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Physics Condensed Matter

cond-mat Watch Condensed Matter

Saturday 14 March

Soft Condensed Matter

Inferring the dynamics of glass-forming liquids from static structure across thermal states

Hidemasa Bessho, Takeshi Kawasaki and Hayato Shiba

In this study, we demonstrate the generalizability of graph neural networks in predicting the dynamic heterogeneity of model glass-forming liquids across different temperatures. While previous approaches have often been limited to making predictions at the specific temperatures used during training, we find that our proposed framework - T-BOTAN - enables interpolation to temperatures not included in the training set. We show that the dynamical behavior, the associated four-point correlations, and even the macroscopic temperature can be estimated with sufficient accuracy solely from static particle configurations at untrained temperatures. These results suggest that static configurations encode not only local structural features driving dynamic heterogeneity but also fundamental thermodynamic information.
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Materials Science

Nitrogen-Vacancy-Mediated Magnetism in Sputtered GdN Thin Films

Pankaj Bhardwaj, Jyotirmoy Sarkar, Bubun Biswal et al. (+11 more)

Among rare-earth nitrides (RENs), gadolinium nitride (GdN) stands out as a promising material for spintronics owing to its distinctive combination of semiconducting behavior, strong exchange interactions, and intrinsically soft ferromagnetism. Its relatively high Curie temperature and large saturation magnetization make it an attractive candidate for device concepts such as non-volatile memory elements and spin-based transistors, motivating efforts toward low-cost, uniform, and compositionally controlled thin-film growth. In this work, we deposited GdN thin films on SiO2/AlN substrates using DC sputtering under reactive nitridation conditions, with thicknesses varying from 18 to 180 nm, and systematically investigated their structural and magnetic properties. The films exhibit soft ferromagnetic ordering, characterized by a coercive field of approximately 200 Oe and a Curie temperature (Tc) near 70 K. Structural analysis reveals lattice distortions and local strain associated with nitrogen-vacancy defects, whose concentration varies with film thickness. Our theoretical studies establish a direct correlation between the observed Raman modes of the GdN lattice and the reduced magnetization induced by nitrogen vacancies. These vacancies give rise to defect-mediated ferromagnetism, leading to a measurable enhancement of Tc from 68 K to 82 K across the studied thickness range. The observed magnetic behavior is well described by the bound magnetic polaron (BMP) model, confirming that nitrogen vacancies are key contributors to ferromagnetic ordering while preserving the soft-magnetic character intrinsic to GdN. This study underscores the pivotal role of defect engineering in optimizing GdN thin films for spintronics applications.
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All authors Pankaj Bhardwaj, Jyotirmoy Sarkar, Bubun Biswal, Subhransu Kumar Negi, Arijit Sinha, Anirudh Venugopalrao, Sharath Kumar C, Sreelakshmi M Nair, R. S. Patel, Deepshika Jaiswal Nagar, Abhishek Mishra, Srinivasan Raghavan, Umesh Waghmare, Dhavala Suri

Strongly Correlated Electrons

Pressure induced redistribution of oxygen hole states in La$_{4}$Ni$_{3}$O$_{10}$

Guiwen Jiang, Liang Si, George A. Sawatzky et al. (+1 more)

Using density functional calculations and multi-orbital, multi-atom cluster exact diagonalization that includes local exchange and Coulomb interactions, we explored the local low-energy electronic states of trilayer La$_4$Ni$_3$O$_{10}$ via a minimal Ni$_3$O$_{14}$ cluster. We find that, at ambient pressure, starting with all three Ni being nominally 2+ valence, one of the two extra holes is localized in the central NiO$_2$ layer forming a Zhang-Rice singlet (ZRS) with $d_{x^2-y^2}$ orbital. The other hole mainly occupies the antibonding combination of the two interplane apical O $p_z$ orbitals and thereby hybridizes with an out-of-plane three-spin-polaron (3SP) formed by the $d_{z^2}$ orbitals of three NiO$_2$ layers. At high pressure, however, the two extra holes are concentrated on one of two outer layers and the inner layer separately forming the ZRS with $d_{x^2-y^2}$ orbitals. We highlight the similarities between the bilayer La$_3$Ni$_2$O$_7$ and trilayer La$_4$Ni$_3$O$_{10}$ via speculated possible charge and spin configurations as well as the in-plane 3SP on two neighboring clusters suggested by our isolated cluster results.We thereby propose that the hole transfer from apical to in-plane oxygen orbitals of outer layer generates in-plane 3SP-like quasiparticles that act as mobile carriers coupled by interlayer superexchange; while the interplane 3SP-like states may provide the pairing glue. Since the low-pressure phase lacks freely propagating in-plane quasiparticles, this scenario naturally favors SC in the high-pressure phase.
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All authors Guiwen Jiang, Liang Si, George A. Sawatzky, Mi Jiang

Mesoscale and Nanoscale Physics

Eccentricity valley Hall effect

Jin Cao, Shen Lai, Cong Xiao et al. (+2 more)

