a multiscale modeling approach that integrates molecular dynamics simulations, machine learning, and the Elastically Collective Nonlinear Langevin Equation (ECNLE) theory to investigate the glass transition dynamics of
polymer systems. The glass transition temperatures (Tg) of four representative
polymers are estimated using simulations and machine learning model trained on experimental
datasets. These predicted Tg values are used as inputs to the ECNLE theory to compute the temperature dependence of structural relaxation times and
diffusion coefficients, and the dynamic fragility. The Tg values predicted from simulations show good quantitative agreement with experimental data. While machine learning tends to slightly overestimate Tg, the resulting dynamic fragility values remain close to experimental fragilities. Overall, ECNLE calculations using these inputs agree well with broadband dielectric spectroscopy results. Our integrated approach provides a practical and scalable tool for predicting the dynamic behavior of
polymers, particularly in systems where experimental data are limited.
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Materials Science · Cross-listed from eess.IV
PYVALE: A Fast, Scalable, Open-Source 2D Digital Image Correlation (DIC) Engine Capable of Handling Gigapixel Images
Joel Hirst, Lorna Sibson, Adel Tayeb et al. (+10 more)
Background: Digital Image Correlation (DIC) is a widely used full-field measurement technique, but both open-source and commercial packages often have limitations such as operating-system restrictions, lack of support for deployment on computing clusters, and poor scalability to gigapixel-scale images common in Scanning Electron Microscopy DIC (SEM-DIC). Objective: Pyvale is an open-source software package designed for sensor simulation, uncertainty quantification, placement optimization, and calibration/validation. A key component of this is the development of a dedicated 2D DIC module intended for standalone use and integration within broader workflows. Methods: Pyvale provides a user-friendly Python interface with performant compiled routines underneath. At its core is a multithreaded, reliability-guided DIC
algorithm. Its open-source MIT license enables wide deployment, including on computing clusters and in automated pipelines. Results: Benchmarking with the publicly available 2D DIC challenge 2.0
dataset shows that Pyvale achieves metrological performance comparable to existing commercial and open-source DIC codes. It can correlate gigapixel-scale image pairs in under 5 minutes on high-specification desktop workstations, with
memory peaking at approximately 50 GB. Conclusions: Pyvale's strong metrological foundation, coupled with its scalability for SEM-DIC, positions it as a platform for sustained, community-driven development. Its design and licensing provide a foundation for future improvements in open-source DIC and integration into experimental design and validation workflows.
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All authors Joel Hirst, Lorna Sibson, Adel Tayeb, Ben Poole, Megan Sampson, Wiera Bielajewa, Michael Atkinson, Alex Marsh, Rory Spencer, Rob Hamill, Cory Hamelin, Allan Harte, Lloyd Fletcher
Statistical Mechanics
Direct measurement of the Orderphobic Effect
O.D. Lunn, J.G. Downs, K.K. Mandadapu et al. (+2 more)
Fluctuation-induced forces, such as the Critical Casimir Effect (CCE), are fundamental mechanisms driving organization and self-assembly near second-order phase transitions. The existence of a comparable, universal force for systems undergoing a first-order transition has remained an unresolved fundamental question. The proposed Orderphobic Effect is one such potential mechanism. It arises from minimisation of the interfacial free energy between solutes that locally nucleate a disordered phase. Here, we report the first experimental demonstration and quantitative measurement of the Orderphobic Effect. Using a driven, non-
equilibrium quasi-2D granular fluid undergoing a first-order order-disorder transition, we show that specifically designed solutes in an ordered phase nucleate a coexisting “bubble” of the disordered phase. By analysing its capillary fluctuations, we confirm that this phenomenon occurs due to the proximity to phase-coexistence, and we directly quantify the attractive force by measuring the interaction free energy between solutes. The observation of this general fluctuation-mediated force in a non-
equilibrium steady state strongly supports its claimed universality. Our work establishes the Orderphobic Effect as the first-order equivalent to the CCE, providing a new, general route for controlling self-assembly and aggregation in soft matter and non-
equilibrium systems.
