Showing 1–50 of 1,192 results for author: Li, H

Exceptional Alkaline Methanol Electrooxidation on Bi-modified Pt3M Intermetallics: Kinetic Origins and an OH Binding Energy Descriptor

Authors: Lecheng Liang, Hengyu Li, Shao Ye, Peng Li, Kaiyang Xu, Jinhui Liang, Binwen Zeng, Bo Shen, Taisuke Ozaki, Zhiming Cui

Abstract: The exploration of advanced CO-free catalysts and clarifying the ambiguous kinetic origins and governing factors would undoubtedly open up opportunities to overcome the sluggish kinetics of methanol electrooxidation and promote the development of direct methanol fuel cells. Herein, we constructed a family of Bi-modified Pt3M intermetallic catalysts (Bi-Pt3M/C, M=Cr, Mn, Co, Zn, In, Ga, and Sn) tha… ▽ More The exploration of advanced CO-free catalysts and clarifying the ambiguous kinetic origins and governing factors would undoubtedly open up opportunities to overcome the sluggish kinetics of methanol electrooxidation and promote the development of direct methanol fuel cells. Herein, we constructed a family of Bi-modified Pt3M intermetallic catalysts (Bi-Pt3M/C, M=Cr, Mn, Co, Zn, In, Ga, and Sn) that follow CO-free dominated pathway and exhibit exceptional catalytic activity. More significantly, leveraging this platform, we have identified the pivotal factor governing the reaction kinetics in CO-free pathway, namely OH binding energy (OHBE). This arises because the rate-determining step (RDS) encompasses both C-H bond activation and water dissociation, whose respective barriers can be reflected by the OHBE. Accordingly, OHBE can act as an activity descriptor. Specifically, Bi-Pt3In/C stands out from other Bi-Pt3M/C and delivers the unprecedented mass activity of 36.7 A mgPt-1 at peak potential, far exceeding state-of-the-art Pt-based catalysts reported to date. Taking Bi-Pt3In/C as a proof of concept, we clearly elucidate the origin of enhanced MOR activity by combining theoretical calculations, kinetic isotope effects, and formaldehyde electrooxidation. Moreover, there exhibits a volcano-type trend between OHBE and the activity of Bi-Pt3M/C. Beyond the discovery of ultrahigh-performance catalysts, these findings provide a detailed mechanistic picture of RDS and offer an innovative design principle for advanced catalysts. △ Less

Submitted 12 December, 2025; originally announced December 2025.

Generation of mechanical cat-like states via optomagnomechanics

Authors: Hao-Tian Li, Hong-Bin Wang, Zi-Xu Lu, Jie Li

Abstract: We propose an optomagnomechanical approach for preparing a cat-like superposition state of mechanical motion. Our protocol consists of two steps and is based on the magnomechanical system where the magnetostrictively induced displacement further couples to an optical cavity mode via radiation pressure. We first prepare a squeezed mechanical state by driving the magnomechanical system with a two-to… ▽ More We propose an optomagnomechanical approach for preparing a cat-like superposition state of mechanical motion. Our protocol consists of two steps and is based on the magnomechanical system where the magnetostrictively induced displacement further couples to an optical cavity mode via radiation pressure. We first prepare a squeezed mechanical state by driving the magnomechanical system with a two-tone microwave field. We then switch off the microwave drives and send a weak red-detuned optical pulse to the optical cavity to weakly activate the optomechanical anti-Stokes scattering. We show that $k$ phonons can be subtracted from the prepared squeezed state, conditioned on the detection of $k$ anti-Stokes photons from the cavity output field, which prepares the mechanical motion in a cat-like state. The work provides a new avenue for preparing mechanical superposition states by combining opto- and magnomechanics and may find applications in the study of macroscopic quantum states and the test of collapse theories. △ Less

Submitted 11 December, 2025; originally announced December 2025.

Comments: Invited contribution to Quantum Review Letters

Switching of topological phase transition from semiconductor to ideal Weyl states in Cu$_2$SnSe$_3$ family of materials

Authors: Huan Li

Abstract: The exploration of topological phase transition (TPT) mechanisms constitutes a central theme in quantum materials research. Conventionally, transitions between Weyl semimetals (WSMs) and other topological states rely on the breaking of time-reversal symmetry (TRS) or precise manipulation of lattice symmetry, thus constraints the available control strategies and restrict the scope of viable materia… ▽ More The exploration of topological phase transition (TPT) mechanisms constitutes a central theme in quantum materials research. Conventionally, transitions between Weyl semimetals (WSMs) and other topological states rely on the breaking of time-reversal symmetry (TRS) or precise manipulation of lattice symmetry, thus constraints the available control strategies and restrict the scope of viable material systems. In this work, we propose a novel mechanism for TPT that operates without TRS breaking or lattice symmetry modification: a class of semiconductors can be directly transformed into an ideal WSM via bandgap closure. This transition is driven by chemical doping, which simultaneously modulates the band gap and enhances spin-orbit coupling (SOC), leading to band inversion between the valence and conduction bands and thereby triggering the TPT. Using first-principles calculations, we demonstrate the feasibility of this mechanism in the Cu$_2$SnSe$_3$ family of materials, where two pairs of Weyl points emerge with energies extremely close to the Fermi level. The bulk Fermi surface becomes nearly point-like, while the surface Fermi surface consists exclusively of Fermi arcs. This symmetry-independent mechanism bypasses the constraints of conventional symmetry-based engineering, and also offers an ideal platform for probing the anomalous transport properties of WSMs. △ Less

Submitted 10 December, 2025; originally announced December 2025.

Comments: 8 pages, 8 figures

Experimental and Theoretical Revisit of Ca-H Superhydrides: Anharmonic Effects on Phase Stability and Superconductivity

Authors: Wenbo Zhao, Qiushi Li, Ying Sun, Zefang Wang, Hefei Li, Hanyu Liu, Hongbo Wang, Yu Xie, Yanming Ma

Abstract: The prediction of superconductivity above 200 K in CaH6 revolutionized research on hydrogen-rich superconductors, and subsequent experiments have verified this prediction, while unidentified peaks in XRD and the decrease in superconducting temperature upon decompression indicate that unresolved issues remain. In this work, we combine theory and experiment to construct an accurate temperature-press… ▽ More The prediction of superconductivity above 200 K in CaH6 revolutionized research on hydrogen-rich superconductors, and subsequent experiments have verified this prediction, while unidentified peaks in XRD and the decrease in superconducting temperature upon decompression indicate that unresolved issues remain. In this work, we combine theory and experiment to construct an accurate temperature-pressure phase diagram of the Ca-H system and identify the stability ranges of the candidate superconducting phases by considering anharmonic effects. Our results demonstrate that type-I clathrate Ca8H46-delta structures become thermodynamically stable at 0 K when anharmonic effects are considered. Notably, we found that the previously predicted CaH6 phase achieves stability above 500 K, underscoring the significant role of temperature and anharmonic effects in stabilizing this intriguing high-pressure phase. Experimentally, we have successfully synthesized Ca8H46-delta phases at low temperatures, thereby validating our theoretical predictions. Our findings offer insights into the structure and superconducting mechanisms of hydrides. △ Less

Submitted 3 December, 2025; originally announced December 2025.

Pervasive electronic nematicity as the parent state of kagome superconductors

Authors: Muxian Xu, Siyu Cheng, Andrea Capa Salinas, Ganesh Pokharel, Alexander LaFleur, Hong Li, Hengxin Tan, Brenden R. Ortiz, Qinwen Deng, Binghai Yan, Ziqiang Wang, Stephen D. Wilson, Ilija Zeljkovic

Abstract: Kagome superconductors $A$V$_3$Sb$_5$ ($A$ = Cs, K, Rb) have developed into an exciting playground for realizing and exploring exotic solid state phenomena. Abundant experimental evidence suggests that electronic structure breaks rotational symmetry of the lattice, but whether this may be a simple consequence of the symmetry of the underlying 2 $\times$ 2 charge density wave phase or an entirely d… ▽ More Kagome superconductors $A$V$_3$Sb$_5$ ($A$ = Cs, K, Rb) have developed into an exciting playground for realizing and exploring exotic solid state phenomena. Abundant experimental evidence suggests that electronic structure breaks rotational symmetry of the lattice, but whether this may be a simple consequence of the symmetry of the underlying 2 $\times$ 2 charge density wave phase or an entirely different mechanism remains intensely debated. We use spectroscopic imaging scanning tunneling microscopy to explore the phase diagram of the prototypical kagome superconductor CsV$_3$Sb$_5$ as a function of doping. We intentionally suppress the charge density wave phase with chemical substitutions selectively introduced at two distinct lattice sites, and investigate the resulting system. We discover that rotational symmetry breaking of the electronic structure -- now present in short-range nanoscale regions -- persists in all samples, in a wide doping range long after all charge density waves have been suppressed. As such, our experiments uncover ubiquitous electronic nematicity across the $A$V$_3$Sb$_5$ phase diagram, unrelated to the 2 $\times$ 2 charge density wave. This further points towards electronic nematicity as the intrinsic nature of the parent state of kagome superconductors, under which other exotic low-temperature phenomena subsequently emerge. △ Less

Submitted 26 November, 2025; originally announced November 2025.

Stabilization of Tetragonal Phase and Aluminum-Doping Effect in a Bilayer Nickelate

Authors: Jia-Yi Lu, Yi-Qiang Lin, Kai-Xin Ye, Xin-Yu Zhao, Jia-Xin Li, Ya-Nan Zhang, Hao Li, Bai-Jiang Lv, Hui-Qiu Yuan, Guang-Han Cao

Abstract: Recent studies suggest that the tetragonal phase of the Ruddlesden-Popper (RP) bilayer nickelate, La$_3$Ni$_2$O$_7$ or La$_2$PrNi$_2$O$_7$, which is stabilized under high pressures, is responsible for high-temperature superconductivity (HTSC). In this context, realization of the tetragonal phase at ambient pressure could be a rational step to achieve the goal of ambient-pressure HTSC in the nickel… ▽ More Recent studies suggest that the tetragonal phase of the Ruddlesden-Popper (RP) bilayer nickelate, La$_3$Ni$_2$O$_7$ or La$_2$PrNi$_2$O$_7$, which is stabilized under high pressures, is responsible for high-temperature superconductivity (HTSC). In this context, realization of the tetragonal phase at ambient pressure could be a rational step to achieve the goal of ambient-pressure HTSC in the nickelate system. By employing the concept of Goldschmidt tolerance factor, we succeed in stabilizing the tetragonal phase by aluminum doping together with post annealing under moderately high oxygen pressure. X-ray and neutron diffractions verify the tetragonal $I4/mmm$ structure for the post-annealed samples La$_3$Ni$_{2-x}$Al$_x$O$_{7-δ}$ (0.3 $\leq x \leq$ 0.5). The Al-doped samples, including the tetragonal ones, show semiconducting properties, carry localized magnetic moments, and exhibit spin-glass-like behaviors at low temperatures, all of which can be explained in terms of charge carrier localization. Furthermore, high-pressure resistance measurements on post-annealed samples reveal that even a low Al doping ($x$ = 0.05) suppresses superconductivity almost completely. This work gives information about the effect of nonmagnetic impurity on metallicity as well as superconductivity in bilayer nickelates, which would contribute to understanding the superconducting mechanism in RP nickelates. △ Less

Submitted 26 November, 2025; originally announced November 2025.

