CMP Journal 2025-02-04
Statistics
Nature Physics: 2
Physical Review Letters: 15
Physical Review X: 1
arXiv: 89
Nature Physics
A bound on thermalization from diffusive fluctuations
Original Paper | Nonlinear phenomena | 2025-02-03 19:00 EST
Luca V. Delacrétaz
The local equilibration time of quantum many-body systems has been conjectured to satisfy a Planckian bound, so that it always exceeds some value on the order of ℏ/T, where T is the temperature of the system. Here we provide a sharp and universal definition of the local equilibration timescale, and show that it is bounded below by the strong-coupling scale of diffusive fluctuations, which can be expressed in terms of familiar transport parameters. When applied to conformal field theories at a finite temperature, this result produces the Planckian bound. Moreover, this fluctuation bound applies to any local thermalizing system. We study its implication for correlated insulators, metals and disordered fixed points, where it can be used to establish a lower bound on diffusivity in terms of specific heat. Finally, we discuss how the local equilibration time can be directly measured in experiments.
Nonlinear phenomena, Phase transitions and critical phenomena, Superconducting properties and materials
Stirring the false vacuum via interacting quantized bubbles on a 5,564-qubit quantum annealer
Original Paper | Quantum simulation | 2025-02-03 19:00 EST
Jaka Vodeb, Jean-Yves Desaules, Andrew Hallam, Andrea Rava, Gregor Humar, Dennis Willsch, Fengping Jin, Madita Willsch, Kristel Michielsen, Zlatko Papić
False vacuum decay--the transition from a metastable quantum state to a true vacuum state--plays an important role in quantum field theory and non-equilibrium phenomena such as phase transitions and dynamical metastability. The non-perturbative nature of false vacuum decay and the limited experimental access to this process make it challenging to study, leaving several open questions regarding how true vacuum bubbles form, move and interact. Here we observe quantized bubble formation in real time, a key feature of false vacuum decay dynamics, using a quantum annealer with 5,564 superconducting flux qubits. We develop an effective model that captures both initial bubble creation and subsequent interactions, and remains accurate under dissipation. The annealer reveals coherent scaling laws in the driven many-body dynamics for more than 1,000 intrinsic qubit time units. This work provides a method for investigating false vacuum dynamics of large quantum systems in quantum annealers.
Quantum simulation, Statistical physics
Physical Review Letters
Heat as a Witness of Quantum Properties
Research article | Information thermodynamics | 2025-02-04 05:00 EST
A. de Oliveira Junior, Jonatan Bohr Brask, and Patryk Lipka-Bartosik
We present a new approach for witnessing quantum resources, such as entanglement and coherence, based on heat generation. Inspired by Maxwell's demon, we ask what the optimal heat exchange between a quantum system and a thermal environment is when the process is assisted by a quantum memory. We derive fundamental energy constraints in this scenario and show that quantum states can reveal nonclassical signatures via heat exchange. This approach leads to a heat-based witness for quantum properties, offering an alternative to system-specific measurements, as it only relies on fixed energy measurements in a thermal ancilla. We illustrate our findings with the detection of entanglement in isotropic states and coherence in two-spin systems interacting with a single-mode electromagnetic field.
Phys. Rev. Lett. 134, 050401 (2025)
Information thermodynamics, Quantum correlations in quantum information, Quantum information theory, Quantum thermodynamics
Multiseed Krylov Complexity
Research article | Quantum chaos | 2025-02-04 05:00 EST
Ben Craps, Oleg Evnin, and Gabriele Pascuzzi
Krylov complexity is an attractive measure for the rate at which quantum operators spread in the space of all possible operators under dynamical evolution. One expects that its late-time plateau would distinguish between integrable and chaotic dynamics, but its ability to do so depends precariously on the choice of the initial seed. We propose to apply such considerations not to a single operator, but simultaneously to a collection of initial seeds in the manner of the block-Lanczos algorithm. We furthermore suggest that this collection should comprise all simple (few-body) operators in the theory, which echoes the applications of Nielsen complexity to dynamical evolution. The resulting construction, unlike the conventional Krylov complexity, reliably distinguishes integrable and chaotic Hamiltonians without any need for fine-tuning.
Phys. Rev. Lett. 134, 050402 (2025)
Quantum chaos, Quantum information theory, Quantum many-body systems, Quantum spin chains
Volume-Entangled Exact Scar States in the PXP and Related Models in Any Dimension
Research article | Eigenstate thermalization | 2025-02-04 05:00 EST
Andrew N. Ivanov and Olexei I. Motrunich
In this Letter, we report first exact volume-entangled Einstein-Podolsky-Rosen--type scar states hosted by PXP and related Hamiltonians corresponding to various geometric configurations of Rydberg-blockaded atom systems, including the most extensively studied ones such as the chain with periodic boundary conditions (PBCs) and square lattice. We start by introducing a new zero-energy eigenstate of the PBC chain and proceed by generalizing it to a wide variety of geometries and Hamiltonians. We point out the potential experimental relevance of our states by providing a protocol for their preparation on near-term Rydberg quantum devices, which relies only on strictly local measurements and evolution under native Hamiltonians. We also demonstrate the utility of these states for the study of quantum dynamics by describing a protocol for measuring infinite-temperature out-of-time-order correlator functions.
Phys. Rev. Lett. 134, 050403 (2025)
Eigenstate thermalization, Entanglement production, Quantum chaos, Rydberg atoms & molecules, Strongly correlated systems
Qudit Dynamical Decoupling on a Superconducting Quantum Processor
Research article | Open quantum systems & decoherence | 2025-02-04 05:00 EST
Vinay Tripathi, Noah Goss, Arian Vezvaee, Long B. Nguyen, Irfan Siddiqi, and Daniel A. Lidar
Multilevel qudit systems are increasingly being explored as alternatives to traditional qubit systems due to their denser information storage and processing potential. However, qudits are more susceptible to decoherence than qubits due to increased loss channels, noise sensitivity, and crosstalk. To address these challenges, we develop protocols for dynamical decoupling (DD) of qudit systems based on the Heisenberg-Weyl group. We implement and experimentally verify these DD protocols on a superconducting transmon processor that supports qudit operation based on qutrits (\(d=3\)) and ququarts (\(d=4\)). Specifically, we demonstrate single-qudit DD sequences to decouple qutrits and ququarts from system-bath-induced decoherence. We also introduce two-qudit DD sequences designed to suppress the detrimental cross-Kerr couplings between coupled qudits. This allows us to demonstrate a significant improvement in the fidelity of time-evolved qutrit Bell states. Our results highlight the utility of leveraging DD to enable scalable qudit-based quantum computing.
Phys. Rev. Lett. 134, 050601 (2025)
Open quantum systems & decoherence, Quantum algorithms & computation, Quantum computation, Quantum control, Quantum error correction, Quantum information processing, Qudits
Implementing Arbitrary Ising Models with a Trapped-Ion Quantum Processor
Research article | Adiabatic quantum optimization | 2025-02-04 05:00 EST
Yao Lu, Wentao Chen, Shuaining Zhang, Kuan Zhang, Jialiang Zhang, Jing-Ning Zhang, and Kihwan Kim
A promising paradigm of quantum computing for achieving practical quantum advantages is quantum annealing or quantum approximate optimization algorithm, where the classical problems are encoded in Ising interactions. However, it is challenging to build a quantum system that can efficiently map any structured problems. Here, we present a trapped-ion quantum processor that can efficient encode arbitrary Ising models with all-to-all connectivity for up to four spins. We implement the spin-spin interactions by using the coupling of trapped ions to multiple collective motional modes and realize the programmability through phase modulation of the Raman laser beams that are individually addressed on ions. As an example, we realize several Ising models with different interaction connectivities, where the interactions can be ferromagnetic or antiferromagnetic. We confirm the programmed interaction geometry by observing the ground states of the corresponding models through quantum state tomography. Our experimental demonstrations serve as an important basis for realizing practical quantum advantages with trapped ions.
Phys. Rev. Lett. 134, 050602 (2025)
Adiabatic quantum optimization, Quantum control, Quantum information with trapped ions, Quantum simulation, Trapped ions
All Next-to-Next-to-Extremal One-Loop Correlators of AdS Supergluons and Supergravitons
Conformal field theory | 2025-02-04 05:00 EST
Zhongjie Huang (黄中杰), Bo Wang (王波), and Ellis Ye Yuan (袁野)
We bootstrap all of the next-to-next-to-extremal one-loop four-point correlators of supergravitons and supergluons in \({\mathrm{AdS}}_{5}\) using a differential representation, and obtain closed formulas that are valid in both position space and Mellin space simultaneously.
Phys. Rev. Lett. 134, 051601 (2025)
Conformal field theory, Gauge-gravity dualities, Large-N expansion in field theory, Scattering amplitudes, Conformal symmetry, Supersymmetry
Angular Momentum Resolved Inelastic Electron Scattering for Nuclear Giant Resonances
Research article | Electromagnetic transitions | 2025-02-04 05:00 EST
Zhi-Wei Lu, Liang Guo, Mamutjan Ababekri, Jia-Lin Zhang, Xiu-Feng Weng, Yuanbin Wu, Yi-Fei Niu, and Jian-Xing Li
Giant resonances (GRs) provide crucial insights into nuclear physics and astrophysics. Exciting GRs using particles like electrons is effective, yet the angular momentum (AM) transfer of electrons, including both intrinsic spin and orbital degrees of freedom in inelastic scattering, has never been studied. Here, we investigate AM transfer in GRs excited by plane-wave and vortex electrons, developing a comprehensive AM-resolved inelastic electron scattering theory. We find that even plane-wave electrons can model-independently extract transition strengths of higher multipolarity by selecting specific AM states of scattered electrons. Additionally, relativistic vortex electrons with an orbital angular momentum of \(\pm{}1\) can be efficiently generated. Vortex electrons can also be used to extract GR transition strength as in the plane-wave case, regardless of the position of the nucleus relative to the beam axis. Furthermore, relativistic vortex electrons with larger orbital angular momentum can be generated for on-axis nuclei due to AM conservation. Our method offers new perspectives for nuclear structure research and paves the way for generating vortex particles.
Phys. Rev. Lett. 134, 052501 (2025)
Electromagnetic transitions, Giant resonances, Inelastic scattering reactions, Lepton induced nuclear reactions, Nuclear reactions, Nuclear structure & decays, Polarization phenomena
Effects of Neutron-Antineutron Transitions in Neutron Stars
Neutron star cooling | 2025-02-04 05:00 EST
Itzhak Goldman, Rabindra N. Mohapatra, Shmuel Nussinov, and Robert Shrock
We analyze effects of neutron-antineutron transitions in neutron stars, specifically on (i) cooling, (ii) rotation rate, and (iii) for binary pulsars, the increase in the orbital period. We show that these effects are negligibly small.
Phys. Rev. Lett. 134, 052701 (2025)
Neutron star cooling, Neutron stars & pulsars, Baryon & lepton number symmetries
Efficient In Situ Generation of Photon-Memory Entanglement in a Nonlinear Cavity
Research article | Quantum entanglement | 2025-02-04 05:00 EST
Hoi-Kwan Lau, Hong Qiao, Aashish A. Clerk, and Tian Zhong
Parametrically driving an optical cavity that simultaneously couples to an atomic ensemble quantum memory enables in situ generation of multimode photon-memory entanglement. A high-rate bipartite photon-memory entanglement can be generated even after discarding one entangled optical mode. This protocol can be realized with existing technologies based on photonic resonators integrated with a rare-earth-ion doped quantum memory. The proposed scheme shows significant advantages in entanglement generation rates compared with prevailing quantum memory protocols and experiments, with theoretical ebit rates of tens of MHz without fine-tuned operating conditions. Such a photon-memory entanglement source offers a versatile resource for quantum networking and interconnect applications.
Phys. Rev. Lett. 134, 053602 (2025)
Quantum entanglement, Quantum interconnects, Quantum memories, Quantum optics, Optical parametric oscillators & amplifiers, Rare-earth doped crystals, Cavity resonators
Emergence of Capillary Waves in Miscible Coflowing Fluids
Research article | Capillary waves | 2025-02-04 05:00 EST
Alessandro Carbonaro, Giovanni Savorana, Luca Cipelletti, Rama Govindarajan, and Domenico Truzzolillo
We show that capillary waves can exist at the boundary between miscible coflowing fluids. We unveil that the interplay between transient interfacial stresses and confinement drives the progressive transition from the well-known inertial regime, characterized by a frequency independent wave number, \(k\sim {\omega }^{0}\), to a capillary wave scaling, \(k\sim {\omega }^{2/3}\), unexpected for miscible fluids. This allows us to measure the effective interfacial tension between miscible fluids and its rapid decay on timescales never probed so far, which we rationalize with a model going beyond square-gradient theories. Our work potentially opens a new avenue to measure transient interfacial tensions at the millisecond scale in a controlled manner.
Phys. Rev. Lett. 134, 054001 (2025)
Capillary waves, Surface & interfacial phenomena, Classical fluids, Liquid-liquid interfaces, Microfluidic devices, Two-fluid & multi-fluid model
Continuum Damping of Topologically Protected Edge Modes at the Boundary of Cold Magnetized Plasmas
Research article | Electromagnetic waves & oscillations | 2025-02-04 05:00 EST
Roopendra Singh Rajawat, G. Shvets, and V. Khudik
The recent extension of topological ideas to continuous systems with broken time-reversal symmetry, such as magnetized plasmas, provides new insights into the nature of topologically protected surface plasma waves (TSPWs). We demonstrate a unique characteristic of TSPWs propagating above the electron cyclotron frequency: their collisionless damping via coupling to the continuum of resonant modes localized inside a smooth plasma-vacuum interface. We show that damped TSPWs retain their unidirectional nature and immunity against backscattering, and that these properties can be used to generate highly localized energy sinks using sheared magnetic field.
Phys. Rev. Lett. 134, 055301 (2025)
Electromagnetic waves & oscillations, Plasma waves, Topological phases of matter, Wave-wave, wave-particle interactions
Revealing the Orbital Origins of Exotic Electronic States with Ti Substitution in Kagome Superconductor \({\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}\)
Research article | Charge density waves | 2025-02-04 05:00 EST
Zihao Huang, Hui Chen, Hengxin Tan, Xianghe Han, Yuhan Ye, Bin Hu, Zhen Zhao, Chengmin Shen, Haitao Yang, Binghai Yan, Ziqiang Wang, Feng Liu, and Hong-Jun Gao
The multiband kagome superconductor \({\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}\) exhibits complex orbital textures on the Fermi surface, making the orbital origins of its cascade of correlated electronic states and superconductivity a major scientific puzzle. Chemical doping of the kagome plane can simultaneously tune the exotic states and the Fermi-surface orbital texture and thus offers a unique opportunity to correlate the given states with specific orbitals. In this Letter, by substituting V atoms with Ti in the kagome superconductor \({\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}\), we reveal the orbital origin of a cascade of its correlated electronic states through the orbital-resolved quasiparticle interference. We analyze the quasiparticle interference changes associated with different orbitals, aided by first-principles calculations. We have observed that the in-plane and out-of-plane vanadium \(3d\) orbitals cooperate to form unidirectional coherent states in pristine \({\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}\), whereas the out-of-plane component disappears with doping-induced suppression of charge density wave and global electronic nematicity. In addition, the Sb \({p}_{z}\) orbital plays an important role in both the pseudogap and superconducting states in \({\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}\). Our findings offer new insights into multiorbital physics in quantum materials that are generally manifested with intriguing correlations between atomic orbitals and symmetry-encoded correlated electronic states.
Phys. Rev. Lett. 134, 056001 (2025)
Charge density waves, Pair density wave, Pseudogap, Superconductivity, Kagome lattice, Density functional calculations, Scanning tunneling spectroscopy
Augmentation of Universal Potentials for Broad Applications
Research article | Optimization problems | 2025-02-04 05:00 EST
Joe Pitfield, Florian Brix, Zeyuan Tang, Andreas Møller Slavensky, Nikolaj Rønne, Mads-Peter Verner Christiansen, and Bjørk Hammer
Universal potentials open the door for DFT level calculations at a fraction of their cost. We find that for application to systems outside the scope of its training data, pretrained CHGNet [Deng et al., Nat. Mach. Intell. 5, 1031 (2023)] has the potential to succeed out of the box, but can also fail significantly in predicting the ground state configuration. We demonstrate that via fine-tuning or a \(\mathrm{\Delta }\)-learning approach it is possible to augment the overall performance of universal potentials for specific cluster and surface systems. We utilize this to investigate and explain experimentally observed defects in the Ag(111)-O surface reconstruction and explain the mechanics behind their formation.