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All authors O.D. Lunn, J.G. Downs, K.K. Mandadapu, J.P. Garrahan, M.I. Smith
Materials Science
Effect of uniaxial compressive stress on polarization switching and domain wall formation in tetragonal phase BaTiO3 via machine learning potential
Po-Yen Chen and Teruyasu Mizoguchi
Ferroelectric materials such as BaTiO3 exhibit spontaneous polarization that can be reoriented by an external electric field, forming the basis of various
memory, actuator, and sensor applications. The polarization switching behavior, however, is strongly influenced by mechanical boundary conditions due to the intrinsic electromechanical coupling in ferroelectrics. In this study, we employ a machine learning interatomic potential to investigate the effect of uniaxial compressive stress on polarization switching and domain wall
evolution in the tetragonal phase of BaTiO3. This study revealed a critical stress about 120 MPa which 90 degree polarization switching occurs. Beyond the critical stress, larger supercells exhibit lower activation energies for polarization switching with 180-degree domain wall formation and weaker constraints from periodic boundary conditions, thereby facilitating domain-wall formation. Besides, Increasing compressive stress reduces both the remnant polarization and the coercive field, while a double hysteresis loop emerges at a stress level of 80 MPa. These findings provide atomistic insights into stress-controlled ferroelectric switching and highlight the crucial role of mechanical loading in designing reliable ferroelectric devices.
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Superconductivity
Finite-momentum bound pairs of two electrons in an altermagnetic metal
Hui Hu, Zhao Liu, Jia Wang et al. (+1 more)
We solve the two-electron problem on a square
lattice with d-wave altermagnetism, considering both on-site and nearest-neighbor attractive interactions. The altermagnetic
spin-splitting in the single-particle dispersion naturally gives rise to a ground state of two-electron bound pairs with nonzero center-of-mass momentum. The emergence of finite-momentum bound states suggests that altermagnetic
spin splitting may favor pairing at nonzero center-of-mass momentum, which could be relevant for proposed Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconductivity in altermagnetic systems. Additionally, when the nearest-neighbor attraction is strong, the resulting finite-momentum bound pairs exhibit a mixture of both
spin-singlet and
spin-triplet characteristics, suggesting the possibility of unconventional
superconductors, where
spin-singlet and
spin-triplet pairings coexist.
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All authors Hui Hu, Zhao Liu, Jia Wang, Xia-Ji Liu
Strongly Correlated Electrons
Emergent Gauge Flux and Spin Ordering in Magnetized Triangular Spin Liquids: Applications to Hofstadter-Hubbard Model
Jiahao Yang, Hao Tian, Si-Yu Pan et al. (+1 more)
Motivated by recent progress in moiré superlattices and
spin-1/2 triangular-
lattice antiferromagnets, we study how orbital
magnetic flux and Zeeman coupling compete or cooperate in generating internal U(1) gauge flux in a triangular
spin liquid. We show that orbital flux favors a
chiral spin liquid with staggered internal flux, whereas Zeeman coupling destabilizes the spinon
Fermi-pocket state toward a Landau-level state with spontaneous uniform internal flux and conical
spin order. We demonstrate this mechanism in a
spin-$1/2$ $J_1$-$J_2$-$J_{\chi}$ model, and further identify thermal
Hall and
magnetic signatures that distinguish these regimes, with potential applications to moiré Hofstadter-Hubbard systems and triangular-
lattice antiferromagnets.
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All authors Jiahao Yang, Hao Tian, Si-Yu Pan, Gang v. Chen
Materials Science
Discovery of Ferroelectric Twin Boundaries in a Photoactive Halide Perovskite
Weilun Li, Qimu Yuan, Michael B. Johnston et al. (+1 more)
Halide perovskites have emerged as promising materials for next-generation photovoltaics,
laser sources and X-ray detectors. There is intense debate as to whether some photoactive halide perovskites exhibit ferroelectric behaviour and whether it might be possible to utilise the bulk photovoltaic effect to enhance the performance of halide perovskite
solar cells. Here, using low-dose scanning transmission electron microscopy, we discover the existence of ferroelastic twin boundaries in vapor-deposited CsPbI3 thin films, parallel to {110} and {112}. Remarkably, despite photoactive CsPbI3 being centrosymmetric and non-polar, we observe directly that Pb atoms shift at {110} twin boundaries driving a local ferroelectric-like polarisation. These polar twin walls form an intrinsic array of nanoscale functional interfaces, spaced ~30-50 nm apart, embedded within the non-polar perovskite
lattice. In contrast, {112} twin boundaries remain non-polar but strongly suppress octahedral tilt and off-centre Cs atom displacements, revealing a different untapped ferroic degree of freedom. These discoveries together uncover previously hidden ferroic functionality in halide perovskite
semiconductors, opening opportunities for enhanced conductivity and photovoltaic behaviour through domain wall engineering.