Valleytronics harnesses the valley degree of freedom – energy-degenerate extrema in the electronic band structure – for information storage and processing. Valley Hall effect (VHE) is a cornerstone of valleytronics, enabling electric generation of pure valley currents. While extensively studied in systems with valleys located at time-reversal-breaking points, here, we shift the paradigm to valleytronic platforms with time-reversal-invariant valleys (TRIVs), revealing a novel phenomenon: eccentricity VHE. Unlike conventional VHE, the valley Hall angle for eccentricity VHE is an intrinsic geometric property, governed solely by the eccentricity of the valley Fermi surface, rendering it highly robust against variations in temperature or carrier density. Eccentricity VHE emerges universally across all 25 layer groups supporting TRIVs. We demonstrate these distinctive features in monolayer GeS$_{2}$ via first-principles calculations, predicting a significant valley Hall angle of 0.74. This effect can be detected through nonlocal transport measurements exhibiting characteristic scaling behavior, or, in certain cases, through valley-layer coupling. Our findings reveal a critical overlooked facet of valley Hall physics, transcend the established VHE paradigm, and significantly broadens the scope of valleytronics.
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All authors Jin Cao, Shen Lai, Cong Xiao, Qian Niu, Shengyuan A. Yang

Mesoscale and Nanoscale Physics · Cross-listed from physics.optics

Probing strong coupling in core–shell nanoparticles with fast electron beams

Annika Brandt, Christos Tserkezis, Carsten Rockstuhl et al. (+1 more)

Collective optical excitations, such as localized surface plasmons in metallic nanoparticles and Mie resonances in high-index dielectrics, play a central role in nanoscale light–matter interactions. When such optical modes interact with electronic transitions in matter under suitable conditions, they can couple strongly, analogous to two coupled harmonic oscillators, forming hybrid light–matter states. In this work, we probe this coupling in core–shell nanoparticles using fast electrons in electron energy-loss (EEL) and cathodoluminescence (CL) spectroscopy. Owing to their highly localized fields, fast electrons can excite modes inaccessible with light-based spectroscopies, including higher-order nonradiative modes, which offer greater field confinement and potentially stronger coupling. Here, we develop an analytical framework to calculate the EEL and CL probabilities for spherical core–shell nanoparticles under aloof and penetrating electron trajectories. This formalism is applied to two representative systems: an excitonic core with a metallic shell, and a silicon core with an excitonic shell. Our main focus is to examine how the electron beam position and velocity affect our ability to probe this coupling. Depending on the electron beam parameters, we find that the spectral signature of strong coupling remains robust in plasmonic nanospheres. In contrast, it can be significantly suppressed or even completely obscured in dielectric nanospheres. Our developed formalism enables a deeper understanding of the coupling mechanisms in electron–light–matter interactions, thereby accelerating progress in single-nanoparticle-based polaritonic studies.
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All authors Annika Brandt, Christos Tserkezis, Carsten Rockstuhl, P. Elli Stamatopoulou

Disordered Systems and Neural Networks

Optimality and annealing path planning of dynamical analog solvers

Shu Zhou, K. Y. Michael Wong, Juntao Wang et al. (+3 more)

Recently proposed analog solvers based on dynamical systems, such as Ising machines, are promising platforms for large-scale combinatorial optimization. Yet, given the heuristic nature of the field, there is very limited insight on optimality guarantees of the solvers, as well as how parameter schedules shape dynamics and outcomes. Here, we develop a dynamical mean-field framework to analyze Ising-machine dynamics for finding the ground state energy of the Sherrington-Kirkpatrick(SK) model of spin glasses and identify mechanisms that enable rapid convergence to provenly near-optimal energies. For a fixed target energy density Ec, we show that solutions are typically reached within O(1) matrix vector multiplications, indicating constant time complexity. We further delineate theoretical limitations arising from different parameter-scheduling trajectories and demonstrate a pronounced benefit of temperature-only annealing for the Coherent Ising Machine. Building on these insights, we propose a general framework for designing optimized parameter schedules, thereby improving the practical effectiveness of Ising machines for complex optimization tasks. The superior performance of the dynamical solvers is illustrated by the attainment of the ground state energy of the SK model.
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All authors Shu Zhou, K. Y. Michael Wong, Juntao Wang, David Shui Wing Hui, Daniel Ebler, Jie Sun

Soft Condensed Matter

Tunable Cooperative Motion, Rigidity, and Glassy Dynamics in Knotted Ring Polymer Melts

Yue-Tong Dong, Jack F. Douglas and Wen-Sheng Xu

We present a molecular dynamics study of the influence of knot complexity and molecular mass on glass formation upon cooling in knotted ring polymer melts. We find that cooperative motion, rigidity, and glassy dynamics can be tuned over a wide range by knots. By leveraging these knotting constraints, we assess the validity of prevalent models of glass formation, including the string model based on cooperative particle motion, the localization model emphasizing fluctuations in local particle mobility, and the shoving model derived from emergent elastic properties in relation to material stiffness. In line with our previous findings on polymeric and other glass-forming liquids, we demonstrate that all these models of glass formation provide a quantitative description of segmental relaxation as a function of knot complexity, molecular mass, and temperature, despite their apparently distinct conceptual foundations. Our study thus provides additional evidence for an underlying unity among various theoretical frameworks and for the presence of quantitative relations between the characteristic properties emphasized by these models. Furthermore, we discuss dynamic and elastic heterogeneities in relation to fragility and stiffness variations of knotted ring polymer melts, with a focus on how these trends relate to other glass-forming liquids where fragility is tuned over a large range.
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Materials Science