Comments: 13 pages, 6+8 figures, 1+2 tables

pH Regulates Ion Dynamics in Carboxylated Mixed Conductors

Authors: Zeyuan Sun, Mengting Sun, Rajiv Giridharagopal, Robert C. Hamburger, Siyu Qin, Haoxuan Li, Mitchell C. Hausback, Yulong Zheng, Bohyeon Kim, Heng Tan, Thomas E. Gartner III, Elizabeth R. Young, Christopher J Takacs, David S. Ginger, Elsa Reichmanis

Abstract: Coupled ionic and electronic transport underpins processes as diverse as electrochemical energy conversion, biological signaling, and soft adaptive electronics. Yet, how chemical environments such as pH modulate this coupling at the molecular scale remains poorly understood. Here, we show that the protonation state of carboxylated polythiophenes provides precise chemical control over ion dynamics,… ▽ More Coupled ionic and electronic transport underpins processes as diverse as electrochemical energy conversion, biological signaling, and soft adaptive electronics. Yet, how chemical environments such as pH modulate this coupling at the molecular scale remains poorly understood. Here, we show that the protonation state of carboxylated polythiophenes provides precise chemical control over ion dynamics, doping efficiency, solvent uptake and mechanical response. The findings establish molecular acidity as a general strategy to program ionic preference and mechanical stability, offering design principles for pH-responsive mixed conductors and soft electronic materials that couple ionic, electronic, and mechanical functionality. △ Less

Submitted 12 November, 2025; originally announced November 2025.

Comments: 46 pages, 5 figures, 16 supplemental figures, 3 supplemental tables

Tuning Stability of AB3-Type Alloys by Suppressing Magnetism

Authors: Hung Ba Tran, Toyoto Sato, Ryuhei Sato, Hiroyuki Saitoh, Shin-ichi Orimo, Hao Li

Abstract: Hydrogen is a promising clean energy carrier, yet effective and reversible storage remains challenging. AB3-type intermetallic alloys are promising for solid-state hydrogen storage due to intermediate thermodynamic stability and rapid hydrogen uptake. Optimizing stability and gravimetric density is hindered by competing thermodynamic and magnetic effects. Here, we analyze AB3 compounds (A = Ca, Y,… ▽ More Hydrogen is a promising clean energy carrier, yet effective and reversible storage remains challenging. AB3-type intermetallic alloys are promising for solid-state hydrogen storage due to intermediate thermodynamic stability and rapid hydrogen uptake. Optimizing stability and gravimetric density is hindered by competing thermodynamic and magnetic effects. Here, we analyze AB3 compounds (A = Ca, Y, Mg; B = Co, Ni) and ternary alloys CaxYyMg1-x-yB3 using first-principles calculations and Monte Carlo simulations. We find a direct correlation between formation energy and total magnetic moment that dictates alloy stability, explaining the trade-off in hydrogen storage. In Co-rich systems with large lattice volumes, formation energy rises with magnetization, showing magnetism as the dominant factor. Mg-rich compositions achieve high gravimetric densities, but strong magnetism destabilizes the system, requiring Y substitution to suppress magnetic moments. Replacing Co with Ni weakens magnetism: YNi3 is nonmagnetic, while CaNi3 and MgNi3 are weakly polarized, allowing thermodynamic stability across compositions. Notably, CaMg2Ni9 combines high theoretical capacity (3.32 wt%) with good reversibility. Mg-rich Ni-based alloys are predicted to offer negative formation energies with the highest gravimetric densities (up to 3.40 wt%). These results show that controlling magnetism via transition-metal substitution is key to overcoming the stability-capacity trade-off in AB3 hydrogen storage materials. △ Less

Submitted 11 November, 2025; originally announced November 2025.

Physical properties and first-principles calculations of an altermagnet candidate Cs$_{1-δ}$V$_2$Te$_2$O

Authors: Chang-Chao Liu, Jing Li, Ji-Yong Liu, Jia-Yi Lu, Hua-Xun Li, Yi Liu, Guang-Han Cao

Abstract: We report the crystal growth, structure, physical properties, and first-principles calculations of a vanadium-based oxytelluride Cs$_{1-δ}$V$_2$Te$_2$O. The material possesses two-dimensional V$_2$O square nets sandwiched by tellurium layers, with local crystallographic symmetry satisfying the spin symmetry for a $d$-wave altermagnet. An antiferromagnetic transition at 293 K is unambiguously evide… ▽ More We report the crystal growth, structure, physical properties, and first-principles calculations of a vanadium-based oxytelluride Cs$_{1-δ}$V$_2$Te$_2$O. The material possesses two-dimensional V$_2$O square nets sandwiched by tellurium layers, with local crystallographic symmetry satisfying the spin symmetry for a $d$-wave altermagnet. An antiferromagnetic transition at 293 K is unambiguously evidenced from the measurements of magnetic susceptibility and specific heat. In addition, a secondary transition at $\sim$70 K is also observed, possibly associated with a Lifshitz transition. The first-principles calculations indicate robust Néel-type collinear antiferromagnetism in the V$_2$O plane. Consequently, spin splittings show up in momentum space, in relation with the real-space mirror/rotation symmetry. Interestingly, the V-$d_{yz}/d_{xz}$ electrons, which primarily contribute the quasi-one-dimensional Fermi surface, turns out to be fully orbital- and spin-polarized, akin to the case of a half metal. Our work lays a solid foundation on the potential applications utilizing altermagnetic properties in vanadium-based oxychalcogenides. △ Less

Submitted 10 November, 2025; originally announced November 2025.

Comments: 10 pages, 7 figures, and 2 tables

Altermagnetic Spin Precession and Spin Transistor

Authors: Li-Shuo Liu, Kai Shao, Hai-Dong Li, Xiangang Wan, Wei Chen, D. Y. Xing

Abstract: Altermagnets hold great potential for spintronic applications, yet their intrinsic spin dynamics and associated transport properties remain largely unexplored. Here, we investigate spin-resolved quantum transport in a multi-terminal setup based on a $d$-wave altermagnet. It is found that the altermagnetic spin splitting in momentum space induces an interesting spin precession in real space, giving… ▽ More Altermagnets hold great potential for spintronic applications, yet their intrinsic spin dynamics and associated transport properties remain largely unexplored. Here, we investigate spin-resolved quantum transport in a multi-terminal setup based on a $d$-wave altermagnet. It is found that the altermagnetic spin splitting in momentum space induces an interesting spin precession in real space, giving rise to characteristic spin patterns. This altermagnetic spin precession manifests as a spatial modulation of the Hall voltage, whose oscillation period provides a direct measure of the spin-splitting strength. When the altermagnetism is electrically tunable, the proposed setup functions as a prototype for a highly efficient spin transistor. The key physical effects are shown to be robust against dephasing and crystalline warping. Our work not only identifies a fingerprint signature of altermagnets, offering a direct probe of the altermagnetic spin splitting, but also represents an important step toward bridging their fundamental physics with practical spintronic applications. △ Less

Submitted 7 November, 2025; originally announced November 2025.

Benchmarking Non-perturbative Many-Body Approaches in the Exactly Solvable Hatsugai-Kohmoto Model

Authors: Hui Li, Ziyu Li, Chen-run Yu

Abstract: The accurate simulation of strongly correlated electron systems remains a central challenge in condensed matter physics, motivating the development of various non-perturbative many-body methods. Such methods are typically benchmarked against the numerical exact determinant quantum Monte Carlo (DQMC) in the Hubbard model; however, DQMC is limited by the fermionic sign problem and the uncertainties… ▽ More The accurate simulation of strongly correlated electron systems remains a central challenge in condensed matter physics, motivating the development of various non-perturbative many-body methods. Such methods are typically benchmarked against the numerical exact determinant quantum Monte Carlo (DQMC) in the Hubbard model; however, DQMC is limited by the fermionic sign problem and the uncertainties of numerical analytic continuation. To address these issues, we use the exactly solvable Hatsugai-Kohmoto (HK) model as a benchmarking platform to evaluate three many-body approximations: $GW$, $HGW$, and $SGW$. We compare the Green's functions, spectral functions, and response functions obtained from these approximations with the exact solutions. Our analysis shows that the $GW$ approximation, often considered insufficient for describing strong correlation, exhibits a previously unreported solution branch that accurately reproduces Mott physics in the HK model. In addition, using a covariant formalism, we find that $HGW$ provides an accurate description of charge response, while $SGW$ performs well for spin correlations. Overall, our work demonstrates that the HK model can effectively benchmark many-body approximations and helps refine the understanding of $GW$ methods in strongly correlated regimes. △ Less

Submitted 4 November, 2025; originally announced November 2025.

Nonlinear transport fingerprints of tunable Fermi-arc connectivity in magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$

Authors: K. X. Jia, H. C. Li, M. H. Zou, H. Geng, Hua Jiang

Abstract: Fermi arcs in Weyl semimetals provide a unique platform for surface-state engineering, yet di rectly tracking of their evolution under surface tuning remains experimentally challenging. Here we theoretically propose that nonreciprocal charge transport can serve as a direct probe of Fermi arc Lifshitz transitions (FALT). We show that different surface terminations in Co3Sn2S2 can produce f… ▽ More Fermi arcs in Weyl semimetals provide a unique platform for surface-state engineering, yet di rectly tracking of their evolution under surface tuning remains experimentally challenging. Here we theoretically propose that nonreciprocal charge transport can serve as a direct probe of Fermi arc Lifshitz transitions (FALT). We show that different surface terminations in Co3Sn2S2 can produce f inite and highly tunable second-order nonreciprocal signals, which can be further modulated by adjusting the surface potential. Strikingly, we show that the second-order conductivity exhibits sign changes as the Fermi arc connectivity is tuned across FALT driven by gating or chemical potential variation. This behavior arises from the chiral nature of electron velocities on the Fermi arcs, and is highly sensitive to surface termination and symmetry breaking. Our findings establish nonreciprocal transport as an electrically measurable fingerprint of FALT and propose new strategies that could be directly applied in devices for in situ engineering and detecting transport properties in topological materials. △ Less

Submitted 3 November, 2025; originally announced November 2025.

