Soft Condensed Matter · Cross-listed from physics.bio-ph
Emergent Self-Organisation of Intelligent Active Particles
Priyanka Iyer, Segun Goh and Gerhard Gompper
Intelligent active particles are characterized by self-propulsion, directional sensing of their environment, information processing, decision making and goal-oriented self-steering. This implies, in particular, the prevalence of non-reciprocal interactions, and the importance of information propagation through
agent groups. Examples include biological systems (
cells, insects, birds, fish, pedestrians) as well as engineered systems (nano- and microbots). As many
agents move in an aqueous medium, hydrodynamic interactions strongly affect the dynamics. The emergent dynamics includes the formation of swarms and flocks, predator-prey behavior, and the
navigation in complex environments.
Read the full abstract ▾
Statistical Mechanics
Anomalous Floquet Heating from Sparse Long-Range Interactions
Chenyue Guo, Andrea Pizzi and Hongzheng Zhao
Regular
lattices of interacting particles under a periodic drive typically heat with rate $\gamma \sim e^{-\mathcal{O}(\omega)}$ which is exponentially suppressed in drive frequency $\omega$. Here, we show that sparse infinite-range interactions, which have recently become accessible in
quantum simulators, can lead to anomalous heating with rate $\gamma \sim e^{-\mathcal{O}(\sqrt{\omega})}$. This anomaly originates from the broad distribution of coordination numbers across the network: as the driving frequency increases, heating becomes dominated by sites with larger coordination numbers, making the characteristic local energy scale relevant for heating grow with frequency. For small-world networks, we develop an analytic theory that thoroughly matches our large scale numerics. Finally, we discuss how network
topology can serve as a control knob for engineering non-
equilibrium phases of matter. Our results uncover a new mechanism for Floquet heating and suggest new routes toward stabilizing nonequilibrium phases in driven systems with programmable interaction networks.
Read the full abstract ▾
Materials Science
Multicomponent Grain Boundary Segregation Dilute-Limit Model and Its Effect on Nanocrystalline Stability
Georgiy Marchiy, Feodor Kuznetsov, Dmitry Samsonov et al. (+1 more)
Grain boundary segregation of solutes is a powerful tool for stabilizing nanocrystalline materials against grain growth. However, analytical models have been largely restricted to binary systems, leaving the stabilization potential of multicomponent
alloys poorly understood. In this work, we develop an analytical framework for an arbitrary number of solutes in the dilute limit of grain boundary concentrations based on segregation energy spectra computed via molecular dynamics. We demonstrate that multicomponent segregation synergistically expands the range of nanocrystalline
alloys that are thermodynamically stable against both grain growth and phase separation. Crucially, the model reveals that the cosegregation of almost any solutes enhances stability against phase separation, while the cosegregation of solutes with anti-correlated segregation spectra can suppress temperature-driven desegregation. This framework proposes a predictive tool for the rational design of thermally stable nanocrystalline
alloys using multicomponent doping.
Read the full abstract ▾
All authors Georgiy Marchiy, Feodor Kuznetsov, Dmitry Samsonov, Eugene Mukhin
Soft Condensed Matter · Cross-listed from physics.flu-dyn
Temperature distribution measurement on three-phase contact line in liquid nitrogen using two-color temperature-sensitive paint
Shione Fujiwara, Yasuhiro Egami, Osamu Kawanami et al. (+1 more)
Cryogenic phase-change phenomena play an important role in a wide range of engineering applications, including cryogenic cooling systems, superconducting technologies, and space propulsion systems. In particular, the three-phase contact line is recognized as a key region governing evaporation and heat transfer. However, direct measurements of temperature distributions near cryogenic three-phase contact lines remain limited because conventional infrared thermography becomes increasingly difficult at extremely low temperatures. In this study, a two-color temperature-sensitive paint (2C-TSP) technique was applied to visualize the temperature field around a
liquid-nitrogen three-phase contact line. A temperature-sensitive dye and a temperature-insensitive reference dye were incorporated into a single coating, enabling robust temperature measurements based on luminescence intensity ratios by compensating for changes in optical intensity caused by refraction and reflection at the
liquid-gas interface. Temperature distributions were measured under three heating conditions with heat fluxes of 110, 430, and 900 W/m2. The measured temperature fields revealed a localized temperature minimum at the observed three-phase contact line, suggesting localized cooling associated with phase change. Quantitative analysis showed that the average temperature in the
liquid region remained nearly constant, whereas the temperature in the gas region increased with increasing heat flux. These observations reveal a non-uniform thermal structure around the cryogenic three-phase contact line. The present results demonstrate that 2C-TSP is a promising technique for direct visualization of temperature fields around cryogenic three-phase contact lines and provides new insights into phase-change phenomena in
liquid nitrogen.
