CMP Journal 2025-05-09
Statistics
Physical Review Letters: 8
Physical Review X: 2
arXiv: 71
Physical Review Letters
Unveiling Eigenstate Thermalization for Non-Hermitian systems
Research article | Eigenstate thermalization | 2025-05-08 06:00 EDT
Sudipto Singha Roy, Soumik Bandyopadhyay, Ricardo Costa de Almeida, and Philipp Hauke
The eigenstate thermalization hypothesis (ETH) has been highly influential in explaining thermodynamic behavior of closed quantum systems. As of yet, it is unclear whether and how the ETH applies to non-Hermitian systems. Here, we introduce a framework that extends the ETH to non-Hermitian systems, within which expectation values of local operators reproduce statistical and scaling predictions known from Hermitian ETH. We illustrate the validity of the framework on non-Hermitian random-matrix and Sachdev-Ye-Kitaev models. Further, we show numerically how the static ETH predictions become imprinted onto the dynamics of local observables. Finally, we present a prescription for observing both ETH-obeying and ETH-violating regimes in an optical-lattice experiment that implements a disordered interacting Hatano-Nelson model. Our results generalize the celebrated ETH to the non-Hermitian setting, and they show how it affects the system dynamics, and how the salient signatures can be observed in present-day cold-atom experiments.
Phys. Rev. Lett. 134, 180405 (2025)
Eigenstate thermalization, Non-Hermitian systems, Exact diagonalization, Random matrix theory, Sachdev-Ye-Kitaev model
Enabling Strong Neutrino Self-Interaction with an Unparticle Mediator
Research article | Cosmic ray propagation | 2025-05-08 06:00 EDT
Saeid Foroughi-Abari, Kevin J. Kelly, Mudit Rai, and Yue Zhang
Recent explorations of the cosmic microwave background and the large-scale structure of the universe have indicated a preference for sizable neutrino self-interactions, much stronger than what the standard model offers. When interpreted in the context of simple particle-physics models with a light, neutrinophilic scalar mediator, some of the hints are already in tension with the combination of terrestrial, astrophysical, and cosmological constraints. We take a novel approach by considering neutrino self-interactions through a mediator with a smooth, continuous spectral density function. We consider Georgi’s unparticle with a mass gap as a concrete example and point out two useful effects for mitigating two leading constraints. (i) The Unparticle is ‘’broadband’—it occupies a wide range of masses which allows it to pass the early universe constraint on effective number of extra neutrinos ($\mathrm{\Delta }{N}_{\mathrm{eff}}$) even if the mass gap lies below the MeV scale. (ii) Scattering involving unparticles is less resonant, which lifts the constraint set by IceCube based on a recent measurement of ultra-high-energy cosmogenic neutrinos. Our analysis shows that an unparticle mediator can open up ample parameter space for strong neutrino self-interactions of interest to cosmology and serves a well-motivated target for upcoming experiments.
Phys. Rev. Lett. 134, 181001 (2025)
Cosmic ray propagation, Cosmic rays & astroparticles, Cosmology, Hypothetical particle physics models, Neutrino interactions, Particle astrophysics, Hypothetical particles, Neutrinos, Conformal symmetry, Cosmic ray & astroparticle detectors
Hints of Nonminimally Coupled Gravity in DESI 2024 Baryon Acoustic Oscillation Measurements
Research article | Alternative gravity theories | 2025-05-08 06:00 EDT
Gen Ye, Matteo Martinelli, Bin Hu, and Alessandra Silvestri
The cosmic microwave background (CMB) and baryon acoustic oscillations (BAO) are two of the most robust observations in cosmology. The recent BAO measurements from the DESI collaboration have presented, for the first time, inconsistency between BAO and CMB within the standard cosmological model $\mathrm{\Lambda }\mathrm{CDM}$, indicating a preference for dynamical dark energy over a cosmological constant. We analyze the theoretical implication of the DESI BAO observation for dark energy and gravity employing a nonparametric reconstruction approach for both the dark energy equation of state ${w}_{\mathrm{DE}}(a)$ and the effective field theory coefficients. We find that the DESI data can rule out quintessence dark energy by indicating a crossing of the phantom divide at $z\lesssim 1$. Furthermore, when analyzed within the broad context of Horndeski gravity which includes general relativity and many known modified gravity theories such as generalized Galileons, $f(R)$, and Brans-Dicke, our result implies that gravity should be nonminimally coupled to explain the observations, establishing the DESI result as the first hint of modified gravity. Based on these insights, we propose the thawing gravity model to explain the nonminimal coupling and phantom crossing indicated by observation, which also fits better to DESI BAO, CMB, and type Ia Supernovae data than $\mathrm{\Lambda }\mathrm{CDM}$.
Phys. Rev. Lett. 134, 181002 (2025)
Alternative gravity theories, Cosmology, Dark energy, Evolution of the Universe
Detecting Phase Coherence of 2D Bose Gases via Noise Correlations
Research article | Cold atoms & matter waves | 2025-05-08 06:00 EDT
Shinichi Sunami, Vijay P. Singh, Erik Rydow, Abel Beregi, En Chang, Ludwig Mathey, and Christopher J. Foot
We measure the noise correlations of two-dimensional (2D) Bose gases after free expansion and use them to characterize the in situ phase coherence across the Berezinskii-Kosterlitz-Thouless (BKT) transition. The noise correlation function features a characteristic spatial oscillatory behavior in the superfluid phase, which gives direct access to the superfluid exponent. This oscillatory behavior vanishes above the BKT critical point, as we demonstrate for both single-layer and decoupled bilayer 2D Bose gases. Our Letter establishes noise interferometry as an important general tool to probe and identify many-body states of quantum gases, extending its application to previously inaccessible correlation properties in multimode systems.
Phys. Rev. Lett. 134, 183407 (2025)
Cold atoms & matter waves, Ultracold gases, Atom interferometry
Detecting and Focusing on a Nonlinear Target in a Complex Medium
Research article | Wave scattering | 2025-05-08 06:00 EDT
Antton Goïcoechea, Jakob Hüpfl, Stefan Rotter, François Sarrazin, and Matthieu Davy
Wavefront shaping techniques allow waves to be focused on a diffraction-limited target deep inside disordered media. To identify the target position, a guidestar is required that typically emits a frequency-shifted signal. Here, we present a noninvasive matrix approach operating at a single frequency only, based on the variation of the field scattered by a nonlinear target illuminated at two different incident powers. The local perturbation induced by the nonlinearity serves as a guide for identifying optimal incident wavefronts. We demonstrate maximal focusing on electronic devices embedded in chaotic microwave cavities and extend our approach to temporal signals. Finally, we exploit the programmability offered by reconfigurable smart surfaces to enhance the intensity delivered to a nonlinear target. Our results pave the way for deep imaging protocols that use any type of nonlinearity as feedback, requiring only the measurement of a monochromatic scattering matrix.
Phys. Rev. Lett. 134, 183802 (2025)
Wave scattering, Nonlinear waves, Random & disordered media, Imaging & optical processing
Interfacial Heat Transport via Evanescent Radiation by Hot Electrons
Research article | Heat transfer | 2025-05-08 06:00 EDT
William D. Hutchins, Saman Zare, Mehran Habibzadeh, Sheila Edalatpour, and Patrick E. Hopkins
We predict an additional thermal transport pathway across metal-nonmetal interfaces with large electron-phonon nonequilibrium via evanescent radiative heat transfer. In such systems, electron scattering processes vary drastically and can be leveraged to guide heat across interfaces via radiative heat transport without engaging the lattice directly. We employ the formalism of fluctuational electrodynamics to simulate the spectral radiative heat flux across the interface of a metal film and a nonmetal substrate. We find that the radiative conductance can exceed $300\text{ }\text{ }\mathrm{MW}\text{ }{\mathrm{m}}^{- 2}\text{ }{\mathrm{K}}^{- 1}$ at an electron temperature of 5000 K for an emitting tungsten film on a hexagonal boron nitride substrate, becoming comparable to its conductive counterpart. This allows for a more holistic approach to the heat flow across interfaces, accounting for electron-phonon nonequilibrium and ultrafast near-field phonon-polariton coupling.
Phys. Rev. Lett. 134, 186302 (2025)
Heat transfer, Phonon polariton, Thermal boundary conductance, Nonequilibrium systems, Solid-solid interfaces, Density functional theory, Fermi liquid theory, S-matrix method in transport
Tensor-Monopole-Induced Topological Boundary Effects in Four-Dimensional Acoustic Metamaterials
Research article | Acoustic metamaterials | 2025-05-08 06:00 EDT
Qingyang Mo, Shanjun Liang, Cuicui Lu, Jie Zhu, and Shuang Zhang
Gauge field theory provides the mathematical and conceptual framework to describe and understand topological singularities such as Weyl points and magnetic monopoles. While singularities associated with vector electromagnetic gauge fields have been well studied, those of higher-form tensor gauge fields, like the four-dimensional (4D) tensor monopoles predicted by string theory, have remained largely theoretical or limited to experimental demonstration in pure synthetic dimensions, thereby not allowing investigations of the associated boundary effects. Here, we present a 4D system with tensor monopoles using engineered acoustic metamaterials. Our momentum space combines three real momentum dimensions and a geometric parameter as the fourth. By varying this fourth momentum, we experimentally reveal two distinct topological surface states in 3D subsystems: Fermi-arc surface states in a gapless subsystem and Dirac-cone surface states in a gapped subsystem. Our work introduces a novel platform for exploring new topological structures associated with tensor gauge field and topological phenomena in higher dimensions.
Phys. Rev. Lett. 134, 186601 (2025)
Acoustic metamaterials, Surface states, Topological insulators
Erratum: Boundary Critical Behavior of the Three-Dimensional Heisenberg Universality Class [Phys. Rev. Lett. 126, 135701 (2021)]
| 2025-05-08 06:00 EDT
Francesco Parisen Toldin
Phys. Rev. Lett. 134, 189901 (2025)
Physical Review X
Isotope Substitution and Polytype Control for Point Defects Identification: The Case of the Ultraviolet Color Center in Hexagonal Boron Nitride
Research article | Defects | 2025-05-08 06:00 EDT
J. Plo, A. Pershin, S. Li, T. Poirier, E. Janzen, H. Schutte, M. Tian, M. Wynn, S. Bernard, A. Rousseau, A. Ibanez, P. Valvin, W. Desrat, T. Michel, V. Jacques, B. Gil, A. Kaminska, N. Wan, J. H. Edgar, A. Gali, and G. Cassabois
A new methodology to identify point defects in materials combines isotope substitution, polytype control, and first-principles calculations. Applied to hexagonal boron nitride, it identifies a UV color center as a carbon dimer.
Phys. Rev. X 15, 021045 (2025)
Defects, Luminescence, Layered crystals, Ab initio calculations
Small Polaron-Induced Ultrafast Ferroelectric Restoration in ${\mathrm{BiFeO}}_{3}$
Research article | Ferroelectricity | 2025-05-08 06:00 EDT
Wenfan Chen, Tian Wang, Chun-Chieh Yu, Yuancheng Jing, Xiaosong Li, and Wei Xiong
Ultrafast light excitation in BiFeO3 triggers ferroelectric recovery within 0.5 ps, driven by polaron formation–not free electron relaxation. This reveals a new design principle for fast, light-responsive materials.
Phys. Rev. X 15, 021046 (2025)
Ferroelectricity, Ultrafast femtosecond pump probe
arXiv
Advancing Antiferromagnetic Nitrides via Metal Alloy Nitridation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Qianying Wang, Zexu He, Lele Zhang, Qian Li, Haitao Hong, Ting Cui, Dongke Rong, Songhee Choi, Qiao Jin, Chen Ge, Can Wang, Qinghua Zhang, Liang Cheng, Jingbo Qi, Kui-juan Jin, Gang-Qin Liu, Er-Jia Guo
Nitride materials, valued for their structural stability and exceptional physical properties, have garnered significant interest in both fundamental research and technological applications. The fabrication of high-quality nitride thin films is essential for advancing their use in microelectronics and spintronics. Yet, achieving single-crystal nitride thin films with excellent structural integrity remains a challenge. Here, we introduce a straightforward yet innovative metallic alloy nitridation technique for the synthesis of stable single-crystal nitride thin films. By subjecting metal alloy thin films to a controlled nitridation process, nitrogen atoms integrate into the lattice, driving structural transformations while preserving high epitaxial quality. Combining nanoscale magnetic imaging with a diamond nitrogen-vacancy (NV) probe, X-ray magnetic linear dichroism, and comprehensive transport measurements, we confirm that the nitridated films exhibit a robust antiferromagnetic character with a zero net magnetic moment. This work not only provides a refined and reproducible strategy for the fabrication of nitride thin films but also lays a robust foundation for exploring their burgeoning device applications.