Research Paradigm of Materials Science Tetrahedra with Artificial Intelligence

Shiyun Zhang, Yibo Yao, Haoquan Long et al. (+4 more)

The classical material tetrahedron that represents the Structure-Property-Processing-Performance-Characterization relationship is the most important research paradigm in materials science so far. It has served as a protocol to guide experiments, modeling, and theory to uncover hidden relationships between various aspects of a certain material. This substantially facilitates knowledge accumulation and material discovery with desired functionalities to realize versatile applications. In recent years, with the advent of artificial intelligence (AI) techniques, the attention of AI towards scientific research is soaring. The trials of implementing AI in various disciplines are endless, with great potential to revolutionize the research diagram. Despite the success in natural language processing and computer vision, how to effectively integrate AI with natural science is still a grand challenge, bearing in mind their fundamental differences. Inspired by these observations and limitations, we delve into the current research paradigm dictated by the classical material tetrahedron and propose two new paradigms to stimulate data-driven and AI-augmented research. One tetrahedron focuses on AI for materials science by considering the Matter-Data-Model-Potential-Agent diagram. The other demonstrates AI research by discussing Data-Architecture-Encoding-Optimization-Inference relationships. The crucial ingredients of these frameworks and their connections are discussed, which will likely motivate both scientific thinking refinement and technology advancement. Despite the widespread enthusiasm for chasing AI for science, we must analyze issues rationally to come up with well-defined, resolvable scientific problems in order to better master the power of AI.
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All authors Shiyun Zhang, Yibo Yao, Haoquan Long, Dingwen Tao, Guangming Tan, Wei-Hua Wang, Yuan-Chao Hu

Materials Science

Giant Full-Space Anomalous Hall Effect Induced by Non-Coplanar Spin State in Mn-Rich Mn3Sn

Yiming Liu, Xin Liu, Jiayao Zhu et al. (+6 more)

Antiferromagnets are promising candidates for next-generation spintronic devices owing to their negligible stray fields and ultrafast spin dynamics. The noncollinear antiferromagnet $\mathrm{Mn}_{3}\mathrm{Sn}$ exhibits a large anomalous Hall effect (AHE). However, its specific noncollinear spin configuration leads to the forbiddance of the anomalous Hall conductivity from the (0001) basal plane, $\sigma_{(0001)}$, limiting practical applications. Here, using first-principles density functional theory, we demonstrate that Mn enrichment in $\mathrm{Mn}_{3}\mathrm{Sn}$ drives a magnetic transition from the coplanar $120^\circ$ spin configuration to a non-coplanar state with moments tilted toward the $c$-axis. This transition is primarily mediated by four-spin ring exchange interaction in the local triangular lattice, which breaks the time-reversal symmetry and generates a giant intrinsic anomalous Hall conductivity over the full three-dimensional space in $\mathrm{Mn}_{3}\mathrm{Sn}$. We predict that $\sigma_{(0001)}$ reaches as high as $\sim\!-468~\Omega^{-1}\cdot\mathrm{cm}^{-1}$, and an enhanced $\sigma_{(01\bar{1}0)}$ of $\sim\!-229~\Omega^{-1}\cdot\mathrm{cm}^{-1}$ is expected in light Mn self-doping of $\mathrm{Mn}_{3}\mathrm{Sn}$ ($\mathrm{Mn}_{3.125}\mathrm{Sn}_{0.875}$). Unlike previously reported mechanisms relying on external magnetic fields or strain, our approach exploits intrinsic compositional tuning to stabilize a non-coplanar magnetic ground state for realizing a strong full-space AHE in antiferromagnets, providing another viable pathway toward high-performance, low-power spintronic devices.
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All authors Yiming Liu, Xin Liu, Jiayao Zhu, Fengxian Ma, Li Ma, Dewei Zhao, Guoke Li, Congmian Zhen, Denglu Hou

Statistical Mechanics · Cross-listed from physics.soc-ph

Measuring Primitive Accumulation: An Information-Theoretic Approach to Capitalist Enclosure in PIK2, Indonesia

Sandy Hardian Susanto Herho, Alfita Puspa Handayani, Karina Aprilia Sujatmiko et al. (+5 more)