Read the full abstract ▾
All authors Shione Fujiwara, Yasuhiro Egami, Osamu Kawanami, Yu Matsuda
Mesoscale and Nanoscale Physics
Enabling Electrical Readout of Néel vector reversal in a van der Waals Antiferromagnet
Raghvendra Posti, Ravi Kumar Bandepalli, Wenhao Liu et al. (+14 more)
Owing to its robustness against external perturbations and intrinsically ultrafast dynamics, the Néel vector in antiferromagnets (AFMs) can enable the development of next-generation spintronic and magnonic devices for
memory and computing applications. To realize AFM-based
magnetic memory devices, one of the key requirements is to demonstrate electrical readout of 180-degree reversal of Néel vector in thin film AFMs, which remains critically missing. In this work, we report experimental demonstration of a novel transport methodology to detect Néel vector reversal in atomically thin films of a van der Waals (vdW) based A-type AFM. For this, we utilize
spin-dependent electronic band properties of CrSBr by coupling it to a
spin-polarized layer, separated by a tunnel barrier. In this configuration, the
spin-dependent tunnelling magnetoresistance (MR) becomes sensitive to the relative orientation between the magnetization of the reference electrode and the interfacial sublattice magnetization of the AFM layer, in turn enabling electrical detection of the Néel vector orientation. Importantly, the observed MR can also reveal 180-degree reversal of Néel vector in even-layers of CrSBr, wherein adjacent sublattice
magnetic layers are exactly compensated and the net magnetization vanishes and thus establishes a broadly applicable strategy for electrical detection of Néel vector in vdW-based AFMs.
Read the full abstract ▾
All authors Raghvendra Posti, Ravi Kumar Bandepalli, Wenhao Liu, Anshuman Sahoo, Pratyush Saud, Zixin Zhai, Aswin L. N. Kondusamy, Zhenhong Cui, I-Hsuan Kao, Aalok Tiwari, Thomas Poirier, James H. Edgar, Kenji Watanabe, Takashi Taniguchi, Bing Lv, Jyoti Katoch, Simranjeet Singh
Strongly Correlated Electrons
Magnetoelectric flat band induced by a $\sqrt{3}\times\sqrt{3}$ charge density wave in monolayer CrSe$_2$
Pablo Savino, M. del Carmen Fuente Santiago, Jan Phillips et al. (+4 more)
We investigate the electronic and
magnetic properties of the polar $\sqrt{3}\times\sqrt{3}$ charge-density-wave (CDW) phase of CrSe$_2$ using ab initio calculations. The CDW introduces a polar distortion out of the van der Waals plane that couples to the
spin-polarized Cr d states resulting in a remarkably flat electronic band exactly at the
Fermi level. We provide a microscopic understanding of the origin of the flat band by analyzing in detail the structural reconstruction, the effects of orbital hybridization,
crystal-field splittings,
spin-orbit coupling and electronic correlations. Our calculations show that due to the polar nature of the CDW distortion, an electric field can act as an external switch to induce the CDW phase, providing a way to manipulate strong correlations in the system.
Read the full abstract ▾
All authors Pablo Savino, M. del Carmen Fuente Santiago, Jan Phillips, Javier Corral Sertal, Adolfo O. Fumega, Santiago Blanco-Canosa, Victor Pardo
Materials Science
Breaking Bottlenecks in Solid Electrolyte Discovery with Large Artificial Intelligence Models
Eric Jianfeng Cheng, Min Hong, Zhiquan Zeng et al. (+22 more)
Solid electrolytes (SEs) are central to next-generation metal batteries, yet their discovery remains constrained by fragmented data, limited transferability of simulations, and slow experimental iteration. Unlike catalysis, where surface reactivity dominates, SEs require simultaneous optimization of bulk ion transport, defect chemistry, mechanical integrity, and interfacial stability. Here, we outline a framework for autonomous SE discovery enabled by large artificial intelligence (AI) models, including machine learning interatomic potentials (MLIPs) and large
language models (LLMs). We discuss the
evolution from static materials databases to dynamic, self-updating knowledge systems, the role of MLIPs in bridging density functional theory (DFT) and long-timescale ion migration, and the emergence of LLMs as engines for literature mining, hypothesis generation, and scientific
reasoning. We further describe a closed-loop architecture integrating AI-driven candidate design, multiscale simulation, uncertainty-aware selection, and experimental validation. Such systems shift SE research from intuition-guided exploration to data-informed, self-improving cycles. We conclude by highlighting challenges in data standardization, interfacial complexity, and reproducibility, and we propose design principles for building autonomous laboratories for solid-state battery materials.
