Materials Science
Order-disorder duality of high entropy alloys extends non-linear optics
Valentin A. Milichko, Ekaterina Gunina, Nikita Kulachenkov et al. (+21 more)
Order versus disorder in the structure of materials plays a key role in the theoretical prediction of their properties. However, this structural description appears to be ineffective for new families of materials such as high
entropy alloys (HEAs), which combine crystallographic order with chemical disorder. Here, we demonstrate for five-element HEAs as pure solid solutions that the chemical disorder of the elements decorating their cubic structure underlies the generation of second optical harmonics, overcoming the theoretical limit imposed on centrosymmetric
crystals. Moreover, we discover that this disorder, inherent to HEAs, sets a threshold for non-linear light emission from the 4th to the 26th order. As a consequence of the 0.5 eV broadening of the energy levels of the five elements of the HEA, the emission spectrum covers broad visible (400-650 nm) and infrared (800-1600 nm) ranges. In addition to the challenge of theoretically predicting non-linear effects in unconventional materials, the duality of structural order and chemical disorder in HEAs offers the opportunity to design sustainable alternatives to urgently needed optical materials.
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All authors Valentin A. Milichko, Ekaterina Gunina, Nikita Kulachenkov, Maxime Vergès, Luis Casillas Trujillo, Maria Timofeeva, Jaafar Ghanbaja, Stéphanie Bruyère, Andrey Krasilin, Mikhail Petrov, Michael Feuerbacher, Yann Battie, Rachel Grange, Jean-Pascal Borra, Jean-François Pierson, Vincent Fournée, Thierry Belmonte, Janez Zavašnik, Björn Alling, Joseph Kioseoglou, Ivan Iorsh, Julian Ledieu, Uroš Cvelbar, Alexandre Nominé
Mesoscale and Nanoscale Physics
Soliton formation in a bound state in the continuum GaN waveguide polariton laser
V. Develay, O. Bahrova, I. Septembre et al. (+11 more)
We study polaritonic bound states in the continuum (BIC) created in GaN waveguides. The existence of
symmetry-protected BICs is confirmed by the suppression of light emission and the observation of a polarization
vortex in momentum space. Upon increasing the pumping, polariton population accumulates at the BIC and we observe polariton lasing from the blueshifted BIC states. The assessment of the polariton BIC emission energy and of its real and momentum space wavefunctions as a function of pumping power, i.e. of polariton density, indicates the formation of a bright
soliton above the lasing threshold.
Soliton formation at the BIC is induced by the combination of negative mass BIC and of repulsive polariton-polariton and polariton-reservoir interactions.
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All authors V. Develay, O. Bahrova, I. Septembre, D. Bobylev, C. Brimont, L. Doyennette, B. Alloing, H. Souissi, E. Cambril, S. Bouchoule, J. Zúñiga-Pérez, D. Solnyshkov, G. Malpuech, T. Guillet
Soft Condensed Matter
An elasto-viscoplastic thixotropic model for fresh concrete capturing flow-rest transition
Jidu Yu, Bodhinanda Chandra, Christopher Wilkes et al. (+2 more)
The flow properties of fresh concrete are critical in the construction industry, as they directly affect casting quality and the durability of the final structure. Although non-Newtonian fluid models, such as the Bingham model, are widely used to model these flow properties, they often fail to capture key phenomena, including flow stoppage, and frequently rely on ad hoc, non-physical regularization or stabilization techniques to mitigate numerical instabilities at low shear rates. To address these limitations, this study proposes an elasto-viscoplastic constitutive model within the continuum mechanics framework, which treats fresh concrete as a solid-like material with a rate-dependent yield stress. The model inherently captures the transition from elastic response to viscous flow following Bingham rheology, and vice versa, enabling accurate prediction of flow cessation without ad hoc criteria. Additionally, a thixotropy
evolution law is incorporated to account for the time-dependent behavior resulting from physical flocculation and shear-induced deflocculation. The proposed model is implemented within the Material Point Method (MPM), whose Lagrangian formulation facilitates tracking of history-dependent variables and robust simulation of large deformation flows. Numerical examples demonstrate the model's effectiveness in reproducing a range of typical concrete flow scenarios, offering a more physically consistent numerical tool for optimizing concrete construction processes and minimizing defects.