Phys. Rev. Lett. 134, 056201 (2025)
Optimization problems, Potential energy surfaces, Surface & interfacial phenomena, Clusters, Thin films, Density functional theory, Machine learning
Origin of Interstitial Doping Induced Coercive Field Reduction in Ferroelectric Hafnia
Research article | Ferroelectric domains | 2025-02-04 05:00 EST
Tianyuan Zhu, Liyang Ma, Xu Duan, Shiqing Deng, and Shi Liu
Hafnia-based ferroelectrics hold promise for nonvolatile ferroelectric memory devices. However, the high coercive field required for polarization switching remains a prime obstacle to their practical applications. A notable reduction in coercive field has been achieved in ferroelectric \(\mathrm{Hf}{(\mathrm{Zr})}_{1+x}{\mathrm{O}}_{2}\) films with interstitial Hf(Zr) dopants [Science 381, 558 (2023)], suggesting a less-explored strategy for coercive field optimization. Supported by density functional theory calculations, we demonstrate the \(Pca{2}_{1}\) phase, with a moderate concentration of interstitial Hf dopants, serves as a minimal model to explain the experimental observations, rather than the originally assumed rhombohedral phase. Large-scale deep potential molecular dynamics simulations suggest that interstitial defects promote the polarization reversal by facilitating \(Pbcn\)-like mobile 180^ domain walls. A simple prepoling treatment could reduce the switching field to less than \(1\text{ }\text{ }\mathrm{MV}/\mathrm{cm}\) and enable switching on a subnanosecond timescale. High-throughput calculations reveal a negative correlation between the switching barrier and dopant size and identify a few promising interstitial dopants for coercive field reduction.
Phys. Rev. Lett. 134, 056802 (2025)
Ferroelectric domains, Ferroelectricity, Ferroelectrics, Density functional theory, High-throughput calculations, Machine learning
Statistical Mechanics Approach to DNA-Driven Droplet Deformation and Adhesion
Research article | Adhesion | 2025-02-04 05:00 EST
Nicolas Judd, Angus McMullen, Sascha Hilgenfeldt, and Jasna Brujic
Adhesion of soft particles with mobile linkers is of importance in colloidal self-assembly, the binding of vesicles, and tissue organization in biology. Here we derive and experimentally test an equilibrium theory that captures the adhesion of DNA-coated emulsion droplets. Notably, we identify a transition from spherical to deformed droplet binding at a characteristic DNA coverage that depends on molecular properties and surface tension. Fitting the data reveals a weak effective binding strength of \(3.7\pm{}0.3{\mathrm{K}}_{\mathrm{B}}\mathrm{T}\) owing to entropic costs of confinement, crowding, and stretching. Our results pave the path to materials design informed by the choice of molecular-scale parameters.
Phys. Rev. Lett. 134, 058202 (2025)
Adhesion, Biomimetic & bio-inspired materials, Elastic deformation, Self-assembly, Thermodynamics
Physical Review X
Hybrid Josephson Rhombus: A Superconducting Element with Tailored Current-Phase Relation
Research article | Critical current | 2025-02-04 05:00 EST
L. Banszerus, C. W. Andersson, W. Marshall, T. Lindemann, M. J. Manfra, C. M. Marcus, and S. Vaitiekėnas
A circuit containing four superconducting devices called Josephson junctions can be finely tuned for various technological applications.
Phys. Rev. X 15, 011021 (2025)
Critical current, Josephson effect, Josephson junctions, Semiconductors, Superconducting devices, Superconductors, Resistivity measurements
arXiv
A neutral-atom Hubbard quantum simulator in the cryogenic regime
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-04 20:00 EST
Muqing Xu, Lev Haldar Kendrick, Anant Kale, Youqi Gang, Chunhan Feng, Shiwei Zhang, Aaron W. Young, Martin Lebrat, Markus Greiner
Ultracold fermionic atoms in optical lattices offer pristine realizations of Hubbard models, which are fundamental to modern condensed matter physics and the study of strongly-correlated quantum materials. Despite significant advancements, the accessible temperatures in these optical lattice material analogs are still too high to address many open problems beyond the reach of current numerical techniques. Here, we demonstrate a several-fold reduction in temperature, bringing large-scale quantum simulations of the Hubbard model into an entirely new regime. This is accomplished by transforming a low entropy product state into strongly-correlated states of interest via dynamic control of the model parameters, which is extremely challenging to simulate classically and so explored using the quantum simulator itself. At half filling, the long-range antiferromagnetic order is close to saturated, leading to a temperature of \(T/t=0.05_{-0.05}^{0.06}\) based on comparisons to numerically exact simulations. Doped away from half-filling no unbiased numerical simulation is available. Importantly, we are able to use quantum simulation to identify a new pathway for achieving similarly low temperatures with doping. This is confirmed by comparing short-range spin correlations to state-of-the-art, but approximate, constrained-path auxiliary field quantum Monte Carlo simulations. Compared to the cuprates, the reported temperatures correspond to a reduction from far above to significantly below room temperature, where physics such as the pseudogap and stripe phases may be expected. Our work opens the door to quantum simulations that solve open questions in material science, develop synergies with numerical methods and theoretical studies, and lead to discoveries of new physics.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
7+20 pages, 5+9 figures, comments welcome
Disordered Weyl semimetal as an array of coupled Hubbard chains
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
We demonstrate that a disordered magnetic Weyl semimetal may be mapped onto a two-dimensional array of coupled replicated Hubbard chains, where the Hubbard \(U\) is directly related to the variance of the disorder potential. This is a three-dimensional generalization of a similar mapping of the two-dimensional quantum Hall plateau transition to a one-dimensional Hubbard chain. We demonstrate that this mapping leads to the conclusion that the Weyl semimetal becomes a diffusive metal with a nonzero density of states at arbitrarily weak disorder, in agreement with recent work. We also discuss the absence of localization in strongly disordered Weyl semimetals from the viewpoint of this mapping.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 2 figures
Theory of ab initio downfolding with arbitrary range electron-phonon coupling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Norm M. Tubman, Christopher J. N. Coveney, Chih-En Hsu, Andres Montoya-Castillo, Marina R. Filip, Jeffrey B. Neaton, Zhenglu Li, Vojtech Vlcek, Antonios M. Alvertis
Ab initio downfolding describes the electronic structure of materials within a low-energy subspace, often around the Fermi level. Typically starting from mean-field calculations, this framework allows for the calculation of one- and two-electron interactions, and the parametrization of a many-body Hamiltonian representing the active space of interest. The subsequent solution of such Hamiltonians can provide insights into the physics of strongly-correlated materials. While phonons can substantially screen electron-electron interactions, electron-phonon coupling has been commonly ignored within ab initio downfolding, and when considered this is done only for short-range interactions. Here we propose a theory of ab initio downfolding that accounts for all mechanisms of electron-phonon coupling on equal footing, regardless of the range of the interactions. Our practical computational implementation is readily compatible with current downfolding approaches. We apply our approach to polar materials MgO and GeTe, and we reveal the importance of both short-range and long-range electron-phonon coupling in determining the magnitude of electron-electron interactions. Our results show that in the static limit, phonons reduce the on-site repulsion between electrons by 40% for MgO, and by 79% for GeTe. Our framework also predicts that overall attractive nearest-neighbor interactions arise between electrons in GeTe, consistent with superconductivity in this material.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Semi-group influence matrices for non-equilibrium quantum impurity models
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Michael Sonner, Valentin Link, Dmitry A. Abanin
We introduce a framework for describing the real-time dynamics of quantum impurity models out of equilibrium which is based on the influence matrix approach. By replacing the dynamical map of a large fermionic quantum environment with an effective semi-group influence matrix (SGIM) which acts on a reduced auxiliary space, we overcome the limitations of previous proposals, achieving high accuracy at long evolution times. This SGIM corresponds to a uniform matrix-product state representation of the influence matrix and can be obtained by an efficient algorithm presented in this paper. We benchmark this approach by computing the spectral function of the single impurity Anderson model with high resolution. Further, the spectrum of the effective dynamical map allows us to obtain relaxation rates of the impurity towards equilibrium following a quantum quench. Finally, for a quantum impurity model with on-site two-fermion loss, we compute the spectral function and confirm the emergence of Kondo physics at large loss rates.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
6+3 pages, 4 figures
Single electron interference and capacitive edge mode coupling generates \(\Phi_0/2\) flux periodicity in Fabry-Perot interferometers in the integer quantum Hall regime
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Shuang Liang, James Nakamura, Geoffrey C. Gardner, Michael J. Manfra
Electronic Fabry-Perot interferometers operated in the quantum Hall regime facilitate study of coherent charge transport and interactions between localized charges and propagating edge modes. Experimental observations of flux periodicity \(\phi_{0}/2\), where \(\phi_0=h/e\) is the magnetic flux quantum, for interference of the outermost edge mode in the integer quantum Hall regime have been attributed to an exotic electron pairing mechanism. We present measurements of an AlGaAs/GaAs Fabry-Perot interferometer operated in the integer quantum Hall regime for filling factors \(1\leq \nu \leq 3\) that has been designed to simultaneously express measurable bulk-edge and edge-edge couplings. At integer fillings \(\nu=2\) and \(\nu=3\), we observe interference with flux periodicity \(\phi_{0}/2\) for the outermost edge mode. However, our analysis indicates that the periodicity \(\phi_0/2\) is not driven by electron pairing, but rather is the result of capacitive coupling between multiple isolated edge modes and the outer edge. In our experiment, the interfering unit of charge for the outermost edge mode at \(\nu=2\) and \(\nu=3\) was determined to be \(e^\ast=1\), where the effective charge \(e^\ast\) is normalized to the charge of a single electron. Our measurements demonstrate that the magnitude of the interfering charge can be determined in operando in a Fabry-Perot interferometer.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 4 figures
Spin dynamics in the Dirac \(U(1)\) spin liquid YbZn\(_2\)GaO\(_5\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Hank C. H. Wu, Francis L. Pratt, Benjamin M. Huddart, Dipranjan Chatterjee, Paul A. Goddard, John Singleton, D. Prabhakaran, Stephen J. Blundell
YbZn\(_2\)GaO\(_5\) is a promising candidate for realizing a quantum spin liquid (QSL) state, particularly owing to its lack of significant site disorder. Pulsed-field magnetometry at 0.5 K shows magnetization saturating near 15 T, with a corrected saturation moment of 2.1(1) \(\mu_\mathrm{B}\) after subtracting the van Vleck contribution. Our zero-field \(\mu\)SR measurements down to milliKelvin temperatures provide evidence for a dynamic ground state and the absence of magnetic order. To probe fluctuations in the local magnetic field at the muon site, we performed longitudinal field \(\mu\)SR experiments. These results provide evidence for spin dynamics with a field dependence that is consistent with a U1A01 Dirac QSL as a plausible description of the ground state.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 7 figures
Electrically induced negative differential resistance states mediated by oxygen octahedra coupling in manganites for neuronaldynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Azminul Jaman, Lorenzo Fratino, Majid Ahmadi, Rodolfo Rocco, Bart J. Kooi, Marcelo Rozenberg, Tamalika Banerjee
The precipitous rise of consumer network applications reiterates the urgency to redefine computing hardware with low power footprint. Neuromorphic computing utilizing correlated oxides offers an energy-efficient solution. By designing anisotropic functional properties in LSMO on a twinned LAO substrate and driving it out of thermodynamic equilibrium, we demonstrate two distinct negative differential resistance states in such volatile memristors. These were harnessed to exhibit oscillatory dynamics in LSMO at different frequencies and an artificial neuron with leaky integrate-and-fire dynamics. A material based modelling incorporating bond angle distortions in neighboring perovskites and capturing the inhomogeneity of domain distribution and propagation explains both the NDR regimes. Our findings establish LSMO as an important material for neuromorphic computing hardware.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
The electrostatic charge on a falling water drop
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-04 20:00 EST
Schuyler Arn, Pablo Illing, Joshua Mendez Harper, Justin C. Burton
Fluid triboelectrification, also known as flow electrification, remains an under-explored yet ubiquitous phenomenon with potential applications in various fields, from material science to planetary evolution. Building upon previous efforts to position water within the triboelectric series, we investigate the charge on individual, millimetric water drops falling through air. Our experiments measured the charge and mass of each drop using a Faraday cup mounted on a mass balance, and connected to an electrometer. For pure water in a glass syringe with a grounded metal tip, we find the charge per drop (\(\Delta q/\Delta m\)) was approximately -5 pC/g to -1 pC/g. This was independent of the release height of the drop, tip diameter and length, tip cleaning preparation, and whether the experiment was shielded with a Faraday cage. Biasing the tip to different voltages allowed for linear control of the drop charge, and the results were consistent with known electrochemical effects, namely the Volta potential expected between most metals and bulk water (\(\approx\) -0.5 V). Introducing insulating plastic materials into the experiment (from the syringe body or tip) imparted large amounts of charge on the drops with apparent stochastic charge evolution. Together these results show that the flow electrification of water is more complex than previously reported, and is driven by various, material-dependent electrostatic processes.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
9 pages, 6 figures
Spin-reorientation driven topological Hall effect in Fe4GeTe2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Alapan Bera, Soumik Mukhopadhyay
Iron-based van der Waals (vdW) ferromagnets with relatively high ordering temperatures are a current research focus due to their significance in fundamental physics and potential applications in spintronics. Competing magnetic interactions and anisotropies can give rise to nontrivial spin textures in these materials, resulting in novel topological features. Fe4GeTe2 (F4GT) is a nearly room-temperature vdW ferromagnet, well known for hosting a spin-reorientation transition (SRT) arising from the interplay of perpendicular magnetic anisotropy (PMA) and shape anisotropy. In this work, we investigate the angle-dependent magneto-transport properties of F4GT single crystals. We report a large topological Hall effect (THE) in a multi-layer F4GT originating from the SRT-driven non-coplanar spin textures. The THE appears at the in-plane orientation of the external magnetic field and persists over a wide range of temperatures around SRT. Additionally, we find a thickness-sensitive THE signal for the c axis orientation of the magnetic field at a low-temperature regime which is associated with a reentrant Lifshitz transition.