Read the full abstract ▾
All authors Eric Jianfeng Cheng, Min Hong, Zhiquan Zeng, Chuanyu Liu, Qian Wang, Melissa Jane Meadowcroft, Vlad Badilita, Carlos Miguel Costa, Senentxu Lanceros-Méndez, Ying Li, Chenyao Ma, Weibo Gong, Surendra Martha, Aloysius Soon, Piao Ma, Di Zhang, Teguh Ariyanto, Sudaryanto, Hiroshi Kakinuma, Jie Zhao, Jiayu Peng, Pengfei Ou, Jun Lu, Shin-ichi Orimo, Hao Li
Materials Science
Dimensional Confinement Driven Scattering Inversion in NaCrTe$_2$
Himanshu Sharma, Bhawna Sahni, Tanusri Saha-Dasgupta et al. (+1 more)
Dimensionality reduction provides a powerful route to tune the electronic and
magnetic properties of van der Waals materials, yet its influence on electronic transport remains complex due to competing effects from
quantum confinement and modified scattering mechanisms. Here, we investigate this interplay in an
antiferromagnetic semiconductor $\text{NaCrTe}_2$ using first-principles calculations combined with the Boltzmann transport equation beyond the constant relaxation time approximation. Our results show that the monolayer limit induces a coupled magnetostructural reconstruction, reducing the band gap from $0.44$ eV (bulk) to $0.15$ eV (monolayer) and significantly enhancing the static dielectric constant. This
evolution triggers a fundamental scattering inversion: whereas bulk transport is limited by polar optical
phonon (POP) scattering, the monolayer becomes dominated by acoustic deformation potential (ADP) scattering. We show that this crossover originates from the simultaneous suppression of the Fröhlich interaction through enhanced dielectric screening and the amplification of acoustic scattering due to pronounced
lattice softening. These results clarify how the interplay between dielectric screening,
lattice stiffness, and band
topology governs transport in low-dimensional
magnetic semiconductors, providing a framework to optimize their electronic performance.
Read the full abstract ▾
All authors Himanshu Sharma, Bhawna Sahni, Tanusri Saha-Dasgupta, Aftab Alam
Statistical Mechanics
From Continuous-Time Random Walks to Laplace Tails
Omer Hamdi, Stanislav Burov and Eli Barkai
During Brownian motion, the displacement is normally distributed, a classical fact aligned with the central limit
theorem. However, single particle tracking in complex media such as glasses, living
cells, and colloidal suspensions often reveals pronounced exponential decay of the displacement distribution, known as Laplace tails. In a short letter, two of us presented the emergence of Laplace tails in the continuous time random walk (CTRW) framework. Here, a detailed complementary study is presented. By exploring the behavior of $Q_t(n)$, the probability that exactly $n$ renewals occur during time $t$, we develop a rate function-like framework for this quantity, valid for finite $t$. We show that $Q_t(n)$ exhibits exponential tails, which in turn give rise to exponential tails of the positional probability density function $P(x,t)$. Favorable comparison to finite-time numerical simulations and asymptotic large deviation rate functions establishes the validity of our results over a wide temporal range.
Read the full abstract ▾
Statistical Mechanics
The impact of population heterogeneity on the redundancy principle
Sergei Fedotov, Daniel Fears and Daniel Han
Biological signaling is often governed by extreme value statistics, where a rapid response relies on the fastest few out of a large redundant group of searchers. While extreme first passage time (FPT) theory is well established for homogeneous ensembles, its sensitivity to population heterogeneity remains open. We show that averaging over a heterogeneous population of memoryless random walkers gives rise to ensemble self-reinforcement. This heterogeneity drastically changes both the FPT and minimum FPT densities relative to a homogeneous ensemble with identical mean rates. The modal and minimum FPTs are an order of magnitude smaller for heterogeneous populations relative to homogeneous ones. Our exact analytical predictions establish that population heterogeneity is a parameter that biology can exploit and not merely noise to be averaged away.
Read the full abstract ▾
Materials Science
Quintic-Anharmonicity-Assisted Three-Phonon Scattering: A Previously Overlooked Same-Order Channel to Four-Phonon Scattering
Yi Xia
Four-
phonon scattering is widely regarded as the leading higher-order anharmonic correction to conventional three-
phonon description of anharmonic scattering and
lattice thermal transport. Here we show that diagrammatic perturbation theory contains another
phonon linewidth contribution of the same perturbation order, arising from the coupling between cubic and quintic anharmonic vertices. We derive and implement this contribution from first principles and identify it as a quintic-anharmonicity-assisted three-
phonon scattering channel. Although this process shares energy-conservation structure of the conventional three-
phonon process, its perturbative order and temperature dependence resemble those of the conventional four-
phonon process. For Si, we find that
phonon scattering from this additional channel is comparable to four-
phonon scattering over a broad frequency and temperature range, leading to a similar accelerated reduction of
lattice thermal conductivity at high temperatures. We further show that in strongly anharmonic AgCl, this channel can become comparable to the ordinary three-
phonon scattering even at room temperature. These results demonstrate that the commonly observed high-temperature enhanced scattering and suppression of
lattice thermal conductivity might not be attributed uniquely to four-
phonon process, and establish quintic-anharmonicity-assisted three-
phonon scattering as a previously overlooked same-order channel in anharmonic
lattice dynamics, which may be leveraged to uncover hidden microscopic thermal transport mechanisms.
