CMP Journal 2025-04-08
Statistics
Nature: 1
Nature Materials: 1
Nature Nanotechnology: 1
Nature Physics: 2
Physical Review Letters: 17
Physical Review X: 2
arXiv: 112
Nature
A Nd@C82-polymer interface for efficient and stable perovskite solar cells
Original Paper | Energy | 2025-04-07 20:00 EDT
Yuexin Lin, Zhichao Lin, Shili Lv, Yuan Shui, Wenjing Zhu, Zuhong Zhang, Wenhan Yang, Jinbo Zhao, Hao Gu, Junmin Xia, Danning Wang, Fenqi Du, Annan Zhu, Jin Liu, Hairui Cai, Bin Wang, Nan Zhang, Haibin Wang, Xiaolong Liu, Tao Liu, Chuncai Kong, Di Zhou, Shi Chen, Zhimao Yang, Tao Li, Wei Ma, Guojia Fang, Luis Echegoyen, Guichuan Xing, Shengchun Yang, Tao Yang, Wenting Cai, Meng Li, Wei Huang, Chao Liang
A critical challenge in the commercialization of perovskite solar cells (PSCs) is the simultaneous attainment of high power conversion efficiency (PCE) and high stability. Employing polymers interfaces in PSCs can enhance durability by blocking water and oxygen, and by suppressing ions interdiffusion, but their electronic shielding poses a challenge for efficient and stable PSCs1-3. In this study, we report a magnetic endohedral metallofullerene Nd@C82-polymer coupling layer, which features ultra-fast electron extraction and in-situ encapsulation, thereby promoting homogeneous electron extraction and suppressing ions interdiffusion. The Nd@C82-polymer coupling layer in PSCs exhibited PCE of 26.78% (certified 26.29%) and 23.08% with an aperture area of 0.08 square centimetres and 16 square centimetres (modules), respectively. The unencapsulated devices retained ~82% of the initial PCE after 2,500 hours of continuous 1-sun maximum power point operation at 65 °C.
Energy, Solar cells
Nature Materials
Frustrated spin-1/2 chains in a correlated metal
Original Paper | Magnetic properties and materials | 2025-04-07 20:00 EDT
X. Y. Li, A. Nocera, K. Foyevtsova, G. A. Sawatzky, M. Oudah, N. Murai, M. Kofu, M. Matsuura, H. Tamatsukuri, M. C. Aronson
Electronic correlations lead to heavy quasiparticles in three-dimensional (3D) metals, and their collapse can destabilize magnetic moments. It is an open question whether there is an analogous instability in one-dimensional (1D) systems, unanswered due to the lack of metallic spin chain materials. We report neutron scattering measurements and density matrix renormalization group calculations establishing spinons in the correlated metal Ti4MnBi2, confirming that its magnetism is 1D. Ti4MnBi2 is inherently frustrated, forming near a quantum critical point that separates different phases at temperature T = 0. One-dimensional magnetism dominates at the lowest T, and is barely affected by weak interchain coupling. Ti4MnBi2 is a previously unrecognized metallic spin chain in which 3D conduction electrons become strongly correlated due to their coupling to 1D magnetic moments.
Magnetic properties and materials, Phase transitions and critical phenomena
Nature Nanotechnology
Li+(ionophore) nanoclusters engineered aqueous/non-aqueous biphasic electrolyte solutions for high-potential lithium-based batteries
Original Paper | Batteries | 2025-04-07 20:00 EDT
Xiyue Zhang, Travis P. Pollard, Sha Tan, Nan Zhang, Jijian Xu, Yijie Liu, An L. Phan, Weiran Zhang, Fu Chen, Chongyin Yang, Enyuan Hu, Xiao-Qing Yang, Oleg Borodin, Chunsheng Wang
The use of aqueous/non-aqueous biphasic electrolyte solutions in Li-based battery systems circumvents the limitations of poor reductive stability of aqueous electrolyte solutions, broadening their electrochemical stability window. However, aqueous/non-aqueous electrolytes suffer from biphasic mixing and high impedance when Li ions cross the biphasic interface. Here we propose the use of 12-crown-4 (12C4) and tetraglyme (G4) as lithium ionophores to form Li+(ionophore) nanoclusters in both non-aqueous and aqueous phases to overcome the interface challenges in biphasic electrolytes. The Li+(ionophore) nanoclusters have the H2O-excluding inner Li+ solvation structure in non-polar 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE), allowing fast charge transport across the biphasic interface without solvent mixing or water shuttling. A tailored electrolyte formulation comprising the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, 12C4, TTE and H2O solvents (labelled LiTFSI-12C4@TTE/H2O) demonstrates low impedance (2.7 Ω cm-2) at the TTE/H2O interface and enabling 2,000 cycles of prelithiated graphite||LiFePO4 coin cells at 850 mA g-1 with an average Coulombic efficiency of 99.8%. Single-layer 22.5 mAh Li||LiMn2O4 pouch cells using LiTFSI-12C4@TTE/H2O electrolyte with G4 delivered a stable discharge capacity of about 1.3 mAh cm-2 for 80 cycles at 0.5 mA cm-2.
Batteries, Electrochemistry, Energy storage, Materials for energy and catalysis
Nature Physics
Concurrent spin squeezing and field tracking with machine learning
Original Paper | Atomic and molecular physics | 2025-04-07 20:00 EDT
Junlei Duan, Zhiwei Hu, Xingda Lu, Liantuan Xiao, Suotang Jia, Klaus Mølmer, Yanhong Xiao
Squeezing and entanglement play crucial roles in approaches for quantum metrology. Yet, demonstrating quantum enhancement in continuous signal tracking remains a challenging endeavour because simultaneous entanglement generation and signal perturbations are often incompatible. We demonstrate that concurrent steady-state spin squeezing and sensing are possible using continuous quantum non-demolition measurements under constant optical pumping. We achieve a sustained spin-squeezed state with a large ensemble of hot atoms using metrologically relevant steady-state squeezing. We further employ the system to track different types of continuous time-fluctuating magnetic fields, and we demonstrate the use of deep learning models to infer the time-varying fields from an optical measurement. The quantum enhancement due to spin squeezing was verified by a degraded performance in test experiments where the spin squeezing was deliberately prevented. These results represent an advance in continuous quantum-enhanced metrology with entangled atoms, including the training and application of a deep neural network to infer complex time-dependent perturbations.
Atomic and molecular physics, Quantum metrology
Mode-resolved, non-local electron-phonon coupling in two-dimensional spectroscopy
Original Paper | Electronic properties and materials | 2025-04-07 20:00 EDT
Sheng Qu, Vishal K. Sharma, Jaco J. Geuchies, Maksim Grechko, Mischa Bonn, Falko Pientka, Heejae Kim
Electron-phonon coupling is fundamental to condensed-matter physics, governing various physical phenomena and properties in both conventional and quantum materials. Here we propose and demonstrate two-dimensional electron-phonon coupling spectroscopy that can directly extract the electron-phonon coupling matrix elements for specific phonon modes and different electron energies. Using this technique, we measure the electron energy dependence of the electron-phonon coupling strength for individual phonon modes. It allows us to identify distinct signatures distinguishing non-local Su-Schrieffer-Heeger-type couplings from local Holstein-type couplings. Applying this methodology to a methylammonium lead iodide perovskite, we reveal particularly different properties, for example, temperature dependence or anisotropy, of the electron-phonon couplings of two pronounced phonon modes. Our approach provides insights into the microscopic origin of the electron-phonon coupling and has potential applications in phonon-mediated ultrafast control material properties.
Electronic properties and materials, Ultrafast photonics
Physical Review Letters
Universal Stochastic Equations of Monitored Quantum Dynamics
Research article | Dynamical phase transitions | 2025-04-07 06:00 EDT
Zhenyu Xiao, Tomi Ohtsuki, and Kohei Kawabata
We investigate the monitored quantum dynamics of Gaussian mixed states and derive the universal Fokker-Planck equations that govern the stochastic time evolution of entire density-matrix spectra, obtaining their exact solutions. From these equations, we reveal an even-odd effect in purification dynamics: whereas entropy exhibits exponential decay for an even number $N$ of complex fermions, algebraic decay with divergent purification time occurs for odd $N$ as a manifestation of dynamical criticality. Additionally, we identify the universal fluctuations of entropy in the chaotic regime, serving as a nonunitary counterpart of the universal conductance fluctuations in mesoscopic electronic transport phenomena. Furthermore, we elucidate and classify the universality classes of nonunitary quantum dynamics based on fundamental symmetry. We also validate the universality of these analytical results through extensive numerical simulations across different types of models.
Phys. Rev. Lett. 134, 140401 (2025)
Dynamical phase transitions, Hybrid quantum systems, Open quantum systems, Quantum correlations in quantum information, Quantum measurements, Quantum transport, Fokker-Planck equation, Random matrix theory
Quantum Trails and Memory Effects in the Phase Space of Chaotic Quantum Systems
Research article | Chaos | 2025-04-07 06:00 EDT
Andrea Pizzi
The eigenstates of a chaotic system can be enhanced along underlying unstable periodic orbits in so-called quantum scars, making it more likely for a particle launched along one such orbits to be found still there at long times. Unstable periodic orbits are, however, a negligible part of the phase space, and a question arises regarding the structure of the wave function elsewhere. Here, we address this question and show that a weakly dispersing dynamics of a localized wave packet in phase space leaves a ‘’quantum trail’’ on the eigenstates, that is, makes them vary slowly when moving along trajectories in phase space, even if not periodic. The quantum trails underpin a remarkable dynamical effect: for a system initialized in a localized wave packet, the long-time phase-space distribution is enhanced along the short-time trajectory, which can result in ergodicity breaking. We provide the general intuition for these effects and prove them in the stadium billiard, for which an unwarping procedure allows us to visualize the phase space on the two-dimensional space of the page.
Phys. Rev. Lett. 134, 140402 (2025)
Chaos, Quantum interference effects, Quantum scars, Billiards, Quantum billiards, Semiclassical methods
Novel Azimuthal Observables from Two-Photon Collision at ${e}^{+}{e}^{- }$ Colliders
Research article | Chiral perturbation theory | 2025-04-07 06:00 EDT
Yu Jia, Jian Zhou, and Ya-jin Zhou
In this Letter, we advocate a set of novel azimuthal-angle-related observables associated with exclusive hadron production from two-photon fusion at ${e}^{+}{e}^{- }$ colliders, taking the $\gamma \gamma \rightarrow \pi \pi $ as a benchmark process. As a direct consequence of the linearly polarized quasireal photons emitted off the electron and positron beams, the $\mathrm{cos}2\phi $ azimuthal asymmetry in dipion production is predicted within the transverse-momentum-dependent factorization framework. In numerical analysis, we take the helicity amplitudes of $\gamma \gamma \rightarrow \pi \pi $ determined from the partial wave solutions in dispersion relation as input, and find that the predicted $\mathrm{cos}2\phi $ azimuthal modulation may reach 40% for the typical kinematical setup of Belle 2 and BESIII experiments. Future accurate measurement of this azimuthal asymmetry may facilitate the direct extraction of the relative phase between two helicity amplitudes with photon helicity configurations $++$ and $+- $. This knowledge provides a valuable input for the dispersive determination of the hadronic light-by-light contributions.
Phys. Rev. Lett. 134, 141901 (2025)
Chiral perturbation theory, Particle phenomena, Quantum chromodynamics, Mesons, Photons, Polarization
Phases of Theories with ${\mathbb{Z}}_{N}$ 1-Form Symmetry, and the Roles of Center Vortices and Magnetic Monopoles
Research article | Color confinement | 2025-04-07 06:00 EDT
Mendel Nguyen, Tin Sulejmanpasic, and Mithat Ünsal
We analyze the phases of theories having a microscopic ${\mathbb{Z}}{N}$ 1-form symmetry, starting with a topological BF theory and deforming it so that only the microscopic symmetry is preserved. These theories have a well-defined notion of confinement, prototypical examples being pure $\mathrm{SU}(N)$ and ${\mathbb{Z}}{N}$ gauge theories in the continuum and on the lattice. Our analysis shows that the generic phases are in $d=2$, only the confined phase; in $d=3$, both the confined phase and the topological BF phase; and in $d=4$, the confined phase, the topological BF phase, and a Coulomb phase. We construct a ${\mathbb{Z}}_{N}$ lattice gauge theory with a deformation that, surprisingly, produces up to ($N- 1$) photons. We give an interpretation of these findings in terms of the behaviors of two competing drivers of confinement—magnetic monopoles and center vortices—and conclude that proliferation of center vortices is necessary but insufficient for confinement, while proliferation of magnetic monopoles is both necessary and sufficient.
Phys. Rev. Lett. 134, 141902 (2025)
Color confinement, Gauge theories, Lattice field theory, Monopoles, Topological field theories, Vortices in field theory
Observation of $t\overline{t}$ Production in Pb+Pb Collisions at $\sqrt{ {s}_{\mathrm{NN}}}=5.02\text{ }\text{ }\mathrm{TeV}$ with the ATLAS Detector
Research article | Quark-gluon plasma | 2025-04-07 06:00 EDT
G. Aad et al. (ATLAS Collaboration)
*et al.*Top quarks and antiquarks have been detected in heavy-ion collisions at the Large Hadron Collider, showing that all six quark flavors were present in the Universe’s first moments.
Phys. Rev. Lett. 134, 142301 (2025)
Quark-gluon plasma, Relativistic heavy-ion collisions, Top quark
Suppressing the Decoherence of Alkali-Metal Spins at Low Magnetic Fields
Research article | Atomic & molecular collisions | 2025-04-07 06:00 EDT
Mark Dikopoltsev, Avraham Berrebi, Uriel Levy, and Or Katz
Interactions of electron spins with rotational degrees of freedom during collisions or with external fields are fundamental processes that limit the coherence time of spin gases. We experimentally study the decoherence of hot cesium spins dominated by spin rotation interaction during binary collisions with ${\mathrm{N}}_{2}$ molecules or by absorption of near-resonant light. We report an order of magnitude suppression of the spin decoherence rate by either of those processes at low magnetic fields. This work extends the use of magnetic fields as a control knob, not only to suppress decoherence from random spin-conserving processes in the spin-exchange relaxation free (SERF) regime but also to suppress processes that relax electron spins rather than conserve them.
Phys. Rev. Lett. 134, 143201 (2025)
Atomic & molecular collisions, Light-matter interaction, Optical pumping, Quantum optics
Light-Field Dressing of Transient Photoexcited States above the Fermi Energy
Research article | Electronic structure | 2025-04-07 06:00 EDT
Fei Wang, Wanying Chen, Changhua Bao, Tianyun Lin, Haoyuan Zhong, Hongyun Zhang, and Shuyun Zhou
Time-periodic light field provides an emerging pathway for dynamically engineering quantum materials by forming hybrid states between photons and Bloch electrons. So far, experimental progress on light-field dressed states has been mainly focused on the occupied states; however, it is unclear if the transient photoexcited states above the Fermi energy ${E}{F}$ can also be dressed, leaving the dynamical interplay between photoexcitation and light-field dressing elusive. Here, we provide direct experimental evidence for light-field dressing of the transient photoexcited surface states above ${E}{F}$, which exhibits distinct dynamics with a delay response as compared to light-field dressed states below ${E}_{F}$. Our work reveals the dual roles of the pump pulse in both photoexcitation and light-field dressing, providing a more comprehensive picture with new insights on the light-induced manipulation of transient electronic states.
Phys. Rev. Lett. 134, 146401 (2025)
Electronic structure, Light-matter interaction, Floquet systems, Topological insulators, Time & angle resolved photoemission spectroscopy
Higher Berry Curvature from the Wave Function. I. Schmidt Decomposition and Matrix Product States
Research article | Symmetry protected topological states | 2025-04-07 06:00 EDT
Ophelia Evelyn Sommer, Xueda Wen, and Ashvin Vishwanath
Higher Berry curvature (HBC) is the proposed generalization of Berry curvature to infinitely extended systems. Heuristically, HBC captures the flow of local Berry curvature in a system. Here, we provide a simple formula for computing the HBC for extended $d=1$ systems at the level of wave functions using the Schmidt decomposition. We also find a corresponding formula for matrix product states and show that for translationally invariant matrix product states this gives rise to a quantized invariant. We demonstrate our approach with an exactly solvable model and numerical calculations for generic models using the infinite density matrix renormalization group algorithm.
Phys. Rev. Lett. 134, 146601 (2025)
Symmetry protected topological states, Topological phases of matter, Transport phenomena, Topological materials, Tensor network methods
Photonic Chiral State Transfer near the Liouvillian Exceptional Point
Research article | Phase transitions | 2025-04-07 06:00 EDT
Huixia Gao, Konghao Sun, Dengke Qu, Kunkun Wang, Lei Xiao, Wei Yi, and Peng Xue
The first experimental confirmation of transient chiral dynamics near a Liouvillian exceptional point reveals a scaling law for chirality, suggesting a general experimental scheme to study dissipative quantum systems.
Phys. Rev. Lett. 134, 146602 (2025)
Phase transitions, Quantum state transfer, Topological effects in photonic systems, Topological phase transition, Topological phases of matter, Exceptional points, Non-Hermitian systems, Chiral symmetry
Nanoscale Casimir Force Softening Originated from Quantum Surface Responses
Research article | Casimir effect & related phenomena | 2025-04-07 06:00 EDT
Hewan Zhang and Kun Ding
Strong coupling between vacuum fields and quantum matter occurs at the nanoscale and broadens the horizon of light-matter interaction. Nanoscale Casimir force, as an exhibition of vacuum fields, inevitably experiences the influence of surface electron responses due to their quantum character, which are ignorable in micron Casimir force. Here, we develop a three-dimensional conformal map method to tackle typical experimental configurations with surface electron contributions to Casimir force purposely and delicately included. Based on this method, we reveal that quantum surface responses (QSRs) can either enhance or suppress the nanoscale Casimir force, depending on materials and crystal facets. The mechanism is demonstrated to be the Casimir force softening, which results from QSRs effectively altering the distance seen by the Casimir interaction. With such an understanding, we then provide a recipe to handle the nanoscale Casimir force between nanoscale complex objects. Our findings not only highlight the interaction between QSRs and vacuum fields but also provide a recipe for theoretical and experimental investigation of nanoscale fluctuation-type problems.
Phys. Rev. Lett. 134, 146901 (2025)
Casimir effect & related phenomena, Light-matter interaction, Surface & interfacial phenomena, Nanoparticles, Green’s function methods, Series expansions & exact enumeration, Transformation optics
Generalized Einstein Relation for Markovian Friction Coefficients from Molecular Trajectories
Research article | Brownian motion | 2025-04-07 06:00 EDT
J. M. Hall and M. G. Guenza
We present a generalized Einstein relation for the friction coefficients associated with an underlying memory kernel in terms of observable time correlation functions. There is considerable freedom in the correlations involved, and this allows the expression to be tailored to the particular system to achieve numerical stability. We demonstrate this by recovering the site-specific friction coefficients from trajectories of a freely diffusing model trimer, and we show that the accuracy is greatly improved over established Volterra inversion methods for kernel extraction.
Phys. Rev. Lett. 134, 147101 (2025)
Brownian motion, Fluctuation-dissipation theorem, Protein dynamics, structure & function, Coarse graining, Langevin equation
Dissipation-Driven Emergence of a Soliton Condensate in a Nonlinear Electrical Transmission Line
Research article | Complex systems | 2025-04-07 06:00 EDT
Loic Fache, Hervé Damart, François Copie, Thibault Bonnemain, Thibault Congy, Giacomo Roberti, Pierre Suret, Gennady El, and Stéphane Randoux
We present an experimental study on the perturbed evolution of Korteweg–de Vries soliton gases in a weakly dissipative nonlinear electrical transmission line. The system’s dynamics reveal that an initially dense, fully randomized soliton gas evolves into a coherent macroscopic state identified as a soliton condensate through nonlinear spectral analysis. The emergence of the soliton condensate is driven by the spatial rearrangement of the systems’s eigenmodes and by the proliferation of new solitonic states due to nonadiabatic effects, a phenomenon not accounted for by the existing hydrodynamic theories.
Phys. Rev. Lett. 134, 147201 (2025)
Complex systems, Solitons
Statistical Mechanics of Frustrated Assemblies and Incompatible Graphs
Research article | Elasticity | 2025-04-07 06:00 EDT
José M. Ortiz-Tavárez, Zhen Yang, Nicholas Kotov, and Xiaoming Mao
A graph theory framework for the statistical mechanics of geometrically frustrated assemblies offers a concise mathematical relation between frustration and structure.