Direct Observation and Optical Manipulation of Exciton-polariton Parametric Scattering Lasing in Temporal

Authors: Junxing Dong, Si Shen, Jingzhuo Wang, Lisheng Wang, Yifan Zhang, Huashan Li, Xianghu Wang, Wei Gao, Yongzheng Fang, Hai Zhu

Abstract: The hybrid light-matter character of exciton-polaritons gives rise to distinct polariton parametric scattering (PPS) process, which holds promise for frontier applications in polaritonic quantum devices. However, the stable excitation and coherent optical manipulation of PPS remain challenging due to scattering bottlenecks and rapid dephasing effect in polariton many-body systems. In this study, w… ▽ More The hybrid light-matter character of exciton-polaritons gives rise to distinct polariton parametric scattering (PPS) process, which holds promise for frontier applications in polaritonic quantum devices. However, the stable excitation and coherent optical manipulation of PPS remain challenging due to scattering bottlenecks and rapid dephasing effect in polariton many-body systems. In this study, we first report the direct observation and optical amplification of non-degenerate intermode PPS lasing at room temperature (RT). The specific polariton branch of strong-coupled nanobelt planar microcavity is resonantly excited by a near-infrared (NIR) femtosecond laser via two-photon absorption (TPA) scheme, and the non-degenerate signal- and idler-states are stimulated. Angle-resolved dispersion patterns clearly reveal the evolution of the pump-, signal-, and idler-states under different excitation powers. Based on our self-constructed ultrafast femtosecond resonant optical trigger set-up, a selective enhancement and modulation of the signal-state is realized. Furthermore, the dynamic measurements of nonlinear signal-state enhancement process demonstrate a sub-picosecond response time (0.4ps), confirming its potential for ultrafast optical manipulation. Our work establishes a platform for exploring TPA-driven PPS laser and provides a novel optical modulation route for polariton-based optoelectronic devices. △ Less

Submitted 31 October, 2025; originally announced November 2025.

Applications of Machine Learning in Polymer Materials: Property Prediction, Material Design, and Systematic Processes

Authors: Hongtao Guo Shuai Li Shu Li

Abstract: This paper systematically reviews the research progress and application prospects of machine learning technologies in the field of polymer materials. Currently, machine learning methods are developing rapidly in polymer material research; although they have significantly accelerated material prediction and design, their complexity has also caused difficulties in understanding and application for r… ▽ More This paper systematically reviews the research progress and application prospects of machine learning technologies in the field of polymer materials. Currently, machine learning methods are developing rapidly in polymer material research; although they have significantly accelerated material prediction and design, their complexity has also caused difficulties in understanding and application for researchers in traditional fields. In response to the above issues, this paper first analyzes the inherent challenges in the research and development of polymer materials, including structural complexity and the limitations of traditional trial-and-error methods. To address these problems, it focuses on introducing key basic technologies such as molecular descriptors and feature representation, data standardization and cleaning, and records a number of high-quality polymer databases. Subsequently, it elaborates on the key role of machine learning in polymer property prediction and material design, covering the specific applications of algorithms such as traditional machine learning, deep learning, and transfer learning; further, it deeply expounds on data-driven design strategies, such as reverse design, high-throughput virtual screening, and multi-objective optimization. The paper also systematically introduces the complete process of constructing high-reliability machine learning models and summarizes effective experimental verification, model evaluation, and optimization methods. Finally, it summarizes the current technical challenges in research, such as data quality and model generalization ability, and looks forward to future development trends including multi-scale modeling, physics-informed machine learning, standardized data sharing, and interpretable machine learning. △ Less

Submitted 29 October, 2025; originally announced October 2025.

Comments: 55 pages, 6 tables, 9 figures, a systematic review on the research progress and application prospects of machine learning in polymer materials

Design principles for amorphous solid-state electrolytes

Authors: Qifan Yang, Xiao Fu, Xuhe Gong, Jingchen Lian, Liqi Wang, Ruijuan Xiao, Yong-Sheng Hu, Hong Li

Abstract: Amorphous solid-state electrolytes (SSEs) offer unique advantages for next-generation batteries, but their rational design is hindered by an unclear structure-property relationship. This study establishes universal design principles through atomistic simulations of 32 amorphous Li-M-X systems (M = B, Al, Si, P; X = F, Cl, Br, I, O, S, Se, N). We identify four structure types governed by a rule tha… ▽ More Amorphous solid-state electrolytes (SSEs) offer unique advantages for next-generation batteries, but their rational design is hindered by an unclear structure-property relationship. This study establishes universal design principles through atomistic simulations of 32 amorphous Li-M-X systems (M = B, Al, Si, P; X = F, Cl, Br, I, O, S, Se, N). We identify four structure types governed by a rule that saturated M-X groups with more negative charges preferentially form M-X-M chains, identify paddle-wheel and cooperative migration as two favorable transport mechanisms that are significantly enhanced in amorphous structures. We also pinpoint Oxides and fluorides as optimal for electrochemical and hydrolytic stability, and reveal bulk modulus as a simple predictor for $Li^+$ mobility. These insights are integrated into a practical design diagram, providing a novel and valuable framework for advancing high-performance amorphous SSEs. △ Less

Submitted 27 October, 2025; originally announced October 2025.

A Probability Space at Inception of Stochastic Process

Authors: Liteng Yang, Yuliang Liu, Jing Liu, Hongxuan Li, Wei Chen

Abstract: Recently, progress has been made in the theory of turbulence, which provides a framework on how a deterministic process changes to a stochastic one owing to the change in thermodynamic states. It is well known that, in the framework of Newtonian mechanics, motions are dissipative; however, when subjected to periodic motion, a system can produce nondissipative motions intermittently and subject to… ▽ More Recently, progress has been made in the theory of turbulence, which provides a framework on how a deterministic process changes to a stochastic one owing to the change in thermodynamic states. It is well known that, in the framework of Newtonian mechanics, motions are dissipative; however, when subjected to periodic motion, a system can produce nondissipative motions intermittently and subject to resonance. It is in resonance that turbulence occurs in fluid flow, solid vibration, thermal transport, etc. In this, the findings from these physical systems are analyzed in the framework of statistics with their own probability space to establish their compliance to the stochastic process. In particular, a systematic alignment of the inception of the stochastic process with the signed measure theory, signed probability space, and stochastic process was investigated. It was found that the oscillatory load from the dissipative state excited the system and resulted in a quasi-periodic probability density function with the negative probability regimes. In addition, the vectorial nature of the random velocity splits the probability density function along both the positive and negative axes with slight asymmetricity. By assuming that a deterministic process has a probability of 1, we can express the inception of a stochastic process, and the subsequent benefit is that a dynamic fractal falls on the probability density function. Moreover, we leave some questions of inconsistency between the physical system and the measurement theory for future investigation. We believe that the establishment of the probability density function of resonance nondissipative dynamics in contemporary statistics should make many mathematical tools available and the analytical formulas for the random velocity and probability density function can provide a convenient platform for the development of statistics. △ Less

Submitted 8 October, 2025; originally announced October 2025.

Comments: 14 pages, 1 figure

Mechanism of the electrochemical hydrogenation of graphene

Authors: Y. -C. Soong, H. Li, Y. Fu, J. Tong, S. Huang, X. Zhang, E. Griffin, E. Hoenig, M. Alhashmi, Y. Li, D. Bahamon, J. Zhong, A. Summerfield, R. N. Costa Filho, C. Sevik, R. Gorbachev, E. C. Neyts, L. F. Vega, F. M. Peeters, M. Lozada-Hidalgo

Abstract: The electrochemical hydrogenation of graphene induces a robust and reversible conductor-insulator transition, of strong interest in logic-and-memory applications. However, its mechanism remains unknown. Here we show that it proceeds as a reduction reaction in which proton adsorption competes with the formation of H2 molecules via an Eley-Rideal process. Graphene's electrochemical hydrogenation is… ▽ More The electrochemical hydrogenation of graphene induces a robust and reversible conductor-insulator transition, of strong interest in logic-and-memory applications. However, its mechanism remains unknown. Here we show that it proceeds as a reduction reaction in which proton adsorption competes with the formation of H2 molecules via an Eley-Rideal process. Graphene's electrochemical hydrogenation is up to $10^6$ times faster than alternative hydrogenation methods and is fully reversible via the oxidative desorption of protons. We demonstrate that the proton reduction rate in defect-free graphene can be enhanced by an order of magnitude by the introduction of nanoscale corrugations in its lattice, and that the substitution of protons for deuterons results both in lower potentials for the hydrogenation process and in a more stable compound. Our results pave the way to investigating the chemisorption of ions in 2D materials at high electric fields, opening a new avenue to control these materials' electronic properties. △ Less

Submitted 23 October, 2025; v1 submitted 22 October, 2025; originally announced October 2025.

Report number: 10741

Journal ref: Nature Communications 16, 10741 (2025)

Synergistic effects of rare-earth doping on the magnetic properties of orthochromates: A machine learning approach

Authors: Guanping Xu, Zirui Zhao, Muqing Su, Hai-Feng Li

Abstract: Multiferroic materials, particularly rare-earth orthochromates (RECrO$_3$), have garnered significant interest due to their unique magnetic and electric-polar properties, making them promising candidates for multifunctional devices. Although extensive research has been conducted on their antiferromagnetic (AFM) transition temperature (N$\acute{\textrm{e}}$el temperature, $T_\textrm{N}$), ferroelec… ▽ More Multiferroic materials, particularly rare-earth orthochromates (RECrO$_3$), have garnered significant interest due to their unique magnetic and electric-polar properties, making them promising candidates for multifunctional devices. Although extensive research has been conducted on their antiferromagnetic (AFM) transition temperature (N$\acute{\textrm{e}}$el temperature, $T_\textrm{N}$), ferroelectricity, and piezoelectricity, the effects of doping and substitution of rare-earth (RE) elements on these properties remain insufficiently explored. In this study, convolutional neural networks (CNNs) were employed to predict and analyze the physical properties of RECrO$_3$ compounds under various doping scenarios. Experimental and literature data were integrated to train machine learning models, enabling accurate predictions of $T_\textrm{N}$, besides remanent polarization ($P_\textrm{r}$) and piezoelectric coefficients ($d_{33}$). The results indicate that doping with specific RE elements significantly impacts $T_\textrm{N}$, with optimal doping levels identified for enhanced performance. Furthermore, high-entropy RECrO$_3$ compounds were systematically analyzed, demonstrating how the inclusion of multiple RE elements influences magnetic properties. This work establishes a robust framework for predicting and optimizing the properties of RECrO$_3$ materials, offering valuable insights into their potential applications in energy storage and sensor technologies. △ Less

Submitted 22 October, 2025; originally announced October 2025.