Materials Science (cond-mat.mtrl-sci)
22 pages; 4 figures
Quantum critical scaling of altermagnetism
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Sondre Duna Lundemo, Flavio S. Nogueira, Asle Sudbø
The term altermagnetism has recently been introduced to describe the Néel order of a class of materials whose magnetic sublattices are neither related by translation nor inversion. While these materials arguably have large technological potential, little effort has been devoted to studying the universal distinction of this phase of matter compared to collinear antiferromagnetism. Employing a recently proposed minimal microscopic model, we explicitly derive a nonlinear sigma model describing long-wavelength fluctuations of the staggered magnetization in this system, including quantum effects to leading order. The term that distinguishes the altermagnetic nonlinear sigma model from its antiferromagnetic counterpart is an interaction term that derives directly from the Berry phase of the microscopic spin degrees of freedom. Its effects on the one-loop renormalization group flow in $ d=2+\epsilon$ dimensions are examined. Extending the theory to describe the fermionic excitations of the metallic altermagnet, we find an effective low-energy model of $ d$ -wave spin-split Dirac fermions interacting with the magnetic fluctuations. Using a Dyson-Schwinger approach, we derive the many-body effects on the dynamical critical scaling due to the competition between the long-range Coulomb interaction and the fluctuations of the staggered magnetization.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
14 pages, 6 figures
Parity anomaly from LSM: exact valley symmetries on the lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Salvatore D. Pace, Minho Luke Kim, Arkya Chatterjee, Shu-Heng Shao
We show that the honeycomb tight-binding model hosts an exact microscopic avatar of its low-energy SU(2) valley symmetry and parity anomaly. Specifically, the SU(2) valley symmetry arises from a collection of conserved, integer-quantized charge operators that obey the Onsager algebra. Along with lattice reflection and time-reversal symmetries, this Onsager symmetry has a Lieb-Schultz-Mattis (LSM) anomaly that matches the parity anomaly in the IR. Indeed, we show that any local Hamiltonian commuting with these symmetries cannot have a trivial unique gapped ground state. We study the phase diagram of the simplest symmetric model and survey various deformations, including Haldane’s mass term, which preserves only the Onsager symmetry. Our results place the parity anomaly in 2+1D alongside Schwinger’s anomaly in 1+1D and Witten’s SU(2) anomaly in 3+1D as ‘t Hooft anomalies that can arise from the Onsager symmetry on the lattice.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), High Energy Physics - Theory (hep-th)
7 pages plus appendices
Electromagnetic response and emergent topological orders in transition metal dichalcogenide MoTe$_2$ bilayers
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Tianhong Lu, Yi-Ming Wu, Luiz H. Santos
Twisted bilayer transition metal dichalcogenides, such as MoTe$ _2$ , provide a versatile platform for exploring correlated topological phases. This work investigates the interplay of perpendicular magnetic and electric fields in tuning the electronic structure and emergent topological orders of twisted bilayer MoTe$ _2$ (t-MoTe$ _2$ ) across two distinct regimes: a low-twist-angle phase ($ \theta\approx2.1^\circ$ ) hosting multiple Chern bands of identical Chern numbers per valley, and a higher-angle phase ($ \theta\approx 3.89^\circ$ ) featuring Haldane-like bands with opposite Chern numbers. Using a continuum model incorporating moiré potentials up to second harmonics, we compute the Hofstadter fractal spectra under applied fields, revealing Landau fan structures and magnetic-flux-dependent band topology. These fractal spectra are useful in studying emergent topological orders in terms of the composite fermion picture, where the statistical Chern-Simons flux is approximated as a uniform gauge field. We demonstrate that the system hosts both Jain-sequence fractional Chern insulators (FCIs) and non-Jain “fractal FCIs” with higher Chern numbers. The electric field suppresses composite fermion gaps and induces topological quantum phase transitions. Furthermore, our analysis extends to valley-contrasting flux attachment, proposing pathways to describe fractional quantum spin Hall states.
Strongly Correlated Electrons (cond-mat.str-el)
Main text: 9 pages and 8 figures
Disorder-Free Localization and Fragmentation in a Non-Abelian Lattice Gauge Theory
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-09 20:00 EDT
Giovanni Cataldi, Giuseppe Calajó, Pietro Silvi, Simone Montangero, Jad C. Halimeh
We investigate how isolated quantum many-body systems equilibrate when quenched far from equilibrium under non-Abelian gauge-symmetry constraints. By encoding gauge superselection sectors into static $ \mathrm{SU}(2)$ background charges, we map out the dynamical phase diagram of a $ 1+1D$ $ \mathrm{SU}(2)$ lattice gauge theory with dynamical matter. We uncover three distinct regimes: (i) an ergodic phase, (ii) a fragmented phase that is nonthermal but delocalized, and (iii) a disorder-free many-body localized regime. In the latter, a superposition of superselection sectors retains spatial matter inhomogeneities in time, as confirmed by distinctive temporal scalings of entropy. We highlight the non-Abelian nature of these phases and argue for potential realizations on qudit processors.
Quantum Gases (cond-mat.quant-gas), High Energy Physics - Lattice (hep-lat), Quantum Physics (quant-ph)
13 pages, 7 figures
Beyond fixed-size skyrmions in nanodots: switchable multistability with ferromagnetic ring
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Mateusz Zelent, Maciej Krawczyk, Konstantin Y. Guslienko
We demonstrate a novel approach to control and stabilize magnetic skyrmions in ultrathin multilayer nanostructures through spatially engineered magnetostatic fields generated by ferromagnetic nanorings. Using analytical modeling and micromagnetic simulations, we show that the stray fields from a Co/Pd ferromagnetic ring with out-of-plane magnetic anisotropy significantly enhance Néel-type skyrmion stability in an Ir/Co/Pt nanodot, even without Dzyaloshinskii-Moriya interaction. Most notably, we observe a multistability phenomenon, where skyrmions can be stabilized at two or more distinct equilibrium diameters depending on the ring’s magnetization orientation. These stable states exhibit energy barriers substantially exceeding thermal fluctuations at room temperature, suggesting practical applications for robust multibit memory storage. By tuning geometric parameters of the ferromagnetic ring, we demonstrate precise control over skyrmion size and stability, opening pathways for advanced spintronic nanodevices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Dissipation meets conformal interface: How the relaxation rate is suppressed
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Ruhanshi Barad, Qicheng Tang, Xueda Wen
Conformal interfaces play an important role in quantum critical systems. In closed systems, the transmission properties of conformal interfaces are typically characterized by two quantities: One is the effective central charge $ c_{\text{eff}}$ , which measures the amount of quantum entanglement through the interface, and the other is the transmission coefficient $ c_{\text{LR}}$ , which measures the energy transmission through the interface. In the present work, to characterize the transmission property of conformal interfaces in open quantum systems, we propose a third quantity $ c_{\text{relax}}$ , which is defined through the ratio of Liouvillian gaps with and without an interface. Physically, $ c_{\text{relax}}$ measures the suppression of the relaxation rate towards a steady state when the system is subject to a local dissipation. We perform both analytical perturbation calculations and exact numerical calculations based on a free fermion chain at the critical point. It is found that $ c_{\text{relax}}$ decreases monotonically with the strength of the interface. In particular, $ 0\le c_{\text{relax}}\le c_{\text{LR}}\le c_{\text{eff}}$ , where the equalities hold if and only if the interface is totally reflective or totally transmissive. Our result for $ c_{\text{relax}}$ is universal in the sense that $ c_{\text{relax}}$ is independent of (i) the dissipation strength in the weak dissipation regime and (ii) the location where the local dissipation is introduced. Comparing to the previously known $ c_{\text{LR}}$ and $ c_{\text{eff}}$ in a closed system, our $ c_{\text{relax}}$ shows a distinct behavior as a function of the interface strength, suggesting its novelty to characterize conformal interfaces in open systems and offering insights into critical systems under dissipation.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
17 pages, many figures
Quantum geometry and magnon Hall transport in an altermagnet
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Erlend Syljuåsen, Alireza Qaiumzadeh, Asle Sudbø
We compute magnon Hall conductivities in a minimal model of a two-dimensional altermagnet. To do so, we derive an analytic expression for the relevant quantum geometric tensor describing two-band bosonic Bogoliubov Hamiltonians, providing insight into the geometric, topological, and transport properties. The magnon thermal Hall and spin Nernst conductivities are shown to directly depend on the altermagnetic parameter, which may serve as an experimental probe of altermagnetism.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
9 pages, 6 figures
Coexistence of superconductivity and topological band in a van der Waals Sn1-xInxBi2Te4 crystal
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-09 20:00 EDT
Hoyeon Jeon, Saban Hus, Jewook Park, Qiangsheng Lu, Seoung-Hun Kang, Mina Yoon, Robert G. Moore, Jiaqiang Yan, Michael A. McGuire, An-Ping Li
The realization of topological surface states and superconductivity within a single material platform is a crucial step toward achieving topologically nontrivial superconductivity. This can be achieved at an interface between a superconductor and a topological insulator, or within a single material that intrinsically hosts both superconductivity and topological surface states. Here we use scanning tunneling microscopy to study Sn1-xInxBi2Te4 crystals. Spectroscopic evidence reveals the coexistence of topological surface states and superconductivity on the same surface of the crystals. The Te-terminated surface exhibits a single U-shaped superconducting gap with a size of up to 311 {\mu}eV, alongside Dirac bands outside the gap. Analysis of the vortex structure and differential conductance suggests weak-coupling s-wave superconductivity. The absence of observed zero modes suggests that shifting the Fermi level closer to the Dirac point of the topological bands is necessary to realize a topological superconducting state.
Superconductivity (cond-mat.supr-con)
Dehybridization transition in Kondo insulators and heavy fermions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
In strongly correlated multi-band systems, like inter-metallics, heavy fermions or Kondo insulators, electron-electron and electron-phonon scattering of the electrons in the bands give rise, at finite temperatures, to a damping of these quasi-particles. This is responsible for producing an effective dehybridization between the electrons in the large conduction bands and those in the narrow, correlated band. This dehybridization effect has been used to explain the transport properties of inter-metallics and ARPES experiments in heavy fermions at sufficiently high temperatures. A new insight into this problem has been recently proposed using the theory of non-Hermitian systems. In this note, we review previous work on dehybridization in Kondo insulators and strongly correlated metals within this new perspective. For this purpose, we use a parametrization of the self-energy of the strongly correlated electrons obtained from LDA+DMFT calculations. We discuss the nature of the dehybridization transition and its consequences in the electronic spectrum and transport properties.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 7figures
$Δ$SCF in \texttt{VASP} for excited-state defect computations: tips and pitfalls
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Yihuang Xiong, Geoffroy Hautier
$ \Delta$ SCF with constrained occupations have been wildly used to investigate the excited-state and optical properties of defects. Recent studies have demonstrated that combining $ \Delta$ SCF with hybrid functionals yields good accuracy in predicting defect properties. The Vienna Ab initio Simulation Package (\texttt{VASP}) is one of the most widely used quantum mechanical packages based on plane-wave methods. Despite the increasing application of $ \Delta$ SCF as implemented in \texttt{VASP} for defect studies, detailed walkthroughs explaining how to conduct these calculations remain limited, making this approach a nontrivial task. Applying $ \Delta$ SCF with hybrid functionals can present convergence challenges; worse, it may sometimes converge to incorrect excited states and can go largely unnoticed. This document aims to serve as a concise guide outlining what we think might be the appropriate approach for performing $ \Delta$ SCF calculations in \texttt{VASP}. We benchmark this method by simulating excited states for a particularly challenging system: the neutral charge state of the silicon vacancy (SiV$ ^0$ ) defect in diamond. By highlighting potential pitfalls, we hope this document encourages further discussion within the community and assists researchers experiencing difficulties with this technique. The guidelines provided here are largely based on private discussions with Oscar Bulancea Lindvall from Link{ö}ping University and Chris Ciccarino from Stanford University.