Large-scale land enclosure for speculative mega-development constitutes a non-equilibrium spatial process whose velocity, topology, and irreversibility remain poorly quantified. We study the Pantai Indah Kapuk 2 (PIK2) coastal mega-development north of Jakarta, Indonesia, using eight years (2017–2024) of Sentinel-2 land-use/land-cover (LULC) data at 10-meter resolution. The landscape is projected onto a Marxian probability simplex partitioning terrestrial pixels into Commons, Agrarian, and Capital fractions. Fisher-Rao (FR) geodesic distances on this simplex identify a transformation pulse of $0.405$~rad/yr during 2019–2020, coinciding with major construction activity. Absorbing Markov chain analysis yields expected absorption times into the built environment of $46.0$~years for cropland and $38.1$~years for tree cover, with a pooled built-area self-retention rate of $96.4\%$. Percolation analysis reveals that a giant connected component containing $89$–$95\%$ of all built pixels persists at occupation probabilities $p \in [0.096, 0.162]$, far below the random percolation threshold $p_c \approx 0.593$, indicating planned rather than stochastic spatial growth. The box-counting fractal dimension of the urban boundary increases from $d_f = 1.316$ to $1.397$, consistent with increasingly irregular frontier expansion. These results suggest that information-geometric and statistical-mechanical tools can characterize the kinematic and topological signatures of capitalist spatial accumulation with quantitative precision.
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All authors Sandy Hardian Susanto Herho, Alfita Puspa Handayani, Karina Aprilia Sujatmiko, Faruq Khadami, Iwan Pramesti Anwar, Rusmawan Suwarman, Dasapta Erwin Irawan, Deny Juanda Puradimaja

Mesoscale and Nanoscale Physics

First-principles modeling of electrostatics and transport in 2D topological transistors

Hyeonseok Choi, Yosep Park, Subeen Lim et al. (+1 more)

We develop a simulation framework for electrostatic and transport modeling of 2D Topological insulator field-effect transistor (2D TIFETs), based solely on first-principles calculations using density functional theory (DFT). We find that careful consideration of basis set and symmetry constraints in DFT calculations is crucial for determining critical electric field ($E_c$), defined as the electric field intensity at which the topological phase transition occurs. Using ballistic Landauer-B$\"u$ttiker formula and local potential profile, the drain current-gate bias voltage ($I_D$-$V_G$) characteristics were obtained and switching behavior was studied. A comparison with the $\mathbf{k}\cdot\mathbf{p}$ model reveals the necessity of DFT calculations for investigating realistic edge dispersions. Our approach provides an efficient and rigorous simulation methodology for mesoscopic transport in 2D TIFETs.
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All authors Hyeonseok Choi, Yosep Park, Subeen Lim, Yeonghun Lee

Materials Science

Cobalt Binary Compounds for Advanced Interconnect Materials

Gyungho Maeng and Yeonghun Lee

The industrial standard copper (Cu) interconnects face a substantial resistivity increase at thinner linewidths, posing a well-known challenge to limit overall device performance. To address this issue, we have evaluated the potential properties of cobalt (Co) based binary compounds as replacements for Cu. Co is considered as a promising alternative due to its potential for enhanced reliability and low resistivity at sub-nanoscale dimensions. Furthermore, the combination of elements provides a possibility to engineer novel properties, transcending the limitations of elemental metals and expanding the search space for next-generation interconnects. In this study, a high-throughput screening method was used to identify several Co-based binary compounds with superior electronic transport and reliability at reduced thickness. The findings demonstrate that specific Co-based binary compounds hold significant potential to overcome the performance limitations of scaled interconnects.
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Strongly Correlated Electrons

Entanglement Rényi Negativity across the Finite-Temperature Transition in the O(3) Universality Class

Dong-Xu Liu, Yi-Ming Ding, Zhe Wang et al. (+1 more)

The fate of quantum entanglement at finite-temperature phase transitions remains an open question, particularly for continuous symmetry breaking where zero-temperature Goldstone modes generate long-range correlations. Using large-scale quantum Monte Carlo simulations, we investigate the third Rényi negativity across the O(3) transition in the three-dimensional Heisenberg antiferromagnet. The first such study for a thermal critical point with continuous symmetry. We uncover two fundamental results. First, the negativity exhibits a pure area law at the critical point, with the subleading constant term vanishing within statistical uncertainty. This demonstrates that thermal fluctuations completely destroy the long-range entanglement present at zero temperature. The divergent classical correlation length leaves no imprint on quantum entanglement itself. Second, despite this absence of singular behavior in the negativity, its temperature derivative follows the exact scaling of the specific heat, yielding critical exponents -{\alpha}/{\nu}=0.190(1) and 1/{\nu}=1.350(5) in precise agreement with the O(3) universality class. Our work establishes that while quantum entanglement is blind to thermal criticality, its thermodynamic derivatives encode the full universal scaling, revealing an unexpected connection between entanglement and classical phase transitions. Furthermore, this also provides further evidence that Rényi negativity can still effectively shield classical correlations in systems with continuous symmetry.
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All authors Dong-Xu Liu, Yi-Ming Ding, Zhe Wang, Zheng Yan

Materials Science

Revealing Hydroxide Ion Transport Mechanisms in Commercial Anion-Exchange Membranes at Nano-Scale from Machine-learned Interatomic Potential Simulations

Jonas Hänseroth, Muhammad Nawaz Qaisrani, Mostafa Moradi et al. (+2 more)