Read the full abstract ▾
Statistical Mechanics
Out-of-equilibrium scaling of the particle density in quantum fermionic wires after a critical quenching of the chemical potential
H. Panagopoulos and E. Vicari
We study the out-of-
equilibrium scaling behavior of the particle density in
quantum fermionic Kitaev wires, after instantaneous
quantum quenches (QQs) of the chemical potential within their
quantum critical region. The critical scaling of the ground-state particle density is known to be subleading at its Ising-like
quantum transition, hidden by regular and logarithmic terms arising from peculiar mixings with the identity operator. This situation changes along the out-of-
equilibrium dynamics arising from QQs of the chemical potential to the critical point, starting from the ground state for
Hamiltonian parameters within the critical region. We analytically show that the difference between the post-QQ particle density and its critical value develops an out-of-
equilibrium scaling behavior, in terms of the dynamic scaling variable $\theta\sim t/\xi^z$ (where $t>0$ is the post-QQ time, $\xi$ is the length scale of the initial state, and $z$ is the dynamic critical exponent) associated with the post-QQ time
evolution. The scaling function turns out to have a peculiar singular behavior in the $\theta\to 0$ limit, apparently related to the anomalous
equilibrium scaling behavior of the particle density at the starting point of the QQ protocol. This provides analytical evidence of earlier
conjectures on the general emergence of post-QQ dynamic scaling behaviors of the subtracted particle density (supported by numerical finite-size scaling analyses), unlike their
equilibrium counterpart which turns out to be dominated by nonuniversal contributions.
Read the full abstract ▾
Soft Condensed Matter · Cross-listed from physics.bio-ph
Uniaxial poroelastic tendon model with crimped fibre recruitment reveals hysteresis
Zoe C. Godard, Sarah L. Waters and Derek E. Moulton
Fibre recruitment plays an important role in tendon. Due to their large water content, a popular modelling approach for tendons is poroelasticity. Within this framework some tendon studies have included fibres, though none have included crimped fibre recruitment. We present a one dimensional poroelastic model in which the solid skeleton is composed of a soft neo-Hookean background
matrix and crimped fibrils which do not bear load (FIB model). As the tissue is stretched, fibrils are straightened and contribute to load bearing. The fibre-reinforced tissue is compared to a tissue with a purely neo-Hookean (NH) skeleton in response to a uniaxial constant applied load (loading) and release of the load (unloading). The system dynamics are governed by a
diffusion equation where the
diffusion coefficient depends on stiffness. Within tendon parameter ranges, the FIB model is softer than the NH model, and so approaches steady state more slowly during loading. The presence of stiff, crimped fibrils increases bulk extension without excessively straining the fibrils, providing a natural protection mechanism for the tendon's structural components to load, in agreement with experiments. During unloading, the FIB model is much slower to relax as the tissue softens due to fibril re-crimping. This asymmetry in loading and unloading manifests as a hysteresis loop in the stress-strain curve averaged over the tendon. The hysteresis is reduced with increasing applied load. To the authors' knowledge, the finding of hysteresis within this framework is novel. The inclusion of fibrils allows for clearer biological interpretation and potential comparison to data. While the stress law employed in this study is bespoke for the application at hand by accounting for crimp and fibril recruitment, other fibril constitutive laws can readily be considered and incorporated into this framework.
Read the full abstract ▾
Disordered Systems and Neural Networks
The Physics of Topological Defects in Glasses
Arabinda Bera, Peter Schall, Timothy W. Sirk et al. (+2 more)
Topological defects play a central role in the mechanical behavior of crystalline materials, yet their relevance to amorphous solids has only recently begun to emerge. Over the last few years, theoretical, computational, and experimental studies have revealed the presence of well-defined topological invariants in vibrational eigenmodes, non-affine displacement fields, and deformation-induced vector fields of glasses. These defects have been shown to correlate strongly with soft spots, localized plastic rearrangements, yielding, and shear-band formation, suggesting a new perspective on the microscopic origins of plasticity in disordered materials. In this review, we provide a comprehensive overview of recent developments in the rapidly growing field of topological defects in glasses. We discuss the underlying theoretical concepts, including Burgers vectors, non-affine plasticity, vibrational modes, and topological invariants, and review recent numerical and experimental advances. Finally, we assess the current achievements, limitations, and open questions, and discuss future directions toward a unified topological description of plasticity and mechanical failure in amorphous solids.
Read the full abstract ▾
All authors Arabinda Bera, Peter Schall, Timothy W. Sirk, Vijayakumar Chikkadi, Alessio Zaccone
Statistical Mechanics · Cross-listed from math-ph
Typical geometry of self-repelling polymers in a constant force field
Kamil Khettabi and Yvan Velenik
We study a general class of self-repelling
polymers on $\mathbb Z^2$, including the simple random walk, the self-avoiding walk and the repulsive Domb-Joyce model, in the presence of a constant force field acting on each monomer. Conditioning the
polymer to have fixed length and fixed endpoints, we identify the limiting free energy and prove that typical trajectories concentrate exponentially near a deterministic macroscopic shape. This shape is characterized as the unique minimizer of a variational problem and can be interpreted as a geodesic of a height-dependent Finsler metric. We also analyze two limiting regimes with universal features: for small field strength, in the symmetric case, the geodesic is close to a classical catenary, while for large field strength it converges to a universal polygonal shape governed by the nearest-neighbor
lattice constraint.