Materials Science (cond-mat.mtrl-sci)
Waveguide Excitation and Spin Pumping of Chirally Coupled Quantum Dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Savvas Germanis, Xuchao Chen, René Dost, Dominic J. Hallett, Edmund Clarke, Pallavi K. Patil, Maurice S. Skolnick, Luke R. Wilson, Hamidreza Siampour, A. Mark Fox
We report on an integrated semiconductor chip where a single quantum dot (QD) is excited in-plane via a photonic-crystal waveguide through its nearest p-shell optical transition. The chirality of the waveguide mode is exploited to achieve both directional absorption and directional emission, resulting in a substantial enhancement in directional contrast, as measured for the Zeeman components of the waveguide-coupled QD. This remote excitation scheme enables high directionality (greater than or equal to 0.95) across approximately 56% of the waveguide area, with significant overlap with the Purcell-enhanced region, where the electric field intensity profile is near its peak. In contrast, local excitation methods using an out-of-plane excitation beam focused directly over the area of the QD achieve only approximately 25% overlap. This enhancement increases the likelihood of locating Purcell-enhanced QDs in regions that support high directionality, enabling the experimental demonstration of a six-fold enhancement in the decay rate of a QD with greater than 90% directionality. The remote p-shell excitation protocol establishes a new benchmark for waveguide quantum optics in terms of the combination of Purcell enhancement and high directionality, thereby paving the way for on-chip excitation of spin-based solid-state quantum technologies in regimes of high beta-factor.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Optics (physics.optics), Quantum Physics (quant-ph)
11 pages, 4 figures
Proposal for Spin-Superfluid Quantum Interference Device
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Yanyan Zhu, Eric Kleinherbers, Leonid Levitov, Yaroslav Tserkovnyak
In easy-plane magnets, the spin-superfluid phase was predicted to facilitate coherent spin transport. So far, experimental evidence remains elusive. In this letter, we propose an indirect way to sense this effect via the spin-superfluid quantum interference device (spin SQUID) -- inspired by its superconducting counterpart (rf SQUID). The spin SQUID is constructed as a quasi-one-dimensional (1D) magnetic ring with a single Josephson weak link, functioning as an isolated device with a microwave response. The spin current is controlled by an in-plane electric field through Dzyaloshinskii-Moriya interaction. This interaction can be interpreted as a gauge field that couples to the spin supercurrent through the Aharonov-Casher effect. By investigating the static and dynamic properties of the device, we show that the spin current and the harmonic frequencies of the spin superfluid are periodic with respect to the accumulated Aharonov-Casher phase and are, therefore, sensitive to the radial electric flux through the ring in units of the electric flux quantum, suggesting a potential electric-field sensing functionality. For readout, we propose to apply spectroscopic analysis to detect the frequency of the harmonic modes.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
6 pages, 4 figures
Stress Accommodation in Nanoscale Dolan Bridges Designed for Superconducting Qubits
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-04 20:00 EST
Sueli Skinner-Ramos, Matthew L. Freeman, Douglas Pete, Rupert M. Lewis, Matthew Eichenfield, C. Thomas Harris
Josephson junctions are the principal circuit element in numerous superconducting quantum information devices and can be readily integrated into large-scale electronics. However, device integration at the wafer scale necessarily depends on having a reliable, high-fidelity, and high-yield fabrication method for creating Josephson junctions. When creating Al/AlOx based superconducting qubits, the standard Josephson junction fabrication method relies on a sub-micron suspended resist bridge, known as a Dolan bridge, which tends to be particularly fragile and can often times fracture during the resist development process, ultimately resulting in device failure. In this work, we demonstrate a unique Josephson junction lithography mask design that incorporates stress-relief channels. Our simulation results show that the addition of stress-relief channels reduces the lateral stress in the Dolan bridge by more than 70% for all the bridge geometries investigated. In practice, our novel mask design significantly increased the survivability of the bridge during device processing, resulting in 100% yield for over 100 Josephson junctions fabricated.
Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
A combined statistical mechanical and ab initio approach to understanding H2O/CO2 co-adsorption in mmen-Mg2(dobpdc)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Jonathan R. Owens, Bojun Feng, Jie Liu, David Moore
We study the effects of H2O on CO2 adsorption in an amine-appended variant of the metal-organic framework Mg2(dobpdc), which is known to exhibit chaining behavior that presents in a step-shaped adsorption isotherm. We first show how the presence of different levels of local H2O affects this chaining behavior and the energetics of CO2 adsorption, based on a series of ab initio calculations, giving insight into the atomic-scale environment. In particular, we predict a novel adsorbed configuration, in which H2O and CO2 intertwine to make a braided chain down the MOF pore. We then show how an existing lattice model can be adapted to incorporate the effect of water, and predict the CO2 isotherms for the various water levels, observing a sharp shift the uptake at low partial pressures. In addition to the physical further work on this and related materials.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
6 pages, 4 figures, letter
Aspects of the normal state resistivity of cuprate superconductors Bi2201 and Tl2201
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Samantha Shears, Michael Arciniaga, B Sriram Shastry
Planar normal state resistivity data from two families of hole doped single layer cuprate superconductors \(Bi2201\) (Bi\(_2\)Sr\(_2\)CuO\(_{6+x}\)) and \(Tl2201\) (Tl\(_2\)Ba\(_2\)CuO\(_{6+x}\)) are calculated using the extremely correlated Fermi liquid theory (ECFL). This theory was recently employed for understanding the three families of single layer cuprate superconductors LSCO, BSLCO and NCCO. Adding these two systems accounts for essentially all single layer compounds where data is available for a range of densities and temperatures. The added case of \(Bi2201\) is of particular interest since it was the original system where the almost linear in temperature resistivity was reported in 1990, and has been followed up by a systematic doping analysis only recently in 2022. The \(Tl2201\) system has two distinct set of band parameters that fit the same Fermi surface, providing new challenges and insights into the ECFL theory.
Strongly Correlated Electrons (cond-mat.str-el)
Magnetism from multiparticle ring exchange in moir'e Wigner crystals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
We investigate the multiparticle ring exchange couplings of the two-dimensional triangular Wigner crystal in external commensurate triangular and honeycomb potentials, using a semiclassical approach valid in the regime where Coulomb interactions dominate over electronic kinetic energy. In this limit, increasing the strength of the potential drives a transition from a ferromagnet to a \(120^\circ\) Néel antiferromagnet for both external potential types. In the triangular case, we find that the transition occurs already for a weak potential, whereas in the honeycomb case, it occurs when the potential is nearly two orders of magnitude larger. Our results are relevant to the magnetism of generalized Wigner crystal phases observed at certain rational fillings of the moiré superlattice in transition-metal dichalcogenide heterobilayers.
Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 6 figures
First-principle study of surface structure estimation in \(L1_0\)-FePd(001)/graphene heterojunction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Ryusuke Endo, Naohiro Matsumoto, Samuel Vergara, Masaki Kobayashi, Hikari Shinya, Hiroshi Naganuma, Tomoya Ono, Mitsuharu Uemoto
In this study, we present a theoretical and computational investigation of the atomic-scale structure of the heterointerface formed between the (001) surface of \(L1_0\)-ordered iron palladium (FePd) alloy and graphene (Gr), namely, \(L1_0\)-FePd(001)/Gr. Using the density functional theory (DFT) calculations, we demonstrate that the topmost surface layer consisting of Pd (Pd-terminated surface) becomes more energetically stable than Fe, and Pd-terminated surfaces are not conducive to Gr adsorption. On the other hand, under oxygen atmosphere conditions, our calculation suggests the presence of Fe-terminated surfaces with Gr-covered structures reproducing recent experimental observations; besides, the presence of Fe-O bonds by the surface oxidization is also consistent with X-ray photoelectron spectroscopy. These findings are crucial for understanding the fabrication processes of interfaces in Fe-based \(L1_0\) alloy materials.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
21 pages, 8 figures
Efficient calculation of phonon dynamics through a low-rank solution of the Boltzmann equation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Nikhil Malviya, Navaneetha K. Ravichandran
Exotic nondiffusive heat transfer regimes such as the second sound, where heat propagates as a damped wave at speeds comparable to those of mechanical disturbances, often occur at cryogenic temperatures (T) and nanosecond timescales in semiconductors. First-principles prediction of such rapid, low-T phonon dynamics requires finely-resolved temporal tracking of large, dense, and coupled linear phonon dynamical systems arising from the governing linearized Peierls-Boltzmann equation (LPBE). Here, we uncover a rigorous low-rank representation of these linear dynamical systems, derived from the spectral properties of the phonon collision matrix, that accelerates the first-principles prediction of phonon dynamics by a factor of over a million without compromising on the computational accuracy. By employing this low-rank representation of the LPBE, we predict strong amplification of the wave-like second sound regime upon isotopic enrichment in diamond - a finding that would have otherwise been computationally intractable using the conventional brute-force approaches. Our framework enables a rapid and accurate discovery of the conditions under which wave-like heat flow can be realized in common semiconductors.
Materials Science (cond-mat.mtrl-sci)
Momentum distribution of He-3 in one dimension
New Submission | Other Condensed Matter (cond-mat.other) | 2025-02-04 20:00 EST
The one-particle density matrix of a one-dimensional system of fermions featuring a hard-core repulsive interaction at short distances can be computed (numerically) exactly by means of the continuous-space Worm Algorithm, without any sign instability. We present here results for this quantity, and the related momentum distribution, for a He-3 fluid. It is shown that effects of quantum statistics are observable in both the fully polarized and in the unpolarized system, with only a relatively small suppression in the latter case.
Other Condensed Matter (cond-mat.other)
Five pages, five figures in color
A Simple and General Equation for Matrix Product Unitary Generation
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Matrix Product Unitaries (MPUs) have emerged as essential tools for representing locality-preserving 1D unitary operators, with direct applications to quantum cellular automata and quantum phases of matter. A key challenge in the study of MPUs is determining when a given local tensor generates an MPU, a task previously addressed through fixed-point conditions and canonical forms, which can be cumbersome to evaluate for an arbitrary tensor. In this work, we establish a simple and efficient necessary and sufficient condition for a tensor \(M\) to generate an MPU of size \(N\), given by \(\operatorname{Tr}(\mathbb{E}_M^N) = \operatorname{Tr}(\mathbb{E}_T^N) = 1\), where \(\mathbb{E}_M\) and \(\mathbb{E}_T\) are the transfer matrices of \(M\) and \(T = MM^\dagger\). This condition provides a unified framework for characterizing all uniform MPUs and significantly simplifies their evaluation. Furthermore, we show that locality preservation naturally arises when the MPU is generated for all system sizes. Our results offer new insights into the structure of MPUs, highlighting connections between unitary evolution, transfer matrices, and locality-preserving behavior, with potential extensions to higher-dimensions.
Strongly Correlated Electrons (cond-mat.str-el), Mathematical Physics (math-ph)
First-principles study of dielectric properties of ferroelectric perovskite oxides with on-site and inter-site Hubbard interactions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Min Chul Choi, Wooil Yang, Young-Woo Son, Se Young Park
We study the atomic and electronic structures of ferroelectric perovskite oxides, BaTiO\(_3\), LiNbO\(_3\), and PbTiO\(_3\) using ab initio extended Hubbard functionals in which the on-site and inter-site Hubbard interactions are determined self-consistently, adapted from the pseudohybrid density functional proposed by Agapito-Curtarolo-Buongiorno Nardelli. Band structures, ferroelectric distortions, polarization, Born effective charges, and switching barriers are calculated with extended Hubbard functionals, that are compared with those using local density approximation (LDA), generalized gradient approximation (GGA), and Hybrid (HSE06) functionals. The properties of all three compounds calculated by extended Hubbard functionals are in good agreement with experimental data. We find a substantial increase in band gaps due to the inter-site Coulomb interactions, which show better agreement with \(GW\) results compared to those from LDA and GGA functionals. The crucial role of the inter-site Coulomb interactions in restoring the suppressed polar instability, which is computed when only the on-site Hubbard interactions are considered, is also highlighted. Overall, we find that the properties calculated using our extended Hubbard functionals exhibit trends similar to those obtained with the HSE06 functional, while reducing computational costs by over an order of magnitude. Thus, we propose that the current method is well-suited for high-throughput calculations for perovskite oxides, offering significantly improved accuracy in computing band gap and other related physical properties such as the shift current photovoltaic effect and band alignments in ferroelectric heterostructures.
Materials Science (cond-mat.mtrl-sci)
13 pages, 5 figures
Cu Intercalation-stabilized 1T'-MoS2 with Electrical Insulating Behavior
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Huiyu Nong, Junyang Tan, Yujie Sun, Rongjie Zhang, Yue Gu, Qiang Wei, Jingwei Wang, Yunhao Zhang, Qinke Wu, Xiaolong Zou, Bilu Liu
The intercalated two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted much attention for their designable structure and novel properties. Among this family, host materials with low symmetry such as 1T' phase TMDCs are particularly interesting because of their potentials in inducing unconventional phenomena. However, such systems typically have low quality and poor stability, hindering further study in the structure-property relationship and applications. In this work, we intercalated Cu into 1T' MoS2 with high crystallinity and high thermal stability up to ~300 oC. We identified the distribution and arrangement of Cu intercalators for the first time, and the results show that Cu occupy partial of the tetrahedral interstices aligned with Mo sites. The obtained Cu-1T' MoS2 exhibits an insulating hopping transport behavior with a large temperature coefficient of resistance reaching -4 ~ -2 % K-1. This work broadens the artificial intercalated structure library and promotes structure design and property modulation of layered materials.
Materials Science (cond-mat.mtrl-sci)
20 pages, 4 figures. Accepted
Journal of the American Chemical Society, 2025
Exact solution of the three-state generalized double-chain Potts model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-04 20:00 EST
Pavel Khrapov, Grigory Skvortsov
An exact analytical solution of generalized three-state double-chain Potts model with multi-spin interactions which are invariant under cyclic shift of all spin values is obtained. The partition function in a finite cyclically closed strip of length L, as well as the free energy, internal energy, entropy and heat capacity in thermodynamic limit are calculated using transfer-matrix method. Partial magnetization and susceptibility are suggested as the generalization of usual physical characteristics of a system. Proposed model can be interpreted as a generalized version of standard Potts model (which has Hamiltonian expressed through Kronecker symbols) and clock model (with Hamiltonian expressed through cosines). Considering a particular example of the model with plenty of forces, model's ground states are found, figures of its thermodynamic characteristics and discussed their behaviour at low temperature are shown.
Statistical Mechanics (cond-mat.stat-mech)
18 pages, 11 figures
Orbital torques and orbital pumping in two-dimensional rare-earth dichalcogenides
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Mahmoud Zeer, Dongwook Go, Mathias Kläui, Wulf Wulfhekel, Stefan Blügel, Yuriy Mokrousov
The design of spin-orbit torque properties in two-dimensional (2D) materials presents one of the challenges of modern spintronics. In this context, 2D layers involving rare-earth ions \(-\) which give rise to robust magnetism, exhibit pronounced orbital polarization of the states, and carry strong spin-orbit interaction \(-\) hold particular promise. Here, we investigate ferromagnetic Janus H-phase monolayers of 4\(f\)-Eu rare-earth dichalcogenides EuSP, EuSSe, and EuSCl using first-principles calculations. We demonstrate that all compounds exhibit significant spin-orbit torques which originate predominantly in the colossal current-induced orbital response on the Eu \(f\)-electrons. Moreover, we demonstrate that the corresponding orbital torques can be used to drive strong in-plane currents of orbital angular momentum with non-trivial direction of orbital polarization. Our findings promote \(f\)-orbital-based 2D materials as a promising platform for in-plane orbital pumping and spin-orbit torque applications, and motivate further research on educated design of orbital properties for orbitronics with 2D materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
13 pages, 4 figures
A spatially varying differential equation for multi-patch pandemic propagation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
We develop an extension of the Susceptible-Infected-Recovery (SIR) model to account for spatial variations in population as well as infection and recovery parameters. The equations are derived by taking the continuum limit of discrete interacting patches, and results in a diffusion equation with some nonlinear terms. The resulting population dynamics can be reinterpreted as a nonlinear heat flow equation where the temperature vector captures both infected and recovered populations across multiple patches.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)
Revealing Spin and Spatial Symmetry Decoupling: New Insights into Magnetic Systems with Dzyaloshinskii-Moriya Interaction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Yuxuan Mu, Di Wang, Xiangang Wan
It is widely accepted that spin-orbit coupling (SOC) generally locks spin and spatial degrees of freedom, as a result, the spin, despite being an axial vector, is fixed and cannot rotate independently, and the magnetic system should be described by magnetic space groups (MSGs). While as a new type of group, spin space groups (SSGs) have been introduced to approximately describe the symmetry of magnetic systems with negligible SOC, and received significant attention recently. In this work, we prove that in two cases of coplanar spin configurations, there are spin-only operations that strictly hold even with considerable Dzyaloshinskii-Moriya interaction (DMI), and the symmetry of their spin models could be described by the spin-coplanar SSG. In addition, we also find that for spin-collinear cases, regardless the strength of DMI, the magnon systems within the framework of linear spin wave theory (LSWT) also preserve the decoupled spin and spatial rotations, but the symmetry does not belong to the conventional definitions of collinear spin groups. Finally, we discuss the potential realization of these novel symmetries for magnetic candidate materials in rod, layer, and three-dimensional (3D) space groups. Our work extends the applicability of SSGs to magnetic materials with heavy elements, and provides new avenues for exploring novel physical phenomena in magnon topology and transport.