Hydroxide ion transport in anion-exchange membranes fundamentally limits the efficiency of alkaline water electrolysis for green hydrogen production, yet the atomic-scale transport mechanisms remain poorly understood due to the computational challenges associated with modeling ion dynamics. Given that anion-exchange membranes enable alkaline electrolysis with abundant catalysts while avoiding perfluoroalkyl and polyfluoroalkyl materials, a deeper mechanistic understanding of hydroxide transport in these systems is essential for advancing sustainable hydrogen production. Here, we show that large-scale molecular dynamics simulations with fine-tuned machine-learned interatomic potentials provide atomistic insight into hydroxide mobility in a commercial membrane over tens of nanoseconds and over ten nanometer. We find that increasing water content transforms isolated water clusters into a connected hydrogen-bond network that enables long-range proton transfer. Under dry conditions hydroxide ions are trapped near positively charged groups and transport is strongly hindered, whereas well-hydrated membranes exhibit extended proton migration and diffusion coefficients approaching those of dilute aqueous solutions. The simulations reproduce experimental trends in diffusion and activation energies. Our results establish a direct link between nano-scale structure and macroscopic transport. Beyond mechanistic insight, the presented simulation framework enables predictive, simulation-guided optimization of membrane chemistry and architecture, opening a pathway toward the rational design of more efficient anion-exchange membranes for green hydrogen technologies.
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All authors Jonas Hänseroth, Muhammad Nawaz Qaisrani, Mostafa Moradi, Karl Skadell, Christian Dreßler

Quantum Gases · Cross-listed from quant-ph

Quantum Correlations and Entanglement in Generalized Dicke-Ising Models

Santiago F. Caballero-Benitez

Quantum systems inside high-Q cavities offer an excellent testbed for the control of emergent symmetries induced by light and their interplay with quantum matter. Recently several developments in cavity experiments with neutral atoms and other quantum objects such as ions motivate the study of their quantum correlated properties and their entanglement to tailor and control the behavior of the system. Using the enhanced coupling between light and interacting matter we explore the properties of emergent superradiant modes using our newly developed Light-Matter DMRG algorithm with strongly interacting spin chains. We explore a experimentally viable generalization of the transverse Ising chain coupled to the cavity light where it is possible to induce multimode structures tailored by the light pumped into the system. We find a plethora of scenarios can be explored with clear and accesible measurable signatures. This allows to study the physics of emergent orders and strong quantum correlations with quantum spins where the local and long range coupling can be efficiently simulated. We find that quantum spin nematic states with long range order and magnon pairs emerge as the transitions to superradiant phases take place. Notably, we show the cavity field allows the optimization of entanglement between spins for different light induced modes which can be used for quantum state engineering of quantum correlated states. Our methods can be used to model other hybrid quantum systems efficiently.
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Friday 13 March

Materials Science · Cross-listed from physics.ins-det

Indirect monitoring of fast-charge cycling behavior of an energy-storage device-analysis of ambient temperature variations

Pertti O. Tikkanen

I present a reanalysis of temperature data from a publicly available certified laboratory report that documented the self-discharging behavior of an energy-storage device during 10 days. Graphs of temperature variations of both the tested device itself and the test chamber (fume hood) were given mainly for monitoring without further analysis, and variations in the ambient temperature signal were attributed to "other cells being cycled simultaneously in the same fume hood". I show that the ambient temperature signal alone – together with some quite mild and reasonable assumptions – allow to extract previously unpublished information on the simultaneously run test on the other cells: 1) the number of charge/discharge cycles 2) the cycle period, 3) the charge/discharge half-cycle asymmetry, and – most significantly – evidence that 4) the mentioned "other device" completed 338 full charge/discharge cycles at 3C rate at room temperature without any detectable thermal degradation signature.
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Materials Science

Production of Low-Density Aerogel Nuclear Fuels for Use in Fission Fragment Rockets and Novel Reactor Design

Noah D'Amico, Sandeep Puri, Ian Jones et al. (+4 more)

Graphene hydrogels were created and loaded with uranyl nitrate or thorium nitrate and freeze-dried to produce graphene aerogel nuclear fuels. These aerogels had densities between 0.018-0.035 g/cm3 and consisted of ~7.3 +- 0.5% uranium/thorium by mass. The ultra-low density of the aerogels allows for high energy ions to escape the fuel particles without depositing all their energy as heat, as is typical in nuclear fuels. Their measured alpha activity was ~16 pCi/mg, which could be enhanced up to ~49 pCi/mg by decreasing the thickness of aerogel samples to allow all alpha particles to escape. Additionally, high energy neutrons were used to induce fission to provide a source of fission fragments from the aerogel fuels. This novel form of nuclear fuel has potential applications in space propulsion such as fission fragment rocket engines, as well as in terrestrial applications for modular reactors, direct conversion methods, and in medical radiotherapeutics.
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All authors Noah D'Amico, Sandeep Puri, Ian Jones, Andrew Gillespie, Cuikun Lin, Bo Zhao, R. V. Duncan

Materials Science

Coupled Ferroelectricity and Phonon Chirality

Xiang-Bin Han, Cong Yang, Rui Sun et al. (+10 more)