Report number: APPB-D-25-00050

Journal ref: AAPPS Bull. 35, 30 (2025)

Cavity modification of magnetoplasmon mode through coupling with intersubband polaritons

Authors: Lucy L. Hale, Daniele De Bernardis, Stephan Lempereur, Lianhe H. Li, A. Giles Davies, Edmund H. Linfield, Trevor Blaikie, Chris Deimert, Zbigniew R. Wasilewski, Iacopo Carusotto, Jean-Michel Manceau, Mathieu Jeannin, Raffaele Colombelli, Jérôme Faist, Giacomo Scalari

Abstract: We investigate the coupling of a multi-mode metal-insulator-metal cavity to a two-dimensional electron gas (2DEG) in a quantum well in the presence of a strong magnetic field. The TM cavity mode is strongly hybridized with an intersubband transition of the 2DEG, forming a polaritonic mode in the ultrastrong coupling regime, while the TE mode remains an almost purely cavity mode. The magnetoplasmon… ▽ More We investigate the coupling of a multi-mode metal-insulator-metal cavity to a two-dimensional electron gas (2DEG) in a quantum well in the presence of a strong magnetic field. The TM cavity mode is strongly hybridized with an intersubband transition of the 2DEG, forming a polaritonic mode in the ultrastrong coupling regime, while the TE mode remains an almost purely cavity mode. The magnetoplasmon excitation emerging from the presence of the magnetic field couples with both TM and TE modes, exhibiting different coupling strengths and levels of spatial field inhomogeneity. While the strong homogeneity of the bare TE mode gives rise to the standard anticrossing of strong coupling, the inhomogeneous polaritonic TM mode is shown to activate an observable Coulombic effect in the spectral response, often referred to as non-locality. This experiment demonstrates a cavity-induced modification of the 2DEG response and offers a new route to probing the effect of Coulomb interactions in ultrastrongly coupled systems via reshaping of their cavity mode profiles. △ Less

Submitted 21 October, 2025; originally announced October 2025.

Anomalous terahertz nonlinearity in disordered s-wave superconductor close to the superconductor-insulator transition

Authors: Hao Wang, Jiayu Yuan, Hongkai Shi, Haojie Li, Xiaoqing Jia, Xiaohui Song, Liyu Shi, Tianyi Wu, Li Yue, Yangmu Li, Kui Jin, Dong Wu, Jianlin Luo, Xinbo Wang, Tao Dong, Nanlin Wang

Abstract: Detection of the Higgs mode in superconductors using nonlinear terahertz spectroscopy is a key area of interest in condensed matter physics. We investigate the influence of disorder on the nonlinear terahertz response and the Higgs mode in NbN thin films with varying Ioffe-Regel parameters ($k_Fl$). In strongly disordered films near the superconductor-insulator transition (SIT), we observe an anom… ▽ More Detection of the Higgs mode in superconductors using nonlinear terahertz spectroscopy is a key area of interest in condensed matter physics. We investigate the influence of disorder on the nonlinear terahertz response and the Higgs mode in NbN thin films with varying Ioffe-Regel parameters ($k_Fl$). In strongly disordered films near the superconductor-insulator transition (SIT), we observe an anomalous third-harmonic generation (THG) signal above $T_c$, which is absent in both cleaner superconducting and non-superconducting counterparts. The persistence of this normal-state THG signal in a high magnetic field excludes superconducting fluctuations as its origin. Below $T_c$, the THG intensity increases sharply, indicating a dominant contribution from the driven Higgs mode. The THG spectrum of the strongly disordered sample exhibits a broadened, multi-peak structure, which we attribute to quantum path interference between distinct channels involving unpaired electrons and Cooper pairs within emergent superconducting islands. Our findings not only demonstrate how disorder tunes the nonlinear terahertz response but also uncover a strong coupling between electrons responsible for normal-state THG and the superconducting Higgs mode below $T_c$ in strongly disordered samples. △ Less

Submitted 20 October, 2025; originally announced October 2025.

The fate of disorder in twisted bilayer graphene near the magic angle

Authors: Zhe Hou, Hailong Li, Qing Yan, Yu-Hang Li, Hua Jiang

Abstract: In disordered lattices, itinerant electrons typically undergo Anderson localization due to random phase interference, which suppresses their motion. By contrast, in flat-band systems where electrons are intrinsically localized owing to their vanishing group velocity, the role of disorder remains elusive. Twisted bilayer graphene (TBG) at the magic angle $\sim 1.1^\circ$ provides a representative f… ▽ More In disordered lattices, itinerant electrons typically undergo Anderson localization due to random phase interference, which suppresses their motion. By contrast, in flat-band systems where electrons are intrinsically localized owing to their vanishing group velocity, the role of disorder remains elusive. Twisted bilayer graphene (TBG) at the magic angle $\sim 1.1^\circ$ provides a representative flat-band platform to investigate this problem. Here, we perform an atomistic tight-binding quantum transport calculation on the interplay between disorder and flat-bands in TBG devices. This non-phenomenological approach provides direct evidence that moderate disorder enhances conductance, whereas stronger disorder restores localization, revealing a disorder-driven delocalization-to-localization transport behavior. The underlying physical mechanism is understood by an effective inter-moir{é} tunneling strength via spectral flow analysis of a disordered TBG cylinder. Moreover, by comparing magic-angle and large-angle TBG, we demonstrate qualitatively distinct disorder responses tied to the presence of flat-bands. Our quantitative results highlight the unconventional role of disorder in flat-band moir{é} materials and offer insights into the observation of the fractional quantum anomalous Hall effect in disordered moir{é} systems. △ Less

Submitted 16 October, 2025; originally announced October 2025.

Comments: 5 pages, 4 figures; Comments are welcome!

Two-Dimensional Altermagnetism in Epitaxial CrSb Ultrathin Films

Authors: Keren Li, Yuzhong Hu, Yue Li, Ruohang Xu, Heping Li, Kun Liu, Chen Liu, Jincheng Zhuang, Yee Sin Ang, Jiaou Wang, Haifeng Feng, Weichang Hao, Yi Du

Abstract: Altermagnets constitute an emerging class of collinear magnets that exhibit zero net magnetization yet host spin-split electronic bands arising from non-relativistic spin-space-group symmetries. Realization of altermagnetism in the two-dimensional (2D) limit remains an outstanding challenge because dimensional reduction suppresses kZ dispersion and destabilizes the symmetry operations essential fo… ▽ More Altermagnets constitute an emerging class of collinear magnets that exhibit zero net magnetization yet host spin-split electronic bands arising from non-relativistic spin-space-group symmetries. Realization of altermagnetism in the two-dimensional (2D) limit remains an outstanding challenge because dimensional reduction suppresses kZ dispersion and destabilizes the symmetry operations essential for spin compensation. Here, we demonstrate genuine 2D altermagnetism in epitaxial unit-cell-thin films of CrSb grown on Bi2Te3. It reveals a thickness-driven transition from a ferrimagnetic state in 1-unit-cell films to an altermagnetic state above a critical thickness of 7/4 unit cell. The transition originates from interfacial symmetry breaking at the Cr-terminated layer that induces local moment imbalance. With increasing thickness the key spin-space-group symmetries [C2||C6Zt] and [C2||MZ] restores, which leads to altermagnetism with zero net magnetization and momentum-dependent spin splitting. Our results provide the first experimental realization of altermagnetism in the 2D regime and establish a route for integrating stray-field-free spin order into nanoscale spintronic architectures. △ Less

Submitted 14 October, 2025; originally announced October 2025.

Non-Hermitian many-body localization in asymmetric chains with long-range interaction

Authors: Wen Wang, Han-Ze Li, Jian-Xin Zhong

Abstract: Understanding the relationship between many-body localization and spectra in non-Hermitian many-body systems is crucial. In a one-dimensional clean, long-range interaction-induced non-Hermitian many-body localization system, we have discovered the coexistence of static and dynamic spectral real-complex phase transitions, along with many-body ergodic-localized phase transitions. The phase diagrams… ▽ More Understanding the relationship between many-body localization and spectra in non-Hermitian many-body systems is crucial. In a one-dimensional clean, long-range interaction-induced non-Hermitian many-body localization system, we have discovered the coexistence of static and dynamic spectral real-complex phase transitions, along with many-body ergodic-localized phase transitions. The phase diagrams of these two types of transitions show similar non-monotonic boundary trends but do not overlap, highlighting properties distinct from conventional disorder-induced non-Hermitian many-body localization. We also propose a potential experimental realization of this model in cold-atom systems. Our findings provide valuable insights for further understanding the relationship between non-Hermitian many-body localization and non-Hermitian spectra in long-range interacting systems. △ Less

Submitted 9 October, 2025; originally announced October 2025.

Comments: Any comments are welcome

Pronounced orbital-selective electron-electron correlation and electron-phonon coupling in V2Se2O

Authors: Mingzhe Hu, Ziyin Song, Jingwen Cheng, Gexing Qu, Zhanghuan Li, Yu Huang, Jundong Zhu, Guangyu Zhang, Dacheng Tian, Lan Chen, Zhijun Tu, Hechang Lei, Xiaoping Ma, Huaixin Yang, Zhongxu Wei, Genfu Chen, Hongming Weng, Tian Qian, Hang Li

Abstract: Orbital-selective many-body effects, in which electrons occupying different orbitals experience distinct interaction strengths, play a crucial role in correlated multiorbital materials. However, these effects usually manifest in a complex manner, obscuring their microscopic origins. Here, by combining angle-resolved photoemission spectroscopy measurements with theoretical calculations, we reveal p… ▽ More Orbital-selective many-body effects, in which electrons occupying different orbitals experience distinct interaction strengths, play a crucial role in correlated multiorbital materials. However, these effects usually manifest in a complex manner, obscuring their microscopic origins. Here, by combining angle-resolved photoemission spectroscopy measurements with theoretical calculations, we reveal pronounced orbital selectivity in both electron-electron correlation and electron-phonon coupling in the van der Waals material V2Se2O. Electron correlation induces distinct bandwidth renormalization exclusively in the V d_xy-derived band, while the bands mainly composed of the other d orbitals remain essentially unrenormalized. Orbital-resolved analyses identify that the filling number and the bandwidth are decisive factors governing orbital-dependent correlation. Simultaneously, the d_(xz/yz)-derived band exhibits a sharp kink anomaly, arising from enhanced coupling to high-energy phonon modes dominated by oxygen vibrations. Such pronounced orbital selectivity positions V2Se2O as a rare and prototypical platform for unravelling the microscopic mechanisms of orbital-selective electron-electron and electron-phonon interactions, and offers guiding principles for the design of correlated multiorbital materials. △ Less

Submitted 6 October, 2025; originally announced October 2025.

