CMP Journal 2025-01-03

Statistics

Physical Review Letters: 17

arXiv: 106

Physical Review Letters

Topologically Robust Quantum Network Nonlocality

Research article | Nonlocality | 2025-01-03 05:00 EST

Sadra Boreiri, Tamás Kriváchy, Pavel Sekatski, Antoine Girardin, and Nicolas Brunner

We discuss quantum network Bell nonlocality in a setting where the network structure is not fully known. More concretely, an honest user may trust their local network topology, but not the structure of the rest of the network, involving distant (and potentially dishonest) parties. We demonstrate that quantum network nonlocality can still be demonstrated in such a setting, hence exhibiting topological robustness. Specifically, we present quantum distributions obtained from a simple network that cannot be reproduced by classical models, even when the latter are based on more powerful networks. In particular, we show that in a large ring network, the knowledge of only a small part of the network structure (involving only two or three neighboring parties) is enough to guarantee nonlocality over the entire network. This shows that quantum network nonlocality can be extremely robust to changes in the network topology. Moreover, we demonstrate that applications of quantum nonlocality, such as the black-box certification of randomness and entanglement, are also possible in such a setting.

Phys. Rev. Lett. 134, 010202 (2025)

Nonlocality, Quantum correlations in quantum information, Quantum correlations, foundations & formalism, Quantum foundations

Orbital Angular Momentum Experiment Converting Contextuality into Nonlocality

Research article | Nonlocality | 2025-01-03 05:00 EST

Jianqi Sheng, Dongkai Zhang, and Lixiang Chen

It was recently revealed by Cabello in a theoretical Letter [Phys. Rev. Lett. 127, 070401 (2021)] that nonlocality and contextuality, as two intuitively distinctive yet both critical quantum resources, can be surprisingly connected through Bell inequalities associated with state-independent contextuality sets. It provides a general unified method capable of converting contextuality into bipartite nonlocality. However, experimental tests of the inequalities are challenging and noise sensitive, and the requirements for the quantum states purity, dimensionality, and degree of entanglement have blocked the experimental implementation. We report a first experimental test of Cabello's inequalities from state-independent contextuality sets, by leveraging two-photon high-dimensional orbital angular momentum entangled states. Distinguishing from the standard single-particle ways, our experiment spotlights that the state-independent contextuality sets can be tested in a bipartite scenario, by which the ''compatibility'' or ''sharpness'' loopholes can be effectively avoided. Our results provide a new perspective and demonstrate the principle that contextuality, a widely used quantum resource, can be used in different physical scenarios.

Phys. Rev. Lett. 134, 010203 (2025)

Nonlocality, Optical tests of quantum theory, Optical vortices, Quantum correlations, foundations & formalism

Research article | Kinetic theory | 2025-01-03 05:00 EST

Maciej Łebek and Miłosz Panfil

Navier-Stokes equations are shown to emerge from a generalized hydrodynamics description for nearly integrable 1D models.

Phys. Rev. Lett. 134, 010405 (2025)

Kinetic theory, 1-dimensional systems, Ultracold gases, Boltzmann theory, Hydrodynamics, Integrable systems

Experimental Realization of Direct Entangling Gates between Dual-Type Qubits

Research article | Quantum gates | 2025-01-03 05:00 EST

Chenxi Wang, Chuanxin Huang, Hongxuan Zhang, Hongyuan Hu, Zhichao Mao, Panyu Hou, Yukai Wu, Zichao Zhou, and Luming Duan

Dual-type qubits have become a promising way to suppress the crosstalk error of auxiliary operations in large-scale ion trap quantum computation. Here we demonstrate a direct entangling gate between dual-type qubits encoded in the and hyperfine manifolds of ions. Our scheme is economic in the hardware, requiring only a single 532 nm laser system to entangle both qubit types by driving their Raman transitions. We achieve a Bell state fidelity of 96.3(4)% for the dual-type Molmer-Sorensen gate between an ion pair, comparable to that for the same-type or gates. This technique can reduce the overhead for back-and-forth conversions between dual-type qubits in the quantum circuit with wide applications in quantum error correction and ion-photon quantum networks.