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All authors Weilun Li, Qimu Yuan, Michael B. Johnston, Joanne Etheridge
Mesoscale and Nanoscale Physics
Using Andreev bound states and spin to remove domain walls in a Kitaev chain
Wietze D. Huisman, Sebastiaan L. D. ten Haaf, Chun-Xiao Liu et al. (+6 more)
Quantum dot-
superconductor hybrids have been established as a suitable platform for realizing Kitaev chains hosting Majorana bound states. Implementing these structures in a
qubit architecture is expected to result in coherence times that scale exponentially with the lengths of the chains. To scale to longer systems, the phase differences between all superconducting segments in the chain need to be controlled. While this control has been demonstrated by using an external
magnetic flux, ideally it can be achieved with control over intrinsic system parameters. In this work, we investigate whether the relevant phase differences can be tuned through the
spin degree of freedom in each QD, or the chemical potential of the discrete bound states in the hybrid sections. We confirm that both these tuning knobs allow for controlling the phase difference in the couplings between neighbouring QDs, bypassing the requirement to tune an external flux. However, we find that the amplitude of the phase shifts can deviate from a discrete $\pi$-shift. We introduce a spatial variation in the
spin-orbit field as a possible mechanism to explain the observed behaviour and comment on the consequences for experimentally creating long Kitaev chains.
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All authors Wietze D. Huisman, Sebastiaan L. D. ten Haaf, Chun-Xiao Liu, Qingzhen Wang, Alberto Bordin, Florian J. Bennebroek Evertsz', Bart Roovers, Michael Wimmer, Srijit Goswami
Quantum Gases · Cross-listed from physics.atom-ph
Creation of ultracold heteronuclear p-wave Feshbach molecules
Fan Jia, Zhichao Guo, Zerong Huang et al. (+1 more)
We report the first creation of a bulk sample of ultracold heteronuclear p-wave Feshbach molecules in an optically trapped Bose-Bose mixture of 23Na and 87Rb atoms. Using loss spectroscopy and binding energy measurements, we systematically characterize the interspecies p-wave Feshbach resonances near 284 G. Leveraging this understanding, we use magneto-association to form p-wave NaRb Feshbach molecules, producing both pure samples and mixtures of molecules in different p-wave orbitals. We further measure the molecular lifetime and identify atom-molecule and molecule-molecule collisions as the dominant loss mechanisms. This work establishes a previously unavailable ultracold molecule platform that combines orbital anisotropy with heteronuclear constituents, represents a significant step toward realizing tunable p-wave interactions in Bose-Bose mixtures, and provides a foundation for exploring non-zero angular momentum molecules.
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All authors Fan Jia, Zhichao Guo, Zerong Huang, Dajun Wang
Statistical Mechanics
A generalized work theorem for stopped stochastic chemical reaction networks
Xiangting Li and Tom Chou
We establish a generalized work
theorem for
stochastic chemical reaction networks (CRNs). By using a compensated Poisson jump process, we identify a martingale structure in a generalized
entropy defined relative to an auxiliary backward process and extend nonequilibrium work relations to processes stopped at bounded arbitrary times. Our results apply to discrete, mesoscopic chemical reaction networks and remain valid for singular initial conditions and state-dependent termination events. We show how martingale properties emerge directly from the structure of reaction propensities without assuming detailed balance.
Stochastic simulations of a simple chemical kinetic proofreading network are used to explore the dependence of the exponentiated
entropy production on initial conditions and model parameters, validating our new work
theorem relationships. Our results provide new quantitative tools for analyzing biological
circuits ranging from metabolic to gene regulation pathways.
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Mesoscale and Nanoscale Physics
Plasmonic nanocavity-enabled universal detection of layer-breathing vibrations in two-dimensional materials
Wu Heng, Lin Miao-Ling, Yan Sen et al. (+12 more)
Conventional Raman spectroscopy faces inherent limitations in detecting interlayer layer breathing (LB) vibrations with inherently weak electron-
phonon coupling or Raman inactivity in two-dimensional materials, hindering insights into interfacial coupling and stacking dynamics. Here we demonstrate a universal plasmon-enhanced Raman spectroscopy strategy using gold or silver nanocavities to strongly enhance and detect LB modes in multilayer
graphene, hBN, and their van der Waals
heterostructures. Plasmonic nanocavities even modify the linear and circular polarization selection rules of the LB vibrations. By developing an electric-field-modulated interlayer bond polarizability model, we quantitatively explain the observed intensity profiles and reveal the synergistic roles of localized plasmonic field enhancement and interfacial polarizability modulation. This model successfully describes the behavior across different material systems and nanocavity geometries. This work not only overcomes traditional detection barriers but also provides a quantitative framework for probing interlayer interactions, offering a versatile platform for investigating hidden interfacial
phonons and advancing the characterization of layered
quantum materials.
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All authors Wu Heng, Lin Miao-Ling, Yan Sen, Chen Lin-Shang, Zhong-Jie Wang, Zhang Yi-Fei, Zhu Ti-Ying, Su Zheng-Yu, Wang Jun, Liu Xue-Lu Liu, Wei Zhong-Ming, Shi Yan-Meng, Wang Xiang, Ren Bin, Tan Ping-Heng