Materials Science (cond-mat.mtrl-sci)
Synthesis and Characterization of Two-dimensional Cs2AgInCl6 Nanoplates as Building Blocks for Functional Surfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Sasha Khalfin, Noam Veber, Saar Shaek, Betty Shamaev, Shai Levy, Shaked Dror, Yaron Kauffmann, Maria Koifman Khristosov, Yehonadav Bekenstein
Breaking crystal symmetry is essential for engineering emissive double perovskite metal halides. The goal is to overcome their inherently indirect and disallowed optical transitions. Here we introduce a synthesis for silver - Cs2AgInCl6 two-dimensional hybrid nanoplate products that break the symmetry in two ways, their shape and their heterointerfaces. A comparative study between Cs2AgInCl6 nanocubes and nanoplates is presented to emphasize the difference in optical properties. A modified colloidal synthesis for Cs2AgInCl6 yields high-quality nanoplates with small lateral dimensions very different from the symmetric cubes. Each nanoplate is decorated with metallic silver nanoparticles, with diameters on the scale of the thickness of the perovskite nanoplate, forming significant heterointerfaces that further break symmetry. The Cs2AgInCl6 two-dimensional nanoplates also demonstrate facile transformation into larger crystalline nanosheets once deposited on substrates. We thus highlight those nanoplates as potential building blocks for assemblies of functional surfaces.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
The authors Sasha Khalfin and Noam Veber contributed equally
An Inorganic Liquid Crystalline Dispersion with 2D Ferroelectric Moieties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Ziyang Huang, Zehao Zhang, Rongjie Zhang, Baofu Ding, Liu Yang, Keyou Wu, Youan Xu, Gaokuo Zhong, Chuanlai Ren, Jiarong Liu, Yugan Hao, Menghao Wu, Teng Ma, Bilu Liu
Electro-optical effect based liquid crystal devices have been extensively used in optical modulation techniques, in which the Kerr coefficient reflects the sensitivity of the liquid crystals and determines the strength of the device operational electric field. The Peterlin-Stuart theory and the O'Konski model jointly indicate that a giant Kerr coefficient could be obtained in a material with both a large geometrical anisotropy and an intrinsic polarization, but such a material is not yet reported. Here we reveal a ferroelectric effect in a monolayer two-dimensional mineral vermiculite. A large geometrical anisotropy factor and a large inherent electric dipole together raise the record value of Kerr coefficient by an order of magnitude, till \(3.0\times 10^{-4}\) m V\(^{-2}\). This finding enables an ultra-low operational electric field of \(10^2\)-\(10^4\) V m\(^{-1}\) and the fabrication of electro-optical devices with an inch-level electrode separation, which is not practical previously. Because of its high ultraviolet stability (decay <1% under ultraviolet exposure of 1000 hours), large-scale, and energy-efficiency, prototypical displayable billboards have been fabricated for outdoor interactive scenes. The work provides new insights for both liquid crystal optics and two-dimensional ferroelectrics.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
26 pages, 3 figures. Published in National Science Review 2024, 11 (5), nwae108
National Science Review, 2024
Quantitative relations between nearest-neighbor persistence and slow heterogeneous dynamics in supercooled liquids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-04 20:00 EST
Katrianna S. Sarkar, Kevin A. Interiano-Alberto, Jack F. Douglas, Robert S. Hoy
Using molecular dynamics simulations of a binary Lennard-Jones model of glass-forming liquids, we examine how the decay of the normalized neighbor-persistence function \(C_{\rm B}(t)\), which decays from unity at short times to zero at long times as particles lose the neighbors that were present in their original first coordination shell, compares with those of other, more conventionally utilized relaxation metrics. In the strongly-non-Arrhenius temperature regime below the onset temperature \(T_{\rm A}\), we find that \(C_{\rm B}(t)\) can be described using the same stretched-exponential functional form that is often utilized to fit the self-intermediate scattering function \(S(q, t)\) of glass-forming liquids in this regime. The ratio of the bond lifetime \(\tau_{\rm bond}\) associated with the terminal decay of \(C_{\rm B}(t)\) to the \(\alpha\)-relaxation time \(\tau_\alpha\) varies appreciably and non-monotonically with \(T\), peaking at \(\tau_{\rm bond}/\tau_\alpha \simeq 45\) at \(T \simeq T_{\rm x}\), where \(T_{\rm x}\) is a crossover temperature separating the high- and low-temperature regimes of glass-formation. In contrast, \(\tau_{\rm bond}\) remains on the order of the overlap time \(\tau_{\rm ov}\) (the time interval over which a typical particle moves by half its diameter), and the peak time \(\tau_\chi\) for the susceptibility \(\chi_{\rm B}(t)\) associated with the spatial heterogeneity of \(C_{\rm B}(t)\) remains on the order of \(\tau_{\rm imm}\) (the characteristic lifetime of immobile-particle clusters), even as each of these quantities varies by roughly \(5\) orders of magnitude over our studied range of \(T\). Thus, we show that \(C_{\rm B}(t)\) and \(\chi_{\rm B}(t)\) provide semi-quantitative spatially-averaged measures of the slow heterogeneous dynamics associated with the persistence of immobile-particle clusters.
Soft Condensed Matter (cond-mat.soft)
Influence of transition mutations and disorder on charge localization and transfer along B-DNA sequences
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-04 20:00 EST
Pavlos Banev, Anastasia Falliera, Constantinos Simserides
We illuminate the influence of transition mutations and disorder on charge localization and transfer along B-DNA sequences. Homopolymers are the best for charge transfer (cf. Refs.~ ). Hence, we consider as flawless a homopolymer sequence and then disturb it, introducing transition mutations and disorder. We exclude the possibility of charge transfer via the backbone that will be addressed soon in another work. We employ the Tight Binding (TB) Wire model to study the influence of transition mutations and the TB Fishbone Wire model to evaluate the influence of disorder emanating either from the \(\pi\) path or from the backbone. For the TB Wire parameters, we employ the parametrization created in Ref.~, where another TB at atomic level was used, considering all valence orbitals of all atoms. We calculate the HOMO and LUMO regime eigenenergies and eigenvectors, the participation ratio (a measure of the localization of each eigenstate), the time-dependent probability to find the carrier at each site, the mean over time probability at each site, and the mean transfer rate from site to site. Transition mutations increase localization in terms of participation ratio and impede charge transfer in terms of mean probability and transfer rates, provided the TB parameters involving mutated sites are significantly modified relative to the original. Disorder leads to severe modifications of participation ratios, i.e., increase of localization. Relevant changes occur on eigenenergies, mean probabilities at each site, and transfer rates.
Soft Condensed Matter (cond-mat.soft)
22 pages, 20 figures
Vacancy-assisted superfluid drag
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-04 20:00 EST
Thomas G. Kiely, Chao Zhang, Erich J. Mueller
We study superfluid drag in the two-component, two-dimensional Bose-Hubbard model with infinitely strong repulsive interactions. We demonstrate, with a combination of analytic and numeric techniques, that the motion of holes leads to strong dissipationless coupling between currents in the two components. We show that this behavior is attributable to polaronic correlations that emerge in the presence of spin currents, and which can be observed in experiments.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 5 figures
Transition Metal-Vacancy Point Defects in Zinc Oxide as Deep-Level Spin Qubits
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Shimin Zhang, Taejoon Park, Erik Perez, Kejun Li, Xingyi Wang, Yanyong Wang, Jorge D Vega Bazantes, Ruiqi Zhang, Jianwei Sun, Kai-Mei C. Fu, Hosung Seo, Yuan Ping
Zinc oxide (ZnO) is a promising candidate for hosting point defects as spin qubits for quantum information applications, due to its wide band gap, low spin-orbit coupling, and dilute nuclear spin environment. Previously shallow impurities in ZnO were mostly proposed for spin qubit candidates, but deep-level spin defect studies in ZnO are rather sparse, which may be ideally decoupled from the host materials for stable operation. In this work, we theoretically search for deep-level point defects in ZnO with optimal physical properties suitable for optically-addressable spin qubits in the solid-state. Using first-principles calculations for the search, we have predicted the Mo vacancy defect in ZnO owning promising spin and optical properties, including spin-triplet ground state, optical transition in the visible to near-infrared range with high quantum yield, allowed intersystem crossings with a large optically-detected magnetic resonance contrast, and long spin \(T_2\) and \(T_2^\ast\). Notably, we found the Huang-Rhys factor of the defect to be around 5, which is much smaller than those at 10-30 of the most-known defects in ZnO. We also proposed a new protocol for initializing and reading spin qubits, which could be applied in other systems with forbidden longitudinal intersystem crossing. Finally, we compared the spin decoherence driven by the nuclear spin bath and by paramagnetic impurity baths. We found that the paramagnetic impurities are very effective in causing spin decoherence even with very low concentrations, implying that the spin decoherence in ZnO can be likely dominated by them even after isotopic purification.
Materials Science (cond-mat.mtrl-sci)
Anomalous nuclear spin coherence in superconducting Nb\(_3\)Sn
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-04 20:00 EST
Gan Zhai, William P. Halperin, Arneil P. Reyes, Sam Posen, Chiara Tarantini, Manish Mandal, David C. Larbalestier
We have investigated the normal and superconducting states of the technologically important compound Nb\(_3\)Sn using \(^{93}\)Nb nuclear magnetic resonance. From spin-lattice relaxation we find strong suppression of the zero-temperature superconducting order parameter by magnetic field. We have identified an anomalously large electron-nuclear exchange interaction from spin-spin relaxation measurements, an order of magnitude beyond that of the dipole-dipole interaction, and thereby sensitive to vortex dynamics and vortex pinning.
Superconductivity (cond-mat.supr-con)
Fractional vorticity, Bogomol'nyi-Prasad-Sommerfield systems and complex structures for the (generalized) spinor Gross-Pitaevskii equations
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-04 20:00 EST
The (generalized) Gross-Pitaevskii equation (GPE) for a complex scalar field in two spatial dimensions is analyzed. It is shown that there is an infinite family of self-interaction potentials which admit Bogomol'nyi-Prasad-Sommerfield (BPS) bounds together with the corresponding first-order BPS systems. For each member of this family, the solutions of the first-order BPS systems are automatically solutions of the corresponding second-order generalized GPE. The simplest topologically non-trivial solutions of these first-order BPS systems describe configurations with quantized fractional vorticity. The corresponding fraction is related to the degree of non-linearity. The case in which the self-interaction potential is of order six (namely \(|\Psi|^{6}\), which is a relevant theory both in relativistic quantum field theories in \((2+1)\) dimensions in connection with the quantum Hall effect as well as in the theory of the supersolids) is analyzed in detail. Such formalism can also be extended to the case of quantum mixtures with multi-component GPEs. The relationship between these techniques and supersymmetry will be discussed. In particular, despite several standard features, we will show that there are multi-component GPEs that are not supersymmetric (at least, not in the standard sense) and possess a BPS system of the above type.
Quantum Gases (cond-mat.quant-gas), High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), Nuclear Theory (nucl-th)
23 pages, 1 Figure
Structural Dynamics and Strong Correlations in Dynamical Quantum Optical Lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-04 20:00 EST
Adrían U. Ramírez-Barajas, Santiago F. Caballero-Benitez
When placing an ultracold atomic gas inside a cavity, the light-matter coupling is enhanced and nonlinear atomic dynamics are generated, offering a promising platform for quantum simulation of models with short- and long-range interactions. Recently, superradiant self organized phases for ultracold atomic gases inside a cavity, pumped by a blue detuned optical lattice, have been observed. Here, we explore the formation of quantum many-body phases with strongly interacting bosonic atoms inside an optical cavity, subject to transverse blue detuned pumping. We analyze the interplay between superradiant self-organization with superfluid and Mott insulator phases, without the need of including higher lying bands, as the Wannier functions are dynamically linked to the cavity light via backaction. We observe different kinds of structural phase transitions driven by the light inside the cavity and the interplay with atomic collisions. We observe the mode softening at the critical points in the quantum phase transitions which can be measured in future experiments.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Optics (physics.optics), Quantum Physics (quant-ph)
10 pages, 3 figures
Magneto-plasmonic pesponse of nickel nano-rings prepared by electroless method
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Akram Poursharif, Peyman Sahebsara, Seyyed Mahmood Monirvaghefi, Seyedeh Mehri Hamidi Mahshid Kharaziha, Masih Bagheri
Magneto-plasmonic nanostructures have emerged as promising candidates for advanced sensing applications. However, conventional fabrication methods, such as lithography and sputtering, often involve high costs and complex processes. This study introduces a novel approach for fabricating nickel nano-rings (200-600 nm in diameter) utilizing nanosphere lithography and selective electroless deposition on ITO substrates. The resulting nickel-silver-boron (Ni-Ag-B) nanoarrays exhibit uniform, durable coatings with robust covalent bonds, providing a simpler, more cost-effective alternative to traditional methods. The unique ring-shaped geometry of the nano-rings enhances plasmonic effects by concentrating the electromagnetic field, thus outperforming other nanostructures. Unlike thin films, these nano-rings demonstrate surface plasmon resonance (SPR) within the 470-614 nm range when illuminated at a 45\(^°\) incident angle. Moreover, ellipsometry parameter calculations and Magneto-Optical Kerr Effect (MOKE) measurements revealed narrow Full Width at Half Maximum (FWHM) peaks at 512 nm and 560 nm, indicating superior sensitivity for detection compared to conventional SPR and ellipsometry-SPR techniques. Finite element simulations using COMSOL provided valuable insight into the influence of magnetic fields on the electromagnetic response of the nano-rings, confirming their potential for optical communication and highly sensitive sensing technologies. This study addresses limitations in existing magneto-plasmonic systems, offering a scalable and innovative solution for the development of next-generation sensing applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
24 pages, 7 figures
Sensors and Actuators A: Physical 383, 116261 (2025)
Light-induced reorientation transition in an antiferromagnetic semiconductor
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Bryan T. Fichera, Baiqing Lv, Karna Morey, Zongqi Shen, Changmin Lee, Elizabeth Donoway, Alex Liebman-Pelaez, Anshul Kogar, Takashi Kurumaji, Martin Rodriguez-Vega, Rodrigo Humberto Aguilera del Toro, Mikel Arruabarrena, Batyr Ilyas, Tianchuang Luo, Peter Muller, Aritz Leonardo, Andres Ayuela, Gregory A. Fiete, Joseph G. Checkelsky, Joseph Orenstein, Nuh Gedik
Due to the lack of a net magnetic moment, antiferromagnets possess a unique robustness to external magnetic fields and are thus predicted to play an important role in future magnetic technologies. However, this robustness also makes them quite difficult to control, and the development of novel methods to manipulate these systems with external stimuli is a fundamental goal of antiferromagnetic spintronics. In this work, we report evidence for a metastable reorientation of the order parameter in an antiferromagnetic semiconductor triggered by an ultrafast quench of the equilibrium order via photoexcitation above the band gap. The metastable state forms less than 10 ps after the excitation pulse, and persists for longer than 150 ps before decaying to the ground state via thermal fluctuations. Importantly, this transition cannot be induced thermodynamically, and requires the system to be driven out of equilibrium. Broadly speaking, this phenomenology is ultimately the result of large magnetoelastic coupling in combination with a relatively low symmetry of the magnetic ground state. Since neither of these properties are particularly uncommon in magnetic materials, the observations presented here imply a generic path toward novel device technology enabled by ultrafast dynamics in antiferromagnets.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
41 pages, 27 figures
Hardening of Ni-O bond-stretching phonons in LaNiO\(_2\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
We demonstrate that dynamical electron correlation and fluctuating local magnetic moments are crucial for the phonon spectra of the infinite-layer nickelate superconductor, LaNiO\(_2\), using DFT plus dynamical mean-field theory (DFT+DMFT) calculations. We find significant hardening of optical Ni-O bond-stretching phonons when going from non-magnetic to paramagnetic state, and increasing Coulomb interaction will make them even harder. The electron correlation is found to be sensitive to the Ni-O bond-stretching distortions, indicating strong interplay between electron correlation and lattice. We find that the strong local electron correlation will not favor charge orders that couple to the Ni-O bond-stretching phonons, in support of the recent experiment that a \(3a_0\) charge order is absent in the infinite-layer nickelates. Our results emphasize that the effects of local magnetic fluctuations should be fully taken into account when describing the lattice dynamics of the infinite-layer nickelates without long-range magnetic orders, and also provide evidence to ascribe the kink observed in the recent angle-resolved photoemission experiment to possible strong electron coupling to the Ni-O bond-stretching phonons.