Phys. Rev. Lett. 134, 010601 (2025)

Quantum gates, Quantum information with trapped ions, Trapped ions

Multitwist Trajectories and Decoupling Zeros in Conformal Field Theory

Research article | Conformal field theory | 2025-01-03 05:00 EST

Alexandre Homrich, David Simmons-Duffin, and Pedro Vieira

Conformal Regge theory predicts the existence of analytically continued conformal field theory data for complex spin. How could this work when there are so many more operators with large spin compared to small spin? Using planar SYM as a test ground, we find a simple physical picture. Operators do organize themselves into analytic families but the continuation of the higher families have zeros in their structure operator product expansion constants for lower integer spins. They thus decouple. Newton's interpolation series technique is perfectly suited to this physical problem and will allow us to explore the complex spin half-plane.

Phys. Rev. Lett. 134, 011602 (2025)

Conformal field theory, Integrability in field theory

New Standard for the Logarithmic Accuracy of Parton Showers

Research article | Perturbative QCD | 2025-01-03 05:00 EST

Melissa van Beekveld, Mrinal Dasgupta, Basem Kamal El-Menoufi, Silvia Ferrario Ravasio, Keith Hamilton, Jack Helliwell, Alexander Karlberg, Pier Francesco Monni, Gavin P. Salam, Ludovic Scyboz, Alba Soto-Ontoso, and Gregory Soyez

We report on a major milestone in the construction of logarithmically accurate final-state parton showers, achieving next-to-next-to-leading-logarithmic (NNLL) accuracy for the wide class of observables known as event shapes. The key to this advance lies in the identification of the relation between critical NNLL analytic resummation ingredients and their parton-shower counterparts. Our analytic discussion is supplemented with numerical tests of the logarithmic accuracy of three shower variants for more than a dozen distinct event-shape observables in and decays. The NNLL terms are phenomenologically sizeable, as illustrated in comparisons to data.

Phys. Rev. Lett. 134, 011901 (2025)

Perturbative QCD, QCD phenomenology, Quark & gluon jets

Production and Stabilization of a Spin Mixture of Ultracold Dipolar Bose Gases

Research article | Bose gases | 2025-01-03 05:00 EST

Maxime Lecomte, Alexandre Journeaux, Julie Veschambre, Jean Dalibard, and Raphael Lopes

Mixtures of ultracold gases with long-range interactions are expected to open new avenues in the study of quantum matter. Natural candidates for this research are spin mixtures of atomic species with large magnetic moments. However, the lifetime of such assemblies can be strongly affected by the dipolar relaxation that occurs in spin-flip collisions. Here we present experimental results for a mixture composed of the two lowest Zeeman states of atoms, that act as dark states with respect to a light-induced quadratic Zeeman effect. We show that, due to an interference phenomenon, the rate for such inelastic processes is dramatically reduced with respect to the Wigner threshold law. Additionally, we determine the scattering lengths characterizing the -wave interaction between these states, providing all necessary data to predict the miscibility range of the mixture, depending on its dimensionality.

Phys. Rev. Lett. 134, 013402 (2025)

Bose gases, Cold atoms & matter waves, Dipolar atoms, Long-range interactions, Spinor Bose-Einstein condensates, Van der Waals interaction

Nonlinear Optics Using Intense Optical Coherent State Superpositions

Research article | High-order harmonic generation | 2025-01-03 05:00 EST

Th. Lamprou, J. Rivera-Dean, P. Stammer, M. Lewenstein, and P. Tzallas

Superpositions of coherent light states are vital for quantum technologies. However, restrictions in existing state preparation and characterization schemes, in combination with decoherence effects, prevent their intensity enhancement and implementation in nonlinear optics. Here, by developing a decoherence-free approach, we generate intense femtosecond-duration infrared coherent state superpositions (CSSs) with a mean photon number orders of magnitude higher than the existing CSS sources. We utilize them in nonlinear optics to drive the second harmonic generation process in an optical crystal. We experimentally and theoretically show that the nonclassical nature of the intense infrared CSS is imprinted in the second-order autocorrelation traces. Additionally, theoretical analysis shows that the quantum features of the infrared CSS are also present in the generated second harmonic. The findings introduce the optical CSS into the realm of nonlinear quantum optics, opening up new paths in quantum information science and quantum light engineering by creating nonclassical light states in various spectral regions via nonlinear up-conversion processes.