Comments: 30 pages, 12 figures, 1 table

Negative Charge Transfer: Ground State Precursor towards High Energy Batteries

Authors: Eder G. Lomeli, Qinghao Li, Kuan H. Hsu, Gi-Hyeok Lee, Zengqing Zhuo, Bryant-J. Polzin, Jihyeon Gim, Boyu Shi, Eungje Lee, Yujia Wang, Haobo Li, Pu Yu, Jinpeng Wu, Zhi-Xun Shen, Shishen Yan, Lauren Illa, Josh J. Kas, John J. Rehr, John Vinson, Brian Moritz, Yi-Sheng Liu, Jinghua Guo, Yi-de Chuang, Wanli Yang, Thomas P. Devereaux

Abstract: Modern energy applications, especially electric vehicles, demand high energy batteries. However, despite decades of intensive efforts, the highest energy density and commercially viable batteries are still based on LiCoO2, the very first generation of cathode materials. The technical bottleneck is the stability of oxide-based cathodes at high operating voltages. The fundamental puzzle is that we a… ▽ More Modern energy applications, especially electric vehicles, demand high energy batteries. However, despite decades of intensive efforts, the highest energy density and commercially viable batteries are still based on LiCoO2, the very first generation of cathode materials. The technical bottleneck is the stability of oxide-based cathodes at high operating voltages. The fundamental puzzle is that we actually never understood the redox mechanism of LiCoO2. Conventional wisdom generally defines redox to be centered on cations at low voltages, and on anions, i.e. oxygen, at high voltages by forming oxidized chemical states like O2 or peroxo-species. Here, through in-situ and ex-situ spectroscopy coupled with theoretical calculations, we show that high-energy layered cathodes, represented by LiCoO2 and LiNiO2, operate through enhancement of negative charge transfer (NCT) ground states upon charging throughout the whole voltage range - i.e., NCT evolution itself is the intrinsic redox mechanism regardless of voltage ranges. NCT inherently engages high covalency and oxygen holes, leading to optimized performance without conventional redox centers in LiCoO2. The level of NCT, i.e., number of ligand holes, naturally explains many seemingly controversial results. The redefinition of redox mechanism reveals the pathway toward viable high energy battery electrodes. △ Less

Submitted 24 September, 2025; originally announced September 2025.

Comments: 33 pages, paper plus supplementary material, 4 main figures

Emergent Composite Particles from the Universal Exact Identities in Quantum Many-Body Systems with Generic Bilinear Interactions

Authors: Hui Li

Abstract: 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 excitation… ▽ More 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. △ Less

Submitted 22 September, 2025; originally announced September 2025.

Comments: 5 pages, 1 figures

Observation of mirror-odd and mirror-even spin texture in ultra-thin epitaxially-strained RuO2 films

Authors: 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

Abstract: 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 str… ▽ More 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. △ Less

Submitted 19 September, 2025; originally announced September 2025.

Comments: 45 pages, 5 figures, 1 table

Characterization of superconducting germanide and germanosilicide films of Pd, Pt, Rh and Ir formed by solid-phase epitaxy

Authors: Hao Li, Zhongxia Shang, Michael P. Lilly, Maksym Myronov, Leonid P. Rokhinson

Abstract: Facilitated by recent advances in strained Ge/SiGe quantum well (QW) growth technology, superconductor-semiconductor hybrid devices based on group IV materials have been developed, potentially augmenting the functionality of quantum circuits. The formation of highly transparent superconducting platinum germanosilicide (PtSiGe) contacts to Ge/SiGe heterostructures by solid-phase epitaxy between Pt… ▽ More Facilitated by recent advances in strained Ge/SiGe quantum well (QW) growth technology, superconductor-semiconductor hybrid devices based on group IV materials have been developed, potentially augmenting the functionality of quantum circuits. The formation of highly transparent superconducting platinum germanosilicide (PtSiGe) contacts to Ge/SiGe heterostructures by solid-phase epitaxy between Pt and SiGe has recently been reported, although with a relatively low critical temperature $<1\,\mathrm{K}$. Here, we present a comparative study of the superconducting properties of Pt, Pd, Rh, and Ir germanides, along with an in-depth characterization of Ir(Si)Ge films formed by solid-phase epitaxy. For films fabricated under optimal epitaxy conditions, we report $T_\mathrm{c}=3.4\,\mathrm{K}$ ($2.6\,\mathrm{K}$ for IrGe (IrSiGe). High-resolution scanning transmission electron microscopy (HRSTEM) and energy-dispersive X-ray spectroscopy (EDX) reveal that Ir reacts with Ge substrates to form a polycrystalline IrGe layer with a sharp IrGe/Ge interface. △ Less

Submitted 17 September, 2025; originally announced September 2025.

Comments: 25 pages, 9 figures

Kitaev-derived Gapless Spin Liquid in the $K$-$J$-$Γ$-$Γ'$ Quantum Magnet Na$_2$Co$_2$TeO$_6$

Authors: Han Li, Xu-Guang Zhou, Gang Su, Wei Li

Abstract: The realization of quantum spin liquids (QSLs) in Kitaev magnets represents an intriguing topic in frustrated quantum magnetism. Despite prediction in the pure Kitaev honeycomb model, realization of QSLs in realistic systems and materials remain scarce. The recent discovery of cobalt-based compound Na$_2$Co$_2$TeO$_6$ has raised significant research interest. By establishing a realistic $K$-$J$-… ▽ More The realization of quantum spin liquids (QSLs) in Kitaev magnets represents an intriguing topic in frustrated quantum magnetism. Despite prediction in the pure Kitaev honeycomb model, realization of QSLs in realistic systems and materials remain scarce. The recent discovery of cobalt-based compound Na$_2$Co$_2$TeO$_6$ has raised significant research interest. By establishing a realistic $K$-$J$-$Γ$-$Γ'$ model for Na$_2$Co$_2$TeO$_6$ -- with a dominant antiferromagnetic (AFM) Kitaev interaction ($K>0$) that quantitatively explains its thermodynamics measurements -- we reveal an intermediate gapless QSL phase under [111] magnetic fields with tensor-network calculations. We confirm the QSL nature of this phase by demonstrating its adiabatic connection to the intensively studied intermediate QSL of the pure AFM Kitaev model under out-of-plane fields. Our results show excellent agreement with recent high-field experiments, thereby explaining the intermediate-field phase in Na$_2$Co$_2$TeO$_6$. These findings bridge the gap between theoretical proposals for a Kitaev-derived QSL and experimental realization, opening new avenues for exploring exotic quantum states of matter in realistic Kitaev materials. △ Less

Submitted 10 September, 2025; originally announced September 2025.

Comments: 6 pages, 4 figures, Supplementary materials

Intrinsic Topological Dice Flat Band in Yttrium Monochloride Electrides

Authors: Jianqi Zhong, Songyuan Geng, Haoxiang Li, Benjamin T. Zhou

Abstract: In a recent experiment [arXiv:2508.21311] the long-sought dice lattice and its characteristic flat band has been discovered for the first time in the two-dimensional layered electride yttrium monochloride (YCl), in which the interstitial anionic electrons of the electride self-organize into a dice lattice geometry. In this Letter, combining symmetry analysis, relativistic density-functional theory… ▽ More In a recent experiment [arXiv:2508.21311] the long-sought dice lattice and its characteristic flat band has been discovered for the first time in the two-dimensional layered electride yttrium monochloride (YCl), in which the interstitial anionic electrons of the electride self-organize into a dice lattice geometry. In this Letter, combining symmetry analysis, relativistic density-functional theory and realistic tight-binding model calculations, we predict that the dice flat band in YCl is intrinsically topological and characterized by a high Chern number of $\mathcal{C} = \pm 4$. In particular, the intrinsic atomic spin-orbit coupling (SOC) from $4d$-electrons of yttrium atoms creates topological gaps on the scale of 20 meV near $\pm K$ and leads to the emergence of nontrivial Berry curvatures and band topology. Displacement fields applied across the layered electride architecture can easily drive topological phase transitions. Our findings establish the newly discovered YCl electride as the first natural material hosting a dice flat Chern band without any extrinsic band engineering. △ Less

Submitted 7 September, 2025; originally announced September 2025.

Comments: 5+4 pages, 3+1 figures. Comments are welcome

Topology and criticality in non-Hermitian multimodal optical resonators through engineered losses

Authors: Elizabeth Louis Pereira, Hongwei Li, Andrea Blanco-Redondo, Jose L. Lado

Abstract: Non-Hermitian topological matter provides a platform for engineering phenomena that go beyond the capabilities of Hermitian systems, enabling the use of losses to engineer topological phenomena. Non-Hermitian models often rely on artificial platforms made of engineered lattices because controlling losses in natural compounds is challenging. Although typical models for non-Hermitian photonic matter… ▽ More Non-Hermitian topological matter provides a platform for engineering phenomena that go beyond the capabilities of Hermitian systems, enabling the use of losses to engineer topological phenomena. Non-Hermitian models often rely on artificial platforms made of engineered lattices because controlling losses in natural compounds is challenging. Although typical models for non-Hermitian photonic matter are often single mode, photonic systems are often multimodal, producing mixing between different normal modes in each site. In this work, we explore a generalized family of multimodal non-Hermitian lattices, featuring multiple resonant modes. We show that these multimodal models are capable of featuring topological modes and criticality, similar to the artificial single-mode models often considered. We analyze the robustness of these non-Hermitian topological modes to fluctuation of local losses, disorder, and artificial gauge field. We show that these effects can be captured via both a full microscopic model and effective multiorbital models. Specifically, we show that due to their multiorbital nature, the localization properties of non-Hermitian multiorbital models can be controlled by an external gauge field. Our results demonstrate that internal orbital degrees of freedom provide a promising strategy to engineer controllable non-Hermitian topology and criticality. △ Less

Submitted 5 September, 2025; originally announced September 2025.

Physically Interpretable Descriptors Drive the Materials Design of Metal Hydrides for Hydrogen Storage

Authors: Seong-Hoon Jang, Di Zhang, Hung Ba Tran, Xue Jia, Kiyoe Konno, Ryuhei Sato, Shin-ichi Orimo, Hao Li

Abstract: Designing metal hydrides for hydrogen storage remains a longstanding challenge due to the vast compositional space and complex structure-property relationships. Herein, for the first time, we present physically interpretable models for predicting two key performance metrics, gravimetric hydrogen density $w$ and equilibrium pressure $P_{\rm eq,RT}$ at room temperature, based on a minimal set of che… ▽ More Designing metal hydrides for hydrogen storage remains a longstanding challenge due to the vast compositional space and complex structure-property relationships. Herein, for the first time, we present physically interpretable models for predicting two key performance metrics, gravimetric hydrogen density $w$ and equilibrium pressure $P_{\rm eq,RT}$ at room temperature, based on a minimal set of chemically meaningful descriptors. Using a rigorously curated dataset of $5,089$ metal hydride compositions from our recently developed Digital Hydrogen Platform (\it{DigHyd}) based on large-scale data mining from available experimental literature of solid-state hydrogen storage materials, we systematically constructed over $1.6$ million candidate models using combinations of scalar transformations and nonlinear link functions. The final closed-form models, derived from $2$-$3$ descriptors each, achieve predictive accuracies on par with state-of-the-art machine learning methods, while maintaining full physical transparency. Strikingly, descriptor-based design maps generated from these models reveal a fundamental trade-off between $w$ and $P_{\rm eq,RT}$: saline-type hydrides, composed of light electropositive elements, offer high $w$ but low $P_{\rm eq,RT}$, whereas interstitial-type hydrides based on heavier electronegative transition metals show the opposite trend. Notably, Be-based systems, such as Be-Na alloys, emerge as rare candidates that simultaneously satisfy both performance metrics, attributed to the unique combination of light mass and high molar density for Be. Our models indicate that Be-based systems may offer renewed prospects for approaching these benchmarks. These results provide chemically intuitive guidelines for materials design and establish a scalable framework for the rational discovery of materials in complex chemical spaces. △ Less

Submitted 26 October, 2025; v1 submitted 4 September, 2025; originally announced September 2025.