Strongly Correlated Electrons (cond-mat.str-el)
Has been accepted for a publication in PRB
Role of Dirac cones in the anisotropic properties associated with the spin-density wave state of iron pnictides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Garima Goyal, Dheeraj Kumar Singh
The origin of unusual anisotropic electronic properties in the spin-density wave state of iron pnictides has conventionally been attributed to the breaking of four-fold rotational symmetry associated with the collinear magnetic order. By using a minimal two-orbital model, we show that a significant portion of the contribution to the anisotropy may come from the Dirac cones, which are not far away from the Fermi level. We demonstrate this phenomenon by examining optical conductivity and quasiparticle interference in the Dirac-semimetallic state with spin-density wave order, and the latter can be obtained by choosing appropriate interaction parameters and orbital splitting between the \(d_{xz}\) and \(d_{yz}\) orbitals. We further extend this study to investigate the low-energy spin-wave excitations in the Dirac-semimetallic state with spin-density wave order.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 7 figures
Orbital correlations in bilayer nickelates: roles of doping and interlayer coupling
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Garima Goyal, Aastha Jain, Dheeraj Kumar Singh
We study the nature of orbital correlations present in the bilayer nickelate within a minimal two-orbital tight binding model to gain insights into their possible role in stabilizing the less-known weakly-insulating state. The latter has been observed experimentally at ambient pressure. In order to achieve this objective, we examine the static orbital susceptibilities within the random-phase approximation. Our study highlights the sensitivity of orbital correlations to various factors including the interlayer coupling, carrier concentration, band-structure details such as the orbital contents, the number of bands contributing at the Fermi level etc. We relate this sensitiveness to the modification of the Fermi surfaces as well as their orbital contents dependent on aforementioned factors.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
5 pages, 7 figures
Coulomb correlated multi-particle polarons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
The electronic and emission properties of correlated multi-particle states are studied theoretically using \({\bf k}\cdot{\bf p}\) and the configuration interaction methods on a well-known and measured GaAs/AlGaAs quantum dots as a test system. The convergence of the calculated energies and radiative lifetimes of Coulomb correlated exciton, biexciton, positive and negative trions to experimentally observed values is reached when the electron-electron and hole-hole exchange interactions are neglected. That unexpected and striking result uncovers a rich structure of multi-particle states in the studied system, which is further quantitatively compared to published measurements in the literature, obtaining astonishingly good agreement. It is proposed that in real experiments the neglected electron-electron and hole-hole exchange interactions are emitted as acoustic phonons during the radiative recombination of the ground state of complexes, leading to the observation of polaronic multi-particle states. Analysis of their energy spectra provides a direct and measurable insight into the Coulomb correlation, being interesting both on the fundamental level and as possible experimentally tunable property in a wide variety of solid-state systems, in particular associated with quantum computing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
Deep Neural Network for Phonon-Assisted Optical Spectra in Semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Qiangqiang Gu, Shishir Kumar Pandey
Phonon-assisted optical absorption in semiconductors is crucial for understanding and optimizing optoelectronic devices, yet its accurate simulation remains a significant challenge in computational materials science. We present an efficient approach that combines deep learning tight-binding (TB) and potential models to efficiently calculate the phonon-assisted optical absorption in semiconductors with \(ab\) \(initio\) accuracy. Our strategy enables efficient sampling of atomic configurations through molecular dynamics and rapid computation of electronic structure and optical properties from the TB models. We demonstrate its efficacy by calculating the temperature-dependent optical absorption spectra and band gap renormalization of Si and GaAs due to electron-phonon coupling over a temperature range of 100-400 K. Our results show excellent agreement with experimental data, capturing both indirect and direct absorption processes, including subtle features like the Urbach tail. This approach offers a powerful tool for studying complex materials with high accuracy and efficiency, paving the way for high-throughput screening of optoelectronic materials.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
5 pages, 5 figures
Effect of 2\(^\text{nd}\) harmonic current--phase relation on a behavior of a Josephson Traveling Wave Parametric Amplifier
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-04 20:00 EST
Claudio Guarcello, Carlo Barone, Giovanni Carapella, Giovanni Filatrella, Andrea Giachero, Sergio Pagano
We numerically investigate the behavior of a Josephson traveling wave parametric amplifier assuming a current-phase relation with a second--harmonic contribution. We find that varying the weight of harmonic terms in the Josephson current affects the gain profile. The analysis of gain characteristics, phase-space portraits, Poincaré sections, and Fourier spectra demonstrates that the nonsinusoidal contribution influences the operating mode and stability of the device. In particular, we identify the optimal weighting of harmonic contributions that maximizes amplification, achieving gains up to \(\sim 13\;\text{dB}\) in a device without dispersion engineering.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 3 figures
Anomalous Hall effect in highly c-plane oriented Mn\(_{3}\)Ge/Si(100) thin films grown by pulsed laser deposition
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Indraneel Sinha, Purba Dutta, Nazma Firdosh, Shreyashi Sinha, Nirmal Ganguli, Sujit Manna
Antiferromagnetic Mn\(_{3}\)Ge with a non-collinear Kagome structures present exciting prospects for exploring Berry curvature driven anomalous Hall effects (AHE). Despite substantial progress in bulk systems, the synthesis of crystalline thin films directly on silicon with a hexagonal phase presents a particular challenge unless a buffer layer is employed. In this study, we report the synthesis of single phase c-plane oriented hexagonal Mn\(_{3}\)Ge(0001) films on Si(100) using pulsed laser deposition. Under suitable growth conditions, we obtain layer-by-layer films with atomically flat surfaces and interfaces. High-resolution scanning tunneling microscopy study reveals the detail surface atomic structures, where the surface Mn atoms spontaneously arrange into a Kagome lattice. Tunneling spectroscopy (dI/dV) measurement on the atomically resolved Kagome surface show a minima in local density of states near the Fermi level, likely originated from the Weyl crossings near K points. Despite the nearly vanishing magnetization, magnetotransport measurements in 30 nm \(Mn_{3}\)Ge(0001) films show anomalous Hall resistivity up to 0.41 (\(\mu\Omega\cdot\text{cm}\)) at 2 K. Our calculations shed further light on the existence of topological features and the band structures in Mn\(_{3+x}\)Ge\(_{1-x}\) with increasing Mn concentration \(x\). The anomalous Hall response at room temperature in crystalline Mn\(_{3}\)Ge films on Si(100) offer promising potential for the development of antiferromagnetic spintronics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
12 Pages, 6 figures
Magnetic-Field Dependence of Paramagnetic Properties Investigated by 63/65Cu-NMR on the Yb Zigzag-Chain Semiconductor YbCuS2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Fumiya Hori, Shunsaku Kitagawa, Kenji Ishida, Yudai Ohmagari, Takahiro Onimaru
To investigate the paramagnetic properties of YbCuS2 under magnetic fields, we have performed the 63/65Cu-nuclear magnetic resonance (NMR) measurements. The NMR spectra can be reproduced by the simulations of the three-dimensional powder pattern and the additional two-dimensional powder pattern, indicating the partial sample orientation due to the anisotropy of the magnetic properties. These simulations suggest that the ac plane is the easy plane in YbCuS2. The Knight shift K is proportional to the bulk magnetic susceptibility and field-independent. The broad maximum of the nuclear spin-lattice relaxation rate 1/T1 at Tmax ~ 50 K (50 K anomaly) observed at zero magnetic field is quickly suppressed by the magnetic fields. This indicates that the 50 K anomaly is field-dependent. Furthermore, an anomalous enhancement of 1/T1 at low temperatures was observed above 3 T. This field seemingly corresponds to the magnetic field at which a field-induced phase transition occurs below the antiferromagnetic transition temperature TN ~ 1 K. The changes in 1/T1 observed in the paramagnetic state suggest the presence of the complex quantum phenomena under magnetic fields in YbCuS2.
Strongly Correlated Electrons (cond-mat.str-el)
J. Phys. Soc. Jpn. 94, 024706 (2025)
Doped resonating valence bond states: How robust are the spin ice phases in 3D Rydberg arrays
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-04 20:00 EST
Jingya Wang, Changle Liu, Yan-Cheng Wang, Zheng Yan
Rydberg blockade effect provides a convenient platform for simulating locally constrained many-body systems, such as quantum dimer models and quantum loop models, especially their novel phases like topological orders and gapless quantum spin ice (QSI) phases. To discuss the possible phase diagram containing different QSIs in 3D Rydberg arrays, here, we have constructed an extended Rokhsar-Kivelson (RK) Hamiltonian with equal-weight-superposition ground state in different fillings at the RK point. Therefore, both the perfect QSIs with fixed local dimer filling and their monomer-doped states can be simulated directly by Monte Carlo sampling. Using single mode approximation, the excitations of dimers and monomers have also been explored in different fillings. We find that, in the thermodynamical limit, even doping a small amount of monomers can disrupt the topological structure and lead to the existence of off-diagonal long-range order. However, in a finite size (as in cold-atom experiment), the property of QSI will be kept in a certain region like a crossover after doping. The phase diagram containing different QSIs and off-diagonal order phases is proposed.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Nonclassical dynamics of N'eel vector and magnetization accompanied by THz and high-harmonic radiation from ultrafast-light-driven NiO antiferromagnet insulator
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Federico Garcia-gaitan, Adrian E Feiguin, Branislav K Nikolic
Ultrafast-light-driven strongly correlated antiferromagnetic insulators, such as prototypical NiO with large energy gap 4 eV, have recently attracted experimental attention using either above-gap [K. Gillmeister et al., Nat. Commun. 11, 4095 (2020)] or subgap [H. Qiu et al., Nat. Phys. 17, 388 (2021)] energy photons that are of fundamental interest in far-from-equilibrium quantum matter or spintronic applications, respectively. In the latter context, emission of THz radiation is also observed from NiO/Pt bilayers, where heavy metal (HM) Pt introduces strong spin-orbit coupling (SOC). However, microscopic mechanisms of such emission remain obscure because spintronic THz emitters have been amply studied using FM/HM (FM-ferromagnetic metal of conventional type) bilayers, where ultrafast demagnetization takes place and is directly related to THz emission. Conversely, in NiO total magnetization is zero prior to the fs laser pulse (fsLP) application. Here we employ the two-orbital Hubbard-Hund-Heisenberg model and study, via numerically exact nonequilibrium quantum many-body methods, the dynamics of its Neel vector and nonequilibrium magnetization. Additionally, we compute electromagnetic radiation by both time-dependent magnetization and local charge currents arising in either plain NiO or NiO with proximity SOC introduced by HM layer. Our analysis reveals nonclassical dynamics of Neel vector and nonequilibrium magnetization, changing only in length while not rotating, where the former is substantially reduced only in the case above-gap fsLP. In the plain NiO case, THz radiation of interest to applications is insignificant, but adding SOC enhances both current and magnetic dipole contributions to it. Above THz range, we find integer high-harmonic generation, as well as unusual noninteger harmonics for above-gap fsLP pump.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 4 figures, 96 references
Interplay of correlations and Majorana mode from local solution perspective
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Jan Barański, Magdalena Barańska, Tomasz Zienkiewicz, Tadeusz Domański
We study the quasiparticle spectrum of a hybrid system, comprising a correlated (Anderson-type) quantum dot coupled to a topological superconducting nanowire hosting the Majorana boundarymodes. From the exact solution of the low-energy effective Hamiltonian, we uncover a subtle interplay between Coulomb repulsion and the Majorana mode. Our analytical expressions show that the spectral weight of the leaking Majorana mode is sensitive to both the quantum dot energy level and the repulsive potential. We compare our results with estimations by L.S. Ricco et al. Phys. Rev. B 99, 155159 (2019) obtained for the same hybrid structure using the Hubbard-type decoupling scheme, and analytically quantify the spectral weight of the zero-energy (topological) mode coexisting with the finite-energy (trivial) states of the quantum dot. We also show that empirical verification of these spectral weights could be feasible through spin-polarized Andreev spectroscopy.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
J. Phys.: Condens. Matter 37 055302 (2025)
Influence of pressure on properties of multi-gap type-I superconductor BeAu
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-04 20:00 EST
Rustem Khasanov, Riccardo Vocaturo, Oleg Janson, Andreas Koitzsch, Ritu Gupta, Debarchan Das, Nicola P.M. Casati, Maia G. Vergniory, Jeroen van den Brink, Eteri Svanidze
We report on studies of the superconducting and normal state properties of the noncentrosymmetric superconductor BeAu under hydrostatic pressure conditions. The room-temperature equation of state (EOS) reveals the values of the bulk modulus (\(B_0\)) and its first derivative (\(B^\prime_0\)) at ambient pressure to be \(B_0 \simeq 132\)~GPa and \(B^\prime_0 \simeq 30\), respectively. Up to the highest pressures studied (\(p \simeq 2.2\)~GPa), BeAu remains a multi-gap type-I superconductor. The analysis of \(B_{\rm c}(T, p)\) data within the self-consistent two-gap approach suggests the presence of two superconducting energy gaps, with the gap-to-\(T_{\rm c}\) ratios \(\Delta_1/k_{\rm B}T_{\rm c} \sim 2.3\) and \(\Delta_2/k_{\rm B}T_{\rm c} \sim 1.1\) for the larger and smaller gaps, respectively [\(\Delta = \Delta(0)\) is the zero-temperature value of the gap and \(k_{\rm B}\) is the Boltzmann constant]. With increasing pressure, \(\Delta_1/k_{\rm B}T_{\rm c}\) increases while \(\Delta_2/k_{\rm B}T_{\rm c}\) decreases, suggesting that pressure enhances (weakens) the coupling strength between the superconducting carriers within the bands where the larger (smaller) superconducting energy gap has opened. The superconducting transition temperature \(T_{\rm c}\), and the zero-temperature value of the thermodynamic critical field \(B_{\rm c}(0)\) decrease with increasing pressure, with the rates of \({\rm d}T_{\rm c}/{\rm d}p \simeq -0.195\)~K/GPa, and \({\rm d}B_{\rm c}(0)/{\rm d}p = -2.65(1)\)~mT/GPa, respectively. The measured \(B_{\rm c}(0)\) values plotted as a function of \(T_{\rm c}\) follow an empirical scaling relation established for conventional type-I superconductors.
Superconductivity (cond-mat.supr-con)
Tuning the surface energy of fluorinated diamond-like carbon coatings via plasma immersion ion implantation plasma-enhanced chemical vapor deposition with 1,1,1,2-tetrafluoroethane
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Yuhan Tong, Maryam Zahedian, Aiping Zeng, Ricardo Vidrio, Mike Efremov, Shenwei Yin, Hongyan Mei, Patrick Heaney, Jennifer T. Choy
We demonstrate an environmentally friendly and scalable method to create fluorine-doped diamond-like carbon (F-DLC) coatings using plasma immersion ion implantation plasma-enhanced chemical vapor deposition (PIII-PECVD) with 1,1,1,2-tetrafluoroethane. F-DLC films tend to have low wettability and good mechanical flexibility, which make them suitable for applications in biomedical devices and antibiofouling surfaces. We report on the effects of fluorine incorporation on the surface chemistry, surface energy, and morphology of these coatings, showing that our method is effective in increasing the fluorine content in the F-DLC up to 40%. We show that the addition of fluorine leads to a decrease in surface energy, which is consistent with a reduction in surface wettability.
Materials Science (cond-mat.mtrl-sci)
A Microcanonical Inflection Point Analysis via Parametric Curves and its Relation to the Zeros of the Partition Function
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-04 20:00 EST
Julio Cesar Siqueira Rocha, Rodrigo Alves Dias, Bismarck Vaz da Costa
In statistical physics, phase transitions are arguably among the most extensively studied phenomena. In the computational approach to this field, the development of algorithms capable of estimating entropy across the entire energy spectrum in a single execution has highlighted the efficacy of microcanonical inflection point analysis, while Fisher zeros technique has re-emerged as a powerful methodology for investigating these phenomena. This paper presents an alternative protocol for analyzing phase transitions based on parametric microcanonical curves. We also provide a clear demonstration of the relation of the linear pattern of the Fisher's zeros on the complex inverse temperature map (a circle in the complex \(x=e^{-\beta \varepsilon}\) map) with the order of the transition, showing that the specific heat is inversely related to the distance between the zeros. We study various model systems, including the Lennard-Jones cluster, the Ising, the XY, and the Zeeman models, illustrating the characterization of first-order, second-order, and Berezinskii-Kosterlitz-Thouless (BKT) transitions, respectively. By examining the behavior of thermodynamic quantities such as entropy and its derivatives in the microcanonical ensemble, we identify key features - such as loops and discontinuities in parametric curves - which signal phase transitions' presence and nature. We are confident that this approach can facilitate the classification of phase transitions across various physical systems.