The ability to control chirality and chiral phonons offers a route to manipulate the direction of spin and angular-momentum transport. In materials with rigid structural chirality, such as quartz, phonon chirality is fixed by the handedness and cannot be switched. By contrast, ferroelectric materials host a spontaneous polarization that can be reversibly switched by an external electric field. When chirality is coupled to this ferroelectric polarization, it enables electrical switching of crystal chirality and the associated phonon angular momentum, which is compatible with solid-state spintronic architectures, enabling control over chirality-dependent quantum states.1 Here, we report the experimental demonstration of the coupling between ferroelectricity and phonon chirality in the molecular ferroelectric triglycine sulfate. By electrically switching the crystal chirality, we achieve reversible and device-compatible control of phonon chirality, as revealed by in situ time-resolved magneto-optical Kerr effect measurements. The Kerr rotation reverses with electric-field switching, while phonon chirality vanishes in the paraelectric phase and is tunable in the racemic ferroelectric state. Furthermore, density functional theory calculations and circularly polarized Raman spectroscopy further corroborate the opposite circular phonon motions. These results establish an electrically addressable coupling pathway linking ferroelectricity, structural chirality, chiral phonons, and spin, opening a route toward chiral-phonon-enabled spin and phonon control technologies based on ferroelectric materials.
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All authors Xiang-Bin Han, Cong Yang, Rui Sun, Xiaotong Zhang, Thuc Mai, Zhengze Xu, Aryan Jouneghaninaseri, Xiaoning Jiang, Rahul Rao, Yi Xia, Dali Sun, Jun Liu, Xiaotong Li

Strongly Correlated Electrons

Superradiant strongly correlated quantum states in cavity Hubbard model

Kang Wang, Wei-Xuan Chang, Cheng-Yu Bi et al. (+2 more)

In cavity quantum materials, entangling strongly correlated electrons with quantum light provides a unique opportunity to explore novel quantum phases and phase transitions absent in conventional solid-state materials. In this study, we develop a sign-problem-free fermion-photon hybrid Quantum Monte Carlo (QMC) algorithm, and use it to systematically investigate the ground-state phase diagram of a two-dimensional cavity Hubbard model. It is shown that the interplay between the electron correlation and photon condensation gives rise to intriguing quantum phases (e.g. superradiant antiferromagnetic and chiral/$\pi$-flux states), and different quantum phase transitions, such as a first-order superradiant phase transition and a continuous phase transition with Gross-Neveu universality class. The methodology can be readily generalized to more complicated cavity strongly correlated models.
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All authors Kang Wang, Wei-Xuan Chang, Cheng-Yu Bi, Zi Cai, Zi-Xiang Li

Materials Science

Competing Magnetic Ground States in Copper-Doped Pb$_{10}$P$_{6}$O$_{25}$

Lin Hou, Kevin Allen, Christopher Lane et al. (+1 more)

We investigate the electronic and magnetic properties of copper-doped Pb$_{10}$(PO$_4$)$_6$O using a combination of density functional theory and many-body perturbation theory. The flat half-filled electronic band at the Fermi level is found to give way to an incommensurate antiferromagnetic instability with wave vector $(0.28\pi ,\pm 0.47\pi ,\pi )$ within the random phase approximation arising predominantly from Cu-$d_{yz}$ and Cu-$d_{xz}$ orbitals. Moreover, the Heisenberg exchange coupling between neighboring copper atoms is estimated to be $\sim 1$ meV. Our results suggest that magnetism in copper-doped Pb$_{10}$(PO$_4$)$_6$O is localized on the impurity copper site, with no long-range ordering. These findings support the picture that copper behaves as a magnetic impurity within the Pb-apatite matrix.
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All authors Lin Hou, Kevin Allen, Christopher Lane, Jian-Xin Zhu

Statistical Mechanics

On thermalization in many-body classical Floquet systems

Anton Kapustin

It is expected that a generic closed many-body system prepared in a well-behaved initial state and subjected to a periodic drive will eventually thermalize, i.e. approach the state of maximal entropy. This property, while compatible with and even demanded by the physical intuition, is much stronger than ergodicity or mixing and is difficult to justify mathematically. We describe an infinite set of classical many-body Floquet systems of algebraic origin for which thermalization of very general initial states can be proved. For example, we show that a Gibbs state of any sufficiently uniform local differentiable Hamiltonian heats up to infinite temperature at long times. We show that in agreement with the physical intuition, the only obstruction to thermalization is the existence of local observables which are periodic in time.
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Strongly Correlated Electrons · Cross-listed from quant-ph

Quantum contextuality with mixed states of 1D symmetry-protected topological order

Leroy Fagan and Akimasa Miyake

Bell theorems of many-body nonlocality and contextuality serve as a benchmark for proving quantum advantage in that a quantum computer outperforms a classical computer for a certain problem. In practice, however, near-term quantum devices do not prepare perfectly pure states but rather mixed states produced from noisy channels. We investigate noisy quantum advantage by considering thermal mixed states of one-dimensional many-body systems with a symmetry-protected topological (SPT) order. In the pure-state (or zero-temperature) case, these states are known to be useful for measurement-based quantum computation, and to outperform classical computers in a many-body contextuality game, provided string order parameters (SOPs) of SPT are sufficiently large. Here, we show that quantum advantage in mixed states is measured by a combination of twisted SOP and symmetry representation expectation values. Using the minimally entangled typical thermal states algorithm, it is demonstrated that quantum advantage persists to a nonzero critical temperature for finite-sized instances of the many-body contextuality game. While this critical temperature goes to zero in the thermodynamic limit, it is relatively robust to system size, suggesting that these states remain useful for demonstrating genuine "quantumness" of noisy hardware in a scalable fashion. Finally, we show that the quantum winning probability is lower bounded by the global fidelity with the 1D cluster state, so that our contextuality game can provide an operational meaning to benchmark the capacity to create long-range order like SPT states in near-term experimental devices.
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Soft Condensed Matter