Optimizing digital quantum simulation of open quantum lattice models

Authors: Xie-Hang Yu, Hongchao Li, J. Ignacio Cirac, Rahul Trivedi

Abstract: Many-body systems arising in condensed matter physics and quantum optics inevitably couple to the environment and need to be modelled as open quantum systems. While near-optimal algorithms have been developed for simulating many-body quantum dynamics, algorithms for their open system counterparts remain less well investigated. We address the problem of simulating geometrically local many-body open… ▽ More Many-body systems arising in condensed matter physics and quantum optics inevitably couple to the environment and need to be modelled as open quantum systems. While near-optimal algorithms have been developed for simulating many-body quantum dynamics, algorithms for their open system counterparts remain less well investigated. We address the problem of simulating geometrically local many-body open quantum systems interacting with a stationary Gaussian environment. Under a smoothness assumption on the system-environment interaction, we develop near-optimal algorithms that, for a model with $N$ spins and evolution time $t$, attain a simulation error $δ$ in the system-state with $\mathcal{O}(Nt(Nt/δ)^{o(1)})$ gates, $\mathcal{O}(t(Nt/δ)^{o(1)})$ parallelized circuit depth and $\tilde{\mathcal{O}}(N(Nt/δ)^{o(1)})$ ancillas. We additionally show that, if only simulating local observables is of interest, then the circuit depth of the digital algorithm can be chosen to be independent of the system size $N$. This provides theoretical evidence for the utility of these algorithms for simulating physically relevant models, where typically local observables are of interest, on pre-fault tolerant devices. Finally, for the limiting case of Markovian dynamics with commuting jump operators, we propose two algorithms based on sampling a Wiener process and on a locally dilated Hamiltonian construction, respectively. These algorithms reduce the asymptotic gate complexity on $N$ compared to currently available algorithms in terms of the required number of geometrically local gates. △ Less

Submitted 7 September, 2025; v1 submitted 2 September, 2025; originally announced September 2025.

Comments: 61 pages, 6 figures

Experimental realization of dice-lattice flat band at the Fermi level in layered electride YCl

Authors: Songyuan Geng, Xin Wang, Risi Guo, Chen Qiu, Fangjie Chen, Qun Wang, Kangjie Li, Peipei Hao, Hanpu Liang, Yang Huang, Yunbo Wu, Shengtao Cui, Zhe Sun, Timur K. Kim, Cephise Cacho, Daniel S. Dessau, Benjamin T. Zhou, Haoxiang Li

Abstract: Flat electronic bands, where interactions among electrons overwhelm their kinetic energies, hold the promise for exotic correlation physics. The dice lattice has long been theorized as a host of flat bands with intriguing band topology. However, to date, no material has ever been found to host the characteristic flat bands of a dice lattice. Here, using angle-resolved photoemission spectroscopy (A… ▽ More Flat electronic bands, where interactions among electrons overwhelm their kinetic energies, hold the promise for exotic correlation physics. The dice lattice has long been theorized as a host of flat bands with intriguing band topology. However, to date, no material has ever been found to host the characteristic flat bands of a dice lattice. Here, using angle-resolved photoemission spectroscopy (ARPES), we discover a dice-lattice flat band at $E_F$ in the van der Waals (vdW) electride [YCl]$^{2+}$: 2e-. In this system, excess valence electrons from Y deconfine from the cation framework to form an interstitial anionic electron lattice that constitutes the dice lattice. Our ARPES measurements unambiguously identify two sets of dice-lattice bands in YCl, including a nearly dispersionless band at the Fermi level. The flat bands and other dispersive bands observed in ARPES find excellent agreement with first-principles calculations, and theoretical analysis reveals that the near-$E_F$ electronic structure is well captured by a simple dice-lattice model. Our findings thus end the long quest of a real dice flat band material and establish vdW electride YCl as a prototype of dice metals. Our results further demonstrate the anionic electron lattice as a novel scheme for realizing lattice geometries and electronic structures rare to find in conventional crystalline systems. △ Less

Submitted 28 August, 2025; originally announced August 2025.

Superconductivity and Ferroelectric Orbital Magnetism in Semimetallic Rhombohedral Hexalayer Graphene

Authors: Jinghao Deng, Jiabin Xie, Hongyuan Li, Takashi Taniguchi, Kenji Watanabe, Jie Shan, Kin Fai Mak, Xiaomeng Liu

Abstract: Rhombohedral multilayer graphene has emerged as a promising platform for exploring correlated and topological quantum phases, enabled by its Berry-curvature-bearing flat bands. While prior work has focused on separated conduction and valence bands, we probe the extensive semimetallic regime of rhombohedral hexalayer graphene. We survey a rich phase diagram dominated by flavor-symmetry breaking and… ▽ More Rhombohedral multilayer graphene has emerged as a promising platform for exploring correlated and topological quantum phases, enabled by its Berry-curvature-bearing flat bands. While prior work has focused on separated conduction and valence bands, we probe the extensive semimetallic regime of rhombohedral hexalayer graphene. We survey a rich phase diagram dominated by flavor-symmetry breaking and reveal an electric-field-driven band inversion through fermiology. Near this inversion, we find a superconducting-like state confined to a region with emergent electron and hole Fermi surfaces. In addition, two multiferroic orbital-magnetic phases are observed: a ferrovalley state near zero field and a ferroelectric state at large fields around charge neutrality. The latter shows electric-field-reversible magnetic hysteresis, consistent with a $ΔP \cdot M$ multiferroic order parameter. Our fermiology analysis elucidates the correlated semimetal regime in rhombohedral graphene and underscores its potential to host diverse quantum phases. △ Less

Submitted 21 August, 2025; originally announced August 2025.

"DIVE" into Hydrogen Storage Materials Discovery with AI Agents

Authors: Di Zhang, Xue Jia, Tran Ba Hung, Seong Hoon Jang, Linda Zhang, Ryuhei Sato, Yusuke Hashimoto, Toyoto Sato, Kiyoe Konno, Shin-ichi Orimo, Hao Li

Abstract: Data-driven artificial intelligence (AI) approaches are fundamentally transforming the discovery of new materials. Despite the unprecedented availability of materials data in the scientific literature, much of this information remains trapped in unstructured figures and tables, hindering the construction of large language model (LLM)-based AI agent for automated materials design. Here, we present… ▽ More Data-driven artificial intelligence (AI) approaches are fundamentally transforming the discovery of new materials. Despite the unprecedented availability of materials data in the scientific literature, much of this information remains trapped in unstructured figures and tables, hindering the construction of large language model (LLM)-based AI agent for automated materials design. Here, we present the Descriptive Interpretation of Visual Expression (DIVE) multi-agent workflow, which systematically reads and organizes experimental data from graphical elements in scientific literatures. We focus on solid-state hydrogen storage materials-a class of materials central to future clean-energy technologies and demonstrate that DIVE markedly improves the accuracy and coverage of data extraction compared to the direct extraction by multimodal models, with gains of 10-15% over commercial models and over 30% relative to open-source models. Building on a curated database of over 30,000 entries from 4,000 publications, we establish a rapid inverse design workflow capable of identifying previously unreported hydrogen storage compositions in two minutes. The proposed AI workflow and agent design are broadly transferable across diverse materials, providing a paradigm for AI-driven materials discovery. △ Less

Submitted 24 September, 2025; v1 submitted 18 August, 2025; originally announced August 2025.

Comments: 23 pages, 5 figures. The supplementary video is available at the GitHub link provided in the manuscript

Accelerating Amorphous Alloy Discovery: Data-Driven Property Prediction via General-Purpose Machine Learning Interatomic Potential

Authors: Xuhe Gong, Hengbo Zhao, Xiao Fu, Jingchen Lian, Qifan Yang, Ran Li, Ruijuan Xiao, Tao Zhang, Hong Li

Abstract: While traditional trial-and-error methods for designing amorphous alloys are costly and inefficient, machine learning approaches based solely on composition lack critical atomic structural information. Machine learning interatomic potentials, trained on data from first-principles calculations, offer a powerful alternative by efficiently approximating the complex three-dimensional potential energy… ▽ More While traditional trial-and-error methods for designing amorphous alloys are costly and inefficient, machine learning approaches based solely on composition lack critical atomic structural information. Machine learning interatomic potentials, trained on data from first-principles calculations, offer a powerful alternative by efficiently approximating the complex three-dimensional potential energy surface with near-DFT accuracy. In this work, we develop a general-purpose machine learning interatomic potential for amorphous alloys by using a dataset comprising 20400 configurations across representative binary and ternary amorphous alloys systems. The model demonstrates excellent predictive performance on an independent test set, with a mean absolute error of 5.06 meV/atom for energy and 128.51 meV/Å for forces. Through extensive validation, the model is shown to reliably capture the trends in macroscopic property variations such as density, Young's modulus and glass transition temperature across both the original training systems and the compositionally modified systems derived from them. It can be directly applied to composition-property mapping of amorphous alloys. Furthermore, the developed interatomic potential enables access to the atomic structures of amorphous alloys, allowing for microscopic analysis and interpretation of experimental results, particularly those deviating from empirical trends.This work breaks the long-standing computational bottleneck in amorphous alloys research by developing the first general-purpose machine learning interatomic potential for amorphous alloy systems. The resulting framework provides a robust foundation for data-driven design and high-throughput composition screening in a field previously constrained by traditional simulation limitations. △ Less

Submitted 16 August, 2025; originally announced August 2025.

Quantum Quench Dynamics in an Exactly Solvable Two-Dimensional Non-Fermi Liquid System

Authors: Hui Li, Run-Yu Chen, Wen-Yuan Liu, Yin Zhong, Hai-Qing Lin

Abstract: Understanding the behavior of non-Fermi liquids (NFLs) is an important topic in condensed matter physics. Here we introduce an exactly solvable multi-orbital model based on iron oxypnictides and the Hatsugai-Kohmoto model, and provide exact investigations of the 2D NFLs nonequilibrium physics present in this model. Our results reveal fundamental departures from Fermi liquids and prior NFLs in the… ▽ More Understanding the behavior of non-Fermi liquids (NFLs) is an important topic in condensed matter physics. Here we introduce an exactly solvable multi-orbital model based on iron oxypnictides and the Hatsugai-Kohmoto model, and provide exact investigations of the 2D NFLs nonequilibrium physics present in this model. Our results reveal fundamental departures from Fermi liquids and prior NFLs in the well-know SYK model: anomalous short-time scaling $-τ^2 \ln τ$, $O(τ) \sim τ^2$; long-time scaling $ τ^{-1}, τ^{-1/2}, \ln τ/ τ$; a strange critical behavior in the steady-state phase diagram. Our asymptotic results and dynamical critical behavior offer new insights into the orbital-related dynamical physics of 2D NFLs. △ Less

Submitted 15 August, 2025; originally announced August 2025.