Statistical Mechanics (cond-mat.stat-mech)
13 pages, 11 figures
Superlubric Motion of Wave-like Domain Walls in Sliding Ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Changming Ke, Fucai Liu, Shi Liu
Sliding ferroelectrics constructed from stacked nonpolar monolayers enable out-of-plane polarization in two dimensions with exceptional properties, including ultrafast switching speeds and fatigue-free behavior. However, the widely accepted switching mechanism, which posits synchronized long-distance in-plane translation of entire atomic layers driven by an out-of-plane electric field, has shown inconsistencies with experimental observations. We demonstrate that this spinodal decomposition-like homogeneous switching process violates Neumann's principle and is unlikely to occur due to symmetry constraint. Instead, symmetry-breaking domain walls (DWs) and the tensorial nature of Born effective charges are critical for polarization reversal, underscoring the quantum nature of sliding ferroelectrics. Using the Bernal-stacked \(h\)-BN bilayer as a model system, we discover that the coherent propagation of wide, wave-like domain walls is the key mechanism for ferroelectric switching. This mechanism fundamentally differs from the layer-by-layer switching associated with narrow domain walls, which has been established for over sixty years in perovskite ferroelectrics. Moreover, these wave-like DWs exhibit superlubric dynamics, achieving ultrahigh velocities of approximately 4000 m/s at room temperature and displaying an anomalous cooling-promoted switching speed. The unexpected emergence of DW superlubricity in sliding ferroelectrics presents new avenues for enhancing key performance metrics and offers exciting opportunities for applications in cryogenic environments.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Impact of Fixing Spins in a Quantum Annealer with Energy Rescaling
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-04 20:00 EST
Tomohiro Hattori, Hirotaka Irie, Tadashi Kadowaki, Shu Tanaka
Quantum annealing is a promising algorithm for solving combinatorial optimization problems. However, various hardware restrictions significantly impede its efficient performance. Size-reduction methods provide an effective approach for addressing large-scale problems but often introduce additional challenges. A notable hardware restriction is the limited number of decision variables quantum annealing can handle compared to the size of the problem. Moreover, when employing size-reduction methods, the interactions and local magnetic fields in the Ising model--used to represent the combinatorial optimization problem--can become excessively large, making them difficult to implement on hardware. Although prior studies suggest that energy rescaling impacts the performance of quantum annealing, its interplay with size-reduction methods remains unexplored. This study examines the relationship between fixing spins, a promising size-reduction method, and the effects of energy rescaling. Numerical simulations and experiments conducted on a quantum annealer demonstrate that the fixing spins method enhances quantum annealing performance while preserving the spin-chain embedding for a homogeneous, fully connected ferromagnetic Ising model.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
Superconductivity of the hybrid Ruddlesden-Popper La5Ni3O11 single crystals under high pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-04 20:00 EST
Mengzhu Shi, Di Peng, Kaibao Fan, Zhenfang Xing, Shaohua Yang, Yuzhu Wang, Houpu Li, Rongqi Wu, Mei Du, Binghui Ge, Zhidan Zeng, Qiaoshi Zeng, Jianjun Ying, Tao Wu, Xianhui Chen
The discovery of high-temperature superconductivity in La3Ni2O7 and La4Ni3O10 under high pressure indicates that the Ruddlesden-Popper (RP) phase nickelates Rn+1NinO3n+1 (R = rare earth) is a new material family for high-temperature superconductivity. Exploring the superconductivity of other RP or hybrid RP phase nickelates under high pressure has become an urgent and interesting issue. Here, we report a novel hybrid RP nickelate superconductor of La5Ni3O11. The hybrid RP nickelate La5Ni3O11 is formed by alternative stacking of La3Ni2O7 with n=2 and La2NiO4 with n=1 along the c axis. The transport and magnetic torque measurements indicate a density-wave transition at approximately 170 K near ambient pressure, which is highly similar to both La3Ni2O7 and La4Ni3O10. With increasing pressure, high-pressure transport measurements reveal that the density-wave transition temperature (TDW) continuously increases to approximately 210 K with increasing pressure up to 12 GPa before the appearance of pressure-induced superconductivity, and the density-wave transition abruptly fades out in a first-order manner at approximately 12 GPa. The optimal superconductivity with Tconset = 64 K and Tczero = 54 K is achieved at approximately 21 GPa. On the other hand, high-pressure X-ray diffraction experiments reveal a structural phase transition from an orthorhombic structure to a tetragonal structure at approximately 4.5 GPa. In contrast to La3Ni2O7 and La4Ni3O10, the pressure-induced structural transition has no significant effect on either the density-wave transition or the superconductivity, suggesting a minor role of lattice degree of freedom in La5Ni3O11. The present discovery extends the superconducting member in the RP nickelate family and sheds new light on the superconducting mechanism.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
20 pages, 9 fugures, 1 table
Enhancement of Electric Drive in Silicon Quantum Dots with Electric Quadrupole Spin Resonance
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Philip Y. Mai, Pedro H. Pereira, Lucas Andrade Alonso, Ross C. C. Leon, Chih Hwan Yang, Jason C. C. Hwang, Daniel Dunmore, Julien Camirand Lemyre, Tuomo Tanttu, Wister Huang, Kok Wai Chan, Kuan Yen Tan, Jesús D. Cifuentes, Fay E. Hudson, Kohei M. Itoh, Arne Laucht, Michel Pioro-Ladrière, Christopher C. Escott, MengKe Feng, Reinaldo de Melo e Souza, Andrew Dzurak, Andre Saraiva
Quantum computation with electron spin qubits requires coherent and efficient manipulation of these spins, typically accomplished through the application of alternating magnetic or electric fields for electron spin resonance (ESR). In particular, electrical driving allows us to apply localized fields on the electrons, which benefits scale-up architectures. However, we have found that Electric Dipole Spin Resonance (EDSR) is insufficient for modeling the Rabi behavior in recent experimental studies. Therefore, we propose that the electron spin is being driven by a new method of electric spin qubit control which generalizes the spin dynamics by taking into account a quadrupolar contribution of the quantum dot: electric quadrupole spin resonance (EQSR). In this work, we explore the electric quadrupole driving of a quantum dot in silicon, specifically examining the cases of 5 and 13 electron occupancies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Main: 5 pages, 4 figures Supp: 4 pages
Electrically induced bulk and edge excitations in the fractional quantum Hall regime
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Quentin France, Yunhyeon Jeong, Akinori Kamiyama, Takaaki Mano, Ken-ichi Sasaki, Masahiro Hotta, Go Yusa
We apply a voltage pulse to electrically excite the incompressible region of a two-dimensional electron liquid in the \(\nu=2/3\) fractional quantum Hall state and investigate the collective excitations in both the edge and bulk via photoluminescence spectral energy shifts. Introducing an offset in the voltage pulse significantly enhances the excitation signal. Real-space and time-resolved measurements reveal the dynamics of the bulk excitations, with an estimated group velocity of approximately \(3 \times 10^4\) m/s. These bulk excitations align well with the magneto-plasmon model. Our results highlight the topological link between edge and bulk states, providing a novel approach to exploring solid-state analogs of quantum gravity.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), General Relativity and Quantum Cosmology (gr-qc), Quantum Physics (quant-ph)
Surface tension of Bose-Einstein condensate at finite temperature
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-04 20:00 EST
We examine the influence of nonzero temperature on a bounded surface of a dilute Bose gas confined by a hard wall, utilizing the Gross-Pitaevskii theory and the Bogoliubov-de Gennes equation to describe surface excitations. The theoretical calculations are compared with experimental data for liquid helium II, demonstrating excellent agreement. An empirical relation is found for the temperature-dependence of the surface tension. Furthermore, our findings indicate that the contribution of surface excitations remains below 0.7% in the most of recent experiments on Bose-Einstein condensate.
Quantum Gases (cond-mat.quant-gas)
University of percolation at dynamic pseudocritical point
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-04 20:00 EST
Qiyuan Shi, Shuo Wei, Youjin Deng, Ming Li
Universality, encompassing critical exponents, scaling functions, and dimensionless quantities, is fundamental to phase transition theory. In finite systems, universal behaviors are also expected to emerge at the pseudocritical point. Focusing on two-dimensional percolation, we show that the size distribution of the largest cluster asymptotically approaches to a Gumbel form in the subcritical phase, a Gaussian form in the supercritical phase, and transitions within the critical finite-size scaling window. Numerical results indicate that, at consistently defined pseudocritical points, this distribution exhibits a universal form across various lattices and percolation models (bond or site), within error bars, yet differs from the distribution at the critical point. The critical polynomial, universally zero for two-dimensional percolation at the critical point, becomes nonzero at pseudocritical points. Nevertheless, numerical evidence suggests that the critical polynomial, along with other dimensionless quantities such as wrapping probabilities and Binder cumulants, assumes fixed values at the pseudocritical point that are independent of the percolation type (bond or site) but vary with lattice structures. These findings imply that while strict universality breaks down at the pseudocritical point, certain extreme-value statistics and dimensionless quantities exhibit quasi-universality, revealing a subtle connection between scaling behaviors at critical and pseudocritical points.
Statistical Mechanics (cond-mat.stat-mech)
Binary Bosonic Mixtures with Pair Hopping in Synthetic Dimension: Phase Transitions and Demixing Effects
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-04 20:00 EST
We employ the cluster Gutzwiller mean-field method to investigate the ground-state phase diagrams and demixing effects in binary boson mixtures with pair hopping in synthetic dimensions. Our study reveals two novel interspecies paired superfluid phases: the paired super-counter-fluid (PSCF) phase, featuring pairs of two particles of one species and two holes of the other, and the SCFphase, which combines PSCF and super-counter-fluid (SCF) orders. These phases provide new insights into XY ferromagnet states from a pseudo-spin perspective, with SCFand PSCF states corresponding to different XY ferromagnet phases depending on particle filling. We also identify a quantum quadruple critical point in the interexchange asymmetric case. Importantly, we demonstrate that the mixed-demixed critical point is phase-dependent due to pairing hopping, differing from normal two-component bosonic systems. Experimental schemes to observe these novel phases are proposed.
Quantum Gases (cond-mat.quant-gas)
Exact height distribution in one-dimensional Edwards-Wilkinson interface with diffusing diffusivity
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-04 20:00 EST
David S. Dean, Satya N. Majumdar, Sanjib Sabhapandit
We study the height distribution of a one-dimensional Edwards-Wilkinson interface in the presence of a stochastic diffusivity \(D(t)=B^2(t)\), where \(B(t)\) represents a one-dimensional Brownian motion at time \(t\). The height distribution at a fixed point is space is computed analytically. The typical height \(h(x,t)\) at a given point in space is found to scale as \(t^{3/4}\) and the distribution \(G(H)\) of the scaled height \(H=h/t^{3/4}\) is symmetric but with a nontrivial shape: while it approaches a nonzero constant quadratically as \(H\to 0\), it has a non-Gaussian tail that decays exponentially for large \(H\). We show that this exponential tail is rather robust and holds for a whole family of linear interface models parametrized by a dynamical exponent \(z>1\), with \(z=2\) corresponding to the Edwards-Wilkinson model.
Statistical Mechanics (cond-mat.stat-mech)
18 pages, 4 figures
Designing Bimetallic Nanoparticle Catalysts via Tailored Surface Segregation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Yaxin Tang, Mingao Hou, Qian He, Guangfu Luo
Bimetallic nanoparticles serve as a vital class of catalysts with tunable properties suitable for diverse catalytic reactions, yet a comprehensive understanding of their structural evolution under operational conditions as well as their optimal design principles remains elusive. In this study, we unveil a prevalent surface segregation phenomenon in approximately 100 platinum-group-element-based bimetallic nanoparticles through molecular dynamics simulations and derive a thermodynamic descriptor to predict this behavior. Building on the generality and predictability of surface segregation, we propose leveraging this phenomenon to intentionally enrich the nanoparticle surface with noble-metal atoms, thereby significantly reducing their usage while maintaining high catalytic activity and stability. To validate this strategy, we investigate dozens of platinum-based bimetallic nanoparticles for propane dehydrogenation catalysis using first-principles calculations. Through a systematic examination of the catalytic sites on nanoparticle surfaces, we eventually identify several candidates featuring with stable Pt-enriched surface and superior catalytic activity, confirming the feasibility of this approach.
Materials Science (cond-mat.mtrl-sci)
Renormalization-group approach to the Kohn-Luttinger superconductivity: Amplification of the pairing gap from \(\ell^4\) to \(\ell\)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-04 20:00 EST
We revisit the renormalization group (RG) analysis of the Kohn-Luttinger (KL) mechanism for superconductivity. The KL mechanism leads to superconductivity in a system with a repulsive bare interaction. The key ingredient is the screening effect that renders the induced interaction attractive in channels with nonzero angular momentum \(\ell \neq 0\), thereby triggering the Bardeen-Cooper-Schrieffer (BCS) instability. According to the original argument, the resulting gap is exponentially small, with its exponent scaling as \(-\ell^4\). However, the KL mechanism was originally formulated within perturbation theory, where the series is known to converge poorly in certain cases -- most notably, for the p-wave paring gap induced by a repulsive s-wave contact interaction. This poor convergence may be attributed to a divergent integrand in a specific class of diagrams containing both the BCS logarithm and the Kohn anomaly, suggesting that one must resum the Kohn anomaly contributions separately from the BCS logarithm. In this work, we incorporate the Kohn anomaly contribution into the beta function of the RG equation governing the BCS instability near the Fermi surface. Our solution shows that the KL gap exponent is then proportional to \(-\ell\), indicating a significant enhancement of the KL mechanism beyond the previously known result. To illustrate this, we study the spin-triplet p-wave pairing gap arising from a repulsive s-wave contact interaction and compare our RG-based results with those obtained from the Bethe-Salpeter equation in perturbation theory.