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All authors Jidu Yu, Bodhinanda Chandra, Christopher Wilkes, Jidong Zhao, Kenichi Soga
Strongly Correlated Electrons
Universal Entanglement Growth along Imaginary Time in Quantum Critical Systems
Chang-Yu Shen, Shuai Yin and Zi-Xiang Li
Characterizing universal
entanglement features in higher-dimensional
quantum matter is a central goal of
quantum information science and condensed matter physics. While the subleading corner terms in two-dimensional
quantum systems encapsulate essential universal information of the underlying conformal field theory, our understanding of these features remains remarkably limited compared to their one-dimensional counterparts. We address this challenge by investigating the
entanglement dynamics of fermionic systems along the imaginary-time
evolution. We uncover a pioneering non-
equilibrium scaling law where the corner
entanglement entropy grows linearly with the logarithm of imaginary time, dictated solely by the universality class of the
quantum critical point. Through unbiased
Quantum Monte Carlo simulations, we verify this scaling in the interacting Gross-Neveu-Yukawa model, demonstrating that universal data can be accurately recovered from the early stages of relaxation. Our findings significantly circumvent the computational bottlenecks inherent in reaching full
equilibrium convergence. This work establishes a direct link between the fundamental theory of non-
equilibrium critical phenomena and the high-precision determination of universal
entanglement properties on both classical and
quantum platforms, paving the way for probing the rich
entanglement structure of
quantum critical systems.
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Statistical Mechanics
Renormalization group approach to the elastic properties of graphene bilayers
L. Delzescaux and D. Mouhanna
We investigate the effects of thermal fluctuations in
graphene bilayers by means of a nonperturbative renormalization group (NPRG) approach, following the pioneering work of Mauri et al. [Phys. Rev. B 102, 165421 (2020)] based on a self-consistent screening approximation (SCSA). We consider a model of two continuum polymerized membranes, separated by a distance $\ell$, in their flat phase, coupled by interlayer shear, compression/dilatation and elastic terms. Within a controlled truncation of the effective average action, we retain only the contributions that generate a pronounced crossover of the effective bending
rigidity along the renormalization group flow between two regimes: at high running scale $k$, the
rigidity is dominated by the in-plane elastic properties, with $\kappa_{\mathrm{eff}}\sim \ell^{2}(\lambda+2\mu)/2$, whereas at low $k$ it is controlled by the bending
rigidity of two independent monolayers, $\kappa_{\mathrm{eff}}\sim 2\kappa$. This crossover is reminiscent of that observed by Mauri et al. as a function of the wavevector scale $q$, but here it is obtained within a renormalization group framework. This has several advantages. First, although approximations are performed, the NPRG approach allows one, in principle, to take into account all nonlinearities present in the elastic theory, in contrast to the SCSA treatment which requires, already at the formal level, significant simplifications. Second, it demonstrates that the
bilayer problem can be treated as a straightforward extension of the monolayer case, with flow equations that keep the same structure and differ only by
bilayer-specific adjustments. Third, unlike the SCSA, the NPRG framework admits a controlled, systematically improvable, hierarchy of approximations.
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Statistical Mechanics · Cross-listed from math-ph
Quantum Dilogarithms and New Integrable Lattice Models in Three Dimensions
Vladimir V. Bazhanov, Rinat M. Kashaev, Vladimir V. Mangazeev et al. (+1 more)
In this paper we introduce a new class of integrable 3D
lattice models, possessing continuous families of commuting layer-to-layer transfer
matrices. Algebraically, this commutativity is based on a very special construction of local Boltzmann weights in terms of
quantum dilogarithms satisfying the inversion and pentagon identities. We give three examples of such
quantum dilogarithms, leading to integrable 3D
lattice models. The partition function per site in these models can be exactly calculated in the limit of an infinite
lattice by using the functional relations,
symmetry and factorization properties of the transfer
matrix. The results of such calculations for 3D models associated with the Faddeev modular
quantum dilogarithm are briefly presented.