Phys. Rev. Lett. 134, 147401 (2025)
Elasticity, Phase transitions, Self-assembly, Graph theory
Falsifiability Test for Classical Nucleation Theory
Research article | Crystallization | 2025-04-07 06:00 EDT
Camilla Beneduce, Diogo E. P. Pinto, Lorenzo Rovigatti, Flavio Romano, Petr Šulc, Francesco Sciortino, and John Russo
Classical nucleation theory (CNT) is built upon the capillarity approximation, i.e., the assumption that the nucleation properties can be inferred from the bulk properties of the melt and the crystal. Although the simplicity and usefulness of CNT cannot be overstated, experiments and simulations regularly uncover significant deviations from its predictions, which are often reconciled through phenomenological extensions of the CNT, fueling the debate over the general validity of the theory. In this Letter, we present a falsifiability test for any nucleation theory grounded in the capillarity approximation. We focus on cases where the theory predicts no differences in nucleation rates between different crystal polymorphs. We then introduce a system in which all polymorphs have the same free energy (both bulk and interfacial) across all state points. Through extensive molecular simulations, we show that the polymorphs exhibit remarkably different nucleation properties, directly contradicting predictions of CNT. We argue that CNT’s primary limitation lies in its neglect of structural fluctuations within the liquid phase.
Phys. Rev. Lett. 134, 148201 (2025)
Crystallization, Nucleation, Colloids
Rheological Regimes in Agitated Granular Media under Shear
Research article | Fluidized beds | 2025-04-07 06:00 EDT
Olfa D’Angelo, Matthias Sperl, and W. Till Kranz
Agitated granular media have a rich rheology: they exhibit Newtonian behavior at low shear rate and density, develop a yield stress at high density, and cross over to Bagnoldian shear thickening when sheared rapidly—making it challenging to encompass them in one theoretical framework. We measure the rheology of air-fluidized glass particles, spanning 5 orders of magnitude in shear rate. By comparing fluidization-induced to Brownian agitation, we show that all rheological regimes can be delineated by two dimensionless numbers—the P'eclet number, Pe, and the ratio of shear-to-fluidization power, $\mathrm{\Pi }$—and propose a constitutive relation that captures all flow behaviors, qualitatively and quantitatively, in one unified framework.
Phys. Rev. Lett. 134, 148202 (2025)
Fluidized beds, Granular flows, Granular fluids, Non-Newtonian fluids, Mode coupling theory, Rheology techniques
Enhanced Stability and Chaotic Condensates in Multispecies Nonreciprocal Mixtures
Research article | Biological fluid dynamics | 2025-04-07 06:00 EDT
Laya Parkavousi, Navdeep Rana, Ramin Golestanian, and Suropriya Saha
Random nonreciprocal interactions between a large number of conserved densities are shown to enhance the stability of the system toward pattern formation. The enhanced stability is an exact result when the number of species approaches infinity and is confirmed numerically by simulations of the multispecies nonreciprocal Cahn-Hilliard model. Furthermore, the diversity in dynamical patterns increases with an increasing number of components, and novel steady states such as pulsating or spatiotemporally chaotic condensates are observed. Our results may help to unravel the mechanisms by which living systems self-organize via metabolism.
Phys. Rev. Lett. 134, 148301 (2025)
Biological fluid dynamics, Emergence of patterns, Spatiotemporal chaos
Information Gain Limit of Biomolecular Computation
Research article | Biological information processing | 2025-04-07 06:00 EDT
Easun Arunachalam and Milo M. Lin
Biomolecules stochastically occupy different configurations that correspond to distinct functional states. Changing biochemical inputs such as rate constants alters the output probability distribution of configurations, and thus constitutes a form of computation. In the cell, such computations are often coupled to thermodynamic forces such as ATP hydrolysis that drive systems far from equilibrium, resulting in energy expenditure even during times when computations are not being performed. The information-theoretic advantage of this costly computational paradigm is unclear. Here we introduce a theoretical framework showing how much the thermodynamic force enables changes in probability distributions, quantified by the information gain, beyond what is possible at equilibrium. Using this framework, we derive a general expression relating the force to the maximum information gain in an arbitrary computation, revealing how small input changes can exponentially alter outputs. We numerically show that biomolecular systems can closely approach this universal bound, illustrating how energy expenditure is needed to achieve the information processing capabilities observed in nature.
Phys. Rev. Lett. 134, 148401 (2025)
Biological information processing, Biomolecular processes, Nonequilibrium statistical mechanics, Physics of computation, Stochastic thermodynamics, Thermodynamics of computation, Biomolecules, Enzymes, Nonequilibrium systems, Protein interaction networks, Signaling networks, Information theory, Master equation
Physical Review X
Sticking without Contact: Elastohydrodynamic Adhesion
Research article | Adhesion | 2025-04-07 06:00 EDT
Vincent Bertin, Alexandros Oratis, and Jacco H. Snoeijer
Wet adhesion in soft materials follows a two-phase process: a fluid-trapped sticking phase and a sudden snapping phase. This behavior has implications for biology, adhesives, and soft robotics.
Phys. Rev. X 15, 021006 (2025)
Adhesion, Elastic deformation, Lubrication, Lubrication theory, Thin fluid films
Confinement Determines Transport of a Reaction-Diffusion Active Matter Front
Research article | Biological fluid dynamics | 2025-04-07 06:00 EDT
Nicolas Lobato-Dauzier, Ananyo Maitra, André Estevez-Torres, and Jean-Christophe Galas
Confinement of active flows influences chemical signal transport, changing speed by up to a factor of 8, offering insights on biochemical signaling in processes like embryogenesis.
Phys. Rev. X 15, 021007 (2025)
Biological fluid dynamics, Biomimetic & bio-inspired materials, Flow instability, Active nematic gels, DNA, Enzymes, Microtubules, Reaction diffusion systems
arXiv
To roll or not to roll(?) is the yield stress (in soft particulate gels)
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
While it is widely acknowledged that system-spanning particulate structures contribute to the observed yield stress and shear-thinning in attractive colloidal gels, a comprehensive understanding of the underlying microscopic mechanisms remains elusive. In this study, we present findings from coarse-grained simulations focusing on model depletion gels to shed light on this intriguing phenomenon. Contrary to conventional belief, our simulations reveal that the mere presence of attractive interactions and aggregate formation does not sufficiently explain the observed yield stress. Instead, we identify a crucial physics element in the form of microscopic constraints on the relative rotational motion between bonded particles. Through a detailed analysis of microstructure and particle dynamics, we elucidate how these constraints lead to the emergence of yield stress in soft particulate gels. This research provides essential insights into the micromechanical origins of yield stress in soft particulate gels, paving the way for improved understanding and engineering of these versatile materials for various real-world applications.
Soft Condensed Matter (cond-mat.soft)
Monitoring of polymer viscosity by simultaneous ultrasonic and rheological measurements at high and varying temperatures
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Nesrine Houhat (GREMAN), Thibaut Devaux (GREMAN), Samuel Callé (GREMAN), Laksana Saengdee (GREMAN), Séverine Boucaud Gauchet (GREMAN), François Vander Meulen (GREMAN)
A thorough comprehension of the rheological behavior of polymers during industrial processes is essential for optimizing manufacturing efficiency and product quality. The final properties and behavior of resulting polymer parts are known to be directly linked to the thermomechanical evolution of materials during their processing. The non-invasive monitoring of this stage could improve the quality of manufactured equipment. This can be done by tracking viscosity off-line on a rheometer. In this article, an experimental method to monitor the viscosity of polymer materials at high and varying temperatures by using ultrasound is proposed. This method allows us to measure the ultrasonic and rheological properties of a sample, simultaneously and in real-time. An ultrasonic instrumentation is adapted to a rheometer for continuous monitoring. It allows high-temperature range measurements (up to 200°C). A dedicated signal processing algorithm is developed to determine the polymer longitudinal acoustic velocity by considering wave packet overlapping and temperature variation. Results on polyethylene show that ultrasonic parameters appear to be sensitive to changes in the polymer state. It enables more accurate detection of the onset of polymer crystallization. This study paves the way for ultrasonic real-time monitoring of the rotomolding process.
Soft Condensed Matter (cond-mat.soft)
AIP Advances, 2025, 15 (3)
Chirality-Driven Magnetization Emerges from Relativistic Four-Current Dynamics
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Xuechen Zheng (1), Shiv Upadhyay (1), Tian Wang (1), Agam Shayit (1), Jun Liu (2), Dali Sun (3), Xiaosong Li (1) ((1) Department of Chemistry, University of Washington, Seattle, WA, USA, (2) Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA, (3) Department of Physics, North Carolina State University, Raleigh, NC, USA)
Chirality-induced spin selectivity (CISS) is a striking quantum phenomenon in which electron transport through chiral molecules leads to spin polarization – even in the absence of magnetic fields or magnetic components. Although observed in systems such as DNA, helicenes, proteins, and polymers, the fundamental physical origin of CISS remains unresolved. Here, we introduce a time-dependent relativistic four-current framework, in which charge and current densities evolve according to the time-dependent variational principle. Real-time relativistic four-current simulations enable direct analysis of helical currents and induced magnetization dynamics. Applied to helicenes – axially chiral molecules lacking stereocenters – our simulations reveal curvature-induced helical electron currents that generate spontaneous magnetic fields aligned along the molecular axis. These fields are handedness-dependent and reach magnitudes of $ 10^{-1}$ ~Tesla per single helicene strand. Our results suggest that CISS may arise from intrinsic, relativistic curvature-induced helical currents and the associated magnetic fields within chiral molecules. This four-current mechanism offers a self-contained explanation for spin selectivity, independent of interfacial effects or strong spin-orbit coupling. Furthermore, our results lead to several testable hypotheses that can be explored in experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Chemical Physics (physics.chem-ph)
Atomic-scale imaging of graphene nanoribbons on graphene after polymer-free substrate transfer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Amogh Kinikar, Feifei Xiang, Lucia Palomino Ruiz, Li-Syuan Lu, Chengye Dong, Yanwei Gu, Rimah Darawish, Eve Ammerman, Oliver Groening, Klaus Muellen, Roman Fasel, Joshua A. Robinson, Pascal Ruffieux, Bruno Schuler, Gabriela Borin Barin
On-surface synthesis enables the fabrication of atomically precise graphene nanoribbons (GNRs) with properties defined by their shape and edge topology. While this bottom-up approach provides unmatched control over electronic and structural characteristics, integrating GNRs into functional electronic devices requires their transfer from noble metal growth surfaces to technologically relevant substrates. However, such transfers often induce structural modifications, potentially degrading or eliminating GNRs’ desired functionality - a process that remains poorly understood. In this study, we employ low-temperature scanning tunneling microscopy and spectroscopy (STM/STS) to characterize 9-atom-wide armchair GNRs (9-AGNRs) following polymer-free wet-transfer onto epitaxial graphene (EG) and quasi-freestanding epitaxial graphene (QFEG) substrates. Our results reveal that armchair GNRs maintain their structural integrity post-transfer, while GNRs with extended or modified edge topologies exhibit significant structural changes, including partial disintegration. Additionally, STS measurements reveal differences in the Fermi level alignment between GNRs and the graphene substrates, a key factor in optimizing carrier injection efficiency in electronic transport devices. This study establishes a framework for detecting post-processing structural modifications in GNRs, which are often hidden in optical ensemble measurements. By addressing the challenges of substrate transfer and providing new insights into GNR-substrate interactions, these findings pave the way for the reliable integration of atomically precise GNRs into next-generation nanoelectronic and optoelectronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
A thermodynamically consistent free-energy lattice Boltzmann model: Incorporating generalized equilibria derived from the color-gradient approach
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Shimpei Saito, Soumei Baba, Naoki Takada
We extend the chemical-potential-based free-energy lattice Boltzmann (LB) model of Li et al. [Phys. Rev. E 103, 013304 (2021)] by integrating generalized equilibria, originally formulated for the color-gradient LB model using sixth-order Hermite polynomials [Saito et al., Phys Rev E 108, 065305 (2023)], into a thermodynamically consistent framework. Our model is formulated on a three-dimensional D3Q27 lattice with a central-moment collision scheme, simplifying implementation and improving Galilean invariance. Numerical tests, including flat-interface equilibrium, stationary and moving droplets in free space, and wetting on solid surfaces, confirm the model’s capability to accurately simulate multiphase phenomena while maintaining strict thermodynamic consistency.
Statistical Mechanics (cond-mat.stat-mech), Fluid Dynamics (physics.flu-dyn)
10 pages, 7 figures
Tunable Topological Phases in Multilayer Graphene Coupled to a Chiral Cavity
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Sayed Ali Akbar Ghorashi, Jennifer Cano, Ceren B. Dag
Coupling photonic cavity fields to electronic degrees of freedom in 2D materials introduces an additional control knob to the toolbox of solid-state engineering. Here we demonstrate a subtle competition between cavity frequency and interlayer tunneling in graphene stacks that is responsible for topological phase transitions in light-matter Hilbert space and that cannot be captured by mean-field theory in vacuum. A systematic exploration of multilayer graphene heterostructures and stacking configurations in a chiral tHz cavity reveals that linear dispersion enhances the low-energy cavity-induced topological gap. In bilayer graphene, a displacement field drives the low-energy vacuum band from valley-Chern to Chern insulator, comprising a gate-tunable topological phase transition. Furthermore, we show that a chiral cavity breaks not only the time-reversal symmetry of bilayer graphene but also the inversion symmetry, which impacts its edge spectrum. Our findings pave the way for future control and engineering of graphene heterostructures with chiral cavity fields.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
5 Figures in the main text, Supplementary material is appended
Ordering transition of the three-dimensional four-state random-field Potts model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Spin systems exposed to the influence of random magnetic fields are paradigmatic examples for studying the effect of quenched disorder on condensed-matter systems. In this context, previous studies have almost exclusively focused on systems with Ising or continuous symmetries, while the Potts symmetry, albeit being of fundamental importance also for the description of realistic physical systems, has received very little attention. In the present study, we use a recently developed quasi-exact method for determining ground states in the random-field Potts model to study the problem with four states. Extending the protocol applied for the three-state model, we use extensive finite-size scaling analyses of the magnetization, Binder parameter, energy cumulant, specific heat, and the connected as well as disconnected susceptibilities to study the magnetic ordering transition of the model. In contrast to the system in the absence of disorder, we find compelling evidence for a continuous transition, and we precisely determine the critical point as well as the critical exponents, which are found to differ from the exponents of the three-state system as well as from those of the random-field Ising model.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Computational Physics (physics.comp-ph)
16 pages, 12 figures, 6 tables, RevTeX4.1
Micellization of Diblock Copolymer Modified by Cononsolvency Effect
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Xiangyu Zhang, Jing Zong, Dong Meng
Spherical micelle modified by cononsolvency effect is investigated by using self-consistent field theory (SCFT) and random phase approximation, which is formed by diblock copolymers consisted of one permanent hydrophobic block and one hydrophilic block. The addition of the cosolvent will bring about the cononsolvency effect on the hydrophilic block. The result shows that cononsolvency effect will expand the micelle size and changes the critical micelle concentration. By analyzing density profiles predicted by SCFT calculation, the micelle shell exhibits extension-collapse-extension transition with the addition of the cosolvent, which is responsible for the micelle size change. The driving force of the micellization is analyzed in the framework of SCFT calculation. The conventional micelle, which is formed by amphiphilic diblock copolymer in pure solvent, is compared with the micelle modified by cononsolvency effect. The reduction of the core-block - solvent contact area drives the formation of the conventional micelle. But in cononsolvency modified micelle, it is shown that the shell-block - cosolvent favorable interaction also plays the role to minimize the total free energy, whose mechanism is significantly different from that of the conventional micelle.
Soft Condensed Matter (cond-mat.soft)
CREASE-2D Analysis of Small Angle X-ray Scattering Data from Supramolecular Dipeptide Systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Nitant Gupta, Sri V.V.R. Akepati, Simona Bianco, Jay Shah, Dave J. Adams, Arthi Jayaraman
In this paper, we extend a recently developed machine-learning (ML) based CREASE-2D method to analyze the entire two-dimensional (2D) scattering pattern obtained from small angle X-ray scattering measurements of supramolecular dipeptide micellar systems. Traditional analysis of such scattering data would involve use of approximate or incorrect analytical models to fit to azimuthally-averaged 1D scattering patterns that can miss the anisotropic arrangements. Analysis of the 2D scattering profiles of such micellar solutions using CREASE-2D allows us to understand both isotropic and anisotropic structural arrangements that are present in these systems of assembled dipeptides in water and in the presence of added solvents/salts. CREASE-2D outputs distributions of relevant structural features including ones that cannot be identified with existing analytical models (e.g., assembled tubes, cross-sectional eccentricity, tortuosity, orientational order). The representative three-dimensional (3D) real-space structures for the optimized values of these structural features further facilitate visualization of the structures. Through this detailed interpretation of these 2D SAXS profiles we are able to characterize the shapes of the assembled tube structures as a function of dipeptide chemistry, solution conditions with varying salts and solvents, and relative concentrations of all components. This paper demonstrates how CREASE-2D analysis of entire SAXS profiles can provide an unprecedented level of understanding of structural arrangements which has not been possible through traditional analytical model fits to the 1D SAXS data.
Soft Condensed Matter (cond-mat.soft), Machine Learning (cs.LG)
30 Pages, 9 figures
Cluster-based machine learning potentials to describe disordered metal-organic frameworks up to the mesoscale
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Pieter Dobbelaere, Sander Vandenhaute, Veronique Van Speybroeck
Metal-organic frameworks (MOFs) are highly interesting and tunable materials. By incorporating spatial defects into their atomic structure, MOFs can be finetuned to exhibit precise chemical functionalities, extending their applicability in various technological fields. Defect engineering requires a fundamental understanding of the nature of spatial disorder and consequent changes in material properties, which is currently lacking. We introduce the cluster-based learning methodology, enabling the development of state-of-the-art machine learning potentials (MLPs) from defective systems at any length scale. Our method identifies atomic interactions in bulk structures and extracts local environments as finite molecular fragments to augment the model’s training data where needed. We show that cluster-based learning delivers MLPs capable of accurately describing spatial defects in mesoscopic systems with over twenty thousand atoms. Afterwards, we select our best model to investigate some major mechanical properties of spatially disordered UiO-66-derived structures, elucidating the influence of defect concentration and composition on material behaviour. Our analysis includes large supercell structures, demonstrating that (near-) ab initio accuracy is within reach at the mesoscale.
Materials Science (cond-mat.mtrl-sci)
36 pages, 8 figures
Identifying Instabilities with Quantum Geometry in Flat Band Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Jia-Xin Zhang, Wen O. Wang, Leon Balents, Lucile Savary
The absence of a well-defined Fermi surface in flat-band systems challenges the conventional understanding of instabilities toward Landau order based on nesting. We investigate the existence of an intrinsic nesting structure encoded in the band geometry (i.e. the wavefunctions of the flat band(s)), which leads to a maximal susceptibility at the mean-field level and thus determines the instability towards ordered phases. More generally, we show that for a given band structure and observable, we can define two vector fields: one which corresponds to the Bloch vector of the projection operator onto the manifold of flat bands, and another which is “dressed” by the observable. The overlap between the two vector fields, possibly shifted by a momentum vector $ \boldsymbol{Q}$ , fully determines the mean field susceptibility of the corresponding order parameter. When the overlap is maximized, so is the susceptibility, and this geometrically corresponds to “perfect nesting” of the band structure. In that case, we show that the correlation length of this order parameter, even for $ \boldsymbol{Q}\neq \boldsymbol{0}$ , is entirely characterized by a generalized quantum metric in an intuitive manner, and is therefore lower-bounded in topologically non-trivial bands. As an example, we demonstrate hidden nesting for staggered antiferromagnetic spin order in an exactly flat-band model, which is notably different from the general intuition that flat bands are closely associated with ferromagnetism. We check the actual emergence of this long-range order using the determinantal quantum Monte Carlo algorithm. Additionally, we demonstrate that a Fulde-Ferrell-Larkin-Ovchinnikov-like state (pairing with non-zero center of mass momentum) can arise in flat bands upon breaking time-reversal symmetry, even if Zeeman splitting is absent.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
8+15 pages, 3+7 figures
Anisotropic Field Suppression of Morin Transition Temperature in Epitaxially Grown Hematite Thin Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Haoyu Liu, Hantao Zhang, Josiah Keagy, Qinwu Gao, Letian Li, Junxue Li, Ran Cheng, Jing Shi
We have demonstrated the existence of the Morin transition in epitaxially grown hematite thin films exceeding a critical thickness. The Morin transition temperature can be suppressed by magnetic fields applied both parallel and perpendicular to the Dzyaloshinskii-Moriya (DM) vector, exhibiting a distinct anisotropic behavior that is consistent with bulk hematite crystals. Detailed analysis explains the anisotropic behavior and provides a method for determining the DM strength, which remains nearly constant across the sample thickness over four orders of magnitude. Our findings obtained with transport measurements offer a valuable approach for studying antiferromagnetic spin configurations in thin films and nanodevices.