Superconductivity (cond-mat.supr-con), High Energy Physics - Phenomenology (hep-ph), Nuclear Theory (nucl-th)
18 pages, 4 figures
Temperature dependence of nonlinear elastic moduli of polystyrene
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-04 20:00 EST
Andrey V. Belashov, Anna A. Zhikhoreva, Yaroslav M. Beltukov, Irina V. Semenova
Nonlinear elastic properties of polymers and polymeric composites are essential for accurate prediction of their response to dynamic loads, which is crucial in a wide range of applications. These properties can be affected by strain rate, temperature, and pressure. The temperature susceptibility of nonlinear elastic moduli of polymers remains poorly understood. We have recently observed a significant frequency dependence of the nonlinear elastic (Murnaghan) moduli of polystyrene. In this paper we expand this analysis by the temperature dependence. The measurement methodology was based on the acousto-elastic effect, and involved analysis of the dependencies of velocities of longitudinal and shear single-frequency ultrasonic waves in the sample on the applied static pressure. Measurements were performed at different temperatures in the range of 25-65 °C and at different frequencies in the range of 0.75-3 MHz. The temperature susceptibility of the nonlinear moduli \(l\) and \(m\) was found to be two orders of magnitude larger than that of linear moduli \(\lambda\) and \(\mu\). At the same time, the observed variations of \(n\) modulus with temperature were low and within the measurement tolerance. The observed tendencies can be explained by different influence of pressure on relaxation processes in the material at different temperatures.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Phase dependence of the Thermal Memory Effect in Polycrystalline Ribbon and Bulk Ni55Fe19Ga26 Heusler Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
A. Vidal-Crespo, A.F. Manchón-Gordón, J.M. Martín-Olalla, F.J. Romero, J.J. Ipus, M.C. Gallardo, J.S. Blázquez, C.F. Conde
The thermal memory effect, TME, has been studied in Ni55Fe19Ga26 shape memory alloys, fabricated as ribbons via melt-spinning and as pellets via arc-melting, to evaluate its dependence on the martensitic structure and the macrostructure of the samples. When the reverse martensitic transformation is interrupted, a kinetic delay in the subsequent complete transformation is only evident in the ribbon samples, where the 14M modulated structure is the dominant phase. In contrast, degradation of the modulated structure or the presence of the gamma-phase significantly reduces the observed TME. In such cases, the magnitude of the TME approaches the detection limits of commercial calorimeters, and only high-resolution calorimeter at very low heating rate (40 mK h-1) can show the effect. Following the kinetic arrest and subsequent cooling, the reverse martensitic transformation was completed at several heating rates to confirm the athermal nature of the phenomenon.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
30 pages (double spaced) 12 figures
Spontaneous emergence of run-and-tumble-like dynamics in coupled self-propelled robots: experiment and theory
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-04 20:00 EST
Somnath Paramanick, Umashankar Pardhi, Harsh Soni, Nitin Kumar
Drawing inspiration from the motility behaviour of microorganisms, we introduce a highly tunable, robotic system self-actuating into the run-and-tumble (RT)-like motion. It comprises two disk-shaped, centimeter-scale programmable robots individually programmed to perform overdamped active Brownian (AB) motion and connected by a rigid rod. The rod is attached to pivot points located on off-centered, mirror-symmetric points on each robot, allowing for its free rotation at both ends. We show that the collective dynamics of this system execute RT-like motion with characteristic sharp tumble events and exponentially distributed run times, similar to those observed in microorganisms. We further quantify emerging dynamics in terms of tumbling frequency and tune it over a wide range of experimental parameters. We also develop a theoretical model that reproduces our experimental results and elucidates the underlying physical mechanisms governing the rich phase behavior of RT motion. Together, these results highlight the importance of our robotic platform in offering valuable insights into the mechanism of motility characteristics in microorganisms.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
For Supplementary movies and SI file visit: this https URL
Polarizing altermagnets by ultrafast asymmetric spin dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Zhaobo Zhou, Sangeeta Sharma, John Kay Dewhurst, Junjie He
Laser pulses are known to induce symmetric demagnetization; equal loss of magnetic moments in the identical sublattices of antiferromagnets and ferromagnets at ultrashort timescale. This is due to their identical local electronic structures guided by the underlying symmetries. Using time-dependent density functional theory, we demonstrate that laser pulses can drive asymmetric demagnetization dynamics of identical sublattices in the d-wave altermagnet RuO2, resulting in a photo-induced ferrimagnetic state with a net moment of ~0.2 {}B per unit cell. This polarization arises from the momentum-dependent spin splitting, which is unique to altermagnets, and which induces a momentum-dependent optical intersite spin transfer effect. Furthermore, the ferrimagnetic polarization is highly controllable; depends on the direction of the linear polarized laser. The excitation along the spin-polarized planes breaks the symmetry of the momentum-space magnetization distribution, leading to inequivalent spin-resolved charge transfer between sublattices across both momentum and real space. These findings uncover novel laser-driven pathways to control magnetic order in altermagnets, enabling a phase transition from AM to ferri-magnetic state.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Generalized Lanczos method for systematic optimization of neural-network quantum states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Jia-Qi Wang, Rong-Qiang He, Zhong-Yi Lu
Recently, artificial intelligence for science has made significant inroads into various fields of natural science research. In the field of quantum many-body computation, researchers have developed numerous ground state solvers based on neural-network quantum states (NQSs), achieving ground state energies with accuracy comparable to or surpassing traditional methods such as variational Monte Carlo methods, density matrix renormalization group, and quantum Monte Carlo methods. Here, we combine supervised learning, reinforcement learning, and the Lanczos method to develop a systematic approach to improving the NQSs of many-body systems, which we refer to as the NQS Lanczos method. The algorithm mainly consists of two parts: the supervised learning part and the reinforcement learning part. Through supervised learning, the Lanczos states are represented by the NQSs. Through reinforcement learning, the NQSs are further optimized. We analyze the reasons for the underfitting problem and demonstrate how the NQS Lanczos method systematically improves the energy in the highly frustrated regime of the two-dimensional Heisenberg \(J_1\)-\(J_2\) model. Compared to the existing method that combines the Lanczos method with the restricted Boltzmann machine, the primary advantage of the NQS Lanczos method is its linearly increasing computational cost.
Strongly Correlated Electrons (cond-mat.str-el), Machine Learning (cs.LG), Computational Physics (physics.comp-ph)
11 pages, 7 figures, 3 tables
High-Performance Nonvolatile Spin FETs from 2D Metallic Ferromagnetic and Ferroelectric Multiferroic Heterostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
B. Liu, X. Zhang, W. Hou, H. Feng, Zhengei Dai, Zhi-Xin Guo
All-electric-controlled nonvolatile spin field-effect transistors (SFETs) based on two-dimensional (2D) multiferroic van der Waals (vdW) heterostructures hold great promise for advanced spintronics applications. However, their performance is hindered by the limited availability of 2D magnetic materials that can switch effectively between metallic and semiconducting states with sizable bandgaps controlled by ferroelectric polarization. Most studies have focused on materials that are naturally semiconducting, achieving a metallic state by modifying the ferroelectric polarization. In this work, we introduce an innovative approach that uses interface effects to convert inherently metallic 2D magnetic materials into half-metals and induce half-semiconducting behavior through changes in ferroelectric polarization. Density functional theory (DFT) calculations on the CrPS3/Sc2CO2 heterostructure demonstrate that the ferroelectric polarization of Sc2CO2 monolayers can adjust the electronic structure of CrPS3, enabling a switch from half-metallic to half-semiconducting states. Building on these insights, we designed a nonvolatile SFET and analyzed its transport properties using the nonequilibrium Green's function (NEGF) method combined with DFT. Our results show that reversing the ferroelectric polarization achieves an on/off current ratio exceeding 5000000%, and the heterostructure generates nearly 100% spin-polarized current with a current density of up to 6500 {}A/{}m at bias voltage below 0.2 V. These findings highlight a promising pathway for developing high-performance SFETs that surpass existing 2D heterojunction materials.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
5 figures
Interfacial chemistry meets magnetism: comparison of \(Co/Fe_3O_4\) and \(Co/{\alpha}-Fe_2O_3\) epitaxial heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Ewa Madej, Natalia Kwiatek-Maroszek, Kinga Freindl, Józef Korecki, Ewa Młyńczak, Dorota Wilgocka-Ślęzak, Marcin Zając, Jan Zawała, Nika Spiridis
The magnetic and chemical structure of metal/oxide interfaces were studied in cobalt/magnetite, \(Fe_3O_4\), and cobalt/hematite, \({\alpha}-Fe_2O_3\), epitaxial heterostructures using the comprehensive selection of microscopic and spectroscopic methods. It was observed that the cobalt nanostructures and ultrathin films were oxidized at both interfaces, with a thicker cobalt oxide layer in the system with hematite. The formation of cobalt oxides was accompanied by the interfacial reduction of iron that modified magnetic properties of the iron oxides layers. In particular, uncompensated magnetic moments appear in antiferromagnetic hematite, and the orbital magnetic moment of Co grown on magnetite is significantly enhanced for thicknesses below 1 nm. Synchrotron magnetic microscopy showed a direct correlation in the domain structures of the cobalt/iron oxides: ferromagnetic coupling between cobalt and magnetite and between cobalt and the magnetically modified layer of hematite.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Universal fluctuations of localized two interacting particles in one dimension
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-04 20:00 EST
Sen Mu, Gabriel Lemarié, Jiangbin Gong
We investigate the universal fluctuations of localized wavefunction in the Fock space of two interacting particles in one-dimensional disordered systems, focusing on the interplay between random potentials and random long-range interactions. By mapping the system onto a directed polymer problem, we show that random potentials alone produce correlated energies for the sites in the Fock space, giving rise to the fluctuation growth exponent 1/2. Introducing random long-range interactions alters these correlations and drives the system's fluctuations into the Kardar-Parisi-Zhang universality class in (1+1)D with the exponent 1/3. To validate the universality of the observed fluctuation scaling, we study a complex directed polymer model with competing point and columnar disorder. Our results confirm that columnar disorder corresponds to on-site energies in the Fock space from the random potentials, while point disorder models the effects of random long-range interactions between the two particles. These findings provide new insights into the Fock-space perspective for examining disordered quantum many-body systems, and emphasize the critical role of disorder structure in determining the universality class of fluctuations in localized quantum systems.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
10 pages + 6 figures, comments are welcome
How to stay on the physical branch in self-consistent many-electron approaches
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Herbert Eßl, Matthias Reitner, Evgeny Kozik, Alessandro Toschi
We derive the mathematical condition under which the physical solution of the many-electron problem, obtained by self-consistent approaches, becomes unstable upon increasing interaction strength. The validity of our criterion is explicitly verified by performing self-consistent calculations of basic interacting models. In this context, we eventually unveiled the precise connection linking the misleading convergence of self-consistent schemes to the multivaluedness of the Luttinger-Ward functional as well as to the divergences of the irreducible vertex function. Our analysis also explains how a misleading convergence of self-consistent approximations can occur even in parameter regions without vertex divergences. Even more importantly, it allows us to define a general procedure for stabilizing the physical solution, when it is unstable in conventional self-consistent schemes.
Strongly Correlated Electrons (cond-mat.str-el)
Accelerated recrystallization of nanocrystalline films as a manifestation of the inner size effect of the diffusion coefficient
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
S. Petrushenko, S. Dukarov, M. Fijalkowski, V. Sukhov
This paper is devoted to studying the recrystallization of 100 nm thick polycrystalline films of copper and silver. It is found that in copper films deposited by the thermal evaporation method onto a substrate at room temperature, a bimodal crystallite size distribution with maxima at 15 and 35 nm is observed. The bimodal distribution in copper films is preserved during annealing, which leads to a shift of both peaks of the crystallite size distribution histograms to the larger sizes region. In contrast to Cu, micron-sized crystallites are present even in as-deposited Ag films besides the nanosized fraction. These grains are formed due to the phenomenon of self-annealing and weakly evolve during heating owing to grain growth stagnation. The nanosized fraction in as-deposited Ag films is represented by crystallites with the most probable size of 25 nm, which increases to 50 nm as a result of short-term annealing at the temperature of 250°C. The grain-boundary diffusion coefficient was determined, which is more than 10-18 m2/s for both films of metals. The obtained value indicates a multiple intensification of self-diffusion processes in films, the thickness of which allows us to refer them to macroscopic sample
Materials Science (cond-mat.mtrl-sci), Biological Physics (physics.bio-ph)
Extended string-net models with all anyons at finite temperature
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
André O. Soares, Anna Ritz-Zwilling, Jean-Noël Fuchs
String-net models describe a vast family of topological orders in two spatial dimensions, but fail to produce all the expected anyonic excitations. Following arXiv:1502.03433, we consider an extended string-net model by attaching one tail to each plaquette of the lattice, allowing all anyons to emerge as elementary plaquette excitations for arbitrary input categories. The corresponding tube algebra is the mathematical tool needed to construct the anyons from the input category and to obtain their internal multiplicities. We use them to compute the energy level degeneracies and the partition function. In the thermodynamic limit, the latter is dominated by the trivial (vacuum) anyon, so that the topological order is destroyed at any non-zero temperature. In a finite-size system, order survives up to a finite temperature, similarly to the one-dimensional classical Ising model. We confirm this by computing thermal averages of topological projectors, Wegner-Wilson loops and the topological mutual information. The results are also generalized to models with multiple tails per plaquette.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
19 pages, 6 figures
Quantum Geometric Origin of Strain-Induced Ferroelectric Phase Transitions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Jiaming Hu, Ziye Zhu, Yubo Yuan, Wenbin Li, Hua Wang, Kai Chang
Strain-regulated ferroelectric (FE) materials have long attracted significant attention due to their diverse applications. While soft-phonon theory and the (pseudo) Jahn-Teller effect have achieved considerable success in providing phenomenological descriptions and general understanding, the detailed connection between these perspectives and their microscopic dependence on strain regulation remains unclear. Here, under the framework of density-functional perturbation theory (DFPT), we demonstrate that the Berry curvature of electron-phonon coupling (EPC) plays a pivotal role in the interatomic force matrix (IFM). A subsequent model analysis shows that external strain can reverse the polarity of the EPC Berry curvature in (quasi)-degenerate electronic subsystems through band inversion, thereby directly leading to phonon softening. The general theory is then applied to the BiOCl monolayer as a benchmark, which offers an accurate description of the density functional theory (DFT) calculations. This mechanism is further observed across a broad range of materials through ab initio calculations, providing an insightful perspective on EPC quantum geometry in lattice dynamics and FE phase transitions.
Materials Science (cond-mat.mtrl-sci)
6 pages, 2 figures
Axionic Acoustic Phonons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Joan Bernabeu, Alberto Cortijo
The sound propagation properties resulting from a dynamical axion insulator generated from a Weyl semimetal are explored. Due to the axial electron-phonon coupling, the speed of sound in the material and its attenuation is seen to be modified. At the Random Phase Approximation (RPA) level, it is seen that the axion obstructs a stronger modification of the speed of sound for longitudinal waves propagating parallel to the Axionic Charge Density Wave (ACDW) wavevector but not for transverse waves. On the other hand, the attenuation is modified by effects beyond the RPA, but the axionic contribution is negligible. These effects can be probed in sound propagation experiments without invoking the axial anomaly, which would require an additional electric field. We also discuss the importance of axial electron-phonon interactions with respect to the more conventional vector interactions in these systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 6 figures
Dependence of the energy and orbital structure of local states in CuO monolayer on Coulomb parameters
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
I. A. Makarov (1), M. M. Korshunov (1), S. G. Ovchinnikov (1) ((1) Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Russia, Krasnoyarsk)
The dependence of the energies and orbital structure of local states in the CuO monolayer on intra- and interatomic Coulomb interactions on copper and oxygen orbitals is studied. The electronic system is described within the eight-band p-d model in the hole representation with the on-site energies and hopping integrals obtained using density functional theory. CuO cluster multiparticle eigenstates are calculated using exact diagonalization. The difference between the energy dependencies on the Coulomb parameters for the states with the predominant probability density on the d-orbital and the states in which hole occupies p-orbitals leads to crossover of d- and p-states. The ground single-hole and two-hole states which determine the electronic structure of the low-energy excitations have the character of d- or p-orbitals in the different regions of the Coulomb parameters space. The gap between the energies of the dispersionless quasiparticles forming the top of the valence band and conductivity band also have different values in these two regions. The magnitude of this gap and the orbital character of the local multiparticle states change sharply even with an insignificant change in the Coulomb interactions within the boundary region of parameters between the regions in which the local states are formed by the d- or p-orbitals.
Strongly Correlated Electrons (cond-mat.str-el)
30 pages, 10 figures (13 with subfigures), 4 tables, 2 appendices
Fracture in concrete: X-ray tomography with in-situ testing, digital volume correlation and phase-field modeling
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Akanksha Mishra, Pietro Carrara, Michele Griffa, Laura De Lorenzis
We test and simulate the mesoscopic cracking behavior of specimens made of a standard concrete mixture. To this end, we combine stable wedge-splitting fracture experiments performed during X-ray tomography, their analysis with digital volume correlation providing the full three-dimensional displacement field, and phase-field cohesive fracture modeling. In our computations, we apply the measured boundary conditions and model the actual heterogeneous material structure at the mesoscopic scale. Within the phase-field model, we explicitly distinguish among (thus individually represent) the mesostructural features of distinct material phases with size above a threshold of 1 mm, while we homogenize pores and finer aggregates below this threshold within the cementitious mortar matrix, with material parameters characterized accordingly. We compare experimental and numerical results in terms of both local and global quantities.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Damage of bilayer structure in La3Ni2O7-d induced by high pO2 annealing
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-04 20:00 EST
Yulin Zhang, Cuiying Pei, Ning Guo, Longlong Fan, Mingxin Zhang, Lingzhen Wang, Gongting Zhang, Feiyu Li, Yunong Wang, Chao Ma, Wenyong Cheng, Shanpeng Wang, Qiang Zheng, Yanpeng Qi, Junjie Zhang
The discovery of superconductivity with onset temperature of ~80 K in pressurized bilayer Ruddlesden-Popper La3Ni2O7-d has attracted much attention. Despite intense research, determination of the exact oxygen content and understanding of the relationship between superconductivity and oxygen content remain a big challenge. Here, we report a systematical study on the structure and physical properties of La3Ni2O7-d polycrystalline powders which were prepared using sol-gel method at ambient pressure and then annealed under various oxygen pressure. We found that high pO2 annealing with slow cooling results in a new phase, which can be modeled using the hybrid single-layer-trilayer La3Ni2O7 or the tetragonal bilayer La3Ni2O7. Scanning transmission electron microscopy (STEM) measurements revealed significant single layers and trilayers after high oxygen pressure annealing, evidencing damage of the bilayer structure. The superconducting transition under high pressure became weak for high pO2 annealed samples, which is consistent with the damage of the bilayer structure. Our results reveal that the bilayer structure is fragile and post-annealing under near atmosphere pressure of oxygen is suitable to maintain bilayer structure and increase oxygen content at the same time.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
5 figures and 1 table
Emergence of single-particle mobility edge (SPME) in a ladder network under a modified Aubrey-Andre-Harper (AAH) kind distortion
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-04 20:00 EST
This research examines the localization and delocalization phenomena in a two-strand ladder network incorporating a generalized Aubrey-Andre-Harper (AAH) model in different parametric regions. In our model, we have introduced a distortion that is neither periodic (Bloch-type) nor random (Anderson-type) but instead has a slowly varying pseudorandom pattern described by {}n = {}cos(2{}Qn^{}), where 0 < {} < 1. We have demonstrated that in the generalized ladder network in the 0 < {} < 1 limit, it is not possible to see a pure metal-insulator transition due to the presence of a single particle mobility edge (SPME) state. We have shown that at {} = 0.908 (and in its immediate neighborhood), the energy states maintain delocalization up to a considerable distortion strength and that a pure metal-to-insulator transition occurs at {} = 1 as {} increases. We have also demonstrated the phase diagram for the ladder network in the parametric region {}-{}. We extensively studied wave packet dynamics by examining different quantities to establish the claim satisfactorily. We also have studied the multifractality of the quantum network. These findings suggest that this ladder network could serve as a valuable platform for investigating the interplay between localized and extended states.