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All authors Vladimir V. Bazhanov, Rinat M. Kashaev, Vladimir V. Mangazeev, Sergey M. Sergeev
Mesoscale and Nanoscale Physics
Marta Pita-Vidal, Rubén Seoane Souto, Srijit Goswami et al. (+4 more)
Hybrid
semiconductor-
superconductor qubits have recently emerged as a promising alternative to traditional platforms, combining material advantages with device-level tunability. A defining feature is their gate-tunable Josephson coupling, enabling superconducting
qubit architectures with full electric-field control and offering a path toward scalable, low-crosstalk
quantum processors. This approach seeks to merge benefits of superconducting and
semiconductor qubits, for instance by encoding
quantum information in the
spin of a quasiparticle occupying an Andreev bound state, thus combining long coherence times with fast, flexible control. Progress has accelerated through bottom-up engineering of Andreev states in coupled
quantum dot arrays, leading to architectures such as minimal Kitaev chains hosting Majorana zero modes. In parallel,
Hamiltonian-protected designs aim to enhance resilience against local noise and decoherence by exploiting superconducting phase dynamics and discrete charge or flux degrees of freedom. This article reviews recent theoretical and experimental advances in hybrid
qubits, providing an overview of physical mechanisms, device implementations, and emerging architectures, with emphasis on their potential for (topologically) protected
quantum information processing. While many designs remain at proof-of-concept stage, rapid progress suggests practical demonstrations may soon be achievable.
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All authors Marta Pita-Vidal, Rubén Seoane Souto, Srijit Goswami, Christian Kraglund Andersen, Georgios Katsaros, Javad Shabani, Ramón Aguado
Soft Condensed Matter · Cross-listed from physics.flu-dyn
Phase-field modeling of multicomponent vesicles in viscoelastic fluid
Zuowei Wen, Navid Valizadeh, Timon Rabczuk et al. (+1 more)
Multicomponent vesicles suspended in viscoelastic fluids are crucial for understanding a variety of physiological processes. In this work, we develop a continuum surface force (CSF) phase-field model to investigate the hydrodynamics of inextensible multicomponent vesicles in viscoelastic fluid flows with inertial forces. Our model couples a fluid field comprising both Newtonian and Oldroyd-B fluids, a surface concentration field representing the multicomponent distribution on the vesicle membrane, and a phase-field variable governing the membrane
evolution. The viscoelasticity effect of extra stress is well incorporated into the full Navier-Stokes equations in the fluid field. The surface concentration field is determined by Cahn-Hilliard equations, while the membrane
evolution is governed by a nonlinear advection-
diffusion equation. The membrane is coupled to the surrounding fluid through the continuum surface force (CSF) framework. To ensure stable numerical solutions of the highly nonlinear multi-field model, we employ a residual-based variational multiscale (RBVMS) method for the Navier-Stokes equations, a Streamline-Upwind Petrov-Galerkin (SUPG) method for the Oldroyd-B equations, and a standard Galerkin finite element framework for the remaining equations. The system of PDEs is solved using an implicit, monolithic scheme based on the generalized-$\alpha$ time integration method. To enhance spatial accuracy, we employ isogeometric analysis (IGA). We present a series of two-dimensional numerical examples in shear and Poiseuille flows to elucidate the influence of membrane composition and fluid viscoelasticity on the hydrodynamics of multicomponent vesicles.
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All authors Zuowei Wen, Navid Valizadeh, Timon Rabczuk, Xiaoying Zhuang
Soft Condensed Matter
Inverse Bauschinger to Bauschinger Crossover under Steady Shear in Amorphous Solids
Rashmi Priya and Smarajit Karmakar
Directional
memory in amorphous solids is commonly quantified through the Bauschinger effect, yet the observation of the inverse Bauschinger effect suggests that the sign of
memory can invert, pointing to distinct underlying plastic organization. Here, we connect directional
memory to the nature of yielding in steadily sheared amorphous solids. Using simulations of two-dimensional polydisperse glasses, we show that the type of directional
memory (Bauschinger versus inverse Bauschinger) is jointly controlled by deformation history, strain rate, and parent temperature. We identify a critical history amplitude $\gamma_{N,\mathrm{crit}}(T_p,\dot{\gamma})$ and construct a phase diagram that delineates regimes with
memory inversion from those showing only conventional Bauschinger response. Microscopically,
memory inversion correlates with network-like shear-band morphology and plastic healing, whereas conventional
memory is associated with persistent localization and cumulative damage. These results establish directional
memory as an order parameter for a shear-rate and annealing-controlled brittle-ductile crossover and suggest that plastic healing provides a generic route to
memory inversion in disordered solids.