Phys. Rev. Lett. 134, 013601 (2025)

High-order harmonic generation, Quantum states of light

Narrowband Terahertz Emission from a Plasma Oscillator Imbedded in a Plasma Density Gradient

Research article | Laser-plasma interactions | 2025-01-03 05:00 EST

Manoj Kumar, Bernhard Ersfeld, Jaeho Lee, Dohyun Park, Seungyun Kim, Inhyuk Nam, Minseok Kim, Seongjin Jeon, Dino A. Jaroszynski, Hyyong Suk, and Min Sup Hur

A novel method is presented for generating radiation using the beat wave of a bifrequency laser pulse to excite plasma oscillations in a plasma slab that has a density gradient. The plasma wave is localized where it is excited resonantly and becomes a plasma oscillator that produces a beam of radially polarized, terahertz radiation. Particle-in-cell simulations and a theoretical analysis are used to demonstrate its main characteristics, such as its narrow bandwidth. The radiator should have useful applications including driving terahertz-band particle accelerators and for pump-probe experiments.

Phys. Rev. Lett. 134, 015001 (2025)

Laser-plasma interactions, Terahertz generation in plasmas, Laboratory plasma, Particle-in-cell methods

Stability and Mobility of Disconnections in Solute Atmospheres: Insights from Interfacial Defect Diagrams

Research article | Crystal structure | 2025-01-03 05:00 EST

Chongze Hu, Douglas L. Medlin, and Rémi Dingreville

This Letter explores the stability of disconnections (step-dislocation defects) at grain boundaries in binary alloys. We introduce interfacial defect diagrams, derived from atomistic simulations and segregation theory, to predict the stability of disconnections in the temperature-solute concentration phase space and relate it to governing segregation mechanisms. These diagrams reveal multiple stability regimes influenced by solute-induced clustering and pinning effects impacting the thermal migration of disconnections and offering insights into their thermodynamics and kinetic properties.

Phys. Rev. Lett. 134, 016202 (2025)

Crystal structure, Defects, Disclinations & dislocations, Doping effects, Line defects, Microstructure

Piezoresistivity as a Fingerprint of Ferroaxial Transitions

Research article | Electrical conductivity | 2025-01-03 05:00 EST

Ezra Day-Roberts, Rafael M. Fernandes, and Turan Birol

Recent progress in the understanding of the collective behavior of electrons and ions has revealed new types of ferroic orders beyond ferroelectricity and ferromagnetism, such as the ferroaxial state. The latter retains only rotational symmetry around a single axis and reflection symmetry with respect to a single mirror plane, both of which are set by an emergent electric toroidal dipole moment. Because of this unusual symmetry-breaking pattern, it has been challenging to directly measure the ferroaxial order parameter, despite the increasing attention this state has drawn. Here, we show that off-diagonal components of the piezoresistivity tensor (i.e., the linear change in resistivity under strain) transform the same way as the ferroaxial moments, providing a direct probe of such order parameters. We identify two new proper ferroaxial materials through a materials database search, and use first-principles calculations to evaluate the piezoconductivity of the double-perovskite , revealing its connection to ferroaxial order and to octahedral rotation modes.