Materials Science (cond-mat.mtrl-sci)
Pump-induced magnon anticrossing due to three-magnon splitting and confluence
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Tao Qu, Yuzan Xiong, Xufeng Zhang, Yi Li, Wei Zhang
We present a plausible mechanism for achieving magnon-magnon level repulsion spectrum originating from the oscillation between the splitting and confluence in a three-magnon scattering process. When a magnetostatic mode on a YIG sphere is pumped by a microwave signal near the magnon resonance frequency with an increasing amplitude, the generated magnon condensate at half of the pumping frequency exerts a back-action to the original magnon mode. Such a strong nonlinear coupling manifests a striking feature of a ‘bending effect’ of the magnetostatic mode spectra, akin to the anti-crossing observed in a strongly coupled magnon-photon system.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages including Supplemental Materials
Theoretically proposed controlled creation of Bloch-type skyrmions with spin-orbit torque in a chiral-ferromagnet/heavy-metal heterojunction
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Yuto Uwabo, Masahito Mochizuki
The creation and manipulation of magnetic skyrmions in magnetic bilayer heterostructures via spin-orbit torque have been intensively studied in spintronics because of their potential application as information carriers in next-generation magnetic memory devices. However, experimental attempts have not always been successful. In this paper, we theoretically elucidate the underlying reasons for these difficulties and propose a practical method to overcome them by employing magnetic bilayer heterostructures that incorporate a chiral ferromagnetic layer hosting Bloch-type skyrmions instead of the conventional ferromagnetic layer that hosts Néel-type skyrmions. Our micromagnetic simulations demonstrate that Bloch-type skyrmions can be controllably created in this system via spin-orbit torque exerted by a perpendicular spin current. This finding provides a promising platform and method for realizing skyrmion-based spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 8 figures
HOP-graphene: A high-capacity anode for Li/Na-ion batteries unveiled by first-principles calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Nicolas F. Martins, José A. S. Laranjeira, Kleuton A. L. Lima, Luis A. Cabral, L.A. Ribeiro Junior, Julio R. Sambrano
The growing demand for efficient energy storage has driven the search for advanced anode materials for lithium- and sodium-ion batteries (LIBs and SIBs). In this context, we report the application of HOP-graphene (a 5-6-8-membered 2D carbon framework) as a high-performance anode material for LIBs and SIBs using density functional theory simulations. Diffusion studies reveal low energy barriers of 0.70 eV for Li and 0.39 eV for Na, indicating superior mobility at room temperature compared to other carbon allotropes, like graphite. Full lithiation and sodiation accommodate 24 Li and 22 Na atoms, respectively, delivering outstanding theoretical capacities of 1338 mAh/g (Li) and 1227 mAh/g (Na). Bader charge analysis and charge density difference maps confirm substantial electron transfer from the alkali metals to the substrate. Average open-circuit voltages of 0.42 V (Li) and 0.33 V (Na) suggest favorable electrochemical performance. HOP-graphene also demonstrates excellent mechanical strength. These findings position HOP-graphene as a promising candidate for next-generation LIB and SIB anodes.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages
Athos-Graphene: Computational Discovery of an Art-Inspired 2D Carbon Anode for Lithium-Ion Batteries
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Kleuton A. L. Lima, José A. S. Laranjeira, Nicolas F. Martins, Julio R. Sambrano, Alexandre C. Diasc, Douglas S. Galvão, Luiz A. Ribeiro Junior
Two-dimensional (2D) carbon allotropes have attracted growing interest for their structural versatility and potential in energy storage and nanoelectronics. We propose Athos-Graphene (AG), a novel 2D carbon allotrope inspired by the geometric patterns of Brazilian artist Athos Bulcão. Designed using density functional theory, AG features a periodic structure with high thermodynamic and thermal stability, as evidenced by a low cohesive energy of -7.96 eV/atom, the absence of imaginary phonon modes, and robust performance in ab initio molecular dynamics simulations up to 1000 K. It exhibits anisotropic mechanical properties, with Young’s modulus values of 585 GPa and 600 GPa along the x- and y-directions, and Poisson’s ratios of 0.19 and 0.17, respectively. Electronic structure analyses confirm its metallic behavior, while optical studies reveal anisotropic absorption in the visible and UV regions. For lithium-ion storage, Athos-Graphene shows strong Li adsorption (-2.3 to -1.0 eV), a high theoretical capacity of 836.78 mAh/g, and a low average open-circuit voltage of 0.54 V. Lithium diffusion barriers are as low as 0.3 eV on the surface and 0.66 eV between layers, with a high diffusion coefficient greater than 6x10^-6 cm^2/s. These features highlight AG as a promising anode material for high-performance lithium-ion batteries.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages
Theoretical perspectives on optical control of magnetism in spin-charge coupled systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
In this article, we review recent theoretical research on photocontrol of magnetism in several spin-charge coupled systems. The control of magnetism with light has been a central issue in condensed-matter physics, attracting enormous research interest both for fundamental science and for technological applications. This field of research has developed rapidly in recent years along with the development of laser technology. However, because the direct coupling between the light magnetic field and magnetization via the Zeeman coupling is very weak in terms of the energy scale, it is, in principle, difficult to induce dramatic effects as far as this magnetic light-matter interaction is exploited. On the contrary, the interaction between the light electric field and electron charges has an energy scale two to three orders of magnitude larger than that of the magnetic interaction. Therefore, we may realize astonishing photoinduced physical phenomena and novel optical device functions by exploiting this electric light-matter interaction. Spin-charge coupled magnets, e.g., double-exchange magnets, multiferroics materials, and Rashba electron systems, in which spins and charges are strongly coupled through several kinds of mechanisms such as exchange interactions and spin-orbit coupling, are ideal systems for realizing this idea. Recent theoretical studies have revealed that it is possible to control, manipulate and switch the magnetization coupled to electron charges in these systems through exciting and/or driving them with light electric fields. The following three recent topics are discussed as examples of such theoretical studies, that is, photoinduced magnetic phase transitions in irradiated double-exchange models, highly efficient photoinduction of spin polarization in Rashba electron systems, and electromagnon excitations and their intense excitation effects in multiferroic materials.
Strongly Correlated Electrons (cond-mat.str-el)
17 pages, 13 figures, invited article for the Special Topics on Physics of Photodriven Quantum Spin Systems in Journal of the Physical Society of Japan
Proposed controlled creation and manipulation of skyrmions with spin-orbit torque
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Yuto Uwabo, Ryo Fujimoto, Kimimaro Yanai, Masahito Mochizuki
The physical mechanisms underlying current-driven skyrmion motion include the spin-transfer torque exerted by a spin-polarized horizontal electric current and the spin-orbit torque exerted by a perpendicular spin current. Each mechanism requires a specific sample geometry and structural configuration. Regarding current-induced skyrmion creation, skyrmions can be efficiently created at low current densities via spin-transfer torque when an electric current is applied to a nanotrack structure with a small notch. However, an effective and controlled method for skyrmion creation via spin-orbit torque in notched nanotracks has yet to be established. Here we theoretically propose a method for the creation, driving, and deletion of skyrmions in a three-terminal magnetic heterojunction with a notch. Our proposal offers valuable insights into the design of techniques for skyrmion creation and manipulation using spin-orbit torque, which is essential for technical applications of magnetic skyrmions as information carriers in next-generation spintronic memory devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
14 pages, 9 figures, invited article for Special Topic on “Ferroic Materials, Domains, and Domain Walls: Bridging Fundamentals with Next-Generation Technology” in Journal of Applied Physics
Systematic construction of asymptotic quantum many-body scar states and their relation to supersymmetric quantum mechanics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-09 20:00 EDT
Masaya Kunimi, Yusuke Kato, Hosho Katsura
We develop a systematic method for constructing asymptotic quantum many-body scar (AQMBS) states. While AQMBS states are closely related to quantum many-body scar (QMBS) states, they exhibit key differences. Unlike QMBS states, AQMBS states are not energy eigenstates of the Hamiltonian, making their construction more challenging. We demonstrate that, under appropriate conditions, AQMBS states can be obtained as low-lying gapless excited states of a parent Hamiltonian, which has a QMBS state as its ground state. Furthermore, our formalism reveals a connection between QMBS and supersymmetric (SUSY) quantum mechanics. The QMBS state can be interpreted as a SUSY-unbroken ground state.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
18 pages, 2 figures
A versatile setup for symmetry-resolved ultrafast dynamics of quantum materials
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Khalid M. Siddiqui, Hanna Strojecka, Thomas H. Meyland, Nitesh Khatiwada, Nikolaj Klinkby, Daniel Perez-Salinas, Simon E. Wall
Correlated phenomena occur in quantum materials because of the delicate interplay between internal degrees of freedom, leading to multiple symmetry-broken quantum phases. Resolving the structure of these phases is a key challenge, often requiring facilities equipped with x-ray free-electron lasers and electron sources that may not be readily accessible to the average user. Table-top sources that offer alternative means are therefore needed. In this work, we present an all-optical, table-top setup that enables symmetry-resolved studies using linear and nonlinear spectroscopies. We demonstrate the versatility of the setup with chosen examples that underscore the importance of tracking symmetries and showcase the strengths of the setup, which offers a large tunable parameter space.
Strongly Correlated Electrons (cond-mat.str-el), Optics (physics.optics)
14 Pages, 10 figures
Accurate Prediction of Sequential Tensor Properties Using Equivariant Graph Neural Network
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Ting-Wei Hsu, Zhenyao Fang, Arun Bansil, Qimin Yan
Optical spectra serve as a powerful tool for probing the interactions between materials and light, unveiling complex electronic structures such as flat bands and nontrivial topological features. These insights are crucial for the development and optimization of photonic devices, including solar cells, light-emitting diodes, and photodetectors, where understanding the electronic structure directly impacts device performance. Moreover, in anisotropic bulk materials, the optical responses are direction-dependent, and predicting those response tensors still remains computationally demanding due to its inherent complexity and the constraint from crystal symmetry. To address this challenge, we introduce the sequential tensorial properties equivariant neural network (StepENN), a graph neural network architecture that maps crystal structures directly to their full optical tensors across different photon frequencies. By encoding the isotropic sequential scalar components and anisotropic sequential tensor components into l=0 and l=2 spherical tensor components, StepENN ensures symmetry-aware sequential tensor predictions that are consistent with the inherent symmetry constraints of crystal systems. Trained on a dataset of frequency-dependent permittivity tensors for 1,432 bulk semiconductors computed from first-principles methods, our model achieves a mean absolute error (MAE) of 24.216 millifarads per meter (mF/m) on the predicted tensorial spectra with 85.7% of its predictions exhibiting less than 10% relative error, demonstrating its potential for deriving other spectrum-related properties, such as optical conductivity. This framework opens new avenues for the data-driven design of materials with engineered anisotropic optical responses, accelerating material advances in optoelectronic applications.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
18 pages, 6 figures
Improvement of spontaneous orientation polarization by multiple introductions of fluoroalkyl groups
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Masaki Tanaka, Rena Sugimoto, Nobuhumi Nakamura
Spontaneous orientation polarization (SOP) of polar molecules is formed in vacuum-deposited films. SOP is driven by asymmetric intermolecular interactions; however, the design of polar molecules for the improvement of dipole orientation is limited. In this study, we developed SOP molecules with high structural asymmetry by introducing multiple fluoroalkyl groups into a polar molecule. The developed polar molecules exhibited high dipole orientation degrees in vacuum-deposited films and achieved a high surface potential growth rate relative to the film thickness, over -350 mV nm-1, which is a record high for the reported compounds. The developed dipolar films can be used to generate rectification properties for the charge transport of organic films. The findings of this study provide methodologies for the formation of highly anisotropic glassy films, leading to improved performance of organic devices.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Main: 12 pages, 5 figures. SI: 21 page, 18 figures
Topological phase transition to a hidden charge density wave liquid
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Joshua S.H. Lee, Thomas M. Sutter, Goran Karapetrov, Pietro Musumeci, Anshul Kogar
Charge density waves (CDWs), electronic crystals that form within a host solid, have long been speculated to melt into a spatially textured electronic liquid. Though they have not been previously detected, liquid CDWs may nonetheless be fundamental to the phase diagrams of many correlated electron systems, including high temperature superconductors and quantum Hall states. In one of the most promising candidate materials capable of hosting a liquid CDW, 1T-TaS2, a structural phase transition impedes its observation. Here, by irradiating the material with a femtosecond light pulse, we circumvent the structural phase transition to reveal how topological defect dynamics govern the otherwise invisible CDW correlations. Upon photoexcitation, the CDW diffraction peaks broaden azimuthally, initially revealing a hexatic state. At higher temperatures, photoexcitation completely destroys translational and orientational order and only a ring of diffuse scattering is observed, a key signature of a liquid CDW. Our work provides compelling evidence for a defect-unbinding transition to a CDW liquid and presents a protocol for uncovering states that are hidden by other transitions in thermal equilibrium.