Materials Science (cond-mat.mtrl-sci)
Enhanced Reactivity in Janus Transition Metal Dichalcogenide Quantum Dots: Charge-Density Asymmetry and Hydrodesulfurization Potential
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Jair Dominguez, Raul Santoy, Jose Paez, Rodrigo Perez, Luis Pellegrin, Do Minh Hoat, Jonathan Guerrero
Quantum dots (QDs) are nanoscale materials that exhibit unique electronic and optical properties due to quantum confinement effects, making them highly relevant for applications in catalysis, optoelectronics, and energy conversion. While transition metal dichalcogenide (TMD) QDs have been extensively studied in their pristine forms, Janus-type TMD QDs – featuring compositional asymmetry across their atomic layers – offer an additional degree of tunability through charge-density gradients and curvature effects, yet remain comparatively unexplored. In this work, we investigate the electronic and structural properties of Janus TMD QDs composed of molybdenum (Mo) or tungsten (W) in combination with chalcogen elements (S, Se, Te) and oxygen, exploring three distinct structural classes: pristine, non-oxidized Janus, and oxidized Janus phases. Using first-principles calculations, including static DFT and ab initio molecular dynamics (AIMD) simulations, we analyze curvature evolution, electrostatic potential isosurfaces, charge-density asymmetry, and surface formation energies to assess size- and composition-dependent stability. Our findings reveal that oxidation induces significant curvature and charge localization, particularly in W-based systems, enhancing their potential as catalysts for hydrodesulfurization reactions. Additionally, we identify size- and geometry-dependent stability trends, with larger and beta-type QDs exhibiting superior thermodynamic and thermal robustness. These results provide a comprehensive theoretical foundation for the design and synthesis of structurally tunable Janus QDs with tailored properties for catalytic and electronic applications.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
The effects of elastic and inelastic collisions in two- and three-body interactions on the stability of 3D Bose-Einstein condensates
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-08 20:00 EDT
R. Sasireka, O.T. Lekeufack, S. Sabari, A. Uthayakumar
In this paper, we study the stability of three-dimensional Bose-Einstein condensates of finite temperatures at which both elastic and inelastic collisions are taken into account. The modeled governing Gross-Pitaevski equation reveals inclusion of both real and imaginary components in the nonlinear terms. We find the stability region for a wide range of two- and three-body interaction terms with the inclusion of both gain and loss effects by using the Jacobian matrix. We investigate the stability of the system for possible different state of those cases. The stability properties of three-dimensional condensates are strongly altered by tuning the gain rate of their elastic collisions. These strong losses impose severe limitations for using Feshbach resonances. We finally sustain our semi analytical findings with the results of inclusive numerical simulations.
Quantum Gases (cond-mat.quant-gas)
7 pages, 8 figures
Single-Molecule Vibrational Characterization of Binding Geometry Effects on Isocyanide-Metal Interactions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Liya Bi, Zhe Wang, Krista Balto, Andrea R. Tao, Tod A. Pascal, Yanning Zhang, Joshua S. Figueroa, Shaowei Li
Isocyanide-metal binding is governed by sigma-donation and pi-back-bonding, which affects the energy of the isocyanide stretching mode-a characteristic probe for ligand-metal interactions. While extensive correlations exist between structure and spectroscopy in molecular isocyanide-metal systems, isocyanide interactions with metallic crystalline surfaces, where ligands often bind in various geometries, remain poorly understood. Conventional vibrational spectroscopies, such as infrared and Raman, lack the molecular-scale resolution needed to distinguish these inhomogeneous configurations. In contrast, inelastic electron tunneling spectroscopy with scanning tunneling microscopy (STM-IETS) enables direct visualization of ligand adsorption geometries and their vibrational signatures. Using STM-IETS, here we investigate a matal-adsorbed m-terphenyl isocyanie ligand and find that adsorption geometry on Cu(100) induces a significant shift in isocyanide stretching frequency, even greater than replacing Cu(100) with Ag(111). Density functional theory confirms this shift arises from atomic-scale variations in isocyanide-metal binding. This study elucidates how atomic-scale binding influences the vibrational signatures of isocyanide ligands-an often-overlooked factor in understanding isocyanide-metal interactions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Quantum Otto engine mimicking Carnot near pseudotransitions in the 1D extended Hubbard model in the atomic limit
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Onofre Rojas, Moises Rojas, S. M. de Souza
The one-dimensional extended Hubbard model (EHM) in the atomic limit has recently been found to exhibit a curious thermal pseudo-transition behavior, which closely resembles first and second-order thermal phase transitions. This phenomenon, occurring at half-filling, is influenced by the quantum phase transition between the alternating pair (AP) and paramagnetic (PM) phases at zero temperature. In this study, we leverage this anomalous behavior to investigate the performance of quantum many-body machines, using the EHM as the working substance. Our analysis reveals that the quantum Otto engine, when operating in the anomalous region, closely mimics the ideal Carnot engine. In this region, both the work output and thermal efficiency of the Otto engine increase, approaching the performance of a Carnot engine. This highlights the potential of many-body systems, such as the EHM, in enhancing quantum thermodynamic performance. Our findings demonstrate that, although the second law of thermodynamics prevents engines from surpassing Carnot efficiency, the Otto engine can operate remarkably close to this limit in the anomalous region, offering insights into new directions for future research on quantum thermodynamic cycles and working substances.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 9 figures
Accurate and efficient protocols for high-throughput first-principles materials simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Gabriel de Miranda Nascimento, Flaviano José dos Santos, Marnik Bercx, Davide Grassano, Giovanni Pizzi, Nicola Marzari
Advancements in theoretical and algorithmic approaches, workflow engines, and an ever-increasing computational power have enabled a novel paradigm for materials discovery through first-principles high-throughput simulations. A major challenge in these efforts is to automate the selection of parameters used by simulation codes to deliver numerical precision and computational efficiency. Here, we propose a rigorous methodology to assess the quality of self-consistent DFT calculations with respect to smearing and $ k$ -point sampling across a wide range of crystalline materials. For this goal, we develop criteria to reliably estimate average errors on total energies, forces, and other properties as a function of the desired computational efficiency, while consistently controlling $ k$ -point sampling errors. The present results provide automated protocols (named standard solid-state protocols or SSSP) for selecting optimized parameters based on different choices of precision and efficiency tradeoffs. These are available through open-source tools that range from interactive input generators for DFT codes to high-throughput workflows.
Materials Science (cond-mat.mtrl-sci)
SymPlex Plots for Visualizing Properties in High-Dimensional Alloy Spaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
John Cavin, Pravan Omprakash, Adrien Couet, Rohan Mishra
Most conventional alloys have one or two principal elements with additional elements at lower concentrations. In contrast, multiple principal element alloys (MPEAs) offer a new paradigm for alloy design. Optimizing these alloys with many components and phases requires exploring high-dimensional spaces. Traditional visualization tools, such as phase diagrams and convex hulls require plotting dimensions that scale with the number of components, making them unsuitable for MPEAs with four or more elements. Here, we introduce SymPlex plots to enable the visualization of various properties along special paths in high-dimensional compositional spaces. These are radial heatmaps that plot the variation in properties along high-symmetry paths radiating from the parent equimolar MPEA to a set of chosen compositions such as the constituent elements and lower order alloys. SymPlex plots of thermodynamic potentials capture the changes in the energy landscape along the special paths and help visualize the effect of addition or substitution of components on the alloy stability. SymPlex plots of alloy properties, such as density or elastic modulus, help select compositions for targeted applications. By showing connections between compositions and properties in the high-dimensional space with more information concentrated near the equimolar region-as opposed to the corners and edges of the composition space that are more relevant for traditional alloys-SymPlex plots can help guide MPEA design.
Materials Science (cond-mat.mtrl-sci)
Construction of Hopfion Crystals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Wen-Tao Hou, Zhuoxian Xiang, Yizhou Liu, Jiadong Zang
Hopfions, three-dimensional topological solitons characterized by nontrivial Hopf indices, represent a fundamental class of field configurations that emerge across diverse areas of physics. Despite extensive studies of isolated hopfions, a framework for constructing spatially ordered arrays of hopfions, i.e., hopfion crystals, has been lacking. Here, we present a systematic approach for generating hopfion crystals with cubic symmetry by combining the Hopf map with rational mapping techniques. By superposing helical waves in $ \mathbb{R}^4$ , we construct hopfion crystals with tunable Hopf indices and controllable topology. We demonstrate simple cubic, facecentered cubic, and body-centered cubic hopfion crystals, and extend our framework to create crystals of more complex topological structures, including axially symmetric tori, torus links, and torus knots with higher Hopf indices. Our results provide a foundation for searching hopfions in real materials and studying their collective phenomena.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages,7 figures
Electronic and optical properties of two-dimensional flat band triphosphides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Gabriel Elyas Gama Araujo, Lucca Moraes Gomes, Dominike Pacine de Andrade Deus, Alexandre Cavalheiro Dias, Andreia Luisa da Rosa
In this work we use first-principles density-functional theory (DFT)
calculations combined with the maximally localized Wannier function
tight binding Hamiltonian (MLWF-TB) and Bethe-Salpeter equation (BSE)
formalism to investigate quasi-particle effects in 2D electronic and
optical properties of triphosphide based two-dimensional materials
XP$ _3$ (X = Ga, Ge, As; In, Sn, Sb; Tl, Pb and Bi). We find that with
exception of InP$ _3$ , all structures have indirect band gap. A
noticeable feature is the appearance of flat valence bands associated
to phosphorous atoms, mainly in InP$ _3$ and GaP$ _3$ structures. Furthermore,
AIMD calculations show that 2D-XP$ _3$ is stable at room temperature,
with exception of TlP$ _3$ monolayer, which shows a strong distortion
yielding to a phase separation of the P and Tl layers. Finally, we show that
monolayered XP$ _3$ exhibits optical absorption with strong excitonic
effects, thus revealing exciting features of these monolayered
materials.
Materials Science (cond-mat.mtrl-sci)
Automated Polarization Rotation for Multi-Axis Rotational-Anisotropy Second Harmonic Generation Experiments
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Karna A. Morey, Bryan T. Fichera, Baiqing Lv, Zonqi Shen, Nuh Gedik
Rotational anisotropy second harmonic generation (RA-SHG) is a nonlinear optical technique used to probe the symmetry of condensed matter systems. Measuring the dependence of the SHG susceptibility on one or more external parameters, notably strain, field, temperature, or time delay, is an extremely powerful way to probe complex phases of quantum materials. Experimentally, extracting maximal information about the SHG susceptibility tensor requires measurements of S and P polarized input and output combinations, which naturally involves the rotation of the polarizers during data collection. For multi-axis experiments, this has proved challenging since polarization rotation is typically done manually. Automating this process eliminates labor constraints, reduces uncertainty due to low-frequency noise, and expands the type of multi-axis datasets that can be collected; however, it is difficult due to geometrical constraints within the setup. In this work, we design and implement low-cost, high-fidelity automated polarization rotators for use in multi-axis RA-SHG. These polarization rotators utilize an electrical slip ring to transfer power to the rotating RA-SHG optical setup as well as a miniature stepper motor to perform the polarization rotation. We demonstrate this automated system in time-resolved RA-SHG measurements in the non-centrosymmetric semiconductor GaAs. For the multi-axis measurements described above, this automated system permits data averaging over longer periods, vastly expedites data collection, and expands the setup measurement capability. This ultimately opens new frontiers in probing quantum materials using multiple tunable external parameters.
Materials Science (cond-mat.mtrl-sci), Instrumentation and Detectors (physics.ins-det)
7 pages, 5 figures
Rev. Sci. Instrum. 96, 043002 (2025)
Machine Learning Reviews Composition Dependent Thermal Stability in Halide Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Abigail R. Hering, Mansha Dubey, Elahe Hosseini, Meghna Srivastava, Yu An, Juan-Pablo Correa-Baena, Houman Homayoun, Marina S. Leite
Halide perovskites exhibit unpredictable properties in response to environmental stressors, due to several composition-dependent degradation mechanisms. In this work, we apply data visualization and machine learning (ML) techniques to reveal unexpected correlations between composition, temperature, and material properties while using high throughput, in situ environmental photoluminescence (PL) experiments. Correlation heatmaps show the strong influence of Cs content on film degradation, and dimensionality reduction visualization methods uncover clear composition-based data clusters. An extreme gradient boosting algorithm (XGBoost) effectively forecasts PL features for ten perovskite films with both composition-agnostic (>85% accuracy) and composition-dependent (>75% accuracy) model approaches, while elucidating the relative feature importance of composition (up to 99%). This model validates a previously unseen anti-correlation between Cs content and material thermal stability. Our ML-based framework can be expanded to any perovskite family, significantly reducing the analysis time currently employed to identify stable options for photovoltaics.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
21 pages, 5 figures
Slide and Twist: Manipulating Polarization in Multilayer Hexagonal Boron-Nitride
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Sanber Vizcaya, Felipe Perez Riffo, Juan M. Florez, Eric Súarez Morell
This study explores the world of across-layer sliding ferroelectricity in multilayer hexagonal boron nitride (hBN) and gallium nitride (hGaN), aiming to control out-of-plane polarization. By investigating the effects of sliding single or dual layers in various hBN stacking configurations, we uncover methods for reversing polarization with energy barriers between 5 and 30 meV/f.u., making these methods experimentally viable. Our results show that single-interface sliding is more energetically favorable, with lower barriers compared to multiple interfaces. Certain pathways reveal stable polarization plateaus, where polarization remains constant during specific sliding phases, promising robust polarization control. Moreover, rotated multilayer structures maintain consistent net out-of-plane polarization across different rotation angles. In trilayer ABT structures, rotating the top layer and sliding the bottom layer can reverse polarization, expanding device design possibilities. While the primary focus is on hBN, similar phenomena in hGaN suggest broader applicability for this class of polar materials. The identified energy barriers support the feasibility of fabricating devices based on these multilayer structures.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
10 pages, 8 figures, regular paper
Phys. Chem. Chem. Phys., 2025,27, 7189-7198
Orbital-selective band modifications in a charge-ordered kagome metal LuNb$_6$Sn$_6$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Rui Lou, Yumeng Zhang, Erjian Cheng, Xiaolong Feng, Alexander Fedorov, Zongkai Li, Yixuan Luo, Alexander Generalov, Haiyang Ma, Quanxing Wei, Yi Zhou, Susmita Changdar, Walter Schnelle, Dong Chen, Yulin Chen, Jianpeng Liu, Yanfeng Guo, Sergey Borisenko, Denis V. Vyalikh, Claudia Felser, Bernd Büchner, Zhongkai Liu
The origin of the charge order in kagome lattice materials has attracted great interest due to the unique electronic structure features connected to kagome networks and the interplay between electron and lattice degrees of freedom. Recently, compounds with composition $ Ln$ Nb$ _6$ Sn$ _6$ ($ Ln$ = Ce-Nd, Sm, Gd-Tm, Lu, Y) appear as a new family of kagome metals, structurally analogous to $ R$ V$ _6$ Sn$ _6$ ($ R$ = Sc, Y, or rare earth) systems. Among them, LuNb$ _6$ Sn$ _6$ emerges as a novel material hosting charge density wave (CDW) with a $ \sqrt{3}$ $ \times$ $ \sqrt{3}$ $ \times$ $ 3$ wave vector, akin to that in ScV$ _6$ Sn$ _6$ . Here, we employ high-resolution angle-resolved photoemission spectroscopy, scanning tunneling microscopy, and density functional theory calculations to systematically investigate the electronic properties of LuNb$ _6$ Sn$ _6$ . Our observation reveals the characteristic band structures of the “166” kagome system. A charge instability driven by Fermi surface nesting is decisively ruled out through an analysis of the interactions between van Hove singularities. Across the CDW transition, we observe orbital-selective band modifications, with noticeable evolutions of Lu 5$ d$ and Sn 5$ p$ electrons, while Nb 4$ d$ electrons exhibit minimal change, suggesting that the Lu and Sn sites other than the Nb kagome lattice play a key role in the formation of CDW. Our findings substantiate a universal lattice-driven CDW mechanism rather than a charge-instability-driven one in the “166” kagome compounds, making it a distinct material class compared to other charge-ordered kagome systems, such as $ A$ V$ _3$ Sb$ _5$ ($ A$ = K, Rb, Cs) and FeGe.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
17 pages, 4 figures
Minimal thermodynamic cost of computing with circuits
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Abhishek Yadav, Mahran Yousef, David Wolpert
All digital devices have components that implement Boolean functions, mapping that component’s input to its output. However, any fixed Boolean function can be implemented by an infinite number of circuits, all of which vary in their resource costs. This has given rise to the field of circuit complexity theory, which studies the minimal resource cost to implement a given Boolean function with any circuit. Traditionally, circuit complexity theory has focused on the resource costs of a circuit’s size (its number of gates) and depth (the longest path length from the circuit’s input to its output). In this paper, we extend circuit complexity theory by investigating the minimal thermodynamic cost of a circuit’s operation. We do this by using the mismatch cost of a given circuit that is run multiple times in a row to calculate a lower bound on the entropy production incurred in each such run of the circuit. Specifically, we derive conditions for mismatch cost to be proportional to the size of a circuit, and conditions for them to diverge. We also use our results to compare the thermodynamic costs of different circuit families implementing the same family of Boolean functions. In addition, we analyze how heterogeneity in the underlying physical processes implementing the gates in a circuit influences the minimal thermodynamic cost of the overall circuit. These and other results of ours lay the foundation for extending circuit complexity theory to include mismatch cost as a resource cost.
Statistical Mechanics (cond-mat.stat-mech)
Symmetrizing the Constraints – Density Matrix Renormalization Group for Constrained Lattice Models
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Ting-Tung Wang, Xiaoxue Ran, Zi Yang Meng
We develop a density matrix renormalization group (DMRG) algorithm for constrained quantum lattice models that successfully implements the local constraints as symmetries in the contraction of the matrix product states and matrix product operators. Such an implementation allows us to investigate a quantum dimer model in DMRG with substantial circumference on cylindrical geometry for the first time in the literature. We have thence computed the ground state phase diagram of the quantum dimer model on triangular lattice, with the symmetry-breaking characteristics of the columnar solid phase and $ \sqrt{12}\times\sqrt{12}$ valence bond solid phase fully captured, as well as the topological entanglement entropy of the $ \mathbb{Z}_2$ quantum spin liquid phase that extends to the RK point on non-bipartite lattice accurately revealed. Our DMRG algorithm on constrained quantum lattice models opens new opportunities for matrix and tensor-based algorithms for these systems that have immediate relevance towards the frustrated quantum magnets and synthetic quantum simulators.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
10 pages, 5 figures
Rectification and bolometric terahertz radiation detectors based on perforated graphene structures exhibiting plasmonic resonant response
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
V. Ryzhii, C. Tang, M. Ryzhii, T. Otsuji, M. S. Shur
We propose and evaluate the characteristics of the terahertz (THz) detectors based on perforated graphene layers (PGLs). The PGL structures constitute the interdigital in-plane arrays of the graphene microribbons (GMRs) connected by the sets of narrow constrictions, which form the graphene nanoribbon (GNR) bridges. The PGL detector operation is associated with the rectification and hot-carrier bolometric mechanisms. The excitation of plasmonic oscillations in the GMRs can reinforce these mechanisms. The room temperature PGL detector responsivity and detectivity are calculated as function of the radiation frequency and device structure parameters. The effects of the rectification and hot-carrier mechanisms are compared. The PGL THz detectors under consideration can exhibit highly competitive values of responsivity and detectivity.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 6 figures
Electronic Energy Scales of Cr$X_3$ ($X$ = Cl, Br, and I) using High-resolution X-ray Scattering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Chamini Pathiraja, Jayajeewana N. Ranhili, Deniz Wong, Christian Schulz, Yi-De Chuang, Yu-Cheng Shao, Di-Jing Huang, Hsiao-Yu Huang, Amol Singh, Byron Freelon
Chromium tri-halides Cr$ X_3$ ($ X$ = Cl, Br, and I) have recently become a focal point of research due to their intriguing low-temperature,layer-dependent magnetism that can be manipulated by an electric field. This makes them essential candidates for spintronics applications. These magnetic orders are often related to the electronic structure parameters, such as spin-orbit coupling (SOC), Hund’s coupling ($ J_H$ ), $ p-d$ covalency, and inter-orbital Coulomb interactions. Accurately determining such parameters is paramount for understanding Cr$ X_3$ physics. We have used ultra high-resolution resonant inelastic x-ray scattering (RIXS) spectroscopy to study Cr$ X_3$ across phase transition temperatures. Ligand field multiplet calculations were used to determine the electronic structure parameters by incorporating the crystal field interactions in a distorted octahedral with $ C_3$ symmetry. These methods provide the most detailed description of Cr$ X_3$ magneto-optical and electronic energetic (terms) to date. For the first time, the crystal field distortion parameters $ D\sigma$ and $ D\tau$ were calculated, and the energies of $ d$ orbitals have been reported. Our RIXS spectroscopic measurements reveal a clear energy separation between spin-allowed quartet states and spin-forbidden doublet states in Cr$ X_3$ . The role of SOC in Cr $ 2p$ orbitals for the spin-flip excitations has been demonstrated. The determined 10$ Dq$ values are in good agreement with the spectrochemical series, and Racah B follows the Nephelauxetic effect. Such precise measurements offer insights into the energy design of spintronic devices that utilize quantum state tuning within 2D magnetic materials.