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Mesoscale and Nanoscale Physics
Atomic-scale spin sensing of a 2D $d$-wave altermagnet via helical tunneling
Zhuying Wang, Shuikang Yu, Xingkai Cheng et al. (+17 more)
Altermagnetism simultaneously possesses nonrelativistic
spin responses and zero net magnetization, thus combining advantages of ferromagnetism and antiferromagnetism. This superiority originates from its unique dual feature, i.e., opposite-
magnetic sublattices in real space and alternating
spin polarization in momentum space enforced by the same
crystal symmetry. Therefore, the determination of an altermagnetic order and its unique
spin response inherently necessitates atomic-scale
spin-resolved measurements in real and momentum spaces, an experimental milestone yet to be achieved. Here, via utilizing the helical edge (hinge) modes of a higher order topological
insulator as the
spin sensor, we realize
spin-resolved scanning tunneling microscopy which enables us to pin down the dual-space feature of a layered $d$-wave altermagnet, KV$_2$Se$_2$O. In real space, atomic-registered mapping demonstrates the checkerboard
antiferromagnetic order together with density-wave
lattice modulation, and in momentum space,
spin-resolved spectroscopic imaging provides a direct visualization of d-wave
spin splitting of the band structure. Critically, using this new
topology-guaranteed
spin filter we directly reveal the unidirectional,
spin-polarized quasiparticle excitations originating from the
crystal symmetry-paired X and Y valleys around opposite
magnetic sublattices simultaneously –the unique
spin response for $d$-wave altermagnetism. Our experiments establish a solid basis for the exploration and utilization of altermagnetism in layered materials and further facilitate access to atomic-scale
spin sensing and manipulating of 2D
quantum materials.
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All authors Zhuying Wang, Shuikang Yu, Xingkai Cheng, Xiaoyu Xiao, Wanru Ma, Feixiong Quan, Hongxi Song, Kunming Zhang, Yunmei Zhang, Yitian Ma, Wenhao Liu, Priti Yadav, Xiangbiao Shi, Zhijun Wang, Qian Niu, Yang Gao, Bin Xiang, Junwei Liu, Zhenyu Wang, Xianhui Chen
Mesoscale and Nanoscale Physics
Observation of robust one-dimensional edge channels in a three-dimensional quantum spin Hall insulator
Shuikang Yu, Junze Deng, Wenhao Liu et al. (+13 more)
Topologically protected edge channels show prospects for
quantum devices. They have been found experimentally in two-dimensional (2D)
quantum spin Hall insulators (QSHIs), weak topological
insulators and higher-order topological
insulators (HOTIs), but the number of materials realizing these
topologies is still quite limited. Here, we provide evidence for topological edge states within a novel
topology named three-dimensional (3D) QSHIs. Its
topology originates solely from a nonzero $S_z$
spin Chern number for each $k_z$ plane of the
crystal and is realized in bulk $\alpha$-Bi$_4$I$_4$ with trivial
symmetry indicators, as we show by density functional theory calculations. We experimentally observe the related edge states at each type of monolayer and
bilayer step of this material by scanning tunneling microscopy. Consistently, the edge states are neither interrupted, nor backscattered by defects at the step edges corroborating their helical character as expected from the nontrivial
topology. Furthermore, two individual edge channels are directly observed at
bilayer steps without visible interaction gap opening, demonstrating the robustness of these edge modes against vertical stacking. Our results establish $\alpha$-Bi$_4$I$_4$ as the first material realization of a 3D QSHI whose definition goes beyond the scope of topological
symmetry indicators, and provide a pathway for realizing nearly-quantized
spin Hall conductivity per unit
cell in a bulk
crystal.
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All authors Shuikang Yu, Junze Deng, Wenhao Liu, Yunmei Zhang, Yiming Sun, Nikhil Dhale, Sheng Li, Wanru Ma, Zhuying Wang, Ping Wu, Zuowei Liang, Xuecheng Zhang, Bing Lv, Zhijun Wang, Zhenyu Wang, Xianhui Chen
Soft Condensed Matter · Cross-listed from physics.optics
Electromagnetically-Induced Transparency Bridges Disconnected Light-Harvesting Networks
Jun Wang, Rui Li, Yi Li et al. (+2 more)
The energy-transfer efficiency of the natural photosynthesis system seems to be perfectly optimized during the
evolution for millions of years. However, how to enhance the efficiency in the artificial light-harvesting systems is still unclear. In this paper, we investigate the energy-transfer process in the photosystem I (PSI). When there is no effective coupling between the outer
antenna (OA) and the reaction center (RC), the two light-harvesting networks are disconnected and thus the energy transfer is inefficient. In order to repair these disconnected networks, we introduce a bridge with three sites between them. We find that by modulating the level structure of the 3-site bridge to be resonant, the energy transfer via the dark state will be enhanced and even outperform the original PSI. Our discoveries may shed light on the designing mechanism of artificial light-harvesting systems.