Read the full abstract ▾
Statistical Mechanics
Universal Extraction of Quantum Critical Exponents and Phase Transitions via Tailored Hilbert Space
Ye Xiong
Finite-size scaling and the renormalization group form the central toolkit for analyzing
quantum phase transitions (QPTs). In this Letter, we introduce a novel
Hilbert-space tailoring scheme to probe
quantum critical phenomena. Applied to the second-order QPT of the one-dimensional (1D) XY model, our method yields precise critical points and exponents on
lattices containing merely 50 unit
cells. We further establish the universal applicability of this framework via investigations of the Berezinskii-Kosterlitz-Thouless transition in the 1D XXZ chain: critical parameters are recovered with as few as 12
lattice sites. This technique may open an alternative, efficient route to universally characterize QPT across many-body
lattice systems.
Read the full abstract ▾
Other Condensed Matter
The effect of pressure on the splitting in $^3$He in nematic aerogel
V.V. Dmitriev, D.V. Petrova, A.A. Soldatov et al. (+1 more)
Here, we present the results of an investigation of how the pressure affects the splitting of the superfluid transition temperature in $^3$He in anisotropic aerogel. It is well known that boundary conditions significantly influence the properties of superfluid phases in aerogel. When aerogel strands are coated with a $^4$He layer in
magnetic field, new phases, such as the polar, polar-distorted A (DA), polar-distorted B (DB), and $\beta$ phases, become energetically favorable. In contrast, without this coating, the system tends to favor phases resembling the bulk A, B, and A$_1$ phases. Our earlier results showed a nonlinear dependence of the superfluid transition temperature splitting in pure $^3$He, but the range of nonlinearity did not match the theoretical predictions based on
magnetic scattering effects. To further investigate this discrepancy, we performed measurements of the splitting under varying pressures for both pure $^3$He and with $^4$He coverage of the aerogel strands.
Read the full abstract ▾
All authors V.V. Dmitriev, D.V. Petrova, A.A. Soldatov, A.N. Yudin
Materials Science
Proximity-Induced Spin Reorientation in Monolayer CrI$_3$ on Hexagonal WTe$_2$
Dániel Tibor Pozsár, Marcell Balázs Sípos, Amador García-Fuente et al. (+7 more)
Magnetic anisotropy controls the orientation and thermal stability of two-dimensional
magnetic order. Predicting proximity-induced changes in anisotropy requires linking the electronic structure to microscopic
magnetic interactions and finite-temperature behavior. Here we study monolayer CrI$_3$ on hexagonal WTe$_2$ using a first-principles-to-finite-temperature workflow centered on relativistic
spin-
Hamiltonian mapping. We find that WTe$_2$ reorients the CrI$_3$ magnetization from out-of-plane to in-plane and substantially enhances the
magnetic ordering scale within the extracted
spin models. Analysis of the extracted
spin Hamiltonians shows that the reorientation is driven by a substrate-induced change in the balance between symmetric anisotropic exchange and onsite anisotropy. We establish a transferable workflow for proximity-controlled magnetism in two-dimensional van der Waals
heterostructures.
Read the full abstract ▾
All authors Dániel Tibor Pozsár, Marcell Balázs Sípos, Amador García-Fuente, Péter Nemes-Incze, Viktor Ivády, Efrén Navarro-Moratalla, Jaime Ferrer, László Szunyogh, László Oroszlány, Zoltán Tajkov
Soft Condensed Matter
Broadband molecular dynamics simulation of fluid inertial effects in confined Brownian motion
Quentin Thomas, Clara Mefo Sop, Maxime Lavaud et al. (+3 more)
Hydrodynamic
memory governs Brownian motion over a broad range of timescales, from acoustic wave propagation at short times to diffusive relaxation at long times. While confinement-induced corrections to Brownian
diffusion are well established, how confinement modifies the full hydrodynamic response remains less explored. In this Letter, we use molecular-dynamics simulations of a neutrally buoyant colloidal particle in an explicit solvent to resolve the velocity autocorrelation function across a broad hydrodynamic spectrum. In the bulk, the simulations recover compressibility, added mass, the hydrodynamic long-time tail, and Stokes-Einstein
diffusion without adjustable parameters. Near a rigid wall, the velocity correlations become anisotropic, their algebraic tails are modified, and the
diffusion coefficients are reduced. Most importantly, the short-time dynamics reveals a pronounced enhancement of the effective added mass as the wall is approached. As such, the velocity autocorrelation function appears as a central quantity to bridge the zero-frequency mobility and the high-frequency inertial behaviour of a confined Brownian particle.