Materials Science (cond-mat.mtrl-sci)
23 pages, 9 figures
Nontrivial saddle points for spectral form factors of flat band superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
Sankalp Gaur, Emil A. Yuzbashyan, Victor Gurarie
We derive the spectral form factor of a flat band superconductor in two different ways. In the first approach, we diagonalize the Hamiltonian of this system exactly and numerically sum over the exact eigenstates to find the spectral form factor. In the second approach, we use mean field theory to evaluate the same spectral form factor. We demonstrate that both methods produce the same answer. Mean field theory for spectral form factors possesses features not previously seen in the theory of superconductivity, in particular complex gap functions and non-Hermitian effective Hamiltonians. We explicitly show that these features are indeed necessary to obtain the correct spectral form factor.
Superconductivity (cond-mat.supr-con), Quantum Gases (cond-mat.quant-gas)
Fully First-Principles Approach in Studying Topological Magnons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Xiaoqiang Liu, Ji Feng, Zhenhua Qiao, Qian Niu
We develop a fully first-principles approach for spin dynamics based on density functional perturbation theory. We demonstrate that the magnon wavefunction can be expressed by a set of electronic wavefunctions obtained from the decomposition of magnon density profile, enabling the direct calculation of magnonic quantities including Berry curvature and Chern number. As a concrete example, we show that monolayer CrI$ _3$ can host topological magnons driven by spin-orbit coupling. Our model-free approach paves the way for the comprehensive studies of magnons in real materials.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Impact of dislocation densities on the microscale strength of single-crystal strontium titanate
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Jiawen Zhang, Xufei Fang, Wenjun Lu
Dislocations in ceramics at room temperature are attracting increasing research interest. Dislocations may bring a new perspective for tuning physical and mechanical properties in advanced ceramics. Here, we investigate the dislocation density dependent micromechanical properties of single-crystal SrTiO3 by tuning the dislocation densities (from ~10 to the power of 10 per square meter up to ~10 to the power of 14 per square meter). Using micropillar compression tests, we find the samples exhibit a transition from brittle fracture (if no dislocation is present in the pillars) to plastic yield (with pre-engineered dislocations in the pillars). While within the regime of plastic deformation, the yield strength and plastic flow behavior exhibit a strong dependence on the dislocation density. The yield strength first decreases and then increases with the increase of dislocation densities. Detailed examination via post-mortem transmission electron microscopy reveals a complex evolution of dislocation structure, highlighting the critical role played by dislocations in regulating the brittle/ductile behavior in SrTiO3 at room temperature. Our findings shed new light on dislocation-mediated mechanical properties in ceramics and may provide designing guidelines for the prospective dislocation-based devices.
Materials Science (cond-mat.mtrl-sci)
Electron density and compressibility in the Kitaev model with a spatially modulated Phase in the superconducting pairing
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
Fabian G. Medina Cuy, Fabrizio Dolcini
A current flowing through a one-dimensional Kitaev chain induces a spatial modulation in its superconducting pairing, characterized by a wave vector $ Q$ , which is known to induce two types of topological phase transitions: one is the customary band topology transition between gapped phases, while the other is a Lifshitz transition related to the Fermi surface topology and leading to a gapless superconducting phase. We investigate the behavior of the electron density $ \rho$ and the compressibility $ \kappa$ across the two types of transitions, as a function of the model parameters. We find that the behavior of $ \rho$ as a function of $ Q$ and chemical potential $ \mu$ enables one to infer the ground state phase diagram. Moreover, the analysis of the compressibility $ \kappa$ as a function of $ \mu$ enables one to distinguish the two transitions: While $ \kappa$ exhibits a symmetric divergence across the band topology transition, it displays an asymmetric jump across the Lifshitz transition.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 4 figures
Condens. Matter 2025, 10(1), 14
Macroscopic ground state degeneracy of the ferro-antiferromagnetic Heisenberg model on diamond-decorated lattices
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
D. V. Dmitriev, V. Ya. Krivnov, O. A. Vasilyev
We investigate the spin-1/2 Heisenberg model with competing ferromagnetic and antiferromagnetic interactions on diamond-decorated lattices. Tuning the exchange interactions to the boundary of the ferromagnetic phase, we analyze the models with two types of diamond units: distorted and ideal diamonds. In the distorted diamond model, flat bands in the magnon spectra indicate the localized states confined to small regions (`trapping cells’) of the lattice. Remarkably, these trapping cells can host up to five and seven localized states for square and cubic lattices, respectively, leading to the macroscopic ground state degeneracy and high value of residual entropy. The problem of calculating ground state degeneracy reduces to that of non-interacting spins, whose spin value equal to half the number of localized magnons in the trapping cell. In contrast, ideal diamond models feature ground states composed of randomly distributed isolated diamond diagonal singlets immersed in a ferromagnetic background. Counting the ground state degeneracies here maps onto the percolation problem in 2D and 3D lattices. Our analysis shows that ideal diamond models possess even greater ground state degeneracy than their distorted counterparts. These findings suggest that synthesizing diamond-decorated-type compounds holds great promise for low-temperature cooling applications.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
34 pages, 12 figures
Asymptotic analysis of the 2D narrow-capture problem for partially accessible targets
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
In this paper we use singular perturbation theory to solve the 2D narrow capture problem for a set of partially accessible targets $ \calU_k$ , $ k=1,\ldots,N$ , in a bounded domain $ \Omega\subset \R^2$ . In contrast to previous models of narrow capture, we assume that when a searcher finds a target by attaching to the partially adsorbing surface $ \partial \calU_k$ it does not have immediate access to the resources within the target interior. Instead, the searcher remains attached to the surface for a random waiting time $ \tau$ , after which it either gains access to the resources within ({\em surface absorption}) or detaches and continues its search process ({\em surface desorption)}. We also consider two distinct desorption scenarios – either the particle continues its search from the point of desorption or rapidly returns to its initial search position. We formulate the narrow capture problem in terms of a set of renewal equations that relate the probability density and target flux densities for absorption to the corresponding quantities for irreversible adsorption. The renewal equations, which effectively sew together successive rounds of adsorption and desorption prior to the final absorption event, provide a general probabilistic framework for incorporating non-Markovian models of desorption/absorption and different search scenarios following desorption. We solve the general renewal equations in two stages. First, we calculate the Laplace transformed target fluxes for irreversible adsorption by solving a Robbin boundary value problem (BVP) in the small-target limit using matched asymptotic analysis. We then use the inner solution of the BVP to solve the corresponding Laplace transformed renewal equations for non-Markovian desorption/absorption, which leads to explicit Neumann series expansions of the corresponding target fluxes.
Statistical Mechanics (cond-mat.stat-mech), Analysis of PDEs (math.AP)
23 pages, 6 figures
Observing the Glass and Jamming Transitions of Dense Granular Material in Microgravity
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Christopher Mayo, Marlo Kunzner, Matthias Sperl, Jan Philipp Gabriel
The present study investigates a weakly pulsed granular system of polystyrene spheres under long-time microgravity conditions on the International Space Station (ISS). The spheres are measured using Diffusing Wave Spectroscopy (DWS) and are described by mean square displacements (MSDs). Our aim is to use this technique to show the first experimental evidence of glassy dynamics in dense granular media in microgravity and subsequently compare these results with ground-based measurements to see how the nature of these dynamics change without the influence of gravity. Our results show that as we densify the sample in microgravity, glassy dynamics appear at a volume fraction 1.6% lower than on ground. We also show how the influence of gravity can affect how dense a granular system one can prepare by comparing the final jamming point of our sample on the ISS compared to our ground setup. We show that jamming occurs at a volume fraction 0.5% lower in space compared to on ground. Showing that we can create denser states when a granular system is in the presence of a stronger gravitational field.
Soft Condensed Matter (cond-mat.soft), Other Condensed Matter (cond-mat.other)
Fixed Points and Universality Classes in Coupled Kardar-Parisi-Zhang Equations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Dipankar Roy, Abhishek Dhar, Manas Kulkarni, Herbert Spohn
Studied are coupled KPZ equations with three control parameters $ X,Y,T$ . These equations are used in the context of stretched polymers in a random medium, for the spacetime spin-spin correlator of the isotropic quantum Heisenberg chain, and for exciton-polariton condensates. In an earlier article we investigated merely the diagonal $ X=Y$ , $ T=1$ . Then the stationary measure is delta-correlated Gaussian and the dynamical exponent equals $ z = \tfrac{3}{2}$ . We observed that the scaling functions of the dynamic correlator change smoothly when varying $ X$ . In this contribution, the analysis is extended to the whole $ X$ -$ Y$ -$ T$ plane. Solutions are stable only if $ XY \geq 0$ . Based on numerical simulations, the static correlator still has rapid decay. We argue that the parameter space is foliated into distinct universality classes. They are labeled by $ X$ and consist of half-planes parallel to the $ Y$ -$ T$ plane containing the point $ (X,X,1)$ .
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Probability (math.PR)
30 pages, 8 figures
Variational autoencoders understand knot topology
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Anna Braghetto, Sumanta Kundu, Marco Baiesi, Enzo Orlandini
Supervised machine learning (ML) methods are emerging as valid alternatives to standard mathematical methods for identifying knots in long, collapsed polymers. Here, we introduce a hybrid supervised/unsupervised ML approach for knot classification based on a variational autoencoder enhanced with a knot type classifier (VAEC). The neat organization of knots in its latent representation suggests that the VAEC, only based on an arbitrary labeling of three-dimensional configurations, has grasped complex topological concepts such as chirality, unknotting number, braid index, and the grouping in families such as achiral, torus, and twist knots. The understanding of topological concepts is confirmed by the ability of the VAEC to distinguish the chirality of knots $ 9_{42}$ and $ 10_{71}$ not used for its training and with a notoriously undetected chirality to standard tools. The well-organized latent space is also key for generating configurations with the decoder that reliably preserves the topology of the input ones. Our findings demonstrate the ability of a hybrid supervised-generative ML algorithm to capture different topological features of entangled filaments and to exploit this knowledge to faithfully reconstruct or produce new knotted configurations without simulations.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Machine Learning (cs.LG)
10 pages
Bacterial Glass Transition
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Martin Maliet, Nicolas Fix-Boulier, Ludovic Berthier, Maxime Deforet
Bacterial assemblies exhibit rich collective behaviors that control their biological functions, making them a relevant object of study from an active matter physics perspective. Dense bacterial suspensions self-organize into distinct physical phases with intriguing dynamical properties. Here, we study dense two-dimensional films of swimming bacteria using advanced imaging techniques and machine learning. By varying density, we uncover a bacterial glass transition, a direct active matter analogue of equilibrium glass transitions in colloidal and molecular fluids. The transition is marked by a dramatic slowdown of dynamics with minimal structural change. Strong dynamic heterogeneity emerges in space and time, leading to an anomalous violation of the Stokes-Einstein relation and a growing dynamic correlation length, universally observed across five bacterial strains. Our results establish that bacterial colonies exhibit glassy dynamics, but their living, active nature gives them unique properties, paving the way for new research regarding how non-equilibrium physics impacts biology.
Soft Condensed Matter (cond-mat.soft), Quantitative Methods (q-bio.QM)
17 pages, 4 figures, supplementary information (with methods, 12 supp. figures, 2 supp. tables, and 9 supp. videos)
Positive unidirectional anisotropy in Y3Fe5O12/Ir20Mn80 bilayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
E. C. Souza, P. R. T. Ribeiro, J. E. Abrão, F. L. A. Machado, S. M. Rezende
We report an experimental study of the unidirectional anisotropy in bilayers made of the important ferrimagnetic insulator yttrium iron garnet (YIG) and the room temperature antiferromagnet Ir20Mn80 (IrMn). Measurements of the magnetization hysteresis loop in a wide temperature range and ferromagnetic resonance at room temperature revealed an unconventional positive exchange bias (EB). For comparison, we also made FMR measurements in a Py/IrMn bilayer that led to a negative EB with amplitude nearly two orders of magnitude larger than in YIG/IrMn. The presence of the positive EB, in which the hysteresis loop shift occurs in the direction of the field applied during deposition of the films, is attributed to an antiferromagnetic coupling between the spins of the two layers at the interface. The small value of the EB field in YIG/IrMn can be attributed to a competition of the interactions between the spins of the two sublattices of antiferromagnetic IrMn and ferrimagnetic YIG produced by the interface roughness.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Giant Barnett Effect from Moving Dislocations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Eugene M. Chudnovsky, Jorge F. Soriano
We show that moving dislocations generate giant effective local magnetic fields in a crystal lattice that can flip spins. Since massive creation of fast-moving dislocations is associated with a powerful elastic stress, this suggests a new mechanism of the magnetization reversal generated by laser or microwave beams or by electrically induced shear deformation.
Materials Science (cond-mat.mtrl-sci)
7 pages, 8 figures
Kondo effect in a two-dimensional electron gas in the Persistent Spin Helix regime
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
T. O. Puel, M. A. Manya, G. S. Diniz, E. Vernek, G. B. Martins
The Kondo effect arises from many-body interactions between localized magnetic impurities and conduction electrons, affecting electronic properties at low temperatures. In this study, we investigate the Kondo effect within a two-dimensional electron gas subjected to strong spin-orbit coupling in and out of the persistent spin helix regime, a state characterized by a long spin lifetime due to SU(2) symmetry recovery. Using the numerical renormalization group approach, we systematically analyze the influence of spin-orbit coupling strength and the orientation of an external magnetic field on the spectral properties of the impurity. Our findings reveal an entrancing interplay between spin-orbit coupling and the magnetic field, leading to key phenomena such as splitting of the hybridization function, asymmetry in the spectral function of the impurity, and significant tunability of the Kondo temperature due to spin orbit. These results provide valuable insights into the delicate balance between spin-orbit and external magnetic field effects in quantum impurity systems, contributing to a deeper understanding of spintronics and quantum manipulation in low-dimensional materials.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 9 figures, 1 table
Spin-Torque-Driven Non-uniform Dynamics of an Antivortex Core in Truncated Astroid Shaped Nanomagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Ahmet Koral Aykin, Hasan Piskin, Bayram Kocaman, Cenk Yanik, Vedat Karakas, Sevdenur Arpaci, Aisha Gokce Ozbay, Mario Carpentieri, Giovanni Finocchio, Federica Celegato, Paola Tiberto, Sergi Lendinez, Valentine Novosad, Axel Hoffmann, Ozhan Ozatay
Spin textures that are not readily available in the domain structures of continuous magnetic thin films can be stabilized when patterned to micro/nano scales due to the dominant effect of dipolar magnetic interactions. Fabrication of such devices enables a thorough study of their RF dynamics excited by highly concentrated spin-polarized/pure-spin currents. For this purpose, in this study, we have employed a truncated astroid geometry to achieve stable magnetic antivortex core nucleation/annihilation which was detectable using the anisotropic magnetoresistance (AMR) at various temperatures. Furthermore, by depositing a soft magnetic thin film (20 nm thick permalloy) capped with a heavy-metal 2nm Pt layer, we were able to probe the spin orbit torque induced excitations accompanied by self-torque due to half-antivortex cores reminiscent of an isolated-antivortex, yielding GHz frequency oscillations with high quality factors (~50000). The observed RF oscillations can be attributed to a non-uniform domain wall oscillation mode close to the stable-antivortex core nucleation site as seen in micromagnetic simulations. This fundamental study of antivortex core response to spin currents is crucial for the assessment of their potential applications in high frequency spintronic devices such as reservoir computers.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Ab initio screening for BCS-type superconductivity in ThCr$_2$Si$_2$-type compounds
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
Tom Ichibha, Ryo Maezono, Kenta Hongo
In this study, we applied ab initio $ T_\mathrm{c}$ calculations to compounds with the ThCr$ 2$ Si$ 2$ -type structure to search for BCS superconductor candidates. From the 1883 compounds registered in the Inorganic Crystal Structure Database, we excluded those whose chemical compositions would inhibit the emergence of BCS-type superconductivity by giving rise to magnetism or heavy-fermionic behavior. We then focused on 66 compounds confirmed to be dynamically stable through phonon calculations. Among these, for the 24 systems with experimentally reported $ T\mathrm{c}$ values, we verified that the ab initio $ T\mathrm{c}$ calculations exhibit excellent predictive reliability. For the remaining 42 compounds lacking experimental $ T_\mathrm{c}$ values, our predictions identified several new BCS-type superconductor candidates, including SrPb$ _2$ Al$ _2$ $ \left(T_c^\mathrm{calc}=2.2,\mathrm{K}\right)$ .
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Universality in many-body driven systems with an umbilic point
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Johannes Schmidt, Žiga Krajnik, Vladislav Popkov
We study stationary fluctuations of conserved slow modes in a two-lane model of hardcore particles which are expected to show universal behaviour. Specifically, we focus on the properties of fluctuations at a special umbilic point where the characteristic velocities coincide. At large space and time scales, fluctuations are described by a system of stochastic Burgers equations studied recently in [13]. Our data suggest coupling-dependent scaling functions and, even more surprisingly, coupling-dependent dynamical scaling exponents, distinct from KPZ scaling exponent typical for surface growth processes.
Statistical Mechanics (cond-mat.stat-mech), Cellular Automata and Lattice Gases (nlin.CG)
Antiferroelectricity with metastable ferroelectric state from Kittel model
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Amit Kumar Shah, Xin Li, Guodong Ren, Yu Yun, Xiaoshan Xu
We have revisited the Kittel model that describes antiferroelectricity (AFE) in terms of two sublattices of spontaneous polarization and antiparallel couplings. By constructing the comprehensive phase diagram including the antiferroelectric, ferroelectric, and paraelectric phases in the parameter space, we identified a phase with antiferroelectric stable states and ferroelectric metastable states (ASFM) due to the weak coupling between sublattices. We found that the metastability of the ferroelectric phase leads to apparent remanent polarization, depending on the measurement timescale. This explains the observed ferroelectric behavior of orthorhombic hafnia, which is predicted to be an antiferroelctric materials.