Phys. Rev. Lett. 134, 016401 (2025)

Electrical conductivity, Landau theory, Perovskites, Density functional calculations, Group theory

Spin Correlations in the Parent Phase of

Research article | Electronic structure | 2025-01-03 05:00 EST

Hongliang Wo, Bingying Pan, Die Hu, Yu Feng, A. D. Christianson, and Jun Zhao

Elucidating spin correlations in the parent compounds of high-temperature superconductors is crucial for understanding superconductivity. We used neutron scattering to study spin correlations in , an insulating material with reduced electron carriers compared to its superconducting counterpart (), serving as the undoped parent compound. Our findings show a reduced total fluctuating moment in this insulator relative to FeSe and 122 iron pnictides, likely due to increased interlayer distances from intercalation, which enhance fluctuations and reduce the intensity of spin excitations. Moreover, we observed a V-shaped spin wavelike excitation dispersion, contrasting with the twisted hourglass pattern in the superconducting counterpart. Electron doping shifts spin excitation from point to an incommensurate position towards direction below 65 meV. This transition from V-shaped to hourglasslike dispersion, akin to behaviors in hole-doped cuprates, suggests a potential shared mechanism in magnetism and superconductivity across these diverse systems.

Phys. Rev. Lett. 134, 016501 (2025)

Electronic structure, Spin fluctuations, Superconductivity, Strongly correlated systems, Inelastic neutron scattering

Ultrafast Pseudomagnetic Fields from Electron-Nuclear Quantum Geometry

Research article | Electron-phonon coupling | 2025-01-03 05:00 EST

Lennart Klebl, Arne Schobert, Martin Eckstein, Giorgio Sangiovanni, Alexander V. Balatsky, and Tim O. Wehling

Recent experiments demonstrate precise control over coherently excited circular phonon modes using high-intensity terahertz lasers, opening new pathways towards dynamical, ultrafast design of magnetism in functional materials. While the phonon Zeeman effect enables a theoretical description of phonon-induced magnetism, it lacks efficient angular momentum transfer from the phonon to the electron sector. In this work, we put forward a coupling mechanism based on electron-nuclear quantum geometry, with the inverse Faraday effect as a limiting case. This effect is rooted in the phase accumulation of the electronic wave function under a circular evolution of nuclear coordinates. An excitation pulse then induces a transient level splitting between electronic orbitals that carry angular momentum. First-principles simulations on demonstrate that in parts of the Brillouin zone, this splitting between orbitals carrying angular momentum can easily reach 50 meV.

Phys. Rev. Lett. 134, 016705 (2025)

Electron-phonon coupling, Ferroelectricity, Light-induced magnetic effects, Magnetic coupling, Magneto-optical Kerr effect, Pseudo Jahn-Teller effect, Floquet systems, Perovskites, Density functional theory

Hall Mass and Transverse Noether Spin Currents in Noncollinear Antiferromagnets

Research article | Hall effect | 2025-01-03 05:00 EST

Luke Wernert, Bastián Pradenas, Oleg Tchernyshyov, and Hua Chen

Noncollinear antiferromagnets (AFMs) have recently attracted attention in the emerging field of antiferromagnetic spintronics because of their various interesting properties. Because of the noncollinear magnetic order, the localized electron spins on different magnetic sublattices are not conserved even when spin-orbit coupling is neglected, making it difficult to understand the transport of spin angular momentum. Here we study the conserved Noether current due to spin-rotation symmetry of the local spins in noncollinear AFMs. Interestingly, we find that a Hall component of the spin current can be generically created by a longitudinal driving force associated with a propagating spin wave, inherently distinguishing noncollinear AFMs from collinear ones. We coin the corresponding Hall coefficient, an isotropic rank-four tensor, as the Hall (inverse) mass, which generally exists in noncollinear AFMs and their polycrystals. The resulting Hall spin current can be realized by spin pumping in a ferromagnet-noncollinear AFM bilayer structure as we demonstrate numerically, for which we also give the criteria of ideal boundary conditions. Our results shed light on the potential of noncollinear AFMs in manipulating the polarization and flow of spin currents in general spintronic devices.

Phys. Rev. Lett. 134, 016706 (2025)

Hall effect, Spin current, Spintronics, Noncollinear magnets

X-Ray Diffraction Reveals the Consequences of Strong Deformation in Thin Smectic Films: Dilation and Chevron Formation

Research article | Conformation & topology | 2025-01-03 05:00 EST

Jean de Dieu Niyonzima, Haifa Jeridi, Lamya Essaoui, Caterina Tosarelli, Alina Vlad, Alessandro Coati, Sebastien Royer, Isabelle Trimaille, Michel Goldmann, Bruno Gallas, Doru Constantin, David Babonneau, Yves Garreau, Bernard Croset, Samo Kralj, Randall D. Kamien, and Emmanuelle Lacaze

A combination of nonlinear theory and x-ray diffraction experiments of smectic liquid crystals reveals the need for a nonlinear energy term to correctly describe the spacing of smectic layers.