Read the full abstract ▾
All authors Quentin Thomas, Clara Mefo Sop, Maxime Lavaud, Yacine Amarouchene, Thomas Salez, Pascal Damman
Statistical Mechanics · Cross-listed from physics.chem-ph
Investigating causality between principal components in protein dynamics
Debarshi Banerjee, Ali Hassanali and Alessandro Laio
Principal component analysis (PCA) is widely used to characterize collective
protein motions from molecular dynamics (MD) simulations. While PCA identifies the dominant modes of structural fluctuation, it does not reveal whether different principal components (PCs) causally influence each other. Here, we investigate this question using a recently introduced causal-discovery framework [Del Tatto et al, PNAS 2024], which allows to infer putative causal asymmetries between high-dimensional time series. We apply this approach to long-timescale MD trajectories of two
proteins. By analyzing relationships among PCs, we construct directed networks describing how PCs influence one another across time scales. These directional relationships, whose existence is a necessary condition for the presence of a causal link, are not captured by conventional covariance-based analyses and provide information that is complementary to PCA and Time-lagged Independent Component Analysis (TICA). Our results suggest that our causal inference approach can uncover previously hidden aspects of the dynamical organization of
protein motions and offer a new perspective on this very popular class of collective variables.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from nlin.CD
Recursive behavior in a diatomic FPUT lattice
Guo Deng, Andrea Pezzi, Genghong Lin et al. (+1 more)
We study the diatomic FPUT
lattice with cubic anharmonic potential, and analyze the recurrent behaviour of its solutions. We find that two distinct types of recurrence occur. One type is the classic FPUT recurrence; for such recurrence, we find that the relation between recurrence period and nonlinear strength is similar to that in the monatomic case. The other type, which cannot exist in the monatomic
lattice, is the recurrence due to the interactions between modes in the two branches of the dispersion relation. Indeed, we prove the existence of the optical-acoustical-acoustical resonant interaction between three
Fourier modes for which a recurrent behavior in the distribution of the energy is observed. In addition, we develop a reduced
Fourier-space dynamical model that reproduces the same recurrent behavior. We assess the robustness of our results through numerical simulations of the diatomic Toda
lattice and the diatomic granular chain; in both cases, the same recursive behavior is observed. Finally, in the continuous limit, we derive from the diatomic model a system of three coupled PDEs which are known to be integrable.
Read the full abstract ▾
All authors Guo Deng, Andrea Pezzi, Genghong Lin, Miguel Onorato
Statistical Mechanics
Evaluating the solution performance of the augmented Lagrangian function on Ising machines
Shunsuke Awai, Takuro Itoh, Keita Takahashi et al. (+2 more)
We apply the augmented Lagrangian function (ALF) as a formulation for Ising machines and evaluate its performance by time-to-epsilon (\mathrm{TT\varepsilon}). The ALF has been well studied in continuous optimization for its numerical stability and convergence, and its advantage over the penalty function formulation is demonstrated here through the following results. Using the quadratic knapsack problem as a
benchmark, we examine the dependence of \mathrm{TT\varepsilon} on the hyperparameters \mu and \lambda. The augmented Lagrangian formulation reduces \mathrm{TT\varepsilon} by roughly an order of magnitude compared with the penalty function formulation, keeping \mu small while obtaining feasible solutions and, for representative parameter settings, reaching high-precision solutions earlier in the search. These findings indicate that the augmented Lagrangian function is a promising formulation for improving the solution performance of Ising machines.
Read the full abstract ▾
All authors Shunsuke Awai, Takuro Itoh, Keita Takahashi, Kotaro Tanahashi, Shu Tanaka
Materials Science
One-dimensional self-organization of water molecules in proton conducting Andersson-Wadsley titanates
Mathilde Arnaud, Guillaume Benas, Narimane Meziani et al. (+13 more)
Layered alkali titanates with M 2 Ti 2 O 5 chemical formula (MTO, M=K,Rb) belonging to the Andersson-Wadsley perovskite family spontaneously incorporate water to form MTO.(H 2 O) x compounds, which exhibit superionic conductivity. At very low hydration x, scanning electron microscopy evidences one-dimensional heterogeneous patterns oriented along ___ b that are arranged in an orderly manner. At higher hydration, the material is observed to spontaneously exfoliate by creating (001) surfaces. Simulations carried out using Density Functional Theory reveal an ordered arrangement of the guest water molecules in Rb 2 Ti 2 O 5 , with strong hydrogen bonds between the water molecules and the apical oxygen of the host
crystal. At low hydration x, the water molecules form self-organized one dimensional (1D) double chains along ___ b. Further increase of the water content leads to the creation of hydrated (001)-surfaces that are made of densely packed water chains in agreement with the infrared spectroscopy measurements. Rb 2 Ti 2 O 5 exhibits highly anisotropic
proton conductivity, with respect to the
crystal orientation, with super-ionic conductivity along ___ b reaching 3 mS/cm at room temperature after hydration. The combined observations and simulations suggest that these water chains are thus at the root of fast
proton conduction, which is likely powered by a Grotthuss-like mechanism.