Strongly Correlated Electrons (cond-mat.str-el)
Ground-states of the Shastry-Sutherland Lattice Materials Gd$_2$Be$_2$GeO$_7$ and Dy$_2$Be$_2$GeO$_7$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
M. Pula, S. Sharma, J. Gautreau, Sajilesh K. P., A. Kanigel, G. M. Luke
The recent realization that the rare-earth melilites RE$ _2$ Be$ _2$ GeO$ _7$ host the Shastry-Sutherland lattice within planes of RE$ ^{3+}$ ions has sparked a number of studies. This family of materials lacks appreciable site mixing and conductivity, making them promising candidates for the Shastry-Sutherland model. Herein, we present the magnetic ground states of two of these rare-earth melilites: RE = Gd and Dy. We find, through measurements of magnetic susceptibility, magnetization, and specific heat capacity (RE = Dy only), that these two melilites are antiferromagnets (T$ _N$ $ \sim$ 1K). Gd$ _2$ Be$ _2$ GeO$ _7$ , in accordance with its electronic configuration, has isotropic single-ion anisotropy but shows a quadratic contribution to its magnetization. Dy$ _2$ Be$ _2$ GeO$ _7$ has Ising-like single-ion ansiotropy and is likely an effective spin-$ 1/2$ system. Both materials exhibit metamagnetic transitions. We identify this transition in Dy$ _2$ Be$ _2$ GeO$ _7$ , occurring at 86(1)mT for T=500mK, to likely be a spin-flip transition.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 7 figures, 1 table
Giant Tunneling Magnetoresistance in Graphene/$h$-BN Based van der Waals Magnetic Tunnel Junctions via 3$d$ Transition Metal Intercalation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Zhi Yan, Jianhua Xiao, Xujin Zhang, Cheng Fang, Xiaohong Xu
Atomic intercalation offers a powerful route for engineering two-dimensional (2D) materials by precisely tuning interlayer electronic coupling and spin configurations. Here, we propose a generic strategy for the construction of fully 2D magnetic tunnel junctions (MTJs) based on transition metal-intercalated graphene electrodes with $ h$ -BN barrier layer. First-principles calculations reveal that intercalation not only stabilizes uniform atomic dispersion via steric hindrance but also induces robust ferromagnetism in graphene. Manganese- and vanadium-intercalated systems (Mn-Gr and V-Gr) exhibit exceptional spintronic performance, with tunneling magnetoresistance (TMR) showing a pronounced odd-even oscillation as a function of barrier thickness. A giant TMR of $ 4.35 \times 10^8,%$ is achieved in the Mn-Gr system with a monolayer barrier $ h$ -BN ($ n=1$ ), while V-Gr reaches a maximum TMR of $ 1.86 \times 10^5,%$ for a trilayer barrier ($ n=3$ ). Moreover, biaxial strain further enhances the TMR to $ 10^9,%$ and $ 10^7,%$ in Mn-Gr and V-Gr systems, respectively. The devices also exhibit perfect spin filtering and pronounced negative differential resistance, offering new opportunities for high-performance spintronic and memory applications based on 2D van der Waals heterostructures.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
13 pages, 8 figures
The spatial correlation of radiation-induced errors in superconducting devices decays over a millimeter
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-09 20:00 EDT
Francesco Valenti, Anil Murani, Patrick Paluch, Robert Gartmann, Lukas Scheller, Richard Gebauer, Robert Kruk, Thomas Reisinger, Luis Ardila-Perez, Ioan M. Pop
We perform nanosecond-resolution multiplexed readout on six same-chip superconducting microwave resonators. This allows us to pinpoint the impact positions of ionizing radiation on the chip by measuring the differential time of flight of the generated phonons, inducing correlated errors in the device, thereby implementing an on-chip seismic array. We correlate the phase response of each resonator - a proxy for the absorbed energy - to the distance from the impact point to uncover a millimetric decay length for the phonon-mediated radiation poisoning.
Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
Tailoring composite skyrmionic spin textures in an above-room-temperature ferromagnet Fe3-xGaTe2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Songyang Li, Jianfeng Guo, Zizhao Gong, Guojing Hu, Shuo Mi, Chang Li, Yanyan Geng, Manyu Wang, Shumin Meng, Shiyu Zhu, Fei Pang, Wei Ji, Rui Xu, Haitao Yang, Zhihai Cheng
Realizing room-temperature tunable skyrmionic objects in van der Waals ferromagnet offers unparalleled prospects for future spintronics. Here, we report an experimental investigation on the emergence and evolution of skyrmionic spin textures in the non-stoichiometric Fe3-xGaTe2 using magnetic force microscopy. The iron-deficiency-specific magnetic states of stripe, striped skyrmionium and striped skyrmion sack are observed. Through zero-field-cooling and field-cooling measurements, we observed distinct topological transitions and trivial transitions (distinguished by changes in topological charge) emerging during the stepwise evolution of topological spin textures, which enabled us to develop an evolution pathway model. Leveraging this model, the room-temperature stable composite topological spin textures of skyrmionium, skyrmion bag and sack states are further controllably realized via the exclusive topological-transition path (regulated by magnetic field and DMI intensity). Our work provides valuable insights into the room-temperature realization of topological spin textures in Fe3-xGaTe2, and inspires further exploration of their potential applications in heterostructure spintronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
26 pages, 5 figures
Superconductivity in Spin-Orbit coupled SU(8) Dirac Fermions on Honeycomb lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Ankush Chaubey, Basudeb Mondal, Vijay B. Shenoy, Subhro Bhattacharjee
We study superconducting (SC) phases that are naturally proximate to a spin-orbit coupled SU(8) Dirac semi-metal on a honeycomb lattice. This system, which offers enhanced low-energy symmetries, presents an interesting platform for realizing unconventional superconductivity in j=3/2 electrons. In particular, we find 72 superconducting charge-$ 2e$ fermion bilinears which, under classification of microscopic symmetries, lead to 12 different SCs – four singlets, two doublets, and six triplets – 7 of them are gapped and 5 are symmetry-protected nodal SCs. The strong spin-orbit coupling leads to locking of the spin of the Cooper pairs with real-space direction – as is evident from the structure of the Cooper pair wave-functions – leading to unusual non-unitary superconductors (even singlets), and with finite momentum pairing (for the triplets). This results, in many cases, in the magnitude of multiple pairing gaps being intricately dependent on the direction of the SC order-parameter. The present classification of SCs along with normal phases (Phys. Rev. B 108, 245106 (2023)) provides the complete list of naturally occurring phases in the vicinity of such a SU(8) Dirac semi-metal. This study allows for understanding the global phase diagram of such systems, stimulating further experimental work on candidate materials such as metallic halides (MX$ _3$ with M=Zr, Hf, and X=Cl, Br). Further, it provides the starting point for the exploration of unconventional phase transitions in such systems.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con), High Energy Physics - Theory (hep-th)
Internal and External Field Effects upon Crystal Field Excitations in REFeO$_3$ (RE = Nd$^{3+}$, Er$^{3+}$, Yb$^{3+}$, Pr$^{3+}$, and Ho$^{3+}$)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
The crystal field (CF) excitations of Kramers (Nd$ ^{3+}$ , Er$ ^{3+}$ , and Yb$ ^{3+}$ ) and non-Kramers (Pr$ ^{3+}$ and Ho$ ^{3+}$ ) rare earth ions in rare earth orthoferrites REFeO$ _{3}$ were systematically studied by simulations. The optimised CF models were used to study the internal and external field impacts to the CF excitation peaks of these Kramers and non-Kramers ions. The Kramers ions excitations consist of doublets due to the Kramers degeneracy theorem while the non-Kramers ions excitations are non-degenerated singlets. The ground-state doublets of all Kramers ions undergo peak splitting and generate low energy excitation peaks ~ 1 meV under the internal magnetic fields from the Fe$ ^{3+}$ and RE$ ^{3+}$ sublattices. The ground-states of non-Kramers ions may form pseudo doublets due to the accidental degeneracy of two singlet states, as the case of Ho$ ^{3+}$ in HoFeO$ _3$ . Such pseudo-doublet ground states can split and produce low energy excitations just like the Kramers ions. However, singlet ground states of non-Kramers ions without accidental degeneracy, like Pr$ ^{3+}$ , has no ground state excitation and splitting at zero fields. A ground-state singlet excitation shows up under non-zero magnetic fields due to the symmetry breaking induced by the magnetic fields. The internal/external magnetic field effects on CF excitations in REFeO$ _3$ demonstrate strong anisotropies. The local symmetry was confirmed to play the critical role in the CF excitation splitting and anisotropic responses to magnetic fields in REFeO$ _{3}$ . This study provides a consistent in-depth understanding to the abnormal Zeeman splitting effect of the CF ground states in REFeO$ _{3}$ .
Strongly Correlated Electrons (cond-mat.str-el), Other Condensed Matter (cond-mat.other)
30 figures in the main article, 15 figures in the supplemental materials
Microscopic phase-transition theory of charge density waves: revealing hidden transitions of phason and amplitudon
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
We develop a self-consistent phase-transition theory of charge density waves (CDWs), starting from a purely microscopic model. Specifically, we derive a microscopic CDW gap equation $ |\Delta_0(T)|$ , taking into account of thermal phase fluctuations (i.e., thermal excitation of phason) and their influence on CDW pinning (i.e., the phason mass) and CDW gap. We demonstrate that as temperature increases from zero, the phason gradually softens, leading to a depinning transition (where the phason becomes gapless) at $ T_d$ and a subsequent first-order CDW phase transition at $ T_c>T_d$ . The predicted values of $ T_d$ , $ T_c$ as well as the large ratio of $ |\Delta_0(T=0)|/(k_BT_c)$ for the quasi-one-dimensional CDW material (TaSe$ _4$ )$ _2$ I show remarkable quantitative agreements with experimental measurements and explain many of the previously observed key thermodynamic features and unresolved issues in literature. To further validate the theory, we calculate the energy gap of CDW amplitudon and its lifetime, and reveal a transition of amplitudon from a lightly damped to a heavily damped excitation during pinning-depinning transition while its energy gap is nearly unchanged throughout the entire CDW phase. This finding quantitatively captures and explains the recently observed coherent signal in ultrafast THz emission spectroscopy on (TaSe$ _4$ )$ _2$ I.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Novel structures of Gallenene intercalated in epitaxial Graphene
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Emanuele Pompei, Katarzyna Skibińska, Giulio Senesi, Ylea Vlamidis, Antonio Rossi, Stiven Forti, Camilla Coletti, Fabio Beltram, Lucia Sorba, Stefan Heun, Stefano Veronesi
The creation of atomically thin layers of non-exfoliable materials remains a crucial challenge, requiring the development of innovative techniques. Here, confinement epitaxy is exploited to realize two-dimensional gallium via intercalation in epitaxial graphene grown on silicon carbide. Novel superstructures arising from the interaction of gallenene (a monolayer of gallium) with graphene and the silicon carbide substrate are investigated. The coexistence of different gallenene phases, including b010-gallenene and the elusive high-pressure Ga(III) phase, is identified. This work sheds new light on the formation of two-dimensional gallium and provides a platform for investigating the exotic electronic and optical properties of confined gallenene.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Spatially Mapping Phonon Drag in Ultrascaled 5-nm Silicon Nanowire Field-Effect Transistor Based on a Quantum Hydrodynamic Formalism
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Houssem Rezgui, Giovanni Nastasi, Manuel Marcoux, Vittorio Romano
The compelling demand for higher performance and lower thermal energy dissipation in nanoelectronic devices is the major driving force of the semiconductor industry’s quest for future generations of nanotransistors. Over the past 15 years, the miniaturization of silicon-based nanoelectronics predicted by Moore’s law has driven an aggressive scaling down of the transistor structure, including materials, design, and geometries. In this regard, the electronic device community has expanded its focus to ultrascaled transistors targeting 7-nm technology node and beyond. However, these emerging nanodevices are also creating thermal issues that could evidently limit their carrier transfer as a result of strong electron-phonon coupling. We aim to explain the physical origin of self-heating effects in an ultrascaled 5-nm silicon nanowire Field-Effect Transistor. On the basis of the quantum hydrodynamic approach, a possible explanation of phonon drag contribution to thermal conductivity is also discussed. To the best of our knowledge, we report for the first time the impact of the phonon drag effect on the electrical and thermal performance of 5nm gate-all-around silicon nanowire field-effect transistors. Our findings provide a deep insight into the origin of self-heating as a result of mutual electron-phonon coupling. Furthermore, we further demonstrate that the phonon drag effect significantly reduces thermal conductivity by nearly 50% under high bias conditions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Statistical method for A-RNA and B-DNA
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-09 20:00 EDT
Nucleic acids have been regarded as stiff polymers with long-range flexibility and generally modeled using elastic rod models of polymer physics. Notwithstanding, investigations carried out over the past few years on single fragments of order $ \sim 100$ base pairs have revealed remarkable flexibility properties at short scales and called for theoretical approaches that emphasize the role of the bending fluctuations at single sites along the molecule stack. Here, we review a three dimensional mesoscopic Hamiltonian model which assumes a discrete representation of the double stranded (ds) molecules at the level of the nucleotides. The model captures the fundamental local interactions between adjacent sugar-phosphate groups and the pairwise interactions between complementary base pair mates. A statistical method based on the path integral formalism sets the ensemble of the base pair breathing fluctuations which are included in the partition function and permits to derive the thermodynamics and the elastic response of single molecules to external forces. We apply the model to the computation of the twist-stretch relations for fragments of ds-DNA and ds-RNA, showing that the obtained opposite pattern (DNA overtwists whereas RNA untwists versus force) follows from the different structural features of the two helices. Moreover, we focus on the DNA stretching due to the confinement in nano-pores and, finally, on the computation of the cyclization probability of open ends molecules of $ \sim 100$ base pairs under physiological conditions. The mesoscopic model shows a distinct advantage over the elastic rod model in estimating the molecule bendability at short length scale.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Biological Physics (physics.bio-ph), Biomolecules (q-bio.BM)