Splitting probabilities of confined chiral active Brownian particles

Sarafa A. Iyaniwura and Zhiwei Peng

Active particles exhibit self-propulsion, leading to transport behavior that differs fundamentally from passive Brownian motion. In confined or structured domains, activity strongly influence escape probabilities and first-passage behavior. Understanding these effects is essential for describing transport in biological microenvironments, microfluidic devices, and heterogeneous media. In this work, leveraging the backward Fokker–Planck equation, we investigate the splitting probability of chiral active Brownian particles in confined domains, focusing on both a one-dimensional interval and a two-dimensional corrugated channel. Analytical solutions are derived for the one-dimensional case in various asymptotic regimes. In corrugated channels with small aspect ratios, we develop a Fick–Jacobs reduction that yields effective transport equations along the axial direction, whereas for finite aspect ratios, the splitting dynamics are characterized numerically. We demonstrate how channel geometry, particle activity, and chirality modulate the likelihood of escape through different boundaries. Our results provide quantitative predictions for the transport of active matter in complex environments and highlight the interplay between confinement and activity.
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Soft Condensed Matter

Constraint ratio controls viscosity in shear thickening suspensions

Qinghao Mao, Michael van der Naald, Abhinendra Singh et al. (+1 more)

The dramatic viscosity increase observed in dense suspensions under shear poses a major challenge in our understanding of how microscopic contact mechanics translate into macroscopic flow resistance. Here, we introduce a constraint-counting model that incorporates friction and dimensionality naturally without additional assumptions and allows for collapsing of rheological data onto a universal master curve. In this model, we borrow ideas from dry granular jamming physics and classify contacts as either locked or non-locked to define a single state variable, the constraint ratio, which measures the average strength of mechanical constraint per particle. By identifying the constraint ratio as the key control parameter, our framework provides a unifying route toward predictive modeling and rational design of shear-thickening materials.
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All authors Qinghao Mao, Michael van der Naald, Abhinendra Singh, Heinrich M. Jaeger

Mesoscale and Nanoscale Physics · Cross-listed from quant-ph

The Quest for Quantum Advantage in Combinatorial Optimization: End-to-end Benchmarking of Quantum Solvers vs. Multi-core Classical Solvers

Pranav Chandarana, Alejandro Gomez Cadavid, Enrique Solano et al. (+3 more)

We perform an end-to-end benchmark of a hybrid sequential quantum computing (HSQC) solver for higher-order unconstrained binary optimization (HUBO), executed on IBM Heron r3 quantum processors to evaluate the potential of current quantum hardware for combinatorial optimization with sub-second end-to-end runtimes. All reported runtimes include the complete pipeline–from preprocessing to QPU execution and postprocessing–under strict wall-clock accounting. Across 20 benchmark instances, a single hybrid attempt produces high-quality solutions in less than one second, matching the ground-state energy in 14 cases. At the same runtime, CPU-based solvers, including simulated annealing, memetic tabu search, and EasySolve, do not reach the value obtained by HSQC, whereas an enhanced parallel tempering method and the GPU-accelerated solver ABS3 reach or surpass it. These results show that HSQC, executed on a single QPU, can achieve performance competitive with strong classical solvers running on 128 vCPUs or 8 NVIDIA A100 GPUs, while also providing a reproducible system-level benchmark for tracking progress as quantum hardware and hybrid sequential workflows improve.
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All authors Pranav Chandarana, Alejandro Gomez Cadavid, Enrique Solano, Thorsten Koch, Stefan Woerner, Narendra N. Hegade

Superconductivity

Hierarchical structure of primary and hybridization-induced superconducting correlations in bilayer nickelates

Hiroshi Watanabe, Hirofumi Sakakibara and Kazuhiko Kuroki

High-pressure superconductivity in the bilayer nickelate La$_3$Ni$_2$O$_7$, with a transition temperature approaching 80 K, has stimulated intense debate regarding its microscopic origin. Although an $s_{\pm}$ gap symmetry has been widely proposed, the electronic degrees of freedom responsible for pairing remain unsettled. Here we investigate a bilayer two-orbital Hubbard model using the variational Monte Carlo method and reveal a hierarchical pairing structure in bilayer nickelates. The primary pairing interaction originates from the bonding–antibonding splitting of the Ni $3d_{z^2}$ orbitals, while orbital hybridization redistributes superconducting correlations to the $d_{x^2-y^2}$ channel despite its weak intrinsic pairing interaction. This distinction between the origin of pairing and resulting superconducting correlations explains why the two orbital channels exhibit comparable long-range correlations. The resulting $s_{\pm}$ state is robust against changes in Fermi-surface topology. These results reconcile apparently competing theoretical scenarios and provide a comprehensive understanding, highlighting the distinctive role of orbital hybridization in multilayer correlated superconductors.
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Soft Condensed Matter