Read the full abstract ▾
All authors Mathilde Arnaud, Guillaume Benas, Narimane Meziani, Armel Descamps-Mandine, Claudie Josse, Sophia Akkari, Thierry Douillard, Sofia de Sousa Coutinho, Mélanie de Vos, Stéphane Holé, Gwenaëlle Rousse, Rémi Federicci, Sylvain Franger, Paola Giura, Fabio Finocchi, Brigitte Leridon
Materials Science
Nonradiative Multiphonon Model of Deep-Level Transient Spectroscopy: Beyond Henry-Lang Model
Menglin Huang, Shanshan Wang, Junjie Zhou et al. (+2 more)
Deep-level transient spectroscopy (DLTS) is a key experimental method for defect characterization, yet its analysis remains controversial, and the two widely used models developed by Henry and Lang are conflicting. We show that the Henry-Lang model is valid only under the Condon approximation, as well as high-temperature and strong electron-
phonon coupling approximations, which cause incorrect temperature dependence of carrier emission and capture. Here we develop a rigorous nonradiative multiphonon (NMP) model, and demonstrate that the temperature dependence is governed predominantly by effective
phonons with large
phonon wavefunction overlap and high thermal occupation. The effective
phonons are strongly correlated with
lattice relaxation.The neglect of this correlation in existing DLTS models introduces substantial errors when they are used to fit DLTS-measured emission rates. Our comparison for 21 different defects in 12
semiconductors, including Si, SiC and Ga$_2$O$_3$, shows that the Henry-Lang model gives a completely different temperature dependence of carrier capture cross section from that obtained using the rigorous NMP model, with errors reaching up to six orders of magnitude at room temperature. Our study highlights the necessity of revisiting previous DLTS analysis studies using the rigorous NMP model.
Read the full abstract ▾
All authors Menglin Huang, Shanshan Wang, Junjie Zhou, Xinjing Guo, Shiyou Chen
Mesoscale and Nanoscale Physics
Band offsets and stability of WSe$_2$/RuCl$_3$ van der Waals charge-transfer contacts
Thomas S. Nielsen, Edvard Solbrekken, Christian Overby et al. (+7 more)
The layered Mott
insulator $\alpha$-RuCl$_3$ induces degenerate hole-doping in two-dimensional
semiconductors due to its large electron affinity, making it a promising charge-transfer material for establishing ohmic contacts in electronic devices. In order to assess the applicability and guide the design of devices incorporating RuCl$_3$ it is critical to determine the electronic structure and robustness of the band offsets that underpin the transport properties of
semiconductors in contact with RuCl$_3$. Here, we apply micro-focused angle-resolved photoemission spectroscopy to determine the electronic structure of single-layer WSe$_2$ contacted to RuCl$_3$ on hexagonal boron nitride substrates. We find that formation of a functioning WSe$_2$/RuCl$_3$ contact leads to a valence band shift of $(0.68 \pm 0.05)$ eV towards the
Fermi energy in WSe$_2$. The charge transfer effect is challenging to observe as it depends sensitively on fabrication conditions such as solvent exposure, quality of interface encapsulation and heating of RuCl$_3$, imposing strict requirements on device design to attain high-quality contacts.
Read the full abstract ▾
All authors Thomas S. Nielsen, Edvard Solbrekken, Christian Overby, Christian V-B. Fokdal, Alfred J. H. Jones, Zhihao Jiang, Chakradhar Sahoo, Kenji Watanabe, Takashi Taniguchi, Søren Ulstrup
Statistical Mechanics · Cross-listed from quant-ph
Initial-state-dependent dephasing effect in non-Hermitian Su-Schrieffer-Heeger models
Tao Min and Junjie Liu
Understanding the dynamical
evolution of non-Hermitian systems under external dissipation is essential for devising realistic non-Hermitian
quantum devices that surpass the capabilities of their Hermitian counterparts. Dephasing, a major realistic dissipation, has an impact on non-Hermitian systems that remains largely unexplored. Here, we focus on finite-sized non-Hermitian Su-Schrieffer-Heeger (SSH)
lattice models with alternating gain and loss in real space and examine the dynamical
evolution of the trace distance under pure dephasing. By tuning system parameters, this model supports phases with either parity-time or anti-parity-time
symmetries, enabling us to explore the dephasing effect across different non-Hermitian
symmetry regimes within a single platform. While the trace distance exhibits distinct dynamical behaviors across the different phases in the absence of dephasing, its response to dephasing is largely
symmetry-independent but instead initial-state dependent. By varying the initial states, we find that dephasing affects the trace distance in two qualitatively different ways. For initial states that differ only in their coherences, dephasing accelerates the decay of the trace distance, destroying the phase information in much the same way as in Hermitian systems. In contrast, for initial states that differ only in their populations, strong dephasing can partially or completely stabilize the trace distance over a wide transient regime before its eventual decay. We attribute these metastable stabilization phenomena to the alternating gain and loss in the system and confirm their absence in Hermitian counterparts. Our findings reveal the intricate dynamical response of non-Hermitian SSH models to dephasing, thereby facilitating their potential applications.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Gate-Controlled Spin Qubits in Confined Altermagnets
Hamed Vakili
We propose gate-defined
spin qubits in electrostatically confined altermagnetic
quantum dots. Elliptical confinement of the $d$-wave altermagnetic structure produces a low-energy doublet with opposite
spin polarization. For the range of parameters used here, the
qubit states energy gap lies in the microwave range while the leakage gap remains in the meV range. Even without
spin-orbit coupling, time-dependent simulations show that a phase-controlled quadrupolar gate drive about a fixed bias point implements $X_{\pi/2}$ and $X_\pi$ rotations by resonantly modulating the confinement anisotropy. We extend the study to two-
qubits using a double
quantum dot. We show that the double
quantum dot spectrum can be cleanly projected onto isolated
quantum dot product states with a nonzero nonlocal Pauli block in the effective logical two-
qubit Hamiltonian. Resonant central-barrier modulation then drives the logical two-
qubit component close to a maximally entangled state. These calculations show anisotropic altermagnetic
quantum dots as a route to locally gate-controlled
spin qubits without requiring
spin-orbit coupling.