Comments: 8 pages,5 figures

EDIS: A Simulation Software for Dynamic Ion Intercalation/Deintercalation Processes in Electrode Materials

Authors: Liqi Wang, Ruijuan Xiao, Hong Li

Abstract: As the core determinant of lithium-ion battery performance, electrode materials play a crucial role in defining the battery's capacity, cycling stability, and durability. During charging and discharging, electrode materials undergo complex ion intercalation and deintercalation processes, accompanied by defect formation and structural evolution. However, the microscopic mechanisms underlying proces… ▽ More As the core determinant of lithium-ion battery performance, electrode materials play a crucial role in defining the battery's capacity, cycling stability, and durability. During charging and discharging, electrode materials undergo complex ion intercalation and deintercalation processes, accompanied by defect formation and structural evolution. However, the microscopic mechanisms underlying processes such as cation disordering, lattice oxygen loss, and stage structure formation phenomena are still not fully understood. To address these challenges, we have developed the Electrode Dynamic Ion Intercalation/Deintercalation Simulator (EDIS), a software platform designed to simulate the dynamic processes of ion intercalation and deintercalation in electrode materials. Leveraging high-precision machine learning potentials, EDIS can efficiently model structural evolution and lithium-ion diffusion behavior under various states of charge and discharge, achieving accuracy approaching that of quantum mechanical methods in relevant chemical spaces. The software supports quantitative analysis of how variations in lithium-ion concentration and distribution affect lithium-ion transport properties, enables evaluation of the impact of structural defects, and allows for tracking of both structural evolution and transport characteristics during continuous cycling. EDIS is versatile and can be extended to sodium-ion batteries and related systems. By enabling in-depth analysis of these microscopic processes, EDIS provides a robust theoretical tool for mechanistic studies and the rational design of high-performance electrode materials for next-generation lithium-ion batteries. △ Less

Submitted 14 August, 2025; originally announced August 2025.

Observation and Modulation of the Quantum Mpemba Effect on a Superconducting Quantum Processor

Authors: Yueshan Xu, Cai-Ping Fang, Bing-Jie Chen, Ming-Chuan Wang, Zi-Yong Ge, Yun-Hao Shi, Yu Liu, Cheng-Lin Deng, Kui Zhao, Zheng-He Liu, Tian-Ming Li, Hao Li, Ziting Wang, Gui-Han Liang, Da'er Feng, Xueyi Guo, Xu-Yang Gu, Yang He, Hao-Tian Liu, Zheng-Yang Mei, Yongxi Xiao, Yu Yan, Yi-Han Yu, Wei-Ping Yuan, Jia-Chi Zhang , et al. (11 additional authors not shown)

Abstract: In non-equilibrium quantum many-body systems, the quantum Mpemba effect (QME) emerges as a counterintuitive phenomenon: systems exhibiting greater initial symmetry breaking restore symmetry faster than those with less. While theoretical exploration of QME has surged, experimental studies on its multidimensional modulation remain limited. Here, we report the observation and control of QME using a s… ▽ More In non-equilibrium quantum many-body systems, the quantum Mpemba effect (QME) emerges as a counterintuitive phenomenon: systems exhibiting greater initial symmetry breaking restore symmetry faster than those with less. While theoretical exploration of QME has surged, experimental studies on its multidimensional modulation remain limited. Here, we report the observation and control of QME using a superconducting processor featuring a unique fully connected, tunable-coupling architecture that enables precise modulation from short- to long-range interactions. This platform allows independent manipulation of coupling regimes, on-site potentials, and initial states, elucidating their roles in QME. To quantify symmetry restoration, we employ entanglement asymmetry (EA) -- the relative entropy between a subsystem reduced density matrix and its symmetric projection -- as a sensitive probe of symmetry breaking. In strong short-range coupling regimes, EA crossovers during quenches from tilted Néel states confirm the presence of QME. In contrast, in intermediate coupling regimes, synchronized EA and entanglement entropy dynamics reveal the suppression of QME. Remarkably, QME reemerges with the introduction of on-site linear potentials or quenches from tilted ferromagnetic states, the latter proving robust against on-site disorder. Our study provides the first demonstration of flexible QME modulation on a superconducting platform with multiple controllable parameters, shedding light on quantum many-body non-equilibrium dynamics and opening avenues for quantum information applications. △ Less

Submitted 11 August, 2025; originally announced August 2025.

Revealing the Staging Structural Evolution and Li (De)Intercalation Kinetics in Graphite Anodes via Machine Learning Potential

Authors: Liqi Wang, Xuhe Gong, Zicun Li, Ruijuan Xiao, Hong Li

Abstract: Revealing the dynamic structural evolution and lithium transport properties during the charge/discharge processes is crucial for optimizing graphite anodes in lithium-ion batteries, enabling high stability and fast-charging performance. However, the dynamic coupling mechanisms among carbon layer kinetics, lithium (de)intercalation/diffusion, and defects regulation remain insufficiently understood.… ▽ More Revealing the dynamic structural evolution and lithium transport properties during the charge/discharge processes is crucial for optimizing graphite anodes in lithium-ion batteries, enabling high stability and fast-charging performance. However, the dynamic coupling mechanisms among carbon layer kinetics, lithium (de)intercalation/diffusion, and defects regulation remain insufficiently understood. In this study, we developed a universal automated workflow based on machine learning potentials to simulate the dynamic lithium (de)intercalation process. With this approach, the staging structural evolution of lithium-graphite intercalation compounds and their lithium transport behavior were resolved through molecular dynamics simulations. By introducing stacking faults into the graphite structure, we successfully simulated stage transitions driven by carbon layer sliding and reorganization, accompanied by stress release and structural stabilization. The dynamics of carbon layers regulate the lithium (de)intercalation positional selectivity, producing intermediate states with varying lithium concentrations and distributions during cycling. This facilitates the formation and transformation of stage structures while mitigating residual stress accumulation. A fundamental kinetic asymmetry arises between lithium intercalation and deintercalation, driven by the continuous and heterogeneous lithium transport and carbon layer sliding during charge/discharge processes. The carbon defects regulate lithium transport, in which the atomic-scale defects confine intralayer lithium transport and carbon sliding while enabling interlayer transport via dynamic lithium trapping/release mechanisms. Accordingly, for the future design, it is critical to construct structural units with controllable carbon layer sliding/reorganization, and tunable defects to enhance lithium-ion transport. △ Less

Submitted 8 August, 2025; originally announced August 2025.

Magic Entropy in Hybrid Spin-Boson Systems

Authors: Samuel Crew, Ying-Lin Li, Heng-Hsi Li, Po-Yao Chang

Abstract: We introduce entropic measures to quantify non-classical resource in hybrid spin-boson systems. We discuss the stabilizer Rényi entropy in the framework of phase space quantisation and define an analogous hybrid magic entropy and a mutual magic entropy that capture the distribution of quantum magic across spin and bosonic subsystems. We use these entropic measures to demonstrate two key phenomena:… ▽ More We introduce entropic measures to quantify non-classical resource in hybrid spin-boson systems. We discuss the stabilizer Rényi entropy in the framework of phase space quantisation and define an analogous hybrid magic entropy and a mutual magic entropy that capture the distribution of quantum magic across spin and bosonic subsystems. We use these entropic measures to demonstrate two key phenomena: the detection of the superradiant phase transition in the Dicke model and the dynamics of magic in the Jaynes-Cummings model following a quench. We develop a Monte Carlo numerical scheme to enable practical computation in many-body examples. △ Less

Submitted 8 August, 2025; originally announced August 2025.

Comments: 15 pages, 3 figures

Universal Magnetocaloric Effect near Quantum Critical Point of Magnon Bose-Einstein Condensation

Authors: Junsen Xiang, Enze Lv, Qinxin Shen, Cheng Su, Xuetong He, Yinghao Zhu, Yuan Gao, Xin-Yang Liu, Dai-Wei Qu, Xinlei Wang, Xi Chen, Qian Zhao, Haifeng Li, Shuo Li, Jie Yang, Jun Luo, Peijie Sun, Wentao Jin, Yang Qi, Rui Zhou, Wei Li, Gang Su

Abstract: Bose-Einstein condensation (BEC), a macroscopic quantum phenomenon arising from phase coherence and bosonic statistics, has been realized in quantum magnets. Here, we report the observation of a universal magnetocaloric effect (MCE) near a BEC quantum critical point (QCP) in copper sulfate crystal ($CuSO_4 \cdot 5H_2O$). By conducting magnetocaloric and nuclear magnetic resonance measurements, we… ▽ More Bose-Einstein condensation (BEC), a macroscopic quantum phenomenon arising from phase coherence and bosonic statistics, has been realized in quantum magnets. Here, we report the observation of a universal magnetocaloric effect (MCE) near a BEC quantum critical point (QCP) in copper sulfate crystal ($CuSO_4 \cdot 5H_2O$). By conducting magnetocaloric and nuclear magnetic resonance measurements, we uncover a field-driven BEC QCP, evidenced by the universal scaling law $T_c \propto (B_c - B)^{2/3}$ and the perfect data collapse of the magnetic Grüneisen ratio. Thermal excitation triggers a dimensional crossover to a 1D quantum-critical regime, where the MCE scaling strictly matches the universality class of 1D Fermi gases. Notably, the quantum-critical MCE enables cooling down to 12.8 mK without helium-3, with very fast thermal relaxation rate that is critical for high cooling power. This work demonstrates the universal MCE in magnon BEC systems, using a common copper sulfate compound as a paradigmatic example, and paves the way for next-generation sub-Kelvin cooling. △ Less

Submitted 7 August, 2025; originally announced August 2025.

Comments: 20 pages, 15 figures

Multilayer Cryogenic Powder Filters with Low Parasitic Capacitance

Authors: Itishree Pradhan, Hao Li, Alina Rupp, Yosuke Sato, Henri Vo Van Qui, Miuko Tanaka, Toshiya Ideue, Erwann Bocquillon, Masayuki Hashisaka

Abstract: We report the development of a cryogenic powder filter that simultaneously offers high attenuation of radio-frequency (RF) signals in the gigahertz (GHz) range and minimized parasitic capacitance to ground. Conventional powder filters, which consist of a signal line passing through a metal powder-filled housing, attenuate high-frequency signals via the skin effect. However, these designs often suf… ▽ More We report the development of a cryogenic powder filter that simultaneously offers high attenuation of radio-frequency (RF) signals in the gigahertz (GHz) range and minimized parasitic capacitance to ground. Conventional powder filters, which consist of a signal line passing through a metal powder-filled housing, attenuate high-frequency signals via the skin effect. However, these designs often suffer from significant parasitic capacitance between the signal line and the grounded chassis, which can compromise the performance of sensitive measurement setups by limiting their frequency bandwidth. In this work, we demonstrate that a multilayer powder filter design effectively achieves both high RF attenuation and reduced parasitic capacitance. This solution suppresses sample heating due to the unintentional intrusion of RF signals through the wiring, without degrading the performance of the measurement setup. △ Less

Submitted 31 July, 2025; originally announced July 2025.