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All authors Jun Wang, Rui Li, Yi Li, Kai-Ya Zhang, Qing Ai
Materials Science
A First-Principles Investigation of Goldene for Enhanced Hydrogen Evolution Reaction
Ashutosh Krishna Amaram, Aaditya Roy and Raghavan Ranganathan
The recent synthesis of Goldene, a 2D sheet of gold exfoliated from $Ti_3AuC_2$, offers high specific surface area (~260 $m^2g^{-1}$), roughly twice that of fine nanodots (~100 $m^2g^{-1}$), and unique electronic properties due to its dense d-orbital. In this work, we investigate the adsorption of single atom catalyst (SAC) of hydrogen atom on pristine goldene (pG), monovacant goldene (vG), and sulfur-functionalized variants (thiol-pG and thiol-vG) using ab initio calculations. The adsorption energy of a single H atom and $\Delta G_H$, determines the efficiency of the Volmer step of the hydrogen
evolution reaction (HER) and is a key descriptor for HER activity. We explore various potential sites for H adsorption and its impact on descriptors such as Bader charges, d-band shift and the exchange current density.
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Materials Science
Nanoscale determination of the metal-insulator transition in intercalated bulk VSe$_{2}$
Wanru Ma, Ye Yang, Zuowei Liang et al. (+4 more)
Two-dimensional (2D) materials provide unique opportunities to realize emergent phenomena by reducing dimensionality. Using scanning tunneling microscopy combined with first-principles calculations, we determine an intriguing case of a metal-
insulator transition (MIT) in a bulk compound, (TBA)$_{0.3}$VSe$_2$. Atomic-scale imaging reveals that the initial $4a_0 \times 4a_0$ charge density wave (CDW) order in 1T-VSe$_2$ transforms to $\sqrt{7}a_0 \times \sqrt{3}a_0$ ordering upon intercalation, which is associated with an insulating gap with a magnitude of up to approximately 115 meV. Our calculations reveal that this energy gap is highly tunable through electron doping introduced by the intercalant. Moreover, the robustness of the $\sqrt{7}a_0 \times \sqrt{3}a_0$ CDW order against the Lifshitz transition points to the key role of electron-
phonon interactions in stabilizing the CDW state. Our work clarifies a rare example of a CDW-driven MIT in quasi-2D materials and establishes cation intercalation as an effective pathway for tuning both the dimensionality and the carrier concentration without inducing strain or disorder.
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All authors Wanru Ma, Ye Yang, Zuowei Liang, Ping Wu, Fanbao Meng, Zhenyu Wang, Xianhui Chen
Materials Science
Surface Hydrogen Coverage on Pt/Graphene Measured by Carbon Ion ERDA
Chien-Hsu Chen, Huan Niu, Hung-Kai Yu et al. (+2 more)
Graphene, a two-dimensional monolayer of sp2-bonded carbon atoms in a honeycomb
lattice, possesses exceptional electronic, mechanical, and
quantum properties, making it highly attractive for energy storage, spintronics, and microelectronics. Functionalizing
graphene with platinum (Pt) adatoms can further enhance its properties, particularly for hydrogen storage applications. In this study, we experimentally investigate hydrogen adsorption on Pt-decorated
graphene using Elastic
Recoil Detection Analysis (ERDA). By irradiating the Pt/
graphene film with a 4.1 MeV C2+ ion beam and detecting recoiled hydrogen atoms at a 30 degree scattering angle, we obtain the hydrogen depth profile, providing critical insights into its storage behavior.
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All authors Chien-Hsu Chen, Huan Niu, Hung-Kai Yu, Tsung Te Lin, Yao-Tung Hsu
Materials Science
Unveiling Solvent Effects on Femtosecond Laser-Irradiated Au/Fe3O4 Colloidal Nanoparticles: The Acetone Effect
Stéphane Mottin, Żaneta Świątkowska-Warkocka, Marta Wolny-Marszałek et al. (+1 more)
The interplay between
laser parameters and
liquid environments dictates the outcome of femtosecond
laser-induced nanoparticle modification. We present a study of gold and iron
oxide nanoparticles in water and a water-acetone mixture, irradiated with femtosecond
lasers at 808 nm and 404 nm. While aggregation was observed in pure water at both wavelengths, the results revealed a strong stability and a rather unexpected wavelength-dependency in the acetone-water mixture. In this case, 808 nm irradiation produced some decrease in nanoparticle sizes, while 404 nm led to some nanoparticle growth. As a result, the acetone effect is found to be twofold: (i) on one hand, it helps to prevent aggregation; (ii) on the other hand, it acts as a reactive medium allowing to tune the nanoparticle size and composition simply by changing
laser wavelength. So, this work emphasizes that solvent physical properties as well as
laser-induced chemical processes in the solvent are not merely secondary effects but can dominate the final morphological outcome, providing a predictive framework for nanoparticle synthesis.