Materials Science (cond-mat.mtrl-sci)
Ferroelectric Al$_{1-x}$B$_x$N sputtered thin films on n-type Si bottom electrodes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Ian Mercer, Chloe Skidmore, Sebastian Calderon, Elizabeth Dickey, Jon-Paul Maria
Ferroelectric Al$ _{1-x}$ B$ _x$ N thin films are grown on highly doped and plasma treated (100) n-type Si. We demonstrate ferroelectricity for x = <0.01, 0.02, 0.06, 0.08, 0.13, and 0.17 where the n-type Si is both the substrate and bottom electrode. Polarization hysteresis reveals remanent polarization values between 130-140 $ \mu$ C/cm$ ^2$ and coercive field values as low as 4 MV/cm at 1 Hz with low leakage. The highest re-sistivity and most saturating hysteresis occurs with B contents between x = 0.06 and 0.13. We also demonstrate the impact of substrate plasma treatment time on Al$ _{1-x}$ B$ _x$ N crystallinity and switching. Cross-sectional transmission electron microscopy and electron energy loss spectra reveal an amorphous 3.5 nm SiNx layer at the Al$ _{1-x}$ B$ _x$ N interface post-plasma treatment and deposition. The first $ \sim 5$ nm of Al$ _{1-x}$ B$ _x$ N is crystallographically defective. Using the n-type Si substrate we demonstrate Al$ _{1-x}$ B$ _x$ N thick-ness scaling to 25 nm via low frequency hysteresis and CV. Serving as the bottom electrode and sub-strate, the n-type Si enables a streamlined growth process for Al$ _{1-x}$ B$ _x$ N for a wide range of Al$ _{1-x}$ B$ _x$ N compositions and layer thicknesses.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Spreading dynamics in the Hatano-Nelson model with disorder
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-08 20:00 EDT
The non-Hermitian skin effect is the accumulation of eigenstates at the boundaries, reflecting the system’s nonreciprocity. Introducing disorder leads to a competition between the skin effect and Anderson localization, giving rise to the skin-Anderson transition. Here, we investigate wave packet spreading in the disordered Hatano-Nelson model and uncover distinct dynamical behaviors across different regimes. In the clean limit, transport is unidirectionally ballistic ({\Delta}x ~ t) due to nonreciprocity. For weak disorder, where skin and Anderson-localized modes coexist, transport transitions from ballistic at early times to superdiffusive ({\Delta}x ~ t^{2/3}) at long times. In the deeply Anderson-localized regime, initial diffusion ({\Delta}x ~ t^{1/2}) eventually gives way to superdiffusive spreading. We examine how these scaling behaviors emerge from the system’s spectral properties and eigenstate localization behaviors. Our work unveils the rich dynamics driven by nonreciprocity and disorder in non-Hermitian systems.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics), Quantum Physics (quant-ph)
6 pages, 4 figures
On the influence of electrolytic gradient orientation on phoretic transport in dead-end pores
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Kushagra Tiwari, Jitendra Dhakar, Kapil Upadhyaya, Akash Choudhary
Electrolytic diffusiophoresis refers to directional migration of colloids due to interfacial forces that develop in response to local electrolytic concentration ($ c$ ) gradients. This physicochemical transport provides an efficient alternative in numerous microscale applications where advection-induced transport is infeasible. Phoretic withdrawal and injection in dead-end pores can be controlled by orienting salt gradients into or out of the pore; however, the extent to which this orientation influences spatiotemporal transport patterns is not thoroughly explored. In this study, we find that it has a significant influence: colloidal withdrawal in solute-out mode ($ \beta=c_\infty/c_{\text{pore}}<1$ ) is faster and shallower, whereas the solute-in mode enables deeper withdrawal. Similarly, solute-out injection features rapidly propagating wavefronts, whereas the solute-in mode ($ \beta >1$ ) promotes uniform and gradual injection. Each mode’s transport is found to evolve and persist over different time scales. We characterize the performance of these modes and find that while persistence of the solute-out mode strengthens with a growing electrolytic gradient [$ \sim \ln(\beta^{-0.4})$ ], solute-in mode diminishes and eventually its persistence is insensitive to $ \beta$ . We also incorporate the variable mobility model to examine the impact of large zeta potentials, which intensifies the transport of solute-out mode further and weakens the solute-in mode. Additionally, we investigate how osmotic flows of the two modes affect injection and withdrawal patterns. We find that osmosis-induced mixing can counterintuitively inhibit injection effectiveness in solute-out mode. These insights bring attention to the distinctions between different phoretic transport modes and contribute to the rational design and setup of electrolytic gradients in numerous microscale applications.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
12 pages 9 figures
Low-energy effective theory of localization-delocalization transition in noninteger-charged electron wave packets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
We present a low-energy effective theory to describe the localization-delocalization transition, which occurs for wave functions of electrons and holes injected individually by a voltage pulse with noninteger flux quantum. We find that the transition can be described by an effective scattering matrix in a truncated low-energy space, which is composed of two parts. The first part describes the infrared-divergence of the scattering matrix, while the second part represents the high-energy correlation. For short-tailed pulses which decay faster than Lorentzian, the scattering matrix exhibits solely an inverse linear divergence in the infrared limit. The divergence is responsible for the dynamical orthogonality catastrophe, which leads to electron-hole pairs with delocalized wave functions. In contrast, the high-energy correlation can be approximated by a constant term, which leads to electron-hole pairs with localized wave functions. Due to the competition between the two terms, the wave functions can undergo a localization-delocalization transition, which occurs for electrons and holes injected individually by the voltage pulse. As a consequence, the localization-delocalization transitions for all short-tailed pulses can be described by the same effective scattering matrix, suggesting that they belong to the same universality class. For pulses with longer tails, the scattering matrix can exhibit additional infrared-divergences. We show that a Lorentzian pulse gives rise to a logarithmic divergence, while a fractional-powered Lorentzian pulse gives rise to a power-law divergence. The additional divergence can lead to localization-delocalization transitions belonging to different universality classes. These results demonstrate the fine-tuning capabilities of the localization-delocalization transition in time-dependent quantum transport.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Manipulating magnetization by orbital current from a light metal Ti
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Dongxing Zheng, Jingkai Xu, Fatimah Alsayafi, Sachin Krishnia, Dongwook Go, Duc Tran, Tao Yang, Yan Li, Yinchang Ma, Chen Liu, Meng Tang, Aitian Chen, Hanin Algaidi, Hao Wu, Kai Liu, Yuriy Mokrousov, Mathias Kläui, Udo Schwingenschlögl, Xixiang Zhang
The orbital Hall effect, which does not rely on the spin-orbit coupling, has recently emerged as a promising mechanism for electrically manipulating magnetization in thin-film ferromagnets. Despite its potential, direct experimental observation of magnetization switching driven by orbital currents has been challenging, primarily because there is no direct exchange coupling between orbital angular momentum and local spin based magnetic moments. In this study, we present a compensated design to directly probe the contribution of orbital currents in the most promising light metal titanium (Ti), where symmetric layer structures allow zeroing out of the net spin current. By varying the thickness of the Ti layer in Ti(t)/Pt/Co/Pt/Co/Pt multilayers, we demonstrate the ability to control the magnetization switching polarity. We deduce the orbital charge conversion efficiency of the Ti layer to be approximately 0.17. These findings not only confirm the presence of the orbital Hall effect in Ti but also suggest that orbital currents may be promising candidates for developing energy-efficient magnetic devices with enhanced performance and scalability.
Materials Science (cond-mat.mtrl-sci)
Non-equilibrium Dynamics and Universality of 4D Quantum Vortices and Turbulence
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-08 20:00 EDT
The study of quantum vortices provides critical insights into non-equilibrium dynamics across diverse physical systems. While previous research has focused on point-like vortices in two dimensions(2D) and line-like vortices in three dimensions(3D), quantum vortices in four spatial dimensions(4D) are expected to take the form of extended vortex surfaces, thereby fundamentally enriching dynamics. Here, we conduct a comprehensive numerical study of 4D quantum vortices and turbulence. Using a special visualization scheme, we discovered the decay of topological numbers that does not exist in low dimensions, as well as the high-dimensional counterpart of the vortex reconnection process. We further explore quench dynamics across phase transitions in four dimensions and verify the applicability of the higher-dimensional Kibble-Zurek mechanism, including both slow and fast quenches. Our simulations provide numerical evidence of quantum turbulence in four dimensions, characterized by universal power-law behavior: vortex decay scaling as $ t^{-1}$ , an energy spectrum consistent with the classical Kolmogorov law $ k^{-5/3}$ , and a velocity distribution exhibiting a distinct $ v^{-3}$ tail. These findings reveal universal principles governing topological defects in higher dimensions, broadening our understanding of quantum physics in high-dimensional spaces and offering insights for future experimental realizations using synthetic dimensions.
Quantum Gases (cond-mat.quant-gas), Chaotic Dynamics (nlin.CD)
11 pages, 5 figures
TensorSymmetry: a package to get symmetry-adapted tensors disentangling spin-orbit coupling effect and establishing analytical relationship with magnetic order
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Rui-Chun Xiao, Yuanjun Jin, Zhi-Fan Zhang, Zi-Hao Feng, Ding-Fu Shao, Mingliang Tian
The symmetry-constrained response tensors on transport, optical, and electromagnetic effects are of central importance in condensed matter physics because they can guide experimental detections and verify theoretical calculations. These tensors encompass various forms, including polar, axial, i-type (time-reversal even), and c-type (time-reversal odd) matrixes. The commonly used magnetic groups, however, fail to describe the phenomena without the spin-orbit coupling (SOC) effect and cannot build the analytical relationship between magnetic orders with response tensors in magnetic materials. Developing approaches on these two aspects is quite demanding for theory and experiment. In this paper, we use the magnetic group, spin group, and extrinsic parameter method comprehensively to investigate the symmetry-constrained response tensors, then implement the above method in a platform called “TensorSymmetry”. With the package, we can get the response tensors disentangling the effect free of SOC and establish the analytical relationship with magnetic order, which provides useful guidance for theoretical and experimental investigation for magnetic materials.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Intertwined geometries in collective modes of two dimensional Dirac fermions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
It is well known that the time-dependent response of a correlated system can be inferred from its spectral correlation functions. As a textbook example, the zero sound collective modes of a Fermi liquid appear as poles of its particle-hole susceptibilities. However, the Fermi liquid’s interactions endow these response functions with a complex analytic structure, so that this time/frequency relationship is no longer straightforward. We study how the geometry of this structure is modified by a nontrivial band geometry, via a calculation of the zero sound spectrum of a Dirac cone in two dimensions. We find that the chiral wavefunctions fundamentally change the analytic structure of the response functions. As a result, isotropic interactions can give rise to a variety of unconventional zero sound modes, that, due to the geometry of the functions in frequency space, can only be identified via time-resolved probes. These modes are absent in a conventional Fermi liquid with similar interactions, so that these modes can be used as a sensitive probe for the existence of Dirac points in a band-structure.
Strongly Correlated Electrons (cond-mat.str-el)
18 pages, 7 figures
Pressure Induced Anomalous Metal in the Vicinity of the Superconductor Insulator Transition
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
Roy G. Cohen Song, Mark Nikolaevsky, Amitay Cohen, Ran Salem, Shamashis Sengupta, Claire A. Marrache-Kikuchi, Aviad Frydman
The Superconductor-to-Insulator Transition (SIT) in two-dimensional superconductors occurs due to a competition between superconductivity, quantum interferences, Coulomb interactions and disorder. Despite extensive theoretical and experimental investigation, the SIT remains an active research area due to the potential for exotic phases near the transition. One such phase is the Anomalous Metal, which has been claimed to exist between the insulating and superconducting states. This elusive phase, which is not consistent with current theories, is under heavy deliberations nowadays. We present an experimental study of the effect of high pressure on thin films of amorphous indium oxide. Our results show that pressure induces a series of transitions from a Bose insulator through a superconducting phase, metallic phases and finally to a conventional insulator. We suggest that our findings reaffirm the existence of a two-dimensional metal close to the SIT and show that its occurrence requires relatively strong coupling between regions that are weakly superconducting.
Superconductivity (cond-mat.supr-con)
6 pages, 4 figures
Planar Josephson junction devices with narrow superconducting strips: Topological properties and optimization
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
Purna P. Paudel (1), Javad Shabani (2), Tudor D. Stanescu (1) ((1) Institution One, (2) Institution Two)
We study the low-energy physics of planar Josephson junction structures realized in a quasi-two dimensional semiconductor system proximity-coupled to narrow superconducting films. Using both a recursive Green’s function approach and an effective Hamiltonian approximation, we investigate the topological superconducting phase predicted to emerge in this type of system. We first characterize the effects associated with varying the electrostatic potentials applied within the unproximitized semiconductor regions. We then address the problem of optimizing the width of the superconductor films and identifying the optimal regimes characterized by large topological gap values. We find that structures with narrow superconducting films of widths ranging between about $ 100$ nm and $ 200$ nm can support topological superconducting phases with gaps up to $ 40%$ of the parent superconducting gap, significantly larger than those characterizing the corresponding wide-superconductor structures. This work represents the first component of a proposed comprehensive strategy to address this optimization problem in planar Josephson junction structures and realize robust topological devices.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
22 pages, 27 figures
Coupled femto-excitons, free carriers and light
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Deepika Gill, Sam Shallcross, Wenhan Chen, J. Kay Dewhurst, Sangeeta Sharma
Non-equilibrium quantum matter generated by ultrafast laser light opens new pathways in fundamental condensed matter physics, as well as offering rich control possibilities in “tailoring matter by light”. Here we explore the coupling between free carriers and excitons mediated by femtosecond scale laser pulses. Employing monolayer WSe$ _2$ and an {\it ab-initio} treatment of pump-probe spectroscopy we find that, counter-intuitively, laser light resonant with the exciton can generate massive enhancement of the early time free carrier population. This exhibits complex dynamical correlation to the excitons, with an oscillatory coupling between free carrier population and exciton peak height that persists. Our results both unveil “femto-excitons” as possessing a rich femtosecond dynamics as well as, we argue, allowing tailoring of early time light-matter interaction via laser pulse design to control simultaneously excitonic and free carrier physics at ultrafast times.
Materials Science (cond-mat.mtrl-sci)
Light dressed excitons
Circular currents in an antiferromagnetic ring with a side-coupled one-dimensional chain
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Sourav Karmakar, Suparna Sarkar, Santanu K. Maiti
We investigate persistent charge and spin currents in an antiferromagnetic (AFM) quantum ring threaded by an Aharonov-Bohm flux, in the presence of a side-coupled one-dimensional non-magnetic (NM) chain. In the absence of the chain, the spin circular current vanishes exactly due to the symmetry between the up and down spin sub-Hamiltonians. Modeling the system within a tight-binding (TB) framework, we compute the currents using a second-quantized approach. Both charge and spin currents can be selectively tuned by adjusting the ring-chain coupling strength. Temperature plays a crucial role in modulating the currents, and interestingly, we find that they increase significantly with rising temperature–contrary to conventional expectations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 5 figures [Conference Paper]
Surface Dominated Quantum Geometry-Induced Nonlinear Transport in the van der Waals Antiferromagnet CrSBr
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Kamal Das, Yufei Zhao, Binghai Yan
The van der Waals (vdW) antiferromagnet CrSBr has recently garnered significant attention due to its air stability, high magnetic transition temperature, and semiconducting properties. We investigate its nonlinear transport properties and identify a quantum metric dipole-induced nonlinear anomalous Hall effect and nonlinear longitudinal resistivity, which switch sign upon reversing the Néel vector. The significant quantum metric dipole originates from Dirac nodal lines near the conduction band edge within the experimentally achievable doping range. Known the weak interlayer coupling, it is unexpected that the nonlinear conductivities do not scale with sample thickness but are dominantly contributed by surface layers. In the electron-doped region, the top layer dominates the response while the top three layers contribute the most in the hole-doped region. Our results establish topological nodal lines as a guiding principle to design high-performance nonlinear quantum materials and suggest that surface-sensitive transport devices will provide new avenues for nonlinear electronic applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
6 pages, 4 figures, Comments are welcome
Topological Fermi-arc-like surface states in Kramers nodal line metals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Zi-Ting Sun, Ruo-Peng Yu, Xue-Jian Gao, K. T. Law
The discovery of Kramers nodal line metals (KNLMs) and Kramers Weyl semimetals (KWSs) has significantly expanded the range of metallic topological materials to all noncentrosymmetric crystals. However, a key characteristic of this topology - the presence of topologically protected surface states in KNLMs - is not well understood. In this work, we use a model of a $ C_{1v}$ KNLM with curved Kramers nodal lines (KNLs) to demonstrate that Fermi-arc-like surface states (FALSSs), which have a $ \mathbb{Z}_2$ topological origin, appear on surfaces parallel to the mirror plane. These states connect two surface momenta, corresponding to the projections of two touching points on the Fermi surfaces. Notably, as achiral symmetries (mirrors and roto-inversions) are gradually broken, the KNLM transitions into a KWS, allowing the FALSSs to evolve continuously into the Fermi arc states of the KWS. We also explore the conditions under which FALSSs emerge in KNLMs with straight KNLs. Through bulk-boundary correspondence, we clarify the topological nature of KNLMs.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 4 figures
PTST: A polar topological structure toolkit and database
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Guanshihan Du, Yuanyuan Yao, Linming Zhou, Yuhui Huang, Mohit Tanwani, He Tian, Yu Chen, Kaishi Song, Juan Li, Yunjun Gao, Sujit Das, Yongjun Wu, Lu Chen, Zijian Hong
Ferroelectric oxide superlattices with complex topological structures such as vortices, skyrmions, and flux closure domains have garnered significant attention due to their fascinating properties and potential applications. However, progress in this field is often impeded by challenges such as limited data-sharing mechanisms, redundant data generation efforts, high barriers between simulations and experiments, and the underutilization of existing datasets. To address these challenges, we have created the Polar Topological Structure Toolbox and Database(PTST). This community driven repository compiles both standard datasets from high throughput phase field simulations and user submitted nonstandard datasets. The PTST utilizes a Global Local Transformer (GL Transformer) to classify polarization states by dividing each sample into spatial sub blocks and extracting hierarchical features, resulting in ten distinct topological categories. Through the PTST web interface, users can easily retrieve polarization data based on specific parameters or by matching experimental images. Additionally, a Binary Phase Diagram Generator allows users to create strain and electric field phase diagrams within seconds. By providing ready-to-use configurations and integrated machine-learning workflows, PTST significantly reduces computational load, streamlines reproducible research, and promotes deeper insights into ferroelectric topological transitions.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
23 Pages and 6 figures for the main text
Elementary Excitations, Melting Temperature and Correlation Energy in Wigner Crystal
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
We present a fully quantum-mechanical study of the energy-momentum dispersion of running waves, spin-conserving neutral excitations, and spin-reversal neutral excitations in a spin-polarized two-dimensional Wigner crystal (WC). Our results show that the collective modes - plasmon and transverse sound - closely follow classical predictions even at surprisingly low values of $ r_s \sim 8$ . Furthermore, by extracting the shear modulus from the transverse sound speed, we find that quantum mechanical effects enhance the shear modulus at high densities, leading to a (Kosterlitz-Thouless-Halperin-Nelson-Young) melting temperature that exceeds the classical prediction. In addition, we apply the quasi-boson approximation to compute the correlation energy of the 2D WC based on its neutral excitation spectrum. While this approach underestimates the absolute correlation energy compared to quantum Monte Carlo results, it successfully captures the overall trend. These findings establish a robust quantum-mechanical foundation for understanding elementary excitations in Wigner crystals within low-dimensional electron systems and provide valuable theoretical insights for future experimental studies.
Strongly Correlated Electrons (cond-mat.str-el)
18 pages, 8 figures
Strain-Enhanced Altermagnetism in Ca${3}$Ru${2}$O$_{7}$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Andrea León, Carmine Autieri, Thomas Brumme, Jhon W. González
Perovskite compounds exhibit enhanced octahedral distortions coupled with strong electronic correlations, providing a promising platform to explore and tune altermagnetic (AM) order. In this work, we investigate AM phases in Ca$ _{3}$ Ru$ _{2}$ O$ _{7}$ , a well-known perovskite that hosts antiferromagnetism coupled to structural degrees of freedom. We demonstrate that Ca$ _{3}$ Ru$ _{2}$ O$ _{7}$ is a Kramers antiferromagnet in its ground state. However, a Néel-type magnetic configuration reveals a P-2 d-wave AM, hosting orbital-selective altermagnetism analogous to Ca$ _{2}$ RuO$ _{4}$ . We further explore the effects of biaxial strain on the stability between the antiferromagnetic ground state and the AM phase. Our results suggest that the AM phase becomes more stable than the AFM phase below -2% compressive strain. Additionally, strain can either enhance or suppress AM bands, with enhancements reaching up to 9% under tensile strain. To quantify the AM band splitting, we introduce the “Altermagnetic Merit Figure” and analyze the role of electronic localization, delocalization, and octahedral distortions in AM behavior and magnetic stability changes under strain.