Phys. Rev. Lett. 134, 018101 (2025)

Conformation & topology, Distortions & defects, Liquid crystals, Smectic liquid crystals, Thermotropic liquid crystals, Grazing-incidence small-angle x-ray scattering, X-ray diffraction

Colloidal Crystallization on Cones

Research article | Crystal defects | 2025-01-03 05:00 EST

Jessica H. Sun, Grace H. Zhang, Abigail Plummer, Caroline Martin, Nabila Tanjeem, David R. Nelson, and Vinothan N. Manoharan

On conical surfaces with sufficiently small cone angle, dislocations allow colloidal crystals to grow beyond the point of geometric frustration.

Phys. Rev. Lett. 134, 018201 (2025)

Crystal defects, Crystal growth, Crystal orientation, Crystal phenomena, Crystal structure, Crystallization, Depletion interactions, Elastic deformation, Self-assembly

Evolving Motility of Active Droplets is Captured by a Self-Repelling Random Walk Model

Research article | Diffusiophoresis | 2025-01-03 05:00 EST

Wenjun Chen, Adrien Izzet, Ruben Zakine, Eric Clément, Eric Vanden-Eijnden, and Jasna Brujic

In living matter, concentration gradients of nutrients carve the motility of microorganisms in a heterogeneous environment. Here, we use swimming droplets as a model system to study how swimmer-trail interactions guide locomotion. Combining experiments and theory, we show that our non-Markovian droplet model quantitatively captures droplet motility. The two fit parameters provide the first estimate of the effective temperature arising from hydrodynamic flows and the coupling strength of the propulsion force. This framework is general and explains memory effects, droplet hovering, and enhanced collective motion.

Phys. Rev. Lett. 134, 018301 (2025)

Diffusiophoresis, Living matter & active matter, Nonequilibrium statistical mechanics, Random walks, Self-avoiding walks, Stochastic processes

arXiv

A Functional Human Liver Tissue Model: 3D Bioprinted Co-culture Discoids

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Vignesh Subramaniam, Carolina Abrahan, Brett Higgins, Steven J. Chisolm, Baleigh Sweeney, Senthilkumar Duraivel, Leandro Balzano-Nogueira, Glyn D. Palmer, Thomas E. Angelini

To reduce costs and delays related to developing new and effective drugs, there is a critical need for improved human liver tissue models. Here we describe an approach for 3D bioprinting functional human liver tissue models, in which we fabricate disc-shaped structures (discoids) 200 {}m in thickness and 1-3 mm in diameter, embedded in a highly permeable support medium made from packed microgels. We demonstrate that the method is precise, accurate, and scalable; up to 100 tissues per hour can be manufactured with a variability and error in diameter of about 4%. Histologic and immunohistochemical evaluation of printed discs reveal self-organization, cell cohesion, and key liver marker expression. During the course of 3-4 weeks in culture, the tissues stably synthesize albumin and urea at high levels, outperforming spheroid tissue models. We find the tissues express more than 100 genes associated with molecular absorption, distribution, metabolism, and excretion (ADME) at levels within the range of human liver. The liver tissue models exhibit enzymatic formation of metabolites after exposure to multiple test compounds. Together, these results demonstrate the promise of 3D printed discoids for pharmacological and toxicological applications.

arXiv:2501.00086 (2025)

Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Tissues and Organs (q-bio.TO)

34 pages, 7 figures, 2 supplementary figures

Theory of superconducting proximity effect in hole-based hybrid semiconductor-superconductor devices