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All authors Stéphane Mottin, Żaneta Świątkowska-Warkocka, Marta Wolny-Marszałek, Tatiana E Itina
Strongly Correlated Electrons
Fate of Pomeranchuk effect in ultrahigh magnetic fields
Naofumi Matsuyama, So Yokomori, Toshihiro Nomura et al. (+8 more)
The Pomeranchuk effect is a counterintuitive phenomenon where
liquid helium-3 (3He) solidifies under specific pressures, not when cooled, but when heated. This behaviour originates from the
magnetic entropy of
nuclear spins, suggesting a
magnetic field should influence it. However, its detailed response to
magnetic fields remains elusive due to the small
nuclear magneton of 3He and lack of analogous
fermion systems. Here, we show that an electron system also exhibit the Pomeranchuk effect, where the
Fermi liquid state solidifies in a high
magnetic field, unlike conventional electron systems where a field melts an electron solid into a metal. Remarkably, the electron system displays a reentrant
liquid state in ultrahigh fields. These responses are explained by changes in
magnetic entropy and magnetisation, extending the underlying physics to 3He. Our findings clarify
magnetic-field impact on the Pomeranchuk effect and open avenues for
magnetic control of chemical interactions.
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All authors Naofumi Matsuyama, So Yokomori, Toshihiro Nomura, Yuto Ishii, Hiroaki Hayashi, Hajime Ishikawa, Kazuki Matsui, Hatsumi Mori, Koichi Kindo, Yasuhiro H. Matsuda, Shusaku Imajo
Materials Science
A Dual-Gate Altermagnetic Tunnel Junction Based on Bilayer Cr$_{2}$SeO
Yunfei Gao, Aolin Li, Zesen Fu et al. (+3 more)
Altermagnets demonstrate significant potential in spintronics due to their unique non-relativistic
spin-splitting properties, yet altermagnetic devices still face challenges in efficiently switching logic states. Here, we report electrostatically controllable
spin-momentum locking in
bilayer Cr$_{2}$SeO and design a dual-gate altermagnetic tunnel junction (AMTJ), which can switch between high and low resistance states without switching the Néel vector. First-principles calculations demonstrate that vertical electric field can induce significant
spin splitting in
bilayer Cr$_{2}$SeO. Reversing the electric field direction can alter the
spin-momentum locking in
bilayer Cr$_{2}$SeO. Leveraging this electric-field-tunable
spin splitting, the dual-gate AMTJ exhibits an ultrahigh tunneling magnetoresistance (TMR) ratio of $10^{7}$. This work provides theoretical support for the design of fully electrically controlled AMTJs and demonstrates their great potential for applications in spintronic devices.
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All authors Yunfei Gao, Aolin Li, Zesen Fu, Bei Zhang, Haiming Duan, Fangping Ouyang
Materials Science · Cross-listed from physics.chem-ph
Isotope Effects and the Negative Thermal Expansion Phenomena in Ice and Water
B. I. Min and J.-S. Kang
H2O is a unique substance with exceptional thermal properties arising from the subtle interplay between its electronic, phononic, and structural degrees of freedom. Of particular interest in H2O are the negative thermal expansion (NTE) phenomena, observed in its solid phase (ice) at low temperature, and in its
liquid phase (water) near the freezing temperature. Furthermore, ice and water exhibit the abnormal volume isotope effect (VIE), where volume expansions occur when replacing H with its heavier isotope, deuterium (D). In order to capture more conceptual and intuitive understanding of intriguing NTE and VIE phenomena in ice and water, we have explored isotope effects in their NTE and melting properties by employing a type of Born-Oppenheimer-approximation approach and the Lindemann criterion. Our findings demonstrate that unusual isotope effects in these phenomena stem from competition between zero-point-energy
phonons, thermal
phonons, and the hydrogen bonding in H2O. All these components originate from
nuclear quantum mechanical (QM) processes, revealing that QM physics plays a crucial role in the seemingly classical ice/water systems.