Brush-mediated angular constraints reshape structure, rigidity, and percolation in colloidal depletion gels

Ziye Zhuang, Robert A. Campbell, Paniz Haghighi et al. (+2 more)

Colloidal gels, like many other soft and disordered solids derive their mechanical properties not only from the strength of interparticle attraction, but also from the symmetry of the forces that constrain particle motion. While non-central interactions are known to profoundly alter rigidity and elasticity, they are typically introduced through particle anisotropy, surface roughness, or patchy interactions, obscuring their independent role. Here we demonstrate a minimal and geometry-preserving route to emergent non-central forces in colloidal gels by reducing the density of surface-grafted polymer brushes. At low brush density, partial brush interpenetration introduces an effective angular bending rigidity at particle contacts, despite fully isotropic particle geometry. This emergent constraint suppresses local densification, stabilizes low-coordination networks, and produces highly ramified gel structures with enhanced elasticity. Combining experiments, simulations, and mean-field theory, we show that these non-central constraints reorganize structure and mechanics across length scales, shifting gelation boundaries and increasing the elastic modulus by nearly a factor of three. Our results establish surface brush density as a generic control parameter for programming interaction symmetry in soft particulate matter, with implications for rigidity, percolation, and mechanical design in disordered systems.
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All authors Ziye Zhuang, Robert A. Campbell, Paniz Haghighi, Safa Jamali, Ali Mohraz

Materials Science

Analyzing coherent phonon mode-conversion in gradient superlattices with atomistic wave-packet simulations

Evan Wallace Doe, Theodore Maranets and Yan Wang

In this study, we have used atomistic phonon wave-packet simulations to investigate the manifestation of coherent phonons and phonon transmission in gradient superlattices (SL) based on ordered arrangements of varied SL period sizes. We specifically explore how coherent mode-conversion in these quasi-periodic structures changes as function of three key structural parameters: (1) the number of distinct period sizes, (2) the number of periods present for each distinct period size, and (3) the arrangement of period sizes in either an ascending or descending arrangement. Comparisons to periodic SLs and aperiodic SLs are highlighted, revealing that coherent phonons in gradient SLs generally exhibit behaviors characteristic of intermediate states between the fully ordered and disordered structures. Interestingly, changes to the short-range order of GMLs does not significantly influence transmission, indicating that long-range disorder is far more important to coherent mode-conversion. Our results indicate that manipulating the long-range disorder of interfaces could be an effective strategy to tailor phonon thermal conductivity of SL architectures.
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Materials Science

Co2SeO3Cl2: Studies of Emerging Magnetoelectric Coupling in a Polar, Buckled Honeycomb Material

Faith O. Adeyemi, Xudong Huai, Mohamed Kandil et al. (+3 more)

The development of magnetoelectric materials requires chemical design strategies that integrate structural polarity with magnetic lattices capable of supporting competing spin interactions. Here, we demonstrate such an approach in the polar, buckled honeycomb magnet Co2SeO3Cl2. Magnetization and heat-capacity measurements reveal strong magnetic anisotropy and four successive magnetic transitions at 25.4, 16.8, 11, and 3 K. The recovered magnetic entropy through the ordering regime is only around half of the expected 2Rln(2), indicating persistent spin fluctuations. Second-harmonic generation measurements show three pronounced intensity anomalies at 11, 17, and 26 K that coincide with magnetic transitions while revealing that the crystallographic symmetry is preserved. Together, these results demonstrate that polar, buckled honeycomb magnets offer an unconventional phase space for coupling magnetic and electric dipoles in magnetoelectric materials.
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All authors Faith O. Adeyemi, Xudong Huai, Mohamed Kandil, Pradip Karki, Wencan Jin, Thao T. Tran

Statistical Mechanics · Cross-listed from physics.chem-ph

Adaptive tensor train metadynamics for high-dimensional free energy exploration

Nils E. Strand, Siyao Yang, Yuehaw Khoo et al. (+1 more)

A key challenge for molecular dynamics simulations is efficient exploration of free energy landscapes over relevant collective variables (CV). Common methods for enhancing sampling become prohibitively inefficient beyond only a few CVs; in the case of the widely-used metadynamics method, the computational cost of evaluating and storing the bias potential grows exponentially with the number of dimensions. Here, we introduce TT-Metadynamics, in which the accumulated sum of Gaussian functions in the original metadynamics method is periodically compressed into a low-rank tensor train (TT) representation. The TT enables efficient memory use and prevents the computational cost of evaluating the bias potential from increasing with simulation time. We present a "sketching" algorithm that allows us to construct the TT with linear scaling in the number of CVs. Applied to benchmark systems with up to 14 CVs, the accuracy of TT-Metadynamics matches or exceeds that of standard metadynamics in long simulations, particularly in systems with high barriers. These results establish TT-Metadynamics as a scalable and effective method for computing free energies that are functions of several CVs.
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All authors Nils E. Strand, Siyao Yang, Yuehaw Khoo, Aaron R. Dinner