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

D. Michel Pino, Rubén Seoane-Souto, Maria José Calderón, Ramón Aguado, José Carlos Abadillo-Uriel

Hybrid superconductor-semiconductor systems have received a great deal of attention in the last few years because of their potential for quantum engineering, including novel qubits and topological devices. The proximity effect, the process by which the semiconductor inherits superconducting correlations, is an essential physical mechanism of such hybrids. Recent experiments have demonstrated the proximity effect in hole-based semiconductors, but, in contrast to electrons, the precise mechanism by which the hole bands acquire superconducting correlations remains an open question. In addition, hole spins exhibit a complex strong spin-orbit interaction, with largely anisotropic responses to electric and magnetic fields, further motivating the importance of understanding the interplay between such effects and the proximity effect. In this work, we analyze this physics with focus on germanium-based two-dimensional gases. Specifically, we develop an effective theory supported by full numerics, allowing us to extract various analytical expressions and predict different types of superconducting correlations including non-standard forms of singlet and triplet pairing mechanisms with non-trivial momentum dependence; as well as different Zeeman and Rashba spin-orbit contributions. This, together with their precise dependence on electric and magnetic fields, allows us to make specific experimental predictions, including the emergence of f-type superconductivity, Bogoliubov Fermi surfaces, and gapless regimes caused by large in-plane magnetic fields.

arXiv:2501.00088 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)

13 pages, 9 figures, plus Appendices

Evidence for a Dirac spin liquid in the generalized Shastry-Sutherland model

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Atanu Maity, Francesco Ferrari, Jong Yeon Lee, Janik Potten, Tobias Müller, Ronny Thomale, Rhine Samajdar, Yasir Iqbal

We present a multimethod investigation into the nature of the recently reported quantum spin liquid (QSL) phase in the spin- Heisenberg antiferromagnet on the Shastry-Sutherland lattice. A comprehensive projective symmetry group classification of fermionic mean-field Ansätze on this lattice yields 46 U(1) and 80 states. Motivated by density-matrix renormalization group (DMRG) calculations suggesting that the Shastry-Sutherland model and the square-lattice - Heisenberg antiferromagnet putatively share the same QSL phase, we establish a mapping of our Ansätze to those of the square lattice. This enables us to identify the equivalent of the square-lattice QSL (Z2A13) in the Shastry-Sutherland system. Employing state-of-the-art variational Monte Carlo calculations with Gutzwiller-projected wavefunctions improved upon by Lanczos steps, we demonstrate the excellent agreement of energies and correlators between a gapless (Dirac) spin liquid -- characterized by only few parameters -- and approaches based on neural quantum states and DMRG. Furthermore, the real-space spin-spin correlations are shown to decay with the same power law as in the - square lattice model, which also hosts a Dirac spin liquid. Finally, we apply the recently developed Keldysh formulation of the pseudo-fermion functional renormalization group to compute the dynamical spin structure factor; these correlations exhibit the features expected due to Dirac cones in the excitation spectrum, thus providing strong independent evidence for a Dirac QSL ground state. Our finding of a -wave pairing Dirac QSL is consistent with the recently observed signatures of QSL behavior in PrGaBeO and outlines predictions for future experiments.

arXiv:2501.00096 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)

36 pages, 18 figures, 12 tables

Quantum Geometry in Quantum Materials

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Jiabin Yu, B. Andrei Bernevig, Raquel Queiroz, Enrico Rossi, Päivi Törmä, Bohm-Jung Yang

Quantum geometry, characterized by the quantum geometric tensor, is pivotal in diverse physical phenomena in quantum materials. In condensed matter systems, quantum geometry refers to the geoemtric properties of Bloch states in the Brillouin zone. This pedagogical review provides an accessible introduction to the concept of quantum geometry, emphasizing its extensive implications across multiple domains. Specifically, we discuss the role of quantum geometry in optical responses, Landau levels, and fractional Chern insulators, as well as its influence on superfluid weight, spin stiffness, exciton condensates, electron-phonon coupling, etc. By integrating these topics, we underscore the pervasive significance of quantum geometry in understanding emergent behaviors in quantum materials. Finally, we present an outlook on open questions and potential future directions, highlighting the need for continued exploration in this rapidly developing field.