Materials Science (cond-mat.mtrl-sci)
10 pages, 7 figures
Roadmap for Photonics with 2D Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
F. Javier García de Abajo, D. N. Basov, Frank H. L. Koppens, Lorenzo Orsini, Matteo Ceccanti, Sebastián Castilla, Lorenzo Cavicchi, Marco Polini, P. A. D. Gonçalves, A. T. Costa, N. M. R. Peres, N. Asger Mortensen, Sathwik Bharadwaj, Zubin Jacob, P. J. Schuck, A. N. Pasupathy, Milan Delor, M. K. Liu, Aitor Mugarza, Pablo Merino, Marc G. Cuxart, Emigdio Chávez-Angel, Martin Svec, Luiz H. G. Tizei, Florian Dirnberger, Hui Deng, Christian Schneider, Vinod Menon, Thorsten Deilmann, Alexey Chernikov, Kristian S. Thygesen, Yohannes Abate, Mauricio Terrones, Vinod K. Sangwan, Mark C. Hersam, Leo Yu, Xueqi Chen, Tony F. Heinz, Puneet Murthy, Martin Kroner, Tomasz Smolenski, Deepankur Thureja, Thibault Chervy, Armando Genco, Chiara Trovatello, Giulio Cerullo, Stefano Dal Conte, Daniel Timmer, Antonietta De Sio, Christoph Lienau, Nianze Shang, Hao Hong, Kaihui Liu, Zhipei Sun, Lee A. Rozema, Philip Walther, Andrea Alù, Michele Cotrufo, Raquel Queiroz, X.-Y. Zhu, Joel D. Cox, Eduardo J. C. Dias, Álvaro Rodríguez Echarri, Fadil Iyikanat, Andrea Marini, Paul Herrmann, Nele Tornow, Sebastian Klimmer, Jan Wilhelm, Giancarlo Soavi, Zeyuan Sun, Shiwei Wu, Ying Xiong, Oles Matsyshyn, Roshan Krishna Kumar, Justin C. W. Song, Tomer Bucher, Alexey Gorlach, Shai Tsesses, Ido Kaminer, Julian Schwab, Florian Mangold, Harald Giessen, M. Sánchez Sánchez, D. K. Efetov, T. Low, G. Gómez-Santos, T. Stauber, Gonzalo Álvarez-Pérez, Jiahua Duan, Luis Martín-Moreno, Alexander Paarmann, Joshua D. Caldwell, Alexey Y. Nikitin, Pablo Alonso-González, Niclas S. Mueller, Valentyn Volkov, Deep Jariwala, Timur Shegai, Jorik van de Groep
Triggered by the development of exfoliation and the identification of a wide range of extraordinary physical properties in self-standing films consisting of one or few atomic layers, two-dimensional (2D) materials such as graphene, transition metal dichalcogenides (TMDs), and other van der Waals (vdW) crystals currently constitute a wide research field protruding in multiple directions in combination with layer stacking and twisting, nanofabrication, surface-science methods, and integration into nanostructured environments. Photonics encompasses a multidisciplinary collection of those directions, where 2D materials contribute with polaritons of unique characteristics such as strong spatial confinement, large optical-field enhancement, long lifetimes, high sensitivity to external stimuli (e.g., electric and magnetic fields, heating, and strain), a broad spectral range from the far infrared to the ultraviolet, and hybridization with spin and momentum textures of electronic band structures. The explosion of photonics with 2D materials as a vibrant research area is producing breakthroughs, including the discovery and design of new materials and metasurfaces with unprecedented properties as well as applications in integrated photonics, light emission, optical sensing, and exciting prospects for applications in quantum information, and nanoscale thermal transport. This Roadmap summarizes the state of the art in the field, identifies challenges and opportunities, and discusses future goals and how to meet them through a wide collection of topical sections prepared by leading practitioners.
Materials Science (cond-mat.mtrl-sci)
199 pages, 42 figures, 1154 references
Beyond catastrophic forgetting in associative networks with self-interactions
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-08 20:00 EDT
Gianni V. Vinci, Andrea Galluzzi, Maurizio Mattia
Spin-glass models of associative memories are a cornerstone between statistical physics and theoretical neuroscience. In these networks, stochastic spin-like units interact through a synaptic matrix shaped by local Hebbian learning. In absence of self-interactions (i.e., autapses), the free energy reveals catastrophic forgetting of all stored patterns when their number exceeds a critical memory load. Here, we bridge the gap with biology by considering networks of deterministic, graded units coupled via the same Amari-Hopfield synaptic matrix, while retaining autapses. Contrary to the assumption that self-couplings play a negligible role, we demonstrate that they qualitatively reshape the energy landscape, confining the recurrent dynamics to the subspace hosting the stored patterns. This allows for the derivation of an exact overlap-dependent Lyapunov function, valid even for networks with finite size. Moreover, self-interactions generate an auxiliary internal field aligned with the target memory pattern, widening the repertoire of accessible attractor states. Consequently, pure recall states act as robust associative memories for any memory load, beyond the critical threshold for catastrophic forgetting observed in spin-glass models – all without requiring nonlocal learning prescriptions or significant reshaping of the Hebbian synaptic matrix.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Neurons and Cognition (q-bio.NC)
11 pages, 7 figures
Transport through Nodal Surface Semimetal - Superconductor junction in presence or absence of light irradiation
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
We study quantum tunelling via $ s$ -wave superconductor (SC) junction with a topologically charged nodal surface semimetal (NSSM) where a nonsymmorphic symmetry forces the nodal surfaces to stick to the BZ boundary. Due to their unique dispersions close to the two dimensional band crossing, the charge carriers in the NSSM display interesting behavior in the nature of Andreev as well as normal reflections at the SC junction interface, for both subgap and supergap energies. We investigate such behaviors for different incident orientations. Furthermore, we also consider irradiation via light with circular and linear polarization on such systems and probe the stroboscopic temporal evolution of the transport parameters. In particular, we follow a Floquet approach in the limit of high frequency irradiation and witness there many unusal Andreev transport behavior to unfold.
Superconductivity (cond-mat.supr-con)
Initial Draft
Room-temperature dislocation plasticity in ceramics: Methods, Materials, and Mechanisms
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Alexander Frisch, Chukwudalu Okafor, Oliver Preuß, Jiawen Zhang, Katsuyuki Matsunaga, Atsutomo Nakamura, Wenjun Lu, Xufei Fang
Dislocation-mediated plastic deformation in ceramic materials has sparked renewed research interest due to the technological potential of dislocations. Despite the long research history of dislocations as one-dimensional lattice defects in crystalline solids, the understanding of plastically deformable ceramics at room temperature seems lacking. The conventional view holds that ceramics are brittle, difficult to deform at room temperature and exhibit no dislocation plasticity except in small-scale testing such as nanoindentation and nano-micropillar compression. In this review, we attempt to gather the evidence and reports of room-temperature dislocation plasticity in ceramics beyond the nano-/microscale, with a focus on meso-macroscale plasticity. First, we present a mechanical deformation toolbox covering various experimental approaches for assessing the dislocation plasticity, with a focus on bulk plasticity. Second, we provide a materials toolbox listing 44 ceramic compounds that have been reported to exhibit dislocation plasticity at meso-/macroscale under ambient conditions. Finally, we discuss the mechanics of dislocations in ceramics, aiming to establish a foundation for predicting and discovering additional ceramics capable of room-temperature plastic deformation, thereby advancing the development of prospective dislocation-based technologies.
Materials Science (cond-mat.mtrl-sci)
Intrinsic Nonreciprocity in Asymmetric Josephson Junctions with Non-Sinusoidal Current-Phase Relations
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
Josephson junctions (JJs) with non-sinusoidal current-phase relations (CPRs) have gathered increasing attention, partly due to growing interest in topological 2D materials. Understanding how CPR and inhomogeneities in JJs influence their response is crucial for accurate interpretation of experimental observations. This Letter reports that a non-sinusoidal CPR, combined with asymmetries in the JJ, can break spatial symmetry and give rise to the Josephson diode effect (JDE) in the short junction regime. This nonreciprocity is shown to emerge as an intrinsic mechanism related to the maximization of the supercurrent, rather than being solely driven by geometric or material asymmetries. Further analysis shows that JDE efficiency is strongly influenced by the CPR shape but is largely insensitive to junction asymmetry, making the observed nonreciprocity not only a potential experimental signature of unconventional CPRs but also a possible method for probing their properties.
Superconductivity (cond-mat.supr-con)
Raman spectroscopic evidence for linearly dispersed nodes and magnetic ordering in the topological semimetal V$_{1/3}$NbS$_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Shreenanda Ghosh, Chris Lygouras, Zili Feng, Mingxuan Fu, Satoru Nakatsuji, Natalia Drichko
Weyl semimetals are characterized by an electronic structure with linearly dispersed nodes and distinguished chirality, protected by broken inversion or time reversal symmetry. The intercalated transition metal dichalcogenide V$ _{1/3}$ NbS$ _2$ is proposed as a Weyl semimetal. In this study, we report polarization-resolved magnetic and electronic Raman scattering of this material, probing both the magnetic order and the electronic structure. The electronic scattering reveals a linear with frequency continuum of excitations, as the signature of electronic transitions within the proposed Weyl nodes in a two-dimensional electronic structure. Additionally, two-magnon excitations of V moments are observed near 15 meV in the magnetically ordered phase below 50 K. These excitations are well reproduced by calculations based on the Fleury-Loudon theory using spin wave exchange parameters derived from the neutron scattering data of this material and confirm the antiferromagnetic character of the order. These magnetic and electronic scattering, observed in the same spectra, provide independent spectroscopic evidence for a collinear antiferromagnetic Weyl semimetal state in V$ _{1/3}$ NbS$ _2$ .
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
7 pages manuscript plus 3 pages SI, 8 figures
Non-Equilibrium Dynamics of Hard Spheres in the Fluid, Crystalline, and Glassy Regimes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Matthew Kafker, Xerxes D. Arsiwalla
We investigate the response of a system of hard spheres to two classes of perturbations over a range of densities spanning the fluid, crystalline, and glassy regimes within a molecular dynamics framework. Firstly, we consider the relaxation of a “thermal inhomogeneity,” in which a central region of particles is given a higher temperature than its surroundings and is then allowed to evolve under Newtonian dynamics. In this case, the hot central “core” of particles expands and collides with the cold surrounding material, creating a transient radially-expanding “compression wave,” which is rapidly dissipated by particle-particle collisions and interaction with periodic images at the boundary, leading to a rapid relaxation to equilibrium. Secondly, we consider a rapid compression of the spheres into a disordered glassy state at high densities. Such rapidly compressed systems exhibit very slow structural relaxation times, many orders of magnitude longer than thermalization times for simple temperature inhomogeneities. We find that thermal relaxation of the velocity distribution is determined simply by the total collision rate, whereas structural relaxation requires coordinated collective motion, which is strongly suppressed at high density, although some particle rearrangement nevertheless occurs. We further find that collisions propagate significantly faster through glassy systems than through crystalline systems at the same density, which leads to very rapid relaxation of velocity perturbations, although structural relaxation remains very slow. These results extend the validity of previous observations that glassy systems exhibit a hybrid character, sharing features with both equilibrium and non-equilibrium systems. Finally, we introduce the hard sphere causal graph, a network-based characterization of the dynamical history of a hard sphere system, which encapsulates several useful…
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
15 pages, 12 figures
Characterization of NbTiN/HZO/NbTiN MIM Capacitors for high frequency AC Clock & Power Distribution Network for Superconducting Digital Circuits
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
Seifallah Ibrahim, Blake Hodges, Steven Brebels, Julian Gil Pinzon, Trent Josephsen, Ankit Pokhrel, Daniel Perez Lozano, Yann Canvel, Bart Kenens, Amey M. Walke, Gianpiero Maccarrone Lapi, Sara Iraci, Mihaela Popovici, Benjamin Huet, Quentin Herr, Zsolt Tőkei, Anna Herr
A resonant clock-power distribution network is critical for scaling energy efficient superconducting digital technology to practical high integration density circuits. High-k, tunable capacitors enable implementation of a resonant power delivery network supporting circuits with up to 400 Mdevices/cm2. We report the cryogenic characterization of Metal-Insulator-Metal capacitors using a Hafnium Zirconium Oxide (HZO) ferroelectric insulating layer and Niobium Titanium Nitride (NbTiN) superconducting electrodes. The fabricated chip includes capacitor arrays for low frequency characterization and a half-wave transmission line resonator for RF characterization. A specific capacitance of 3 uF/cm2, DC leakage current of 10-8 A/cm2 at 2 V and a constant 5 percent tunability up to 4 GHz were measured at 2.6 K.
Superconductivity (cond-mat.supr-con)
3 Pages, 10 Figures, 1 Table
Topology and Kinetic Pathways of Colloidosome Assembly and Disassembly
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Raymond Adkins, Joanna Robaszewski, Seungwoo Shin, Fridtjof Brauns, Leroy Jia, Ayantika Khanra, Prerna Sharma, Robert Pelcovits, Thomas R. Powers, Zvonimir Dogic
Liquid shells, such as lipid vesicles and soap bubbles, are ubiquitous throughout biology, engineered matter, and everyday life. Their creation and disintegration are defined by a singularity that separates a topologically distinct extended liquid film from a boundary-free closed shell. Such topology-changing processes are essential for cellular transport and drug delivery. However, their studies are challenging because of the rapid dynamics and small length scale of conventional lipid vesicles. We develop fluid colloidosomes, micron-sized analogs of lipid vesicles. We study their stability close to their disk-to-sphere topological transition. Intrinsic colloidal length and time scales slow down the dynamics to reveal vesicle conformations in real time during their assembly and disassembly. Remarkably, the lowest-energy pathway by which a closed vesicle transforms into a disk involves a topologically distinct cylinder-like intermediate. These results reveal universal aspects of topological changes in all liquid shells and a robust platform for the encapsulation, transport, and delivery of nanosized cargoes.
Soft Condensed Matter (cond-mat.soft)
Self-alignment and anti-self-alignment suppress motility-induced phase separation in active systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Marco Musacchio, Alexander P. Antonov, Hartmut Löwen, Lorenzo Caprini
In this article, we investigate the impact of self-alignment and anti-self-alignment on collective phenomena in dense active matter. These mechanisms correspond to effective torques that align or anti-align a particles orientation with its velocity, as observed in active granular systems. In the context of motility-induced phase separation (MIPS) - a non-equilibrium coexistence between a dense clustered phase and a dilute homogeneous phase - both self- and anti-self-alignment are found to suppress clustering. Specifically, increasing self-alignment strength first leads to flocking within the dense cluster, and eventually to the emergence of a homogeneous flocking phase. In contrast, anti-self-alignment induces a freezing phenomenon, progressively reducing particle speed until MIPS is suppressed and a homogeneous phase is recovered. These results are supported by scaling arguments and are amenable to experimental verification in high-density active granular systems exhibiting self- or anti-self-alignment.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Long-living superfluidity of dark excitons in a strip of strained transition metal dichalcogenides double layer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Gabriel Pimenta Martins, Oleg L. Berman, Godfrey Gumbs, Gabriele Grosso
We have proposed the superfluidity of dipolar excitons in a strip of double-layer transition metal dichalcogenides (TMDCs) heterostructures. We have shown that strain causes a shift in k-space between the minimum of the conduction band and the maximum of the valence band. Therefore, we expect that applying strain to this system can cause dark excitons to be created. We have numerically calculated the energy spectrum of dark dipolar excitons in strained MoSe$ _2$ , and we have calculated their binding energies and effective masses. We have shown that the dark dipolar excitons in strained TMDC heterostructures form superfluids, and we have calculated the sound velocity in the energy spectrum of collective excitations, as well as the mean-field critical temperature for superfluidity. We have shown that two separate superfluid flows moving in opposite directions will appear in the system, one on each edge of the strip, forming the double layer. We have seen that the critical temperature for superfluidity increases with the concentration of dark excitons, as well as with the inter-layer separation. The fact that dark excitons cannot decay by the simple emission of photons, makes it so that the superfluids and condensates formed by them have a much longer lifetime than that formed by bright excitons. We propose a way to experimentally verify the predicted phenomena.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 10 figures
Ultrafast switchable polar and magnetic orders by nonlinear light-matter interaction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Haoyu Wei, Daniel Kaplan, Haowei Xu, Ju Li
An outstanding challenge in materials science and physics is the harnessing of light for switching charge order in e.g., ferroelectrics. Here we propose a mechanism through which electrons in ferroelectric bilayers excited with light cause ionic structural transitions. Using perturbation theory within a many-body formalism, we show that the ionic coupling is mediated by a resonant change in electronic occupation functions, ultimately governed by the quantum geometric tensor (QGT) of the ground state. Furthermore, we show that such transitions are generally accompanied by multiferroic order switching. We demonstrate two examples of light-induced structural and polarization switching under this mechanism using first-principle calculations on bilayer CrI$ _{3}$ and MoTe$ _{2}$ . We show that the two materials can switch between atomic stackings with a light intensity threshold of only 10-100 GW/cm$ ^2$ , a value 1-3 orders of magnitude lower than that required by direct light-ion coupling thanks to the superior efficiency of resonant light-electron coupling. Since such switching is fast, highly controllable, contactless, and reversible, it is promising for use in optically controlled nonvolatile memory, nanophotonics and polar electronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 4 figures. Comments welcome
Achieving Altermagnetism in Monolayer Holey Graphyne via Atomic Manipulation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Achieving altermagnetism (AM) in two-dimensional materials is crucial for advancing the development of novel spintronic devices. This study introduces an innovative strategy to realize AM in monolayer materials by adsorbing non-magnetic $ sp$ impurity atoms to construct planar bridges. Using holey graphyne (HGY) as the research object, first-principles calculations reveal that B and S impurity atoms can modulate the local electronic structure and trigger a superexchange mechanism, inducing a collinear compensated antiferromagnetic ground state with pronounced altermagnetic properties. Among these, the B adsorption system exhibits the best magnetic performance, with a N$ \rm \acute{e}$ el temperature reaching approximately 210 K. This work offers a flexible and effective strategy to achieve AM in single-atomic-layer materials and $ p$ -electron systems.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Uncovering the roughness effect on inelastic phonon scattering and thermal conductance at interface via spectral energy exchange
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Understanding the mechanism of interfacial thermal transport is crucial for thermal management of electronics. Recent experiments have shown the strong impact of interfacial roughness on inelastic phonon scattering and interfacial thermal conductance (ITC), while the theoretical modeling and underlying physics remain missing. Through non-equilibrium molecular dynamics simulations with quantum correction, we predict ITC of both sharp and rough Si/Al interfaces in a good agreement with experimental results in a broad range of temperatures. We further introduce a novel spectral energy exchange analysis, which reveals more annihilation of high-frequency phonons and generation of moderate-frequency phonons around the sharp interface compared to its rough counterpart. However, the low-frequency phonons at rough interface shows unexpected stronger inelastic scattering and larger contribution to ITC due to unique emerging interfacial modes. Our work thus promotes both the methodology and understanding of interfacial thermal transport at solid/solid interfaces, and may benefit the design and optimization of thermal interface materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
22 pages, 8 figures
Prethermalization in Fermi-Pasta-Ulam-Tsingou chains
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Gabriel M. Lando, Sergej Flach
The observation of the Fermi-Pasta-Ulam-Tsingou (FPUT) paradox, namely the lack of equipartition in the evolution of a normal mode in a nonlinear chain on unexpectedly long times, is arguably the most famous numerical experiment in the history of physics. Since seventy years after its publication, most studies in FPUT chains still focus on long wavelength initial states similar to the original paper. It is shown here that all characteristic features of the FPUT paradox are rendered even more striking if short(er) wavelength modes are evolved instead. Since not every normal mode leads to equipartition, we also provide a simple technique to predict which modes, and in what order, are excited starting from an initial mode (root) in $ \alpha$ -FPUT chains. The excitation sequences associated with a root are then shown to spread energy at different speeds, leading to prethermalization regimes that become longer as a function of mode excitation number. This effect is visible in observables such as mode energies and spectral entropies and, surprisingly, also in the time evolution of invariant quantities such as Lyapunov times and Kolmogorov-Sinai entropies. Our findings generalize the original FPUT experiment, provide an original look at the paradox’s source, and enrich the vast literature dedicated to studying equipartition in classical many-body systems.
Statistical Mechanics (cond-mat.stat-mech), Chaotic Dynamics (nlin.CD)
13 pages, 10 figures
Competing effect of disorder on phase separation in active systems: from facilitated to hindered growth and rough interfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Pratikshya Jena, Shambhavi Dikshit, Shradha Mishra
We investigate the impact of random pinned disorder on a collection of self propelled particles. To achieve this, we construct a continuum model by formulating the coupled hydrodynamic equations for slow variables i.e, local density and momentum density of particles. The disorder in the system acts as pinning sites, effectively immobilizing the particles that come into contact with them. Our numerical results reveal that weak disorder leads to phase separation in the system at density and activity lower than the typical values for motility induced phase separation. We construct a phase diagram using numerical simulations as well as linearized approximation in the plane of activity and packing fraction of particles at weak disorder densities. As disorder densities rise in the system, kinetic processes slow down, while at high disorder densities, the system becomes heterogeneous and eventually undergoes kinetic arrest. The structure factor tail deviates from Porods law, indicating increased roughness at domain interfaces under strong disorder. Furthermore, we analyze the fractal dimension of the interface as a function of disorder density, highlighting the increasing irregularity of phase separated domains.