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Disordered Systems and Neural Networks
Localization-landscape generalized Mott-Berezinskiĭ formula
Gabriel Hayoun, Ilya A. Gruzberg and Marcel Filoche
We introduce a conceptual reformulation of the Mott-Berezinskiĭ (MB) theory of low-frequency AC conductivity in disordered systems based on localization landscape theory. Instead of assuming uniform localization and fixed hopping distances, transport is described through an effective potential whose geometry encodes the spatial organization and energy-dependent localization of
quantum states. Using the associated Agmon metric, we define a generalized Mott scale that replaces the classical hopping length with a
geometric criterion set by the disorder landscape. This framework naturally incorporates strong spatial inhomogeneity and yields the AC conductivity directly from the effective potential. The standard MB result is recovered as a limiting case. Our approach extends the conceptual foundation of MB theory to arbitrary disordered media and energies approaching the mobility edge, providing a unified description of AC transport in complex
quantum materials.
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Strongly Correlated Electrons
Multi-orbital dynamical mean-field theory with a complex-time solver
Yang Yu, Lei Zhang, Emanuel Gull et al. (+2 more)
We present the combination of a complex-time tensor-network
impurity solver with an analytic continuation scheme based on exponential fitting as an efficient framework for single and multi-orbital dynamical mean-field calculations. By performing time-
evolution along a complex-time contour, the approach balances computational cost with the difficulty of spectral recovery, offering greater flexibility than methods confined to the real or imaginary axis. By complementing the complex-time
evolution with an exponential fitting scheme, we faithfully extract real-time information at negligible cost. The resulting method obtains high-resolution spectra at a significantly lower computational cost than real-time
evolution, offering a promising tool for ab initio studies of strongly correlated materials.
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All authors Yang Yu, Lei Zhang, Emanuel Gull, Xiaodong Cao, Xinyang Dong
Statistical Mechanics · Cross-listed from math-ph
The five-vertex model as a discrete log-gas
Filippo Colomo, Michelangelo Mannatzu and Andrei G. Pronko
We consider the five-vertex model on a rectangular domain of the square
lattice, with the so-called `scalar-product' boundary conditions. We address the evaluation of the free-energy density of the model in the scaling limit, that is when the number of sites is sent to infinity and the mesh of the
lattice to zero, while keeping the size of the domain constant. To this aim, we reformulate the partition function of the model in terms of a discrete log-gas, and study its behaviour in the thermodynamic limit. We reproduce previous results, obtained by using a differential equation approach. Moreover, we provide the explicit form of the resolvent in all possible regimes. This work is preliminary to further studies of limit shape phenomena in the model.
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Statistical Mechanics · Cross-listed from math.PR
Uniqueness of Replica-symmetric Saddle Point for Ising Perceptron
Shuta Nakajima
We study the replica-symmetric saddle point equations for the Ising perceptron with Gaussian disorder and margin $\kappa\ge 0$. We prove that for each $\kappa\ge 0$ there is a critical capacity $\alpha_c(\kappa)=\frac{2}{\pi\,\mathbb E[(\kappa-Z)_+^2]}$, where $Z$ is a standard normal and $(x)_+=\max\{x,0\}$, such that the saddle point equation has a unique solution for $\alpha\in(0,\alpha_c(\kappa))$ and has no solution when $\alpha\ge \alpha_c(\kappa)$. When $\alpha\uparrow \alpha_c(\kappa)$ and $\kappa>0$, the replica-symmetric free energy at this solution diverges to $-\infty$. In the zero-margin case $\kappa=0$, Ding and Sun obtained a conditional uniqueness result, with one step verified numerically. Our argument gives a fully analytic proof without computer assistance. We used GPT-5 to help develop intermediate proof steps and to perform sanity-check computations.
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Materials Science
Anisotropic Photostriction and Strain-modulated Carrier Lifetimes in Orthorhombic Semiconductors
Jianxin Yu, Kun Yang, Jiawen Li et al. (+3 more)
We demonstrate anisotropic photostriction in two-dimensional orthorhombic
semiconductors using time-dependent density functional theory. By tracing the dynamics of photoexcited carriers, we establish a quantitative link between carrier density and
lattice deformation in layered black phosphorus and germanium selenides. The structural response exhibits significant anisotropy, featuring
lattice expansion along the armchair direction and contraction along the zigzag direction, which is attributed to the interplay between charge redistribution and intrinsic
lattice anisotropy. Both the magnitude and orientation of the photostrictive strains can be tuned by photodoping densities, enabling precise control over the photoinduced response. Notably, the photoinduced strains significantly increase carrier recombination lifetimes by suppressing nonradiative recombination, primarily due to the enlarged bandgap and weakened nonadiabatic coupling. These results provide microscopic insight into the origin of anisotropic photostriction in low-dimensional systems and lay the groundwork for light-controllable, directionally sensitive optomechanical devices at the atomic scale.