arXiv:2501.00098 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)

26+6 pages, 6+1 figures

Universal Wilson loop Bound of Quantum Geometry: Bound and Physical Consequences

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Jiabin Yu, Jonah Herzog-Arbeitman, B. Andrei Bernevig

We define the absolute Wilson loop winding and prove that it bounds the quantum metric from below. This Wilson loop lower bound naturally reproduces the known Chern and Euler bounds of the quantum metric, and provides an explicit lower bound of the quantum metric due to the time-reversal protected index, answering a hitherto open question. In general, the Wilson loop lower bound can be applied to any other topological invariants characterized by Wilson loop winding, such as the particle-hole index. As physical consequences of the bound, we show that the time-reversal index bounds superfluid weight and optical conductivity from below, and bounds the direct gap of a band insulator from above.

arXiv:2501.00100 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)

6+16 pages, 2+2 figures

First-principles determination of refractory binary alloy mechanical properties for the microscopic design of complex structural materials

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Surya T. Bijjala, Susan R. Atlas, Pankaj Kumar

The elastic tensor provides valuable insight into the mechanical behavior of a material with lattice strain, such as disordered binary alloys. Density functional theory (DFT)-based methods provide a powerful mechanism for computing and probing the microscopic features of elastic tensor-related properties. Here we present results for the rigid-ion and relaxed-ion elastic tensors computed using density functional perturbation theory (DFPT), for a comprehensive set of structural refractory body-centered cubic (BCC) binary alloys of molybdenum (Mo), niobium (Nb), tantalum (Ta), and tungsten (W). Intermediate quantities (force-response internal-strain tensor, , and displacement-response internal-strain tensor, ) needed to compute the relaxed-ion elastic tensor are used here to map heterogeneity in elastic constants at each lattice site in a given alloy and associated relaxation fields. Derived polycrystalline aggregate properties -- the bulk modulus (), shear modulus (), Young's modulus (), and Poisson's ratio () and elastic anisotropy -- are reported as a function of composition for all binaries. Pugh's ratio () and the Cauchy pressure () derived from computed elastic moduli are analyzed in order to evaluate the effect of alloying on the mechanical properties of the refractory BCC binary alloys. The computed mechanical properties data for the parent unary materials and binary alloys at systematically-varied Mo, Nb, Ta, and W compositions are in excellent agreement with available experimental data. These results, together with computed microscopic field data, establish a foundation for the principled design of compositionally-complex, high-temperature-structural refractory alloys with desired elastic properties.

arXiv:2501.00127 (2025)

Materials Science (cond-mat.mtrl-sci)

26 pages 16 figures

Roles of Structural Coordination and Strain Orientation in the Phase Stability of Ferroelectric HfO

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Adedamola D. Aladese, Xiao Shen

Phase stabilization continues to be a critical issue in hafnium oxide (HfO) due to the interdependence of various contributing factors. Using first-principles calculations, we analyze the effects of strain and doping on stabilizing the ferroelectric phase. We found that combining Y-doping, O-vacancy, and compressive biaxial strain, particularly in the (111) orientation, offers an optimal pathway for stabilizing the ferroelectric phase of HfO. Analysis of structural coordination reveals how compressive strain affects phase competition. Crystallography analysis provides insights into the advantage of the (111) strain orientation compared to the (001) orientation. The impact of dopants is discussed in the context of these findings.

arXiv:2501.00132 (2025)

Materials Science (cond-mat.mtrl-sci)

Effective Lagrangian for the macroscopic motion of Weyl fermions in He-A

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

M. Selch, M. A. Zubkov

We consider macroscopic motion of He-A in global thermodynamic equilibrium within the context of the Zubarev statistical operator method. We formulate the corresponding effective theory in the language of the functional integral. The effective Lagrangian comprising macroscopic motion of fermionic excitations is calculated explicitly for the emergent relativistic fermions of the superfluid He-A-phase in the non-trivial bosonic background due to a space and time dependent matrix-valued vierbein featuring nonzero torsion as well as the Nieh-Yan anomaly. The matrix-valued vierbein formulation comprises an additional two dimensional internal spin space which may be replaced by one featuring a fermionic theory with a real valued vierbein, two Abelian gauge fields and a spin connection mixing the Dirac and internal spin spaces. As an application of the developed theory we consider macroscopic rotation around the axis of the pure integer mass vortices. The corresponding thermodynamical quantities of the normal component are analysed.