Soft Condensed Matter (cond-mat.soft)
13 pages, 7 figures
Drastic softening of Pd nanoparticles induced by hydrogen cycling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Jonathan Zimmerman, Maria Vrellou, Stefan Wagner, Astrid Pundt, Christoph Kirchlechner, Eugen Rabkin
Single crystalline faceted Pd nanoparticles attached to a sapphire substrate were fabricated employing the solid state dewetting method. The as-dewetted nanoparticles tested in compression exhibited all features of dislocation nucleation-controlled plasticity, including the size effect on strength and ultrahigh compressive strength reaching up to 11 GPa. Hydrogen cycling of as-dewetted Pd nanoparticles resulted in their drastic softening and in change of the deformation mode. This softening effect was correlated with the high density of glissile dislocations observed in the cycled particles. This work demonstrates that the nanomechanical behavior of hydride-forming metals can be manipulated by hydrogen cycling.
Materials Science (cond-mat.mtrl-sci)
Scripta Materialia 2024
Spin bond order driven by extended repulsive interactions in doped graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Jin-Ju Ri, Song-Jin O, Chol-Su O
We use the truncated-unity functional renormalization group (TUFRG) to study the many-body instabilities of correlated electrons in graphene doped near the van Hove singularity (VHS). The system is described by an extended Hubbard model including several Coulomb repulsions between neighboring sites. With the repulsion parameters, which have been proven to be suitable for low-energy consideration of graphene, we find a spin bond-ordered phase in the vicinity of the VHS. This phase gives way to a spin-density wave phase when involving a weak additional screening. The ground-state phase diagram is presented in the space of the doping level and the screening parameter. We describe in detail both of these spin-ordered states by using recently developed TUFRG + MF scheme, i.e., a combined approach of TUFRG and mean-field (MF) theory. The collinear states are energetically preferable in both cases of the spin bond order and the spin-density wave. But if the third-nearest neighbor hopping is absent, these spin orders become chiral. The band structures of two collinear spin-ordered states are presented, revealing the metallic behavior of the system.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
14 pages, 5 figures, 2 tables
Interplay Between Structural Defects and Charge Transport Dynamics in MA and FA Modified CsSnI3 Thin Film Semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Gleb V. Segal, Anna A. Zarudnyaya, Anton A. Vasilev, Andrey P. Morozov, Alexandra S. Ivanova, Lev O. Luchnikov, Sergey Yu. Yurchuk, Pavel A. Gostishchev, Danila S. Saranin
Owing high conductivity in microcrystalline thin-films, CsSnI3 perovskite is a promising semiconductor for thermoelectrics and optoelectronics. Rapid oxidation of thin-film and intrinsic lattice strain hinders stabilization of the device performance. Cation engineering of perovskite molecule was considered as an effective strategy to tailor the structural properties and suppress the degradation processes. However, molecular engineering demands a thorough analysis of defect behavior, as it can influence ionic motion, recombination dynamics, and capacitive effects. The effective implementation of CsSnI3 in energy conversion devices requires careful consideration of the specific properties of thin films electrical conductivity, Seebeck coefficient, power factor, as well as electronic transients, and charge transport in the device structures. In this work, we performed a complex investigation for modified CsSnI3 through cation substitution with methyl ammonium (MA) and formamidinium (FA). Our findings highlight a complex interplay between electrical parameters of the bare thin films and stability of the devices (p-i-n diodes) after thermal stress. FA-CsSnI3 showed beneficial results for stabilization under elevated temperatures with improved non-ideality factor in diode structures, enhanced shunt properties and reduced trapping. The photo-induced voltage relaxation spectroscopy performed for MA-CsSnI3 showed relevant traps concentration of 1016 cm-3 with activation energy of 0.52 eV(210K) likely attributed to Sn atom defect. The obtained results are deeply analyzed and discussed.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Stability of spin dynamics in a driven non-Hermitian double well
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-08 20:00 EDT
Zhida Luo, Yurui Yang, Jiaxi Cui, Wenjuan Li, Miaoqian Lu, Wenhua Hai, Yunrong Luo
We study the stability of spin dynamics for a spin-orbit (SO) coupled boson held in a driven non-Hermitian double-well potential. It is surprising to find that when the ratio of the Zeeman field strength to the driving frequency is even, the SO coupling strength can take any value, and suitable parameters can be found to stabilize the quantum spin dynamics of the system. However, when the ratio of the Zeeman field strength to the driving frequency is odd, the SO coupling strength can only take integer or half-integer values for the spin dynamics of the system to possibly be stable.
Quantum Gases (cond-mat.quant-gas)
X-ray particle tracking velocimetry for rheological characterization: Application to material extrusion additive manufacturing
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Julian Kattinger, Stefan Hiemer, Mike Kornely, Julian Ehrler, Phi-Long Chung, Christian Bonten, Marc Kreutzbruck
We introduce X-ray Particle Tracking Velocimetry (XPTV) as a promising method to quantitatively resolve the velocity field and associated rheological quantities of polymer melt flow within the nozzle of a fused filament fabrication (FFF) printer. Employing tungsten powder as tracer particles embedded within a polymer filament, we investigate melt flow dynamics through an aluminum nozzle in a custom-designed experimental setup, based on commercial designs. The velocity profiles obtained via XPTV reveal significant deviations from classical Newtonian flow, highlighting complex heterogeneous and non-isothermal behavior within the melt. From these measurements, we determine the local infinitesimal strain rate tensor and correlate flow-induced non-Newtonian effects to spatially varying temperature distributions, reflecting incomplete thermal homogenization within the nozzle. Our findings demonstrate the capability of XPTV to quantify both velocity fields and rheological properties, underscoring its potential as a future tool for investigating opaque polymer melt flows in additive manufacturing, industrial processing, and rheology. To our knowledge, this represents the first reported application of XPTV in polymer melt rheology, offering a new approach to address measurement challenges previously inaccessible to conventional optical methods.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
16 pages, 15 figures
Palatable pellets – a fundamental framework to produce sustainable pellets via extrusion
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Richard T. Benders, Joshua A. Dijksman, Thomas M. M. Bastiaansen, Raoul Fix, Jasper van der Gucht, Menno Thomas
In pellet manufacturing various ingredients in powder or particle form are pressed together into a dense product, a pellet, with better nutritional, calorific, and handling properties than the individual input ingredients themselves. For this reason, pellet manufacturing is applied to up-convert industrial co-products from various sectors like agriculture, forestry, human food, or bio-energy production, to valorize their waste-streams into more valuable products. However, processing such diverse ingredient streams presents an industrial challenge and raises the important scientific question: “Under which process conditions do loose pellet ingredients bind together to form a mechanically rigid and durable pellet?” In this work we provide new answers to this old research question by determining the causal relationships between processing parameters and physical pellet quality. Systematic pelleting experiments reveal that the interplay of typical process parameters such as steam conditioning temperature, production rate, and die geometry, can be understood in an overarching framework of process interactions. We introduce the concept of the “stickiness temperature,” $ \mathrm{T^\ast}$ , marking the onset of critical enthalpic reactions necessary for pellet agglomeration, the boundary condition for bond formation within a pellet. Our framework demonstrates how $ T^\ast$ is achieved through a combination of steam conditioning and friction, and how these conditions can be controlled by adjusting process parameters. Our findings underscore the significance of pellet temperature in conjunction with die residence time, for optimizing physical pellet quality while reducing energy consumption per kilogram of product. Validating our results in a trial and leveraging existing literature data, our framework provides handles to intelligently enhance the efficiency and sustainability of pelleting processes.
Soft Condensed Matter (cond-mat.soft)
Observation of non-Hermitian bulk-boundary correspondence in non-chiral non-unitary quantum dynamics of single photons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Miao Zhang, Yue Zhang, Shuai Li, Rui Tian, Tianhao Wu, Yingchao Xu, Yi-an Li, Yuanbang Wei, Hong Gao, M. Suhail Zubairy, Fuli Li, Bo Liu
The breakdown of conventional bulk-boundary correspondence, a cornerstone of topological physics, is one of counter-intuitive phenomena in non-Hermitian systems, that is deeply rooted in symmetry. In particular, preserved chiral symmetry is one of the key ingredients, which plays a pivotal role in determining non-Hermitian topology. Nevertheless, chiral symmetry breaking in non-Hermitian systems disrupts topological protection, modifies topological invariants, and substantially reshapes spectral and edge-state behavior. The corresponding fundamentally important bulk-boundary correspondence thus needs to be drastically reconstructed. However, it has so far eluded experimental efforts. Here, we theoretically predict and experimentally demonstrate the bulk-boundary correspondence of a one-dimensional (1D) non-Hermitian system with chiral symmetry breaking in discrete-time non-chiral non-unitary quantum walks of single photons. Through constructing a domain-wall configuration, we experimentally observe the photon localization at the interface of domain-wall structure, clearly indicating the presence of the topological edge mode. The appearance of that matches excellently with the prediction of our introduced non-chiral non-Bloch topological invariants pair. Our work thus unequivocally builds the non-Hermitian bulk-boundary correspondence as a general principle for studying topological physics in non-Hermitian systems with chiral symmetry breaking.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), Optics (physics.optics), Quantum Physics (quant-ph)
13 pages, 8 figures, including Supplementary Material
Pyroelectric doping reversal of MoS2 p-n junctions on ferroelectric domain walls probed by photoluminescence
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Javier Fernández-Martínez, Joan J. Ronquillo, Guillermo López-Polín, Herko P. van der Meulen, Mariola O Ramírez, Luisa E. Bausá
Tailoring the optical properties and electronic doping in transition metal dichalcogenides (TMDs) is a central strategy for developing innovative systems with tunable characteristics. In this context, pyroelectric materials, which hold the capacity for charge generation when subjected to temperature changes, offer a promising route for this modulation. This work employs spatially resolved photoluminescence (PL) to explore the impact of pyroelectricity on the electronic doping of monolayer MoS2 deposited on periodically poled LiNbO3 (LN) substrates. The results demonstrate that pyroelectricity in LN modulates the charge carrier density in MoS2 on ferroelectric surfaces acting as doping mechanism without the need for gating electrodes. Furthermore, upon cooling, pyroelectric charges effectively reverse the doping of p-n junctions on DWs, converting them into n-p junctions. These findings highlight the potential of pyroelectric substrates for tunable and configurable charge engineering in transition metal dichalcogenides and suggest their applicability to other combinations of 2D materials and ferroelectric substrates. They also open avenues for alternative device architectures in nanoelectronic or nanophotonic devices including switches, memories or sensors.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
21 pages, 6 figures
Understanding and Design of Interstitial Oxygen Conductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Highly efficient oxygen active materials that react with, absorb, and transport oxygen is essential for fuel cells, electrolyzers and related applications. While vacancy mediated oxygen ion conductors have long been the focus of research, they are limited by high migration barriers at intermediate temperatures, which hinder their practical applications. In contrast, interstitial oxygen conductors exhibit significantly lower migration barriers enabling faster ionic conductivity at lower temperatures. This review systematically examines both well established and recently identified families of interstitial oxygen ion conductors, focusing on how their unique structural motifs such as corner sharing polyhedral frameworks, isolated polyhedral, and cage like architectures, facilitate low migration barriers through interstitial and interstitialcy diffusion mechanisms. A central discussion of this review focuses on the evolution of design strategies, from targeted donor doping, element screening, and physical intuition descriptor material discovery, which leverage computational tools to explore vast chemical spaces in search of new interstitial conductors. The success of these strategies demonstrates that a significant, largely unexplored space remains for discovering high performing interstitial oxygen conductors. Crucial features enabling high performance interstitial oxygen diffusion include the availability of electrons for oxygen reduction and sufficient structural flexibility with accessible volume for interstitial accommodation. This review concludes with a forward looking perspective, proposing a knowledge driven methodology that integrates current understanding with data centric approaches to identify promising interstitial oxygen conductors outside traditional search paradigms.
Materials Science (cond-mat.mtrl-sci)
30 pages, 15 figures
SLIDE: Automated Identification and Quantification of Grain Boundary Sliding and Opening in 3D
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
C.J.A. Mornout, G. Slokker, T. Vermeij, D. König, J.P.M. Hoefnagels
Grain Boundary (GB) deformation mechanisms such as Sliding (GBS) and Opening (GBO) are prevalent in alloys at high homologous temperatures but are hard to capture quantitatively. We propose an automated procedure to quantify 3D GB deformations at the nanoscale, using a combination of precisely aligned Digital Image Correlation (DIC), electron backscatter diffraction, optical profilometry, and in-beam secondary electron maps. The framework, named Sliding identification by Local Integration of Displacements across Edges (SLIDE), (i) distinguishes GBS from GBO, (ii) computes the datapoint-wise measured in-plane displacement gradient tensor (from DIC), (iii) projects this data onto the theoretical GBS tensor to reject near-GB plasticity/elasticity/noise, and (iv) adds the out-of-plane step from optical profilometry to yield the local 3D GBS/GBO vector; automatically repeated for each $ \sim$ 50nm-long GB segment. SLIDE is validated on a virtual experiment of discrete 3D sliding, and successfully applied to Zn-coated steel experiments, yielding quantitative GBS/GBO activity maps.
Materials Science (cond-mat.mtrl-sci)
The Zintl-Klemm Concept in the Amorphous State: A Case Study of Na-P Battery Anodes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
The Zintl-Klemm concept has long been used to explain and predict the bonding, and thereby the structures, of crystalline solid-state materials. We apply this concept to the amorphous state, examining as an example the diverse disordered Na-P phases that can form in sodium-ion battery anodes. Using first-principles simulations combined with state-of-the-art machine-learning methods, we provide atomic-scale insight into the structural and energetic behaviour of amorphous Na-P phases. We evaluate the applicability of the Zintl-Klemm rules in the amorphous state and discuss implications for future work.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Scaling regimes in slow quenches within a gapped phase
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
We consider the finite-time quench dynamics in the quantum transverse field Ising model which exhibits a second order phase transition from a paramagnetic to a ferromagnetic phase, as the transverse magnetic field is decreased. These dynamics have been thoroughly investigated in previous studies when the critical point is crossed during the quench; here, we quench the system from deep in the paramagnetic phase to just above the critical field so that the system remains in the gapped phase throughout the quench duration. On linearly quenching the infinitely large system, we find that the behavior of mean longitudinal defect density and mean transverse magnetization at the end of the quench falls into three distinct scaling regimes as the quench time is increased. For sufficiently small quench times, these observables remain roughly constant, but for larger quench times, a crossover occurs from the Kibble-Zurek scaling law to the quadratic quench rate law when the Kibble-Zurek time is of the order of relaxation time at the final quench field. These results are shown analytically using power series and uniform asymptotic expansions of the exact solution of the model, and also compared with an adiabatic perturbation theory in the third regime. We find that the above mentioned scaling regimes hold for quenches within the ferromagnetic phase also, and provide a general scaling argument for crossover from the Kibble-Zurek regime to an adiabatic regime for slow quenches within a gapped phase.
Statistical Mechanics (cond-mat.stat-mech)
Fine tuning generative adversarial networks with universal force fields: application to two-dimensional topological insulators
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Despite rapid growth in use cases for generative artificial intelligence, its ability to design purpose built crystalline materials remains in a nascent phase. At the moment inverse design is generally accomplished by either constraining the training data set or producing a vast number of samples from a generator network and constraining the output via post-processing. We show that a general adversarial network trained to produce crystal structures from a latent space can be fine tuned through the introduction of advanced graph neural networks as discriminators, including a universal force field, to intrinsically bias the network towards generation of target materials. This is exemplified utilizing two-dimensional topological insulators as a sample target space. While a number of two-dimensional topological insulators have been predicted, the size of the band-gap, a measure of topological protection, remains a concern in most candidate compounds. The resulting generative network is shown to yield novel topological insulators.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6+2 pages
Probabilistic imaginary-time evolution in state-vector-based and shot-based simulations and on quantum devices
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Satoshi Ejima, Kazuhiro Seki, Benedikt Fauseweh, Seiji Yunoki
Imaginary-time evolution, an important technique in tensor network and quantum Monte Carlo algorithms on classical computers, has recently been adapted to quantum computing. In this study, we focus on probabilistic imaginary-time evolution (PITE) algorithm and derive its formulation in the context of state-vector-based simulations, where quantum state vectors are directly used to compute observables without statistical errors. We compare the results with those of shot-based simulations, which estimate observables through repeated projective measurements. Applying the PITE algorithm to the Heisenberg chain, we investigate optimal initial conditions for convergence. We further demonstrate the method on the transverse-field Ising model using a state-of-the-art trapped-ion quantum device. Finally, we explore the potential of error mitigation in this framework, highlighting practical considerations for near-term digital quantum simulations.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
9 pages, 7 figures
Combining kinetic and thermodynamic uncertainty relations in quantum transport
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Didrik Palmqvist, Ludovico Tesser, Janine Splettstoesser
We study the fluctuations of generic currents in multi-terminal, multi-channel quantum transport settings. In the quantum regime, these fluctuations and the resulting precision differ strongly depending on whether the device is of fermionic or bosonic nature. Using scattering theory, we show that the precision is bounded by constraints set by the entropy production and by the activity in the spirit of thermodynamic or kinetic uncertainty relations, valid for fermionic and bosonic quantum systems and even in the absence of time-reversal symmetry. Furthermore, we derive a combined thermodynamic kinetic uncertainty relation, which is tight over a wide range of parameters and can hence predict the reachable precision of a device.
Since these constraints can be expressed in terms of observables accessible in transport measurements, such as currents and bandwidth, we foresee that the tight thermodynamic kinetic uncertainty-like bounds are also useful as an inference tool: they can be exploited to estimate entropy production from transport observables, such as the charge current and its noise, which are more easily accessible in experiment.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
24 pages, 5 figures
Energy Gap Modulation in Proximitized Superconducting Puddles of Graphene
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-08 20:00 EDT
Yuxiao Wu, Udit Khanna, Eyal Walach, Efrat Shimshoni, Aviad Frydman
We investigated proximity-induced superconductivity in a graphene-insulating InO bilayer system through gate-controlled transport measurements. Distinct oscillations in the differential conductance are observed across both the electron and hole doping regimes, with oscillation amplitudes increasing as the chemical potential moves away from the Dirac point. These findings are explained using a theoretical model of a normal-superconductor-normal (NSN) junction, which addresses reflection and transmission probabilities at normal incidence. From this model, we extract key parameters for the proximitized graphene, including the superconducting energy gap Delta and the effective length scale Ls of the superconducting regions. Near the Dirac point, we observe a minimal Ls and a maximal Delta, aligning with the theory that the gap in strongly disordered superconductors increases as the coherence length of localized pairs decreases. This suggests that spatial confinement in a low-density superconductor leads to an effective increase in the superconducting gap.
Superconductivity (cond-mat.supr-con), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 4 figures
Radio frequency single electron transmission spectroscopy of a semiconductor Si/SiGe quantum dot
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
I. Fattal (1 and 2), J. Van Damme (1 and 2), B. Raes (1), C. Godfrin (1), G. Jaliel (1), K. Chen (1), T. Van Caekenberghe (1 and 2), A. Loenders (1 and 2), S. Kubicek (1), S. Massar (1), Y. Canvel (1), J. Jussot (1), Y. Shimura (1), R. Loo (1 and 3), D. Wan (1), M. Mongillo (1), K. De Greve (1,2 and 4) ((1) IMEC, (2) Department of Electrical Engineering, KU Leuven, (3) Department of Solid-State Sciences, Ghent University and (4) Proximus Chair in Quantum Science and Technology, KU Leuven)
Rapid single shot spin readout is a key ingredient for fault tolerant quantum computing with spin qubits. An RF-SET (radio-frequency single electron transistor) is predominantly used as its the readout timescale is far shorter than the spin decoherence time. In this work, we experimentally demonstrate a transmission-based RF-SET using a multi-module semiconductor-superconductor assembly. A monolithically integrated SET placed next to a double quantum dot in a Si/SiGe heterostructure is wire-bonded to a superconducting niobium inductor forming the impedance-transforming network. Compared to RF reflectometry, the proposed set-up is experimentally simpler without the need for directional couplers. Read-out performance is benchmarked by the signal-to-noise (SNR) of a dot-reservoir transition (DRT) and an interdot charge transition (ICT) in the double quantum dot near the SET as a function of RF power and integration time. The minimum integration time for unitary SNR is found to be 100 ns for ICT and 300 ns for DRT. The obtained minimum integration times are comparable to the state of the art in conventional RF reflectometry set-ups. Furthermore, we study the turn-on properties of the RF-SET to investigate capacitive shifts and RF losses. Understanding these effects are crucial for further optimisations of the impedance transforming network as well as the device design to assist RF read-out. This new RF read-out scheme also shows promise for multiplexing spin-qubit readout and further studies on rapid charge dynamics in quantum dots.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
15 pages, 6 figures. Presented at APS March Meeting 2025
Weak thermal fluctuations impede steering of chiral magnetic nanobots
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Ashwani Kr. Tripathi, Konstantin I. Morozov, Boris Y. Rubinstein, Alexander M. Leshansky
Rotating magnetic field is an efficient method of actuation of synthetic colloids in liquids. In this Letter we theoretically study the effect of the thermal noise on torque-driven steering of magnetic nanohelices. Using a combination of numerical and analytical methods, we demonstrate that surprisingly a weak thermal noise can substantially disrupt the orientation and rotation of the nanohelix, severely impeding its propulsion. The results of Langevin simulations are in excellent agreement with the numerical solution of the Fokker-Planck equation and the analytical effective field approximation.