Read the full abstract ▾
Strongly Correlated Electrons
Fluctuation exchange study on the electron-hole asymmetry of the superconductivity across 1/3 filling in the trilayer Hubbard model
Yushi Yamada, Masataka Kakoi, Masayuki Ochi et al. (+1 more)
We study within the fluctuation exchange approximation the trilayer Hubbard model where three layers of the Hubbard model are coupled by large interlayer hoppings so that the overlap of the bonding, nonbonding, and antibonding bands is relatively small. We pay special
attention to the band fillings close to 1/3, for which the bonding and nonbonding bands as a whole are close to half filling. For relatively small values of the onsite $U$, superconductivity roughly exhibits electron-hole symmetric behavior, as expected for a nearly half-filled two-band system. By contrast, an asymmetry appears when $U$ becomes large, where superconductivity is more favored in the hole-doped regime, i.e., in the regime where electrons are removed from 1/3 filling. We attribute this asymmetry to the asymmetric renormalization of the bonding, nonbonding, and antibonding bands when $U$ is large.
Read the full abstract ▾
All authors Yushi Yamada, Masataka Kakoi, Masayuki Ochi, Kazuhiko Kuroki
Strongly Correlated Electrons
Density-wave order enhances the phonon thermal Hall effect in a trilayer nickelate
Qiaochao Xiang, Enkang Zhang, Xiaokang Li et al. (+6 more)
Ruddlesden–Popper nickelates have emerged as a promising platform for high-temperature superconductivity, yet the role of
lattice degrees of freedom in their correlated normal state remains largely unexplored. Here, we report the observation of a finite
phonon thermal
Hall effect in the trilayer nickelate La$_4$Ni$_3$O$_{10}$ at ambient pressure. Remarkably, the thermal
Hall response is strongly enhanced below the density-wave transition at $T^*\approx140$ K, exhibiting two distinct plateaus in the thermal
Hall resistivity. The characteristic energy scale extracted from the thermal
Hall response ($\sim4.1$ meV) closely matches the
magnon–
phonon crossing span energy ($\sim3.2$ meV), pointing to
magnon–
phonon hybridization as the primary mechanism enhancing the thermal
Hall effect. These results provide new insight into the interplay between
lattice and
spin excitations in nickelates, with implications for understanding both their superconductivity and the multiple possible origins of insulating thermal
Hall signals.
Read the full abstract ▾
All authors Qiaochao Xiang, Enkang Zhang, Xiaokang Li, Xiaodong Guo, Mengfei Zhu, Jun Zhao, Guang-Ming Zhang, Liang Li, Zengwei Zhu
Superconductivity
Multiple phases in K2Cr3As3: a playground for manipulating topological superconductivity
Seigo Ogawa, Tomoki Miyoshi, Saki Uchida et al. (+4 more)
Spin-triplet topological
superconductors are rare but of fundamental interest as they can host Majorana bound states that can be used in fault-tolerant
quantum computing. Recent efforts have been devoted to searching for
spin-triplet states in U-based compounds, but these materials have a low transition temperature (Tc) and coexisting competing orders, which creates significant experimental challenges and often leads to contradictory conclusions. The Cr-based candidate K2Cr3As3 offers a promising alternative: it has a much higher Tc of 6.2 K and no
magnetic order. Here we report a hallmark signature of
spin-triplet superconductivity arising from the internal
spin degrees of freedom via
nuclear magnetic resonance measurements, and demonstrate the high tunability of the topological phases. We discovered three distinct superconducting phases and revealed the
evolution of the paired-
spins direction (d(k)-vector). At low
magnetic fields, K2Cr3As3 evolves from a helical (Phase A) to a
chiral state (Phase B) with a rotation of the d(k)-vector from in-plane to out-of-plane direction upon cooling, although both phases have point nodes in the gap. A linenodal gap is realized in the high-field Phase C, where the d(k)-vector lies in the basal plane. These findings establish K2Cr3As3 as a model
spin-triplet
superconductor and a promising platform for manipulating topological phases.
Read the full abstract ▾
All authors Seigo Ogawa, Tomoki Miyoshi, Saki Uchida, Kazuaki Matano, Shinji Kawasaki, Yoshihiko Inada, Guo-qing Zheng