Enhanced Biaxial Compressive Strain Tuning of 2D semiconductors via Hot Dry Transfer on Polymer Substrates

Authors: Alvaro Cortes-Flores, Eudomar Henríquez-Guerra, Lisa Almonte, Hao Li, Andres Castellanos-Gomez, M. Reyes Calvo

Abstract: Strain engineering is an effective tool for tailoring the properties of two-dimensional (2D) materials, especially for tuning quantum phenomena. Among the limited methods available for strain engineering under cryogenic conditions, thermal mismatch with polymeric substrates provides a simple and affordable strategy to induce biaxial compressive strain upon cooling. In this work, we demonstrate the… ▽ More Strain engineering is an effective tool for tailoring the properties of two-dimensional (2D) materials, especially for tuning quantum phenomena. Among the limited methods available for strain engineering under cryogenic conditions, thermal mismatch with polymeric substrates provides a simple and affordable strategy to induce biaxial compressive strain upon cooling. In this work, we demonstrate the transfer of unprecedentedly large levels of uniform biaxial compressive strain to single-layer WS$_2$ by employing a pre-straining approach prior to cryogenic cooling. Using a hot-dry-transfer method, single-layer WS$_2$ samples were deposited onto thermally expanded polymeric substrates at 100 $^\circ$C. As the substrate cools to room temperature, it contracts, inducing biaxial compressive strain (up to ~0.5%) in the WS$_2$ layer. This pre-strain results in a measurable blueshift in excitonic energies compared to samples transferred at room temperature, which serve as control (not pre-strained) samples. Subsequent cooling of the pre-strained samples from room temperature down to 5 K leads to a remarkable total blueshift of ~200 meV in the exciton energies of single-layer WS$_2$. This energy shift surpasses previously reported values, indicating superior levels of biaxial compressive strain induced by the accumulated substrate contraction of ~1.7%. Moreover, our findings reveal a pronounced temperature dependence in strain transfer efficiency, with gauge factors approaching theoretical limits for ideal strain transfer at 5 K. We attribute this enhanced efficiency to the increased Young's modulus of the polymeric substrate at cryogenic temperatures. △ Less

Submitted 30 July, 2025; originally announced July 2025.

Quantum Criticality by Interaction Frustration in a Square-Planar Lattice

Authors: Yi-Qiang Lin, Chang-Chao Liu, Jia-Xin Li, Bai-Jiang Lv, Kai-Xin Ye, Jia-Wen Zhang, Si-Qi Wu, Ya-Nan Zhang, Ye Chen, Jia-Yi Lu, Jing Li, Hua-Xun Li, Hao Li, Yi Liu, Cao Wang, Yun-Lei Sun, Hao Jiang, Hui-Qiu Yuan, Guang-Han Cao

Abstract: We report experimental and theoretical investigations on ThCr$_2$Ge$_2$C, a metallic compound in which Cr$_2$C planes form a square-planar lattice. Neutron powder diffraction, magnetization, and specific heat measurements reveal no evidence of long-range magnetic order or short-range spin freezing down to 70~mK. Quantum critical behavior was indicated through logarithmic divergences in both the ma… ▽ More We report experimental and theoretical investigations on ThCr$_2$Ge$_2$C, a metallic compound in which Cr$_2$C planes form a square-planar lattice. Neutron powder diffraction, magnetization, and specific heat measurements reveal no evidence of long-range magnetic order or short-range spin freezing down to 70~mK. Quantum critical behavior was indicated through logarithmic divergences in both the magnetic susceptibility and the specific heat divided by temperature. Resistivity measurements exhibit non-Fermi-liquid behavior, with a Fermi liquid recovered under magnetic fields or high pressures. First-principles calculations identify competing nearest-neighbor ($J_1$) and next-nearest-neighbor ($J_2$) exchange interactions, with $J_2/J_1 \sim -0.5$, pointing to strong magnetic frustration. The interaction frustration is reduced, and magnetically ordered phases are stabilized upon the application of negative or positive pressures. This work offers a rare example of zero-field, ambient pressure quantum criticality mainly driven by interaction frustration in a square lattice. △ Less

Submitted 29 July, 2025; originally announced July 2025.

Comments: 17 pages, 13 figures, and 6 tables

Local texture of three-stage CVD SiC fibre by precession electron diffraction (PED) and XRD

Authors: B. Huang, Y. Q. Yang, M. H. Li, Y. X. Chen, X. Luo, M. S. Fu, Y. Chen, Xierong Zeng

Abstract: SiC fibre with the transverse isotropic properties is very important to it reinforced metal matrix composites. In this paper, local texture of the CVD SiC fibre was investigated by means of X-ray diffraction (XRD) and precession electron diffraction (PED) on transmission electron microscopy(TEM). The result from XRD is in agreement with the result obtained from PED. And the result shown that at th… ▽ More SiC fibre with the transverse isotropic properties is very important to it reinforced metal matrix composites. In this paper, local texture of the CVD SiC fibre was investigated by means of X-ray diffraction (XRD) and precession electron diffraction (PED) on transmission electron microscopy(TEM). The result from XRD is in agreement with the result obtained from PED. And the result shown that at the first stage of deposition, the preferred direction of SiC grains is almost random and the distribution of grain size is scattered. At the second and third stages of deposition, there are two kinds of texture in SiC fibre, that is, (110),111. and (110),115.. Furthermore, the grain size at the second and third stages is about 200 nm and it is lower at the third stage than at the second stage because of the lower temperature at the third stage. The [110] preferred direction along axial direction for SiC fibre is beneficial to the axial tensile strength. △ Less

Submitted 20 July, 2025; originally announced July 2025.

Journal ref: Materials Science and Technology, 2014 VOL 30 NO 14 1751

Many-body delocalization with a two-dimensional 70-qubit superconducting quantum simulator

Authors: Tian-Ming Li, Zheng-Hang Sun, Yun-Hao Shi, Zhen-Ting Bao, Yong-Yi Wang, Jia-Chi Zhang, Yu Liu, Cheng-Lin Deng, Yi-Han Yu, Zheng-He Liu, Chi-Tong Chen, Li Li, Hao Li, Hao-Tian Liu, Si-Yun Zhou, Zhen-Yu Peng, Yan-Jun Liu, Ziting Wang, Yue-Shan Xu, Kui Zhao, Yang He, Da'er Feng, Jia-Cheng Song, Cai-Ping Fang, Junrui Deng , et al. (13 additional authors not shown)

Abstract: Quantum many-body systems with sufficiently strong disorder can exhibit a non-equilibrium phenomenon, known as the many-body localization (MBL), which is distinct from conventional thermalization. While the MBL regime has been extensively studied in one dimension, its existence in higher dimensions remains elusive, challenged by the avalanche instability. Here, using a 70-qubit two-dimensional (2D… ▽ More Quantum many-body systems with sufficiently strong disorder can exhibit a non-equilibrium phenomenon, known as the many-body localization (MBL), which is distinct from conventional thermalization. While the MBL regime has been extensively studied in one dimension, its existence in higher dimensions remains elusive, challenged by the avalanche instability. Here, using a 70-qubit two-dimensional (2D) superconducting quantum simulator, we experimentally explore the robustness of the MBL regime in controlled finite-size 2D systems. We observe that the decay of imbalance becomes more pronounced with increasing system sizes, scaling up from 21, 42 to 70 qubits, with a relatively large disorder strength, and for the first time, provide an evidence for the many-body delocalization in 2D disordered systems. Our experimental results are consistent with the avalanche theory that predicts the instability of MBL regime beyond one spatial dimension. This work establishes a scalable platform for probing high-dimensional non-equilibrium phases of matter and their finite-size effects using superconducting quantum circuits. △ Less

Submitted 22 July, 2025; originally announced July 2025.

Comments: main text: 7 pages, 3 figures; supplementary information: 19 pages, 17 figures

Giant magneto-cubic in-plane Hall effect in a nonmagnetic material

Authors: Jie Chen, Jin Cao, Yue Lu, Hang Li, Xiaodong Zhou, Xuekui Xi, Orest Pavlosiuk, Piotr Wiśniewski, Dariusz Kaczorowski, Yong-Chang Lau, Cong Xiao, Yue Li, Yong Jiang, Wenhong Wang, Shengyuan A. Yang

Abstract: In-plane Hall effect (IPHE) triggered by an external magnetic field applied in the transport plane has attracted significant experimental attentions in recent few years 1-6. However, most experiments focus on magnetic materials, where the existence of magnetic ordering may complicate understanding the physics behind, and the relatively small signal magnitudes limit the application of the effect. H… ▽ More In-plane Hall effect (IPHE) triggered by an external magnetic field applied in the transport plane has attracted significant experimental attentions in recent few years 1-6. However, most experiments focus on magnetic materials, where the existence of magnetic ordering may complicate understanding the physics behind, and the relatively small signal magnitudes limit the application of the effect. Here, we report a giant IPHE in a nonmagnetic half-Heusler compound LuAuSn, with a magnitude exceeding all the previously reported values. A -period of IPHE and the consistent cubic dependence on the magnetic field are observed, realizing the long-sought theoretical prediction of magneto-cubic IPHE under threefold rotational symmetry7-9 in an unexpected material. The scaling law analysis and first-principles calculations indicate that extrinsic side jump and skew scattering processes from both impurity and phonon scatterings dominate the observed effect. These findings unravel a new type of magneto-nonlinear IPHE, and its large magnitude and wide-temperature operation may open the door to practical applications of IPHE. △ Less

Submitted 22 July, 2025; originally announced July 2025.

Electro-optic Kerr Effect Induced by Nonlinear Transport in monolayer WTe2

Authors: He-Lin Li, Zhen-Gang Zhu, Gang Su

Abstract: The nonlinear Hall effect (NLHE) can induce optical anisotropy by modifying a material's dielectric tensor, presenting opportunities for novel characterization and device applications. While the magneto-optical Kerr effect (MOKE) probes the linear Hall effect (LHE) in magnetic materials, an analogous optical probe for NLHE in non-magnetic, time-reversal symmetric systems remains highly desirable.… ▽ More The nonlinear Hall effect (NLHE) can induce optical anisotropy by modifying a material's dielectric tensor, presenting opportunities for novel characterization and device applications. While the magneto-optical Kerr effect (MOKE) probes the linear Hall effect (LHE) in magnetic materials, an analogous optical probe for NLHE in non-magnetic, time-reversal symmetric systems remains highly desirable. Here, we theoretically propose and investigate an NLHE-induced Electro-optic Kerr Effect (EOKE) as such a probe. Focusing on monolayer (ML) WTe$_2$, a prototypical NLHE material, our analysis considers contributions from Berry curvature dipole (BCD), Drude, injection, and shift mechanisms. We demonstrate that the EOKE signal in WTe$_2$ is predominantly governed by the BCD. Furthermore, the Kerr angle exhibits temporal oscillations at different optical frequencies, suggesting EOKE as a promising route for the time-resolved detection of NLHE and the dynamic investigation of material topology. △ Less

Submitted 14 July, 2025; originally announced July 2025.

Comments: 8 pages, 5figures