Soft Condensed Matter (cond-mat.soft)
Stochastic storage models in theoretical physics problems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Stochastic storage models based on essentially non-Gaussian noise are considered. The stochastic description of physical systems based on stochastic storage models is associated with generalized Poisson (or shot) noise, in which the jump values can be quite large. Stochastic storage models have a direct physical meaning: some elements enter the system and leave it. Storage processes fit into the general scheme of dynamic systems subject to the additive influence of a random process. The main relationships of storage models are described, and the possibilities of applying the mathematical provisions of stochastic storage processes to various physical problems are indicated. A number of examples of applying the stochastic storage model are considered.
Statistical Mechanics (cond-mat.stat-mech)
41 pages, 4 figures
Inertia-induced scaling and criticality in martensites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Oğuz Umut Salman, Alphonse Finel, Lev Truskinovsky
Martensites subjected to quasistatic deformation are known to exhibit power law distributed acoustic emission in a broad range of scales. However, the origin of the observed scaling behavior and the mechanism of self organization towards criticality remains obscure. Here we argue that the power law structure of the fluctuations spectrum can be interpreted as an effect of inertia. The general insight is that inertial dynamics can become a crucial player when the underlying mechanical system is only marginally stable. We first illustrate the possibility of inertia-induced criticality using an elementary example of mass points connected by bi-stable springs. We then explore the effects of inertia in the fully realistic two and three dimensional continuum models of specific elastic phase transitions in crystals.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)
Frustrated Rydberg Atom Arrays Meet Cavity-QED: Emergence of the Superradiant Clock Phase
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-08 20:00 EDT
Ying Liang, Bao-Yun Dong, Zi-Jian Xiong, Xue-Feng Zhang
Rydberg atom triangular arrays in an optical cavity serve as an ideal platform for understanding the interplay between geometric frustration and quantized photons. Using a large-scale quantum Monte Carlo method, we obtain a rich ground state phase diagram. Around half-filling, the infinite long-range light-matter interaction lifts the ground state degeneracy, resulting in a novel order-coexisted superradiant clock (SRC) phase that completely destroys the fragile order-by-disorder (OBD) phase observed in classical light fields. According to the Ginzburg-Landau theory, this replacement may result from the competition between threefold and sixfold clock terms. Similar to the spin supersolid, the clear first-order phase transition at the $ Z_2$ symmetry line is attributed to the nonzero photon density, which couples to the threefold clock term. Finally, we discuss the low-energy physics in the dimer language and propose that cavity-mediated nonlocal ring exchange interactions may play a critical role in the rich physics induced by the attachment of cavity-QED. Our work opens a new arena of research on the emergent phenomena of quantum phase transitions in many-body quantum optics.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
9 pages, 9 figures, comments are welcome and more information at this http URL
Superconductivity, Anomalous Hall Effect, and Stripe Order in Rhombohedral Hexalayer Graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Erin Morissette, Peiyu Qin, HT Wu, K. Watanabe, T. Taniguchi, J.I.A. Li
We report the discovery of a unique superconducting phase in rhombohedral hexalayer graphene characterized by its simultaneous emergence with both the anomalous Hall effect and stripe charge order. The onset of stripe charge order is revealed through angle-resolved transport measurements, which show thermally activated insulating behavior along one axis and highly conductive transport along the orthogonal direction. Superconductivity develops exclusively along the high-conductivity axis, giving rise to a one-dimensional-like superconducting channel. This superconducting state exhibits first-order transitions under an out-of-plane magnetic field, consistent with a chiral order parameter that breaks time-reversal symmetry. Most remarkably, thermally driven superconducting transitions display pronounced hysteresis-an uncommon phenomenon that reflects the complex interplay among stripe formation, broken time-reversal symmetry, and superconductivity. Together, these results uncover a previously unidentified quantum phase: a chiral superconductor embedded within an anomalous Hall crystal.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
17 pages with method section, 5 figures in main text
Violation of local reciprocity in charge-orbital interconversion
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Hisanobu Kashiki, Hiroki Hayashi, Dongwook Go, Yuriy Mokrousov, Kazuya Ando
We demonstrate a violation of local reciprocity in the interconversion between charge and orbital currents. By investigating orbital torque and orbital pumping in W/Ni bilayers, we show that the charge-orbital interconversion in the bulk of the W layer exhibits opposite signs in the direct and inverse processes – the direct and inverse orbital Hall effects being positive and negative, respectively. This finding provides direct evidence of local non-reciprocity in the charge-orbital interconversion, in agreement with a theoretical prediction. These results highlight the unique characteristics of charge-orbital coupled transport and offer fundamental insights into the mechanisms underlying orbital-current-driven phenomena.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Phonon properties and unconventional heat transfer in quasi-2D $Bi_2O_2Se$ crystal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Jan Zich, Antonín Sojka, Petr Levinský, Martin Míšek, Kyo-Hoon Ahn, Jiří Navrátil, Jiří Hejtmánek, Karel Knížek, Václav Holý, Dmitry Nuzhnyy, Fedir Borodavka, Stanislav Kamba, Čestmír Drašar
Bi2O2Se belongs to a group of quasi-2D semiconductors that can replace silicon in future high-speed/low-power electronics. However, the correlation between crystal/band structure and other physical properties still eludes understanding: carrier mobility increases non-intuitively with carrier concentration; the observed $ T^2$ temperature dependence of resistivity lacks explanation. Moreover, a very high relative out-of-plane permittivity of about 150 has been reported in the literature. A proper explanation for such a high permittivity is still lacking. We have performed infrared (IR) reflectivity and Raman scattering experiments on a large perfect single crystal with defined mosaicity, carrier concentration and mobility. Five of the eight phonons allowed by factor group theory have been observed and their symmetries determined. The IR spectra show that the permittivity measured in the tetragonal plane is as high as $ {\epsilon}_r{\approx}500$ , and this high value is due to a strong polar phonon with a low frequency of 34 $ cm^{-1}$ (1 THz). Such an unusually high permittivity allows the screening of charge defects, leading to the observation of high electron mobility at low temperatures. It also allows effective modulation doping providing a platform for high performance 2D electronics. DFT calculations suggest the existence of a very low frequency acoustic phonon 14 $ cm^{-1}$ (0.4 THz). Both the low frequency phonons cause anomalous phonon DOS, which is reflected in the unconventional temperature dependence of the heat capacity, $ c_M{\approx}T^{3.5}$ . The temperature-dependent, two-component group velocity is proposed to explains the unusual temperature dependence of the thermal conductivity, $ {\kappa}{\approx}T^{1.5}$
Materials Science (cond-mat.mtrl-sci)
v1-preprint
Effective spin model with anisotropic exchange interactions for the spin-orbit coupled Hubbard model at half-filling
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Spin-orbit coupling (SOC) in noncentrosymmetric materials is the source of incommensurate magnetic structures. In semiconductors, it drives the Rashba spin splitting and spin momentum locking, while in magnetic insulators based on transition metals, it induces anisotropic spin exchange interactions, like Dzyaloshinskii-Moriya (DM) interaction which drive chiral magnetism and skyrmion formation. Here, we establish a direct connection between SOC and spin exchange interactions by deriving an effective spin model from the SOC Hubbard model at half-filling. Using a strong-coupling expansion up to fourth order, we identify Heisenberg, Ising-like, and ring exchange interactions, as well as a variety of four-body terms for realistic Hubbard parameters. These parameters constrain the relative strengths of spin interactions, providing a natural interpolation between metallic and insulating phases that host complex magnetic textures.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 7 figures
Machine learning interatomic potential can infer electrical response
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Peichen Zhong, Dongjin Kim, Daniel S. King, Bingqing Cheng
Modeling the response of material and chemical systems to electric fields remains a longstanding challenge. Machine learning interatomic potentials (MLIPs) offer an efficient and scalable alternative to quantum mechanical methods but do not by themselves incorporate electrical response. Here, we show that polarization and Born effective charge (BEC) tensors can be directly extracted from long-range MLIPs within the Latent Ewald Summation (LES) framework, solely by learning from energy and force data. Using this approach, we predict the infrared spectra of bulk water under zero or finite external electric fields, ionic conductivities of high-pressure superionic ice, and the phase transition and hysteresis in ferroelectric PbTiO$ _3$ perovskite. This work thus extends the capability of MLIPs to predict electrical response–without training on charges or polarization or BECs–and enables accurate modeling of electric-field-driven processes in diverse systems at scale.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
IEC-Independent Coupling Between Water Uptake and Ionic Conductivity in Anion-Conducting Polymer Films
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Joan Montes de Oca, Ruilin Dong, Gervasio Zaldivar, Ge Sun, Zhongyang Wang, Shrayesh N. Patel, Paul F. Nealey, Juan J. de Pablo
Anion exchange membranes (AEMs) are promising candidates for replacing proton exchange membranes (PEMs) in electrochemical devices such as fuel cells, electrolyzers, batteries, and osmotic energy extraction systems. However, optimizing the AEM design requires a deeper understanding of the ionic conduction mechanism in the hydrated polymer matrix. This study investigates this mechanism by seeking to understand the relationship between ion exchange capacity (IEC), water absorption, and ionic conductivity in polynorbornene-based thin films. We combine experimental measurements with computational simulations using a newly developed minimal model of the polymer film. Our model is able to reproduce key experimental observations, including water sorption isotherms and ion conduction behavior as a function of relative humidity, and successfully captures the relationship between them. By comparing experimental data with computational results, we explain the commonly reported correlation between conductivity and hydration level and show how the correlation between these variables is affected by the charge density and temperature of the material. Our research advances our understanding of the physical mechanisms that govern the performance of the polyelectrolyte membrane, which is essential for the development of more efficient, stable, and environmentally friendly electrochemical systems.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
17 pages, 8 figures in the main article. The submission also includes a Supporting Information appendix with 23 additional pages and 15 figures
Influence of pore-confined water on the thermal expansion of a zinc-based metal-organic framework
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Nina Strasser, Benedikt Schrode, Ana Torvisco, Sanjay John, Birgit Kunert, Brigitte Bitschnau, Florian Patrick Lindner, Christian Slugovc, Egbert Zojer, Roland Resel
Understanding the reversible intercalation of guest molecules into metal-organic frameworks is crucial for advancing their design for practical applications. In this work, we explore the impact of H$ _{\mathrm{2}}!$ O as a guest molecule on the thermal expansion of the zinc-based metal-organic framework GUT-2. Dehydration is achieved by thermal treatment of hydrated GUT-2. Rietveld refinement performed on temperature-dependent X-ray powder diffraction data confirms the reversible structural transformation. Additionally, it allows the determination of anisotropic thermal expansion coefficients for both phases. The hydrated form exhibits near-zero thermal expansion along the polymer chain direction, moderate expansion In the direction of predominantly hydrogen bonds, and the highest expansion in the direction with only Van der Waals bonding. Upon activation, the removal of H$ _{\mathrm{2}}!$ O molecules triggers a doubling of the thermal expansion coefficient in the direction, where the hydrogen bonds have been removed. Regarding the dynamics of the process, thermal activation in air occurs within 6 hours at a temperature of 50°C and takes only 30 minutes when heating to 90°C. In contrast, full rehydration under standard lab conditions (30 % relative humidity) requires two days. During the activation/dehydration processes no change of the widths of the X-ray diffraction peaks is observed, which shows that the underlying crystal structures remains fully intact during the transition processes. Fitting the transformations by the Avrami equation reveals a quasi one-dimensional evolution of the dehydrated areas for the activation process and a more intricate, predominantly two-dimensional mechanism for the rehydration.
Materials Science (cond-mat.mtrl-sci)
Apparent fractional charge signatures in PbTe quantum dots due to capacitively coupled charge trap dynamics
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Seth Byard, Maksim Gomanko, Sergey M. Frolov
We report the observation of fractional shifts in the experimental stability diagrams of PbTe nanowire quantum dots. Although this behavior may appear to suggest fractional charge transport, akin to that reported in the fractional quantum Hall regime, the quasi-one-dimensionality of the system and absence of an applied magnetic field indicate that the presence of fractional charges is highly unlikely. We instead attribute these effects to the presence of one or more spurious dots, or charge traps, capacitively coupled to the primary dot. Our findings illustrate how signatures of fractional charge transport may be replicated through trivial mesoscopic Coulombic effects.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Data are available through Zenodo at DOI: https://doi.org/10.5281/zenodo.8349309
Chiral magnetic excitations and domain textures of $g$-wave altermagnets
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-08 20:00 EDT
Volodymyr P. Kravchuk, Kostiantyn V. Yershov, Jorge I. Facio, Yaqian Guo, Oleg Janson, Olena Gomonay, Jairo Sinova, Jeroen van den Brink
Altermagnets (AMs) constitute a novel class of spin-compensated materials in which opposite-spin sublattices are connected by a crystal rotation, causing their electronic iso-energy surfaces to be spin-split. While cubic and tetragonal crystal symmetries tend to produce AMs in which the splitting of electronic iso-energy surfaces has $ d$ -wave symmetry, hexagonal AMs, such as CrSb and MnTe, are $ g$ -wave AMs. Here we investigate the purely magnetic modes and spin-textures of $ g$ -wave AMs and show that they are drastically different for easy-axial (CrSb) and easy-planar (MnTe) materials. We show that in CrSb the splitting of the chiral magnon branches possesses $ g$ -wave symmetry, with each branch carrying a fixed momentum-independent magnetic moment. The altermagnetic splitting is not affected by the easy-axial anisotropy and is the same as that in the nonrelativistic limit. The magnon splitting of MnTe, however, does not strictly possess $ g$ -wave symmetry due to its easy-planar anisotropy. Instead the magnetic moment of each branch becomes momentum-dependent, with a distribution that is of $ g$ -wave symmetry. To generalize the concept of the altermagnetic splitting beyond the nonrelativistic limit, we introduce alternative, directly observable splitting parameter which comprises both the magnon eigenenergy and its magnetic moment and possesses the $ g$ -wave symmetry in both easy-axial and easy-planar cases. The associated altermagnetic domain walls in easy-axial CrSb possess a net magnetization with an amplitude that depends on their orientation.
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 9 figures
Screening properties of charge regulated zwitterionic macroion solutions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-08 20:00 EDT
Rashmi Kandari, Rudolf Podgornik, Sunita Kumari
We generalize a calculation scheme for obtaining the screening length in electrolytes and zwitterionic macroions subject to charge regulation by the former. We express the inverse screening parameter in terms of the derivative of the pressure with respect to the chemical potential by bypassing the solution of the PB equation. The screening parameter consists of two parts. The first part is composed of the Debye length evaluated with effective charges of the ions and the macroions, and the second term corresponds to the macroion surface dissociation equilibrium that shows an interesting screening resonance behavior. Furthermore, we discuss the effect of local variables on screening and show that the CR macroions themselves provide a screening mechanism despite the low concentration of free ions. Our findings may shed new light on proteins, protein-membrane, and charged nanoparticles with dissociable surface groups in their bathing solution.
Soft Condensed Matter (cond-mat.soft)
8 pages
Topological Hall effect in ferromagnetic Weyl semimetal Mn$_5$Ge$_3$ originating in competing dipolar interaction and magnetocrystalline anisotropy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-08 20:00 EDT
Achintya Low, Tushar Kanti Bhowmik, Susanta Ghosh, Susmita Changdar, Setti Thirupathaiah
We report the anomalous and topological Hall effect of the ferromagnetic Weyl semimetal Mn$ _5$ Ge$ _3$ . We observe a significant anisotropic anomalous Hall effect (AHE) due to nonzero Berry curvature in the momentum space, such that the anomalous Hall conductivity (AHC) is 965 S/cm for the $ xy$ -plane and 233 S/cm for the $ zx$ -plane of the single crystal. The band structure calculations predict several Weyl and nodal points span across the momentum space, gapped out under the spin-orbit coupling effect, leading to significant $ k$ -space Berry curvature and large AHC. Experimentally, we also demonstrate a sizeable topological Hall effect that is originated by the non-coplanar chiral spin structure due to the competition between the out-of-plane uniaxial magnetocrystalline anisotropy and the dipole-dipole interaction between two Mn sublattices. This study hints at the importance of dipole-dipole interactions in producing the skyrmion lattice in Mn$ _5$ Ge$ _3$ .
Materials Science (cond-mat.mtrl-sci)
6 figs, 12 pages, in press (Phys. Rev. B)
Manipulating phases in many-body interacting systems with subsystem resetting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-08 20:00 EDT
Anish Acharya, Rupak Majumder, Shamik Gupta
Stabilizing thermodynamically unstable phases in many-body systems – such as suppressing pathological neuronal synchronization in Parkinson’s disease or maintaining magnetic order across broad temperature ranges – remains a persistent challenge. In traditional approaches, such phases are stabilized through intervening in the dynamics of all system constituents or introducing additional interactions. Here, we offer a hitherto-unexplored alternative – subsystem resetting, whereby intervention in the dynamics of only a part of the system, and that too only occasionally in time, is implemented through resetting its state to a reset configuration. Just playing with a few parameters, e.g., the nature of the reset configuration and the size of the reset subsystem, one achieves a remarkable and robust control over the phase diagram of the bare dynamics. We demonstrate that these universal effects span a wide variety of scenarios, including equilibrium and non-equilibrium, mean-field and non-mean-field dynamics, with and without quenched disorder. Despite the challenges posed by memory effects, we obtain explicit analytical predictions, validated by simulations.
Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO)
Dimensionality Enhanced Out-of-Plane Spin Currents in NbIrTe$_4$ for Efficient Field-Free Switching of Perpendicular Magnetization
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-08 20:00 EDT
Wei Yang, Xinhe Wang, Jianing Liu, Daming Zhou, Xiaoyang Lin, Ke Zhang, Heloise Damas, Xinyue Wang, Xianyang Lu, Haozhe Yang, Stephane Mangin, Sebastien Petit-Watelot, Michel Hehn, Albert Fert, Juan-Carlos Rojas-Sanchez, Weisheng Zhao
Efficient generation of out-of-plane (OOP) spin currents is crucial for advanced spintronic memory applications. However, the theoretical understanding and experimental implementation of robust OOP spin currents for high-density and low-power magnetization switching remain significant challenges of spintronics. Here, we demonstrate that transitioning NbIrTe$ _4$ from a two-dimensional quantum spin Hall insulator to a three-dimensional type-II Weyl semimetal markedly enhances OOP spin current generation. The bulk topological Weyl semimetal nature of NbIrTe$ _4$ , characterized by its Weyl cone, significantly enhances the OOP spin Berry curvature, enabling an unprecedented OOP spin Hall conductivity exceeding $ 10^5\hbar/2e$ $ \Omega^{-1}m^{-1} $ . This enhancement, surpassing the in-plane component by more than fourfold, enables efficient and field-free spin-orbit torque (SOT) switching of perpendicular magnetization with a low current density of 1.4 MA/cm$ ^2$ . The improved spin Hall conductivity reduces the overall power consumption by more than two orders of magnitude compared to existing systems, such as heavy metals. Our findings highlight the pivotal role of dimensionality in harnessing robust OOP spin currents in topological Weyl semimetals, paving the way for the development of high-density, low-power spintronic memory technologies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
25 pages, 5 figures en the main text plus 27 pages including 9 Notes, 17 supplementary figures and 1 supplementary table