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All authors Jianxin Yu, Kun Yang, Jiawen Li, Sheng Meng, Xinghua Shi, Jin Zhang
Statistical Mechanics
Survey on Lattice Gas Models on 2D Lattices: Critical Behavior of Closed Trajectories
Tianyi Zhou
Lorentz
lattice gases (LLGs) are discrete-time transport models in which a point particle moves ballistically between
lattice sites and is scattered by randomly placed, quenched local scatterers such as “rotators” or “mirrors.” Despite the elementary update rules, LLGs exhibit rich dynamical regimes: typically, trajectories close quickly and the distribution of loop lengths has exponential tails, but at special concentrations of scatterers one observes critical behavior with scale-free statistics and fractal geometry. This survey focuses on the critical behavior of closed trajectories in two-dimensional LLGs, starting from the numerical study of Cao and Cohen, and its relation to percolation-hull scaling and kinetic hull-generating walks. We highlight the scaling hypothesis for loop-length distributions, the emergence of critical exponents $\tau=15/7$, $d_f=7/4$, and $\sigma=3/7$ in several universality classes, and the appearance of alternative exponents in partially occupied models.
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Statistical Mechanics
The Geometric Foundations of Microcanonical Thermodynamics: Entropy Flow Equation and Thermodynamic Equivalence
Loris Di Cairano
We develop a
geometric foundation of microcanonical thermodynamics in which
entropy and its derivatives are determined from the geometry of phase space, rather than being introduced through an a priori ensemble postulate. Once the minimal structure needed to measure constant – energy
manifolds is made explicit, the microcanonical measure emerges as the natural hypersurface measure on each energy shell. Thermodynamics becomes the study of how these shells deform with energy: the
entropy is the logarithm of a
geometric area, and its derivatives satisfy a deterministic hierarchy of
entropy flow equations driven by microcanonical averages of
curvature invariants (built from the shape/Weingarten operator and related
geometric data). Within this framework, phase transitions correspond to qualitative reorganizations of the geometry of energy
manifolds, leaving systematic signatures in the derivatives of the
entropy. Two general structural consequences follow. First, we reveal a thermodynamic covariance: the reconstructed thermodynamics is invariant under arbitrary descriptive choices such as reparametrizations and equivalent representations of the same conserved dynamics. Second, a
geometric microcanonical equivalence is found: microscopic realizations that share the same
geometric content of their energy
manifolds (in the sense of entering the
curvature sources of the flow) necessarily yield the same microcanonical thermodynamics. We demonstrate the full practical power of the formalism by reconstructing microcanonical response and identifying criticality across paradigmatic systems, from exactly solvable mean-field models to genuinely nontrivial short-range
lattice field theories and the 1D long-range XY model with $1/r^\alpha$ interactions.
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Soft Condensed Matter
Understanding the mechanisms of supported lipid membrane reshaping into tubular networks using quantitative DIC microscopy
David Regan, Paola Borri and Wolfgang Langbein
Biological membranes are known to form various structural motifs, from lipid
bilayers to tubular filaments and networks facilitating e.g. adhesion and
cell-
cell communication. To understand the biophysical processes underpinning lipid-lipid interactions in these systems, synthetic membrane models are crucial. Here, we demonstrate the formation of tubular networks from supported lipid membranes of controlled lipid composition on glass. We quantify tube radii using quantitative differential interference contrast (qDIC) and propose a biophysical mechanism for the formation of these structures, regulated by surface tension and lipid exchange with connected supported membranes. Two lipid types are investigated, namely DOPC and DC15PC, exhibiting a
liquid disordered and a solid ordered phase at room temperature, respectively. Tube formation is studied versus temperature, revealing bilamellar layers retracting and folding into tubes upon DC15PC lipids transitioning from
liquid to solid phase, which is explained by lipid transfer from bilamellar to unilamellar layers. This study introduces a novel model system for
bilayer tubes, allowing to elucidate the biophysics of lipid-lipid interactions governing lipid membrane reshaping into tubular structures, important for our understanding of biological membrane filaments.
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