arXiv:2501.00151 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Latex, 48 pages, 5 figures

Theoretical Investigation of Yield-Enhancing Equilibrium Sn Preparation Pathways in N-Doped Diamond

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Aditya Bahulikar, Steven L. Richardson, Rodrick Kuate Defo

The elucidation of the mechanism of Sn formation in diamond is especially important as the Sn color center has the potential to be a superior single-photon emitter when compared to the N and to other Group IV color centers. The typical formation of the Sn involves placing Sn in diamond by ion implantation, but the formation of a charged Sn species requires an additional complication. This complication is related to the energy cost associated with electronic transitions within the host diamond. Effectively, producing the Sn charge state using an electron obtained from a band edge of the host diamond is less energetically favorable than having the Sn receive an electron from a neighboring donor dopant. Among donor dopants, substitutional N (N) is always present in even the purest synthetic or natural diamond sample. The mechanism of electron donation by N has been proposed by Collins for charging the N in diamond and it has been used to interpret many experimental results. Therefore, in this paper we use DFT to explore the pathways for the formation of the Sn charge state due to electron donation arising from the presence of N in the host diamond. Explicitly, defect concentrations are calculated in equilibrium in each of the explored pathways to determine the yield of the Sn throughout each of the pathways. The importance of our work is to suggest experimental ways of enhancing the yield of charged states like the Sn in diamond for transformative applications in optoelectronics and quantum information.

arXiv:2501.00177 (2025)

Materials Science (cond-mat.mtrl-sci)

Angstrom-scale ionic streaming when electrical double-layer concept fails

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Jiajia Lu (1), Shuyong Luan (2), Shenghui Guo (1), Libing Duan (1), Guanghua Du (3), Yanbo Xie (2) ((1) School of Physical Science and Technology, Northwestern Polytechnical University, Xi an, China (2) National Key Laboratory of Aircraft Configuration Design, School of Aeronautics and Institute of Extreme Mechanics, Northwestern Polytechnical University, Xi an, China (3) Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China)

A knowledge gap exists for flows and transport phenomena at the Angstrom scale when the Poisson Nernst Planck equation based on the concept of electrical double layer (EDL) fails. We discovered that streaming conductance becomes pressure dependent in Angstrom channels using latent track membranes. The streaming current emerges only when the applied pressure exceeds a threshold value, which is inconsistent with the existing knowledge as a constant. With increasing channel size, we found that the pressure dependent streaming conductance phenomenon weakens and vanishes into a constant streaming conductance regime when the mean channel radius exceeds 2 nm. The effective surface potential derived from the stream conductance that divides conduction anomalously increases as the channel narrows. We suspect the pressure dependent streaming current is due to the reinforced Coulomb interaction between counterions and deprotonated carboxyl groups at the surface, which is close to the ion channel but different from the electrified 2D materials. The streaming current emerged due to hydrodynamic friction when the counterions were released from the surface. We approximated the stochastic process of counterion dissociation by 1D Kramer escape theory framework and defined the Damkohler Number to describe the transition from nonlinear streaming conductance regime to linear regime as functions of applied pressure and channel radius and well explained the enhanced effective surface potential in confinement.

arXiv:2501.00238 (2025)

Soft Condensed Matter (cond-mat.soft)

Spectra of Magnetoroton and Chiral Graviton Modes of Fractional Chern Insulator

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Min Long, Hongyu Lu, Han-Qing Wu, Zi Yang Meng

Employing the state-of-the-art time-dependent variational principle algorithm, we compute the spectra of charge neutral excitations in the fractional Chern insulator (FCI) on the Haldane honeycomb lattice model with hard-core bosons. The magnetoroton visualized from