full-text view-only version available at this https URL
Brazilian Journal of Physics, vol 55, p 149 (2025)
Orbital-Selective Quasiparticle Depletion across the Density Wave Transition in Trilayer Nickelate La$_4$Ni$3$O${10}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Dong-Hyeon Gim, Chung Ha Park, Kee Hoon Kim
We investigate the evolution of polarized electronic Raman response in trilayer nickelate La$ 4$ Ni$ 3$ O$ {10}$ , uncovering a systematic reduction of the incoherent electron continuum across the density wave transition in the $ A{1g}$ and $ B{1g}$ representations. Analysis based on the Fermi surface band curvatures points to quasiparticle coherence in momentum positions with dominant $ d{x^2-y^2}$ orbital character. Our findings establish the symmetry channels and the active role of $ d_{x^2-y^2}$ orbitals involved in the density wave formation, offering important insight into the electronic and magnetic correlations in the nickelate.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
(Main text) 12 pages, 4 figures. (Supplemental materials) 8 pages, 5 figures
Peak Broadening in Photoelectron Spectroscopy of Amorphous Polymers: the Leading Role of the Electrostatic Landscape
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Laura Galleni, Arne Meulemans, Faegheh S. Sajjadian, Dhirendra P. Singh, Shikhar Arvind, Kevin M. Dorney, Thierry Conard, Gabriele D’Avino, Geoffrey Pourtois, Daniel Escudero, Michiel J. van Setten
The broadening in photoelectron spectra of polymers can be attributed to several factors, such as light source spread, spectrometer resolution, finite lifetime of the hole state, and solid-state effects. Here, for the first time, we set up a computational protocol to assess the peak broadening induced for both core and valence levels by solid-state effects in four amorphous polymers by using a combination of density functional theory, many-body perturbation theory, and classical polarizable embedding. We show that intrinsic local inhomogeneities in the electrostatic environment induce a Gaussian broadening of $ 0.2$ -$ 0.7$ ~eV in the binding energies of both core and semi-valence electrons, corresponding to a full width at half maximum (FWHM) of $ 0.5$ -$ 1.7$ ~eV for the investigated systems. The induced broadening is larger in acrylate- than in styrene- based polymers, revealing the crucial role of polar groups in controlling the roughness of the electrostatic landscape in the solid matrix.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
J. Phys. Chem. Lett. 2024, 15, 3, 834-839
Mean pairwise distances in Rouse polymer subject to fast loop extrusion
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-09 20:00 EDT
Ilya Nikitin, Nikolay Masnev, Sergey Belan
We consider a model of a Rouse polymer extended by the mechanism of active loop extrusion. The model is based on a kinetic equation that is valid provided that the extrusion rate is high enough and the resulting loop ensemble is sufficiently sparse. Within the one-loop approximation of diagrammatic calculations, a semi-analytical method for determining the mean square physical distance between a pair of chain beads as a function of the contour distance between them is developed. The model is based on a kinetic equation that is valid provided that the extrusion rate is high enough and the resulting loop ensemble is sufficiently sparse. Within the framework of the one-loop approximation of diagrammatic calculations, a semi-analytical method for determining the mean square of the physical distance between a pair of chain sections as a function of the contour distance between them is developed. The mean square of the physical distance and its logarithmic derivative as functions of the contour separation are plotted for different values of the equilibrium degree. The results are compared with the case of frozen disorder of sparse loops.
Statistical Mechanics (cond-mat.stat-mech)
3 figures
Spin-glass quantum phase transition in amorphous arrays of Rydberg atoms
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-09 20:00 EDT
L. Brodoloni, J. Vovrosh, S. Julià-Farré, A. Dauphin, S. Pilati
The experiments performed with neutral atoms trapped in optical tweezers and coherently coupled to the Rydberg state allow quantum simulations of paradigmatic Hamiltonians for quantum magnetism. Previous studies have focused mainly on periodic arrangements of the optical tweezers, which host various spatially ordered magnetic phases. Here, we perform unbiased quantum Monte Carlo simulations of the ground state of quantum Ising models for amorphous arrays of Rydberg atoms. These models are designed to feature well-controlled local structural properties in the absence of long-range order. Notably, by determining the Edwards-Anderson order parameter, we find evidence of a quantum phase transition from a paramagnetic to a spin-glass phase. The magnetic structure factor indicates short-range isotropic antiferromagnetic correlations. For the feasible sizes, the spin-overlap distribution features a nontrivial structure with two broad peaks and a sizable weight at zero overlap. The comparison against results for the clean kagome lattice, which features local structural properties similar to those of our amorphous arrays, highlights the important role of the absence of long-range structural order of the underlying array. Our findings indicate a route to experimentally implement the details of a Hamiltonian which hosts a quantum spin-glass phase.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Computational Physics (physics.comp-ph)
10 pages, 7 figures, 1 table
Bulldozing an immersed granular material in a confined channel
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-09 20:00 EDT
Liam C. Morrow, Oliver W. Paulin, Matthew G. Hennessy, Duncan R. Hewitt, Miles L. Morgan, Bjørnar Sandnes, Christopher W. MacMinn
The motion of an immersed granular material in a channel is characterised by complex interactions among the grains, between the grains and the permeating liquid, and between the grains and the channel walls. Here, we develop a reduced-order continuum model for the bulldozing of an immersed, sedimented granular material by a piston in a channel. In our continuum approach, the granular pile and the overlying fluid layer evolve as a system of coupled thin films. We model the granular phase as a dense, porous, visco-plastic material that experiences Coulomb-like friction with the walls. Conservation of mass and momentum under a thin-film approximation leads to an elliptic equation for the velocity of the grains that is coupled with an evolution equation for the height of the granular pile. We solve our model numerically for a variety of different scenarios to explore the interactions between wall friction, internal viscous-like stresses, and fluid flow above and through the pile. We complement our numerical results with a series of experiments that provide insight into the validity and limitations of the model.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Exponential Dependence of Interlayer Exchange Coupling in Fe/MgO(001) Superlattices on Temperature
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Nanny Strandqvist, Tobias Warnatz, Kristbjörg Anna Thórarinsdóttir, Alexei Vorobiev, Vassilios Kapaklis, Björgvin Hjörvarsson
The interlayer exchange coupling in Fe/MgO(001) superlattices is found to increase exponentially with decreasing temperature. Around 150~K, the field induced response changes from discrete switching, governed by field-driven domain propagation, to a collective rotation of the magnetic layers. This transition is accompanied by a change in the magnetic ground state from 180$ ^{\circ}$ (antiferromagnetic) to 90$ ^{\circ}$ alignment between adjacent Fe layers. These effects are argued to arise from quantum well states, defined by the total thickness of the samples.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Probing orbital magnetism of a kagome metal CsV3Sb5 by a tuning fork resonator
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Hengrui Gui, Lin Yang, Xiaoyu Wang, Dong Chen, Zekai Shi, Jiawen Zhang, Jia Wei, Keyi Zhou, Walter Schnelle, Yongjun Zhang, Yu Liu, Alimamy F. Bangura, Ziqiang Wang, Claudia Felser, Huiqiu Yuan, Lin Jiao
The recently discovered kagome metal CsV$ _3$ Sb$ _5$ exhibits a complex phase diagram that encompasses frustrated magnetism, topological charge density wave (CDW), and superconductivity. One CDW state that breaks time-reversal symmetry was proposed in this compound, while the exact nature of the putative magnetic state remains elusive. To examine the thermodynamic state of CsV$ _3$ Sb$ _5$ and assess the character of the associated magnetism, we conducted tuning fork resonator measurements of magnetotropic susceptibility over a broad range of angles, magnetic fields, and temperature. We found a cascade of phase transition in the CDW phase. Of particular interest is a highly anisotropic magnetic structure that arises below about 30K, with a magnetic moment along the $ c$ -axis that has an extremely small magnitude. This magnetic state demonstrates extremely slow dynamics and small saturate field, all suggest that electronic phase below 30K breaks time reversal symmetry and has an unconventional origin.
Materials Science (cond-mat.mtrl-sci)
18 pages, 4 figures,
Nat. Commun. 16, 4275 (2025)
Altermagnetic Skyrmions in 2D Lattices Exhibiting Anisotropic Skyrmion Hall Effect
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Kaiying Dou, Zhonglin He, Wenhui Du, Ying Dai, Baibiao Huang, Yandong Ma
Anisotropic skyrmion Hall effect (A-SkHE) in two-dimensional (2D) magnetic systems represents a captivating phenomenon in condensed-matter physics and materials science. While conventional antiferromagnetic systems inherently suppress this effect through parity-time symmetry-mediated cancellation of Magnus forces acting on skyrmions, A-SkHE is primarily confined to ferromagnetic platforms. Here, we present a paradigm-shifting demonstration of this phenomenon in spin-splitting 2D antiferromagnets through the investigation of altermagnetic skyrmions. Combining comprehensive symmetry analysis with theoretical modeling, we elucidate the mechanism governing A-SkHE realization in 2D altermagnetic systems and establish a quantitative relationship between the transverse velocity of altermagnetic skyrmions and applied current orientation. Using first-principles calculations and micromagnetic simulations, this mechanism is further illustrated in a prototypical altermagnetic monolayer V2SeTeO. Crucially, we identify that the [C2C4zt] symmetry-protected anisotropic field serves as the critical stabilizer for maintaining the A-SkHE in this system. Our results greatly enrich the research on 2D altermagnetism and skyrmions.
Materials Science (cond-mat.mtrl-sci)
Report on Neural-like Criticality in Ag-based Nanoparticle Networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-09 20:00 EDT
Blessing Adejube, Jamie Steel, Joshua Mallinson, Mariia Protsak, Daniil Nikitin, Thomas Strunskus, Andrei Choukourov, Franz Faupel, Simon Anthony Brown, Alexander Vahl
Emulating the neural-like information processing dynamics of the brain provides a time and energy efficient approach for solving complex problems. While the majority of neuromorphic hardware currently developed rely on large arrays of highly organized building units, such as in rigid crossbar architectures, in biological neuron assemblies make use of dynamic transitions within highly parallel, reconfigurable connection schemes. Neuroscience suggests that efficiency of information processing in the brain rely on dynamic interactions and signal propagations which are self-tuned and non-rigid. Brain-like dynamic and avalanche criticality have already been found in a variety of self-organized networks of nanoobjects, such as nanoparticles (NP) or nanowires. Here we report on the dynamics of the electrical spiking signals from Ag-based self-organized nanoparticle networks (NPNs) at the example of monometallic Ag NPNs, bimetallic AgAu alloy NPNs and composite Ag/ZrN NPNs, which combine two distinct NP species. We present time series recordings of the resistive switching responses in each network and showcase the determination of switching events as well as the evaluation of avalanche criticality. In each case, for Ag NPN, AgAu NPN and Ag/ZrN NPN, the agreement of three independently derived estimates of the characteristic exponent provides evidence for avalanche criticality. The study shows that Ag-based NPNs offer a broad range of versatility for integration purposes into physical computing systems without destroying their critical dynamics, as the composition of these NPNs can be modified to suit specific requirements for integration.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
20 pages, 6 figures
Steady-state heat engines driven by finite reservoirs
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-09 20:00 EDT
Iago N. Mamede, Saulo V. Moreira, Mark T. Mitchison, Carlos E. Fiore
We provide a consistent thermodynamic analysis of stochastic thermal engines driven by finite-size reservoirs, which are in turn coupled to infinite-size reservoirs. We consider a cyclic operation mode, where the working medium couples sequentially to hot and cold reservoirs, and a continuous mode with both reservoirs coupled simultaneously. We derive an effective temperature for the finite-size reservoirs determining the entropy production for two-state engines in the sequential coupling scenario, and show that finite-size reservoirs can meaningfully affect the power when compared to infinite-size reservoirs in both sequential and simultaneous coupling scenarios. We also investigate a three-state engine comprising two interacting units and optimize its performance in the presence of a finite reservoir. Notably, we show that the efficiency at maximum power can exceed the Curzon-Ahlborn bound with finite reservoirs. Our work introduces tools to optimize the performance of nanoscale engines under realistic conditions of finite reservoir heat capacity and imperfect thermal isolation.
Statistical Mechanics (cond-mat.stat-mech), Other Condensed Matter (cond-mat.other), Quantum Physics (quant-ph)
5 pages+Supplemental Material (5 pages), 7 figures (3 M+4 SM)
Superconducting susceptibility signal captured in a record wide pressure range
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-09 20:00 EDT
Shu Cai, Jinyu Zhao, Di Peng, Yazhou Zhou, Jing Guo, Nana Li, Jianbo Zhang, Yang Ding, Wenge Yang, Qiaoshi Zeng, Qi Wu, Tao Xiang, Ho-kwang Mao, Liling Sun
In recent years, the resistance signature of the high temperature superconductivity above 250 K in highly compressed hydrides (more than 100 GPa) has garnered significant attention within the condensed matter physics community. This has sparked renewed optimism for achieving superconductivity under room-temperature conditions. However, the superconducting diamagnetism, another crucial property for confirming the superconductivity, has yet to be conclusively observed. The primary challenge arises from the weak diamagnetic signals detected from the small samples compressed in diamond anvil cells. Therefore, the reported results of superconducting diamagnetism in hydrides have sparked intense debate, highlighting the urgent need for workable methodology to assess the validity of the experimental results. Here, we are the first to report the ultrahigh pressure measurements of the superconducting diamagnetism on Nb0.44Ti0.56, a commercial superconducting alloy, in a record-wide pressure range from 5 GPa to 160 GPa. We present detailed results on factors such as sample size, the diamagnetic signal intensity, the signal-to-noise ratio and the superconducting transition temperature across various pressures and different pressure transmitting media. These comprehensive results clearly demonstrate that this alloy is an ideal reference sample for evaluating superconductivity in compressed hydrides,validating the credibility of the experimental systems and superconducting diamagnetic results, as well as determining the nature of the superconductivity of the investigated sample. In addition, these results also provide a valuable benchmark for studying the pressure-induced superconductivity in other material families.
Superconductivity (cond-mat.supr-con)
18 pages,4 figures
Expansion of one-dimensional spinor gases from power-law traps
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-09 20:00 EDT
Ovidiu I. Patu, Gianni Aupetit-Diallo
Free expansion following the removal of axial confinement represents a fundamental nonequilibrium scenario in the study of many-body ultracold gases. Using the stationary phase approximation, we analytically demonstrate that for all one-dimensional spinor gases with repulsive contact interactions, whether bosonic or fermionic, the asymptotic density and momentum distribution can be directly determined from the quasimomentum distribution (Bethe rapidities) of the trapped gas. We efficiently obtain the quasimomentum distribution numerically by solving the integral equations that characterize the ground state of the integrable system within the local density approximation. Additionally, we derive analytical solutions for both weakly and strongly interacting regimes. Unlike in bosonic gases, where rapidity distributions and density profiles vary significantly across interaction regimes, fermionic gases maintain similar profiles in both weakly and strongly interacting limits. Notably, the gas expands self-similarly only when released from a harmonic trap. For other power-law trapping potentials, the asymptotic density profile is strongly influenced by the initial confinement geometry. Our results extend readily to Bose-Fermi mixtures and finite temperatures.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech)
7+7 pages, 2 figures, RevTeX 4.2
Two-dimensional $J_1$-$J_2$ clock model: A cornucopia of emergence
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-09 20:00 EDT
Vishnu Pulloor Kuttanikkad, Abhishodh Prakash, Rajesh Narayanan, Titas Chanda
We present a comprehensive study on the frustrated $ J_1$ -$ J_2$ classical $ q$ -state clock model with even $ q>4$ on a two-dimensional square lattice, revealing a rich ensemble of phases driven by competing interactions. In the unfrustrated regime ($ J_1>2J_2$ ), the model reproduces the standard clock model phenomenology: a low-temperature $ \mathbb{Z}_q$ -broken ferromagnet, an intermediate XY-like critical quasi-long-range-ordered (QLRO) phase with emergent $ U(1)$ symmetry, and a high-temperature paramagnet. For $ J_1<2J_2$ , frustration stabilizes five distinct regimes: the disordered paramagnet, a stripe-ordered phase breaking $ \mathbb{Z}_q\times\mathbb{Z}_2$ symmetry, two $ \mathbb{Z}_2$ -broken nematic phases (one with and one without QLRO), and an exotic stripe phase with emergent discrete $ \mathbb{Z}_q$ spin degrees of freedom prohibited in the microscopic Hamiltonian. Remarkably, this seemingly forbidden $ \mathbb{Z}_q$ order emerges via a relevant operator in the infrared long-wavelength limit, rather than from an irrelevant perturbation, highlighting a non-standard route to emergence. Using large-scale corner transfer matrix renormalization group calculations, complemented by classical Monte Carlo simulations, we map the complete phase diagram and identify Berezinskii-Kosterlitz-Thouless, Ising, first-order, and unconventional Landau-incompatible transitions between different phases. Finally, we propose an effective field-theoretic framework that encompasses these emergent orders and their interwoven transitions.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 4+7 figures
Polymorphic spin ordering in a single-crystalline cobalt-doped Fe3GaTe2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Woohyun Cho, Jaehun Cha, Yoon-Gu Kang, Dong Hyun David Lee, Jaehwan Oh, Dohyun Kim, Sangsu Yer, Jaein Lee, Heemyoung Hong, Yongsoo Yang, Yeong Kwan Kim, Myung Joon Han, Heejun Yang
A single crystalline system typically stabilizes a unique state for spin ordering below a critical temperature. Certain materials exhibit multiple magnetic states, driven by structural phase transitions under varying thermodynamic conditions. Recently, van der Waals magnets have demonstrated subtle interlayer exchange interactions, offering a promising approach to electrically control spin states without structural transformation. Here, we report the emergence of three distinct magnetic states, ferromagnetic ordering and both collinear and non-collinear antiferromagnetic orderings, in a layered single crystalline magnet, cobalt-doped Fe3GaTe2 ((Co, Fe)3GaTe2). These three magnetic phases occur without structural phase transitions, a phenomenon we designate as polymorphic spin ordering in the material. The introduction of 16% Co-doping in Fe3GaTe2 modulates the interlayer magnetic interaction, enabling multiple spin orderings within the same lattice system with three critical temperatures: a Curie temperature for a ferromagnetic state (Tc=210 K) and two Neel temperatures for the collinear (TN1=110 K) and non-collinear (TN2=30 K) antiferromagnetic states. Our findings are supported by magnetic force microscopy, first-principles calculations, and circular dichroism angular photoemission spectroscopy, which reveals varying spin ordering and changes in the topological band structure and Berry curvature at different temperatures within the single-crystalline (Co, Fe)3GaTe2.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Static and dynamic properties of Kitaev-Heisenberg ferromagnet on a triangular lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Kaushal K. Kesharpu, Pavel A. Maksimov
We present an extensive study of ground state and excitations of ferromagnetic anisotropic-exchange Kitaev-Heisenberg model on a triangular lattice using order-by-disorder calculations. It is shown that while bond-dependent terms do not affect the ground state classically, quantum fluctuations select preferred magnetization direction of the ferromagnetic state. Anisotropic terms of the magnetic Hamiltonian also give rise to magnon-magnon interactions that lead to spontaneous decays and spectral renormalization, which we illustrate using non-linear spin-wave theory.
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 7 figures
Engineering second order topological superconductor hosting tunable Majorana corner modes in magnet/$d$-wave superconductor hybrid platform
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Minakshi Subhadarshini, Archana Mishra, Arijit Saha
We propose a theoretical framework for realizing a two-dimensional (2D) second-order topological superconductor (SOTSC) in a hybrid system comprised of a $ d$ -wave superconductor, a quantum spin Hall insulator (QSHI), and a noncollinear magnetic texture deposited on top of the unconventional superconductor. While the interplay of the $ d$ -wave superconductor and QSHI has been studied as a platform to realize Majorana corner modes (MCMs), we show that the addition of the spin texture enables the tunability of these MCMs. Each corner of this hybrid system can host one or two Majorana modes depending on the system parameters, in particular, exchange strength and pitch vector of the spin texture. To characterize the higher order bulk topology, we compute the quadrupolar winding number, which directly corresponds to the number of MCMs acquiring a value of one for four corner modes and two for eight corner modes. We investigate and show the close resemblance in the topological phase diagrams obtained from the low energy effective Hamiltonian that reveals an emergent in-plane Zeeman field and spin-orbit coupling induced by the spin texture, and the real space tight binding lattice model. The microscopic pairing mechanism responsible for the appearance of SOTSC phase is investigated via an effective bulk pairing analysis, while a low-energy edge theory captures the mechanism behind tunability of MCMs. Our result paves the way for realizing SOTC with multiple MCMs which can be tuned via system parameters.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
13 Pages, 6 PDF Figures, Comments are welcome
Machine learning-enabled atomistic insights into phase boundary engineering of solid-solution ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Weiru Wen, Fan-Da Zeng, Ben Xu, Bi Ke, Zhipeng Xing, Hao-Cheng Thong, Ke Wang
Atomistic control of phase boundaries is crucial for optimizing the functional properties of solid-solution ferroelectrics, yet their microstructural mechanisms remain elusive. Here, we harness machine-learning-driven molecular dynamics to resolve the phase boundary behavior in the KNbO3-KTaO3 (KNTO) system. Our simulations reveal that chemical composition and ordering enable precise modulation of polymorphic phase boundaries (PPBs), offering a versatile pathway for materials engineering. Diffused PPBs and polar nano regions, predicted by our model, highly match with experiments, underscoring the fidelity of the machine-learning atomistic simulation. Crucially, we identify elastic and electrostatic mismatches between ferroelectric KNbO3 and paraelectric KTaO3 as the driving forces behind complex microstructural evolution. This work not only resolves the longstanding microstructural debate but also establishes a generalizable framework for phase boundary engineering toward next-generation high-performance ferroelectrics.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
General Hamiltonian description of nonreciprocal interactions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-09 20:00 EDT
Yu-bo Shi, Roderich Moessner, Ricard Alert, Marin Bukov
In a vast class of systems, which includes members as diverse as active colloids and bird flocks, interactions do not stem from a potential, and are in general nonreciprocal. Thus, it is not possible to define a conventional energy function, nor to use analytical or numerical tools that rely on it. Here, we overcome these limitations by constructing a Hamiltonian that includes auxiliary degrees of freedom; when subject to a constraint, this Hamiltonian yields the original non-reciprocal dynamics. We show that Glauber dynamics based on the constrained Hamiltonian reproduces the steady states of the original Langevin dynamics, as we explicitly illustrate for dissipative XY spins with vision-cone interactions. Further, the symplectic structure inherent to our construction allows us to apply the well-developed notions of Hamiltonian engineering, which we demonstrate by varying the amplitude of a periodic drive to tune the spin interactions between those of a square and a chain lattice geometry. Overall, our framework for generic nonreciprocal pairwise interactions paves the way for bringing to bear the full conceptual and methodological power of conventional statistical mechanics and Hamiltonian dynamics to nonreciprocal systems.
Statistical Mechanics (cond-mat.stat-mech), Other Condensed Matter (cond-mat.other), Quantum Gases (cond-mat.quant-gas), Soft Condensed Matter (cond-mat.soft), Quantum Physics (quant-ph)
29 pages, 9 figures
Partitioning Law of Polymer Chains into Flexible Polymer Networks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-09 20:00 EDT
Haruki Takarai, Takashi Yasuda, Naoyuki Sakumichi, Takamasa Sakai
The equilibrium partitioning of linear polymer chains into flexible polymer networks is governed by intricate entropic constraints arising from configurational degrees of freedom of both chains and network, yet a quantitative understanding remains elusive. Using model hydrogels with precisely defined network structures, we experimentally reveal a universal law governing linear polymer partitioning into flexible polymer networks. We establish a novel label-free, contactless method to measure partition ratio, based on the increase in osmotic pressure induced by external polymer chains partitioning into the network. Moreover, we find a universal law in which the partition constant is solely determined by the squared ratio $ (R_g / l_\mathrm{cycle})^2$ , where $ R_g$ is the gyration radius of the polymer chain and $ l_\mathrm{cycle}$ is the characteristic mesh size of the network, as defined by the cycle length.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph), Chemical Physics (physics.chem-ph)
12 pages, 8 figures
Strong tunability of epitaxial relationship and reconstruction at improper ferroelectric interface
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Xin Li, Yu Yun, Guodong Ren, Arashdeep Singh Thind, Amit Kumar Shah, Rohan Mishra, Xiaoshan Xu
The atomic structures at epitaxial film-substrate interfaces determine scalability of thin films and can result in new phenomena. However, it is challenging to control the interfacial structures since they are decided by the most stable atomic bonding. In this work, we report strong tunability of the epitaxial interface of improper ferroelectric hexagonal ferrites deposited on spinel ferrites. The selection of two interface types, related by a 90 deg rotation of in-plane epitaxial relations and featured by disordered and hybridized reconstructions respectively, can be achieved by growth conditions, stacking sequences, and spinel compositions. While the disordered type suppresses the primary K3 structure distortion and ferroelectricity in hexagonal ferrites, the hybridized type is more coherent with the distortion with minimal suppression. This tunable interfacial structure provides critical insight on controlling interfacial clamping and may offer a solution for the long-standing problem of practical critical thickness in improper ferroelectrics.
Materials Science (cond-mat.mtrl-sci)
Exploring unconventional superconductivity in PdTe via Point Contact Spectroscopy
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-09 20:00 EDT
Pritam Das, Sulagna Dutta, Saurav Suman, Amit Vashist, Bibek Ranjan Satapathy, John Jesudasan, Suvankar Chakraverty, Rajdeep Sensarma, Pratap Raychaudhuri
Palladium Telluride (PdTe), a non-layered intermetallic crystalline compound, has captured attention for its unique superconducting properties and strong spin-orbit coupling. In this work, we investigate the superconducting state of PdTe using point-contact Andreev reflection (PCAR) spectroscopy. The experimental data are analyzed using the Blonder-Tinkham-Klapwijk (BTK) model for s, p and d wave symmetries. Our results reveal clear evidence of unconventional superconductivity. The superconducting gap showing features consistent with either p-wave or d-wave pairing symmetries but cannot be fitted with s-wave symmetry. The observed anisotropic gap structure and deviations from conventional BCS behaviour highlight the complex nature of the pairing interactions in PdTe. These findings provide strong evidence of unconventional pairing symmetry in this material.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Electronic and Optical Properties of the Recently Synthesized 2D Vivianites (Vivianenes): Insights from First-Principles Calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Raphael Benjamim de Oliveira, Bruno Ipaves, Guilherme da Silva Lopes Fabris, Surbhi Slathia, Marcelo Lopes Pereira Júnior, Raphael Matozo Tromer, Chandra Sekhar Tiwary, Douglas Soares Galvão
Vivianite (Fe$ _3$ (PO$ _4$ )$ _2$ 8H$ _2$ O) is a naturally occurring layered material with significant environmental and technological relevance. This work presents a comprehensive theoretical investigation of its two-dimensional (2D) counterpart, Vivianene, focusing on its structural, electronic, and optical properties. Using density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations, we evaluate its thermodynamic stability, band structure, density of states, and optical response. Our results confirm that Vivianene retains the main structural features of bulk Vivianite while exhibiting enhanced thermodynamic stability at room temperature. The electronic structure analysis reveals an indirect bandgap of 3.03 eV for Vivianene, which is slightly lower than the 3.21 eV observed for bulk Vivianite, deviating from the expected quantum confinement trend in 2D materials. The projected density of states (PDOS) analysis indicates that Fe d orbitals predominantly contribute to the valence and conduction bands. Optical calculations demonstrate that Vivianene exhibits a higher optical band gap (3.6 eV) than bulk Vivianite (3.2 eV), with significant absorption in the ultraviolet region. The refractive index and reflectivity analyses suggest that most of the incident light is absorbed rather than reflected, reinforcing its potential for optoelectronic applications. These findings provide valuable insights into the fundamental properties of Vivianene and highlight its potential for advanced applications in sensing, optoelectronics, and energy-related technologies.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Polaritonic Quantum Matter
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
D.N. Basov, A. Asenjo-Garcia, P.J. Schuck, X.-Y. Zhu, A. Rubio, A. Cavalleri, M. Delor, M.M. Fogler, Mengkun Liu
Polaritons are quantum mechanical superpositions of photon states with elementary excitations in molecules and solids. The light-matter admixture causes a characteristic frequency-momentum dispersion shared by all polaritons irrespective of the microscopic nature of material excitations that could entail charge, spin, lattice or orbital effects. Polaritons retain the strong nonlinearities of their matter component and simultaneously inherit ray-like propagation of light. Polaritons prompt new properties, enable new opportunities for spectroscopy/imaging, empower quantum simulations and give rise to new forms of synthetic quantum matter. Here, we review the emergent effects rooted in polaritonic quasiparticles in a wide variety of their physical implementations. We present a broad portfolio of the physical platforms and phenomena of what we term polaritonic quantum matter. We discuss the unifying aspects of polaritons across different platforms and physical implementations and focus on recent developments in: polaritonic imaging, cavity electrodynamics and cavity materials engineering, topology and nonlinearities, as well as quantum polaritonics.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics), Quantum Physics (quant-ph)
Nanophotonics, 2025
Robust Critical Connectivity Threshold in Ranked Percolation of Granular Packings
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-09 20:00 EDT
Vasco C. Braz, N. A. M. Araújo
The formation of sintering bridges in amorphous powders affects both flow behavior and perceived material quality. When sintering is driven by surface tension, bridges emerge sequentially, favoring contacts between smaller particles first. Predicting the connectivity percolation threshold is key to understanding and controlling the onset of sintering. We investigate ranked percolation in granular packings, where particles connect based on contact number. While the percolation threshold defined by the fraction of connected particles is non-universal and highly sensitive to particle size dispersion, we find that the critical number of sintered bridges per particle provides a robust estimator across different size distributions. Through numerical simulations and a mean-field approach, we link this robustness to the spatial distribution of contacts. Our results have broader implications for understanding the resilience of spatially embedded networks under targeted attacks.
Soft Condensed Matter (cond-mat.soft)
Josephson current signature of Floquet Majorana and topological accidental zero modes in altermagnet heterostructure
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Amartya Pal, Debashish Mondal, Tanay Nag, Arijit Saha
We theoretically investigate the generation and Josephson current signatures of Floquet Majorana end modes (FMEMs) in a periodically driven altermagnet (AM) heterostructure. Considering a one-dimensional (1D) Rashba nanowire (RNW) proximitized to a regular $ s$ -wave superconductor and a $ d$ -wave AM, we generate both $ 0$ - and $ \pi$ -FMEMs by driving the nontopological phase of the static system. While the static counterpart hosts both topological Majorana zero modes (MZMs) and non-topological accidental zero modes (AZMs), the drive can gap out the static AZMs and generate robust $ \pi$ -FMEMs, termed as topological AZMs (TAZMs). We topologically characterize the emergent FMEMs via dynamical winding numbers exploiting chiral symmetry of the system. Moreover, we consider a periodically driven Josephson junction comprising of RNW/AM-based 1D topological superconduting setup. We identify the signature of MZMs and FMEMs utilizing $ 4\pi$ -periodic Josephson effect, distinguishing them from trivial AZMs exhibiting $ 2\pi$ -periodicty, in both static and driven platforms. This Josephson current signal due to Majorana modes survives even in presence of finite disorder. Our work establishes a route to realize and identify FMEMs in AM-based platforms through Floquet engineering and Josephson current response.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
5 pages main text, 4 PDF figures + 6 pages supplementary material, 5 PDF figures, comments are welcome
Numerical Integration of the KPZ and Related Equations on Networks: The Case of the Cayley Tree
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-09 20:00 EDT
J. M. Marcos, J. J. Meléndez, R. Cuerno, J. J. Ruiz-Lorenzo
The numerical integration of stochastic growth equations on non-Euclidean networks presents unique challenges due to the nonlinearities that occur in many relevant models and of the structural constraints of the networks. In this work, we integrate the KPZ, Edwards-Wilkinson, and tensionless KPZ equations on Cayley trees using different numerical schemes and compare their behavior with previous results obtained for discrete growth models. By assessing the stability and accuracy of these methods, we explore how network topology influences interface growth and how boundary effects shape the observed scaling properties. Our results show good agreement with previous studies on discrete models, reinforcing key scaling behaviors while highlighting some differences. These findings contribute to a better understanding of surface growth on networked substrates and provide a computational framework for studying nonlinear stochastic processes beyond Euclidean lattices.
Statistical Mechanics (cond-mat.stat-mech)
32 pages, 18 figures
Nonlinear optical response of truly chiral phonons: Light-induced phonon angular momentum, Peltier effect, and orbital current
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Hiroaki Ishizuka, Masahiro Sato
The nonlinear optical responses of chiral phonons to terahertz and infrared light are studied using the nonlinear response theory. We show that the photo-induced angular momentum increases with the square of the chiral-phonon relaxation time $ \tau$ , giving a significantly larger angular momentum compared to ordinary phonons. We also find that the photo-induced Peltier effect by chiral phonons occurs through a mechanism distinct from those proposed recently; the induced energy current scales $ \propto\tau^2$ , giving a larger energy current in the clean limit. We prove a linear relation between the generated angular momentum and the energy current. Lastly, we show that the orbital current, an analog of the spin current, occurs through a nonlinear response. These findings demonstrate the unique properties and functionalities of chiral phonons.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
6 pagers, 5 figures
Type-III Weyl Semi-Half-Metal in an Ultralight Monolayer Li$_2$N
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Qingqing Li, Li Chen, Run-Wu Zhang, Botao Fu
The interplay between magnetic ordering and band topology has emerged as a fertile ground for discovering novel quantum states with profound implications for fundamental physics and next-generation electronics. Here, we theoretically predict a new type-III Weyl semi-half-metal (SHM) state in monolayer Li$ _2$ N, uniquely combining magnetic half-metallicity and type-III Weyl semimetal characteristics. First-principles calculations reveal a fully spin-polarized and critically tilted Weyl cone around the Fermi level in monolayer Li$ _2$ N, driven by $ p$ -orbital ferromagnetism. This arises from the symmetry-protected band crossing between a flat valence band and a highly dispersive conduction band, leading to type-III Weyl fermions with strong transport anisotropy. A low-energy $ k{\cdot}p$ Hamiltonian is constructed and corresponding nontrivial edge states are uncovered to capture the topological nature of Li$ _2$ N. Notably, this Weyl SHM phase remains robust under biaxial strain ranging from -2$ %$ to $ 4%$ , with an ideal type-III Weyl fermion emerging alongside a line-like ergodic surface emerging at 3.7$ %$ strain, offering a promising platform for exploring correlated electronic phenomena. Our results establish Li$ _2$ N as a viable candidate for realizing exotic type-III Weyl SHM states and open a new avenue for exploring the intricate interplay among magnetism, topology, and flat-band physics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 4 figures
Magnetic ground states of highly doped two-leg Hubbard ladders with a particle bath
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Hiroaki Onishi, Seiji Miyashita
We investigate the ground-state magnetism of a Hubbard model in a system consisting of a main frame (subsystem) and a particle bath (center sites). The hole doping in the main frame is controlled by adjusting the chemical potential of the particle bath. In the weakly doped region, the saturated ferromagnetic state emerges due to the Nagaoka mechanism [Phys. Rev. B 90, 224426 (2014)]. However, in the highly doped region, a variety of intriguing magnetic states are observed, including partially polarized states and nonmagnetic states. To understand these states, we analyze the state of the subsystem by comparing its properties with those of a two-leg ladder system, which corresponds to the subsystem with the center sites removed. Furthermore, to gain insight into the microscopic origin of the magnetic phase diagram, we study the ground state of the corresponding effective t-J model, derived from the Hubbard model by considering the second-order processes of the electron hopping. The phase diagram is well reproduced by the effective t-J model, which includes the three-site pair-hopping term. To elucidate the competition among different energy contributions, such as potential, kinetic, and magnetic energies, we classify the energies within the effective t-J model.
Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 17 figures
High-fidelity Grain Growth Modeling: Leveraging Deep Learning for Fast Computations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Pungponhavoan Tep, Marc Bernacki
Grain growth simulation is crucial for predicting metallic material microstructure evolution during annealing and resulting final mechanical properties, but traditional partial differential equation-based methods are computationally expensive, creating bottlenecks in materials design and manufacturing. In this work, we introduce a machine learning framework that combines a Convolutional Long Short-Term Memory networks with an Autoencoder to efficiently predict grain growth evolution. Our approach captures both spatial and temporal aspects of grain evolution while encoding high-dimensional grain structure data into a compact latent space for pattern learning, enhanced by a novel composite loss function combining Mean Squared Error, Structural Similarity Index Measurement, and Boundary Preservation to maintain structural integrity of grain boundary topology of the prediction. Results demonstrated that our machine learning approach accelerates grain growth prediction by up to \SI{89}{\times} faster, reducing computation time from \SI{10}{\minute} to approximately \SI{10}{\second} while maintaining high-fidelity predictions. The best model (S-30-30) achieving a structural similarity score of \SI{86.71}{\percent} and mean grain size error of just \SI{0.07}{\percent}. All models accurately captured grain boundary topology, morphology, and size distributions. This approach enables rapid microstructural prediction for applications where conventional simulations are prohibitively time-consuming, potentially accelerating innovation in materials science and manufacturing.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI)
Salt-induced gelation of nonionic sucrose ester dispersions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-09 20:00 EDT
Diana Cholakova, Nevena Pagureva, Monika Hristova, Slavka Tcholakova
The dispersions of nonionic sucrose ester surfactants in water exhibit a highly negative zeta-potential, though its origin remains controversial. The addition of electrolytes to these dispersions may influence their zeta-potential, thus potentially affecting their physicochemical properties. The electrolyte- and pH- driven gelation of aqueous dispersions of commercial sucrose stearate (S970) containing ca. 1:1 monoesters and diesters was studied using optical microscopy, rheological and zeta-potential measurements, and small-angle X-ray scattering techniques. At low electrolyte concentrations and pH $ \gtrapprox$ 5, 0.5-5 wt. % S970 dispersions exhibited low viscosities and behaved as freely flowing liquids. The addition of electrolytes of low concentrations, e.g. 9 mM NaCl or 1.5 mM MgCl$ _2$ , induced the formation of a non-flowing gels. This sol-gel transition occurred due to the partial screening of the diesters particles charge, allowing the formation of an attractive gel network, spanning across the dispersion volume. Complete charge screening, however, led to a gel-sol transition and phase separation. Gel formation was observed also by pH variation without electrolyte addition, whereas the addition of free fatty acids had negligible impact on dispersion properties. These findings support the hypothesis that the negative charge in sucrose ester dispersions arises from hydroxyl anions adsorption on particles surfaces. Gels were formed using just 1.3 wt. % surfactant, and the critical electrolyte concentration for gelation was found to scale approximately with the square of the cation charge, in agreement with the low surface charge density theory. The biodegradable sucrose esters gels offer a sustainable alternative for structuring personal and home care products, replacing the wormlike micelles of synthetic surfactants typically used at much higher surfactant and salt concentrations.
Soft Condensed Matter (cond-mat.soft)
J. Colloid Interface Sci. 2025, 693, 137610
Unconventional magnetoresistance and spin gapless semiconductor like behavior across the Martensitic transformation in off-stoichiometric Co-Fe-Ti-Si Heusler alloy thin films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Mainur Rahaman, Lanuakum A Longchar, Rajeev Joshi, R. Rawat, Archana Lakhani, M. Manivel Raja, S. N. Kaul, S. Srinath
In this work, the effect of anti-site disorder on magnetic, electrical resistivity, transverse magnetoresistance MR, and anomalous Hall resistivity of off-stoichiometric CFTS Heusler alloy thin films, with a particular focus on martensitic phase transformation and spin gapless semiconductor SGS-like behavior, is investigated. These thin films were grown on Si (100) substrate at different substrate temperatures, TS, ranging from 200 C to 550 C using magnetron sputtering, enabling control over the degree of anti-site atomic ordering from disordered A2 to ordered L21. All the films, irrespective of their disorder, exhibit a distinct thermal hysteresis and significant drop in resistivity, crossover from asymmetric to symmetric magnetoresistance, and a sharp increase in MR around 300 K, confirming the occurrence of a thermo-elastic martensitic phase transformation. Detailed analysis of resistivity data indicates that for TS200 and TS350 films, a SGS based two channel model describes the conductivity in the martensite phase, whereas TS450, TS500, and TS550 films, exhibit a usual metallic behavior with a resistivity minimum at low temperatures. All the CFTS films show soft ferromagnetic nature and follow the spin-wave equation up to 390 K. The saturation magnetization and Hall conductivity increase with increasing crystalline order. The scaling relation between the longitudinal resistivity and the anomalous Hall resistivity in the martensite phase revels that skew scattering is the dominating contribution in disordered films, and a change in charge carrier type from hole to electron around the martensitic transformation temperature. The asymmetric MR, persistent up to room temperature, highlights the potential of these films for spintronic applications such as spin valves.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Machine learning model for efficient nonthermal tuning of the charge density wave in monolayer NbSe$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-09 20:00 EDT
Luka Benić, Federico Grasselli, Chiheb Ben Mahmoud, Dino Novko, Ivor Lončarić
Understanding and controlling the charge density wave (CDW) phase diagram of transition metal dichalcogenides is a long-studied problem in condensed matter physics. However, due to complex involvement of electron and lattice degrees of freedom and pronounced anharmonicity, theoretical simulations of the CDW phase diagram at the density-functional-theory level are often numerically demanding. To reduce the computational cost of first principles modelling by orders of magnitude, we have developed an electronic free energy machine learning model for monolayer NbSe$ _2$ that allows changing both electronic and ionic temperatures independently. Our approach relies on a machine learning model of the electronic density of states and zero-temperature interatomic potential. This allows us to explore the CDW phase diagram of monolayer NbSe$ _2$ both under thermal and laser-induced nonthermal conditions. Our study provides an accurate estimate of the CDW transition temperature at low cost and can disentangle the role of hot electrons and phonons in nonthermal ultrafast melting process of the CDW phase in NbSe$ _2$ .
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Computational Physics (physics.comp-ph)
Ballistic-to-diffusive transition in engineered counter-propagating quantum Hall channels
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Aifei Zhang, Kenji Watanabe, Takashi Taniguchi, Patrice Roche, Carles Altimiras, François Parmentier, Olivier Maillet
Exotic quantum Hall systems hosting counter-propagating edge states can show seemingly non-universal transport regimes, usually depending on the size of the sample. We experimentally probe transport in a quantum Hall sample engineered to host a tunable number of counter-propagating edge states. The latter are coupled by Landauer reservoirs, which force charge equilibration over a tunable effective length. We show that charge transport is determined by the balance of up- and downstream channels, with a ballistic regime emerging for unequal numbers of channels. For equal numbers, we observe a transition to a critical diffusive regime, characterized by a diverging equilibration length. Our approach allows simulating the equilibration of hole-conjugate states and other exotic quantum Hall effects with fully controlled parameters using well-understood quantum Hall states.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Longitudinal Josephson effect in systems with pairing of spatially separated electrons and holes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
S.I. Shevchenko, O.M. Konstantynov
Longitudinal non-dissipative current states in bilayer electron-hole systems in the presence of potential barriers that divide the system into left and right sides was investigated. The consideration is performed both for the case of weak carrier coupling (high density) and strong coupling (low density). It is shown that in the high-density limit, the critical current is proportional to the product of the transparencies of the barriers in the electron and hole layers, whereas in the low-density limit, the current is inversely proportional to the sum of the heights of the potential barriers.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 6 figures
Fermi lune and transdimensional orbital magnetism in rhombohedral multilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Min Li, Qingxin Li, Xin Lu, Hua Fan, Kenji Watanabe, Takashi Taniguchi, Yue Zhao, Xin-Cheng Xie, Lei Wang, Jianpeng Liu
The symmetry and geometry of the Fermi surface play an essential role in governing the transport properties of a metallic system. A Fermi surface with reduced symmetry is intimately tied to unusual transport properties such as anomalous Hall effect and nonlinear Hall effect. Here, combining theoretical calculations and transport measurements, we report the discovery of a new class of bulk Fermi surface structure with unprecedented low symmetry, the Fermi lune", with peculiar crescent shaped Fermi energy contours, in rhombohedral multilayer graphene. This emergent Fermi-lune structure driven by electron-electron interactions spontaneously breaks time-reversal, mirror, and rotational symmetries, leading to two distinctive phenomena: giant intrinsic non-reciprocity in longitudinal transport and a new type of magnetism termed transdimensional orbital magnetism”. Coupling the Fermi lune to a superlattice potential further produces a novel Chern insulator exhibiting quantized anomalous Hall effect controlled by in-plane magnetic field. Our work unveils a new symmetry breaking state of matter in the transdimensional regime, which opens an avenue for exploring correlated and topological quantum phenomena in symmetry breaking phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 4 figures ,1 table in main text. 7 figures in Supplementary Materials
Evidence of chiral fermion edge modes through geometric engineering of thermal Hall in $α$-RuCl$_3$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Heda Zhang, Gabor B. Halasz, Sujoy Ghosh, Stephen Jesse, Thomas Z. Ward, David Alan Tennant, Michael McGuire, Jiaqiang Yan
The experimental observation of half-integer-quantized thermal Hall conductivity in the Kitaev candidate material $ \alpha$ -RuCl$ _3$ has served as smoking-gun signature of non-Abelian anyons through an associated chiral Majorana edge mode. However, both the reproducibility of the quantized thermal Hall conductivity and the fundamental nature of the associated heat carriers, whether bosonic or fermionic, are subjects of ongoing and vigorous debate. In a recent theoretical work, it was proposed that varying the sample geometry through creating constrictions can distinguish between different origins of the thermal Hall effect in magnetic insulators. Here, we provide experimental evidence of chiral fermion edge modes by comparing the thermal Hall effect of a geometrically constricted $ \alpha$ -RuCl$ _3$ sample with that of an unconstricted bulk sample. In contrast to the bulk crystals where the thermal Hall signal fades below 5,K, the constricted crystals display a significant thermal Hall signal that remains measurable even at 2,K. This sharp difference agrees well with the theoretical prediction and provides compelling evidence for the contribution of chiral fermion edge modes to the thermal Hall effect in $ \alpha$ -RuCl$ _3$ . More broadly, this work confirms that the geometry dependence of the thermal Hall effect can help identify chiral spin liquids in candidate materials like $ \alpha$ -RuCl$ _3$ and paves the way for the experimental realization of thermal anyon interferometry.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Emergence of Spin-Polarized Unconventional Skin Effect in Hatano-Nelson Model
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-09 20:00 EDT
Moirangthem Sanahal, Subhasis Panda, Snehasish Nandy
The non-Hermitian skin effect (NHSE), a hallmark of non-Hermitian systems, stems from the topological nature of complex energy spectra, typically characterized by a nonzero spectral winding number in one dimension (1D). By investigating 1D spinful Hatano-Nelson model with Abelian gauge fields we uncover a tunable, unconventional spin-polarized NHSE with zero spectral winding, coexisting with a bidirectional conventional NHSE exhibiting nonzero winding. The unconventional skin modes display scale-restricted localization, distinguishing them from the critical NHSE. Upon introducing an external magnetic field coupled to the spin degrees of freedom, these unconventional skin modes are suppressed, leading to spectral instability and the emergence of critical NHSE with system size-dependent non-Bloch spectra. Meanwhile, conventional skin modes persist, but undergo a transition from bidirectional to unidirectional accumulation. Our results provide experimentally accessible predictions, relevant to photonic lattices and ultracold atomic systems with synthetic gauge fields.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 4 figures. Comments are welcome
Reduced Basis Method for Driven-Dissipative Quantum Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-09 20:00 EDT
Hans Christiansen, Virgil V. Baran, Jens Paaske
Reduced basis methods provide an efficient way of mapping out phase diagrams of strongly correlated many-body quantum systems. The method relies on using the exact solutions at select parameter values to construct a low-dimensional basis, from which observables can be efficiently and reliably computed throughout the parameter space. Here we show that this method can be generalized to driven-dissipative Markovian systems allowing efficient calculations of observables in the transient and steady states. A subsequent distillation of the reduced basis vectors according to their explained variances allows for an unbiased exploration of the most pronounced parameter dependencies indicative of phase boundaries in the thermodynamic limit.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)