Statistical Mechanics (cond-mat.stat-mech)
13 pages and 69 figures
(Anti-)Altermagnetism from Orbital Ordering in the Ruddlesden-Popper Chromates Sr\(_{n+1}\)Cr\(_n\)O\(_{3n+1}\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Quintin N. Meier, Alberto Carta, Claude Ederer, Andrés Cano
Altermagnets form a subclass of collinear antiferromagnets with spin-split electronic states. Here, we introduce the Ruddlesden-Popper chromates Sr\(_{n+1}\)Cr\(_n\)O\(_{3n+1}\) (including the perovskite SrCrO\(_3\)) as candidates for antiferromagnetic materials in which altermagnetism emerges from spontaneous orbital ordering, rather than crystal symmetry. Using first-principles calculations, we identify a layer-dependent spin splitting of the electronic states, driven by the interplay between spin and orbital order. We show that if the spin and orbital orders align in adjacent layers, the system exhibits a net spin splitting, and thus altermagnetism. In contrast, if either the spin or the orbital order is reversed in adjacent layers, we observe an anti-altermagnetic state where layerwise compensation leads to net zero spin splitting. We find that for odd \(n\), altermagnetic and anti-altermagnetic phases can coexist, whereas for even \(n\) and in the perovskite limit, the system remains strictly anti-altermagnetic. In both cases, increasing \(n\) favors metallicity. Finally, we indicate that in odd \(n\) compounds, epitaxial strain can promote the altermagnetic phase.
Materials Science (cond-mat.mtrl-sci)
5 pages, 4 figures + supplement
Origin of phonon decoherence
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
Yiming Pan, Christoph Emeis, Stephan Jauernik, Michael Bauer, Fabio Caruso
Phonon decoherence determines the characteristic timescales over which coherent lattice vibrations decay, making it a crucial process for understanding the non-equilibrium dynamics of crystal lattices after excitation by a pump pulse. Here, we report a theoretical and computational investigation of the origin of phonon decoherence within a first-principles many-body framework. We derive quantum kinetic equations for the dynamics of coherent phonons by explicitly accounting for dissipation processes induced by electron-phonon and phonon-phonon interactions. The decoherence rate and frequency renormalization are formulated in terms of the non-equilibrium phonon self energy, providing a framework amenable for ab initio calculations. To validate this approach, we conduct a first-principles study of phonon decoherence for the elemental semimetals antimony and bismuth. The robust agreement with available temperature- and fluence-dependent experimental data confirms the accuracy of our theoretical and computational framework. More generally, our findings reveal that either electron-phonon and phonon-phonon coupling can prevail in determining the decoherence time, depending on the temperature and driving conditions. Overall, this work fills a critical gap in the theoretical understanding of phonon decoherence, providing a predictive framework for determining the timescales of light-induced structural dynamics in driven solids.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Multiphysics simulations of microstructure influence on hysteresis and eddy current losses of electrical steel
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Patrick Kühn, Yangyiwei Yang, Guanyu Chen, Shanelle N. Foster, Herbert Egger, Bai-Xiang Xu
Improving efficiency of electrical machines requires fundamental knowledge on the mechanisms behind magnetic and eddy current losses of the magnetic core materials, with Fe-Si alloy as a prototype. These losses are intrinsically influenced by the microstructure of the materials. This necessitates physics-based, microstructure-informed multiscale simulations. In the present paper, we utilised micromagnetic simulations and computational homogenization methods to calculate the effective hysteresis and effective conductivities of Fe-Si electrical steels. To demonstrate the methodology, binder-jet printed electrical steel material samples with different microstructure were investigated. The microstructure samples were digitized based on both the descriptor-based synthetic reconstruction and SEM-image-based digitization. More samples were generated with varying microstructure features such as grain size and grain boundary phases. The micromagnetic simulations were then performed to investigate the magnetic hysteresis and hysteresis loss. The eddy current loss was also evaluated by using the effective conductivity through computational homogenization. By performing parameter research on a series of synthetic microstructures, effects of average grain size and grain boundary (GB) phase thickness on the hysteresis loss and eddy current loss were unveiled. An average grain size around 120 has the lowest hysteresis loss, although the eddy current loss increases with the grain size. Increasing GB-phase thickness helps reduce both losses. Results indicate the potential to decrease loss of magnetic core materials by microstructure optimization.
Materials Science (cond-mat.mtrl-sci)
Searching for fixed points of dynamical systems by the Explorative Relaxation Reditribution Method
New Submission | Other Condensed Matter (cond-mat.other) | 2025-02-04 20:00 EST
Being able to effectively locate saddle (and other fixed) points in dynamical systems holds tremendous implications in a number of applications in engineering and science, among which the study of rare events in molecular simulations stands as one of the most prominent field of interest. Although there is a vast literature on methods aiming at addressing this challenge, open issues still remain in several aspects such as computational efficiency and easy implementation. In this work, we suggest that the Relaxation Redistribution Method (RRM) - formerly introduced to solve the invariance equation in the context of stiff dynamical systems ruling detailed chemical kinetics - can be reformulated to locate saddle and other fixed points even for stochastic simulators driven by effective energy gradients. This new formulation of the RRM is referred to as the Explorative Relaxation Redistribution Method (ERRM). Benchmarks based on the popular Mueller-Brown and other potentials are used to test the ERRM.
Other Condensed Matter (cond-mat.other)
33 pages, 14 figures
Grain Boundary Segregation and Embrittlement of Aluminum Binary Alloys from First Principles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Nutth Tuchinda, Gregory B. Olson, Christopher A. Schuh
Grain boundary segregation controls properties of polycrystalline materials such as their susceptibility to intergranular cracking. It is of interest to engineer alloy chemistry to enhance grain boundary cohesion to prevent intergranular failure. While there is collectively a large first-principles dataset for grain boundary embrittlement in multiple Al-based binary alloys, the methodologies used for the first principles calculations, as well as the analyzed fracture paths, are variable amongst studies. Here, we reevaluate and compute grain boundary segregation and embrittlement from all-electron first-principles for the {}5001 Al grain boundary. We explicitly evaluate multiple fracture paths, and provide a study case of the chemical trends of the preferred fracture paths across 69 binary Al alloys. The results suggest that neglecting certain low energy fracture paths can lead to errors of estimating embrittlement potency up to the order of 1 eV per solute atom, especially for multiple d-block transition metal solutes that are of engineering interest. The database calculated here also permits a comprehensive comparison between all-electron and pseudopotential methodologies. The effects of Hubbard U density functional theory on grain boundary segregation and embrittlement in Al(Sc) are found not to be significant in terms of the relative energetic calculations of grain boundaries and free surfaces (differences are of order 0.1 eV or less).
Materials Science (cond-mat.mtrl-sci)
Susceptibility anisotropy and absence of ferroelectric order in the Kitaev spin liquid candidate Na\(_2\)Co\(_2\)TeO\(_6\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-04 20:00 EST
C. Dhanasekhar (1,2,3), Monika Jawale (1), Rahul Kumar (4), D. Chandrasekhar Kakarla (2), Sagar Mahapatra (5), Mitch M.C. Chou (3), A.Sundaresan (4), H.D. Yang (2,3), A.V. Mahajan (1) ((1) Department of Physics, Indian Institute of Technology Bombay, Mumbai, India (2) Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (3) Center of Crystal Research, National Sun Yat-sen University, Kaohsiung, Taiwan (4) School of Advanced Materials, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India (5) Department of Physics, Indian Institute of Science Education and Research, Pune, India)
We report the magnetic, magnetodielectric, and electric polarization properties of single crystals of the Co-based Kitaev Spin Liquid (KSL) candidate Na\(_2\)Co\(_2\)TeO\(_6\) (NCTO). The sample shows magnetic transitions at 26 K, 16 K, and 5 K, consistent with the literature. The magnetic measurements along and perpendicular to the Co-honeycomb planes show a strong anisotropy in susceptibility and in Curie-Weiss (C-W) temperatures. The experimental anisotropic C-W temperatures of NCTO qualitatively match with the theoretical C-W temperatures, calculated using the HKTF model [C. Kim , J. Phys.: Condens. Matter , 045802 (2021)]. We find from our temperature- and field-dependent dielectric and pyroelectric (\(I_p\)) current studies (\(H\parallel ab\) and \(E\perp ab\)) that our single crystal NCTO samples do not have a finite electric polarization below 100 K. These \(I_p\) studies confirm the absence of a magnetoelectric coupling and electric polarization properties in the title compound and suggest that the zig-zag AFM structure is more favorable than the triple-\(Q\) structure with AFM Kitaev interactions.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 6 figures, 2 tables
State transitions and hysteresis in a transverse magnetic island chain
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
A chain of dipole-coupled elongated magnetic islands whose long axes are oriented perpendicular to the chain is studied for its magnetization properties. With a magnetic field applied perpendicular to the chain, the competition between dipolar energy, shape anisotropy, and field energy leads to three types of uniform states with distinct magnetizations: (1) oblique to the chain, (2) perpendicular to the chain, and (3) zero due to having alternating dipoles. The response of these states to a slowly varying field is analyzed, focusing on their stability limits and related oscillation modes, and the dependencies on the dipolar and anisotropy constants. Based on identifiable transitions among the three states and their instability points, the theoretically predicted zero-temperature magnetization curves show significant dependence on the anisotropy. The model suggests a path for designing advanced materials with desired magnetic properties. Different geometries and magnetic media for the islands are considered.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
18 pages, 17 figures
Graphene intercalation of the large gap quantum spin Hall insulator bismuthene
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-04 20:00 EST
Lukas Gehrig, Cedric Schmitt, Jonas Erhardt, Bing Liu, Tim Wagner, Martin Kamp, Simon Moser, Ralph Claessen
The quantum spin Hall insulator bismuthene, a two-third monolayer of bismuth on SiC(0001), is distinguished by helical metallic edge states that are protected by a groundbreaking 800 meV topological gap, making it ideal for room temperature applications. This massive gap inversion arises from a unique synergy between flat honeycomb structure, strong spin orbit coupling, and an orbital filtering effect that is mediated by the substrate. However, the rapid oxidation of bismuthene in air has severely hindered the development of applications, so far confining experiments to ultra-high vacuum conditions. Here, we successfully overcome this barrier, intercalating bismuthene between SiC and a protective sheet of graphene. As we demonstrate through scanning tunneling microscopy and photoemission spectroscopy, graphene intercalation preserves the structural and topological integrity of bismuthene, while effectively shielding it from oxidation in air. We identify hydrogen as the critical component that was missing in previous bismuth intercalation attempts. Our findings facilitate ex-situ experiments and pave the way for the development of bismuthene based devices, signaling a significant step forward in the development of next-generation technologies.
Materials Science (cond-mat.mtrl-sci)
Nonaffine motion in flowing highly polydisperse granular media
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-04 20:00 EST
Pablo Eduardo Illing, Eric R. Weeks
We study the particle-scale motion of highly polydisperse hard disks flowing in a two-dimensional bent channel. We use various size distributions of particles, in which the largest particles are up to five times larger than the smallest. The disks are pushed through an L-shaped channel to drive the particle rearrangements. Although the mean flow is essentially independent of the polydispersity, the motion of individual particles becomes more nonaffine on average for higher polydispersity samples. We characterize the nonaffine motion, finding a qualitative difference in the behavior of small and larger particles: the smaller disks have more nonaffine motion, induced by the larger particles.
Soft Condensed Matter (cond-mat.soft)
14 pages, 13 figures, 1 table
Structural and Electronic Evolution of Bilayer Nickelates Under Biaxial Strain
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-04 20:00 EST
H C Regan B. Bhatta, Xiaoliang Zhang, Yong Zhong, Chunjing Jia
The discovery of high-Tc superconductivity around 80K in bilayer nickelate La3Ni2O7 under high pressure has expanded the family of high-Tc superconductors above the nitrogen boiling temperature. Recent studies have further shown that ambient pressure superconductivity with a Tc exceeding 40K can be achieved in compressively strained La3Ni2O7 thin films, offering a tunable platform for investigating the pairing mechanism in high-Tc nickelates. A comprehensive understanding of the structural and electronic properties of bilayer nickelate under epitaxial strain is essential to advance this active field. In this work, we employ first-principles calculations to systematically explore the entire rare-earth (Re) series of bilayer nickelates Re3Ni2O7 in the realistic orthorhombic Amam phase under various compressive and tensile strain conditions. We highlight the materials properties change when strain is applied, and compare these results with those observed under high pressure. Our findings show that 2.5% compressive strain increases the apical Ni-O-Ni bond angle toward 180 degree, and causes the Ni \(d_{z^2}\) bands to move away from the Fermi level. The tight-binding parameters for the 2.5% compressively strained La3Ni2O7 are quite similar to those of the unstrained material, except that the on-site energy difference between the Ni \(d_{z^2}\) and \(d_{x^2-y^2}\) orbitals increases by about 50 percent. Notably, the absence of the \(d_{z^2}\) bands at the Fermi energy under compressive strain contrasts sharply with the electronic structure in the high-pressure {} phase, suggesting that the presence of \(d_{z^2}\) bands at the Fermi energy may not be a requisite for superconductivity.
Superconductivity (cond-mat.supr-con)
Spectra-orthogonal optical anisotropy in wafer-scale molecular crystal monolayers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-04 20:00 EST
Tomojit Chowdhury, Fauzia Mujid, Zehra Naqvi, Ariana Ray, Ce Liang, David A. Muller, Nathan P. Guisinger, Jiwoong Park
Controlling the spectral and polarization responses of two-dimensional (2D) crystals is vital for developing ultra-thin platforms for compact optoelectronic devices. However, independently tuning optical anisotropy and spectral response remains challenging in conventional semiconductors due to the intertwined nature of their lattice and electronic structures. Here, we report spectra-orthogonal optical anisotropy, where polarization anisotropy is tuned independently of spectral response, in wafer-scale, one-atom-thick 2D molecular crystal (2DMC) monolayers synthesized on monolayer transition metal dichalcogenide (TMD) crystals. Utilizing the concomitant spectral consistency and structural tunability of perylene derivatives, we demonstrate tunable optical polarization anisotropy in 2DMCs with similar spectral profiles, as confirmed by room-temperature scanning tunneling microscopy and cross-polarized reflectance microscopy. Additional angle-dependent analysis of the single- and polycrystalline molecular domains reveals an epitaxial relationship between the 2DMC and the TMD. Our results establish a scalable, molecule-based 2D crystalline platform for unique and tunable functionalities unattainable in covalent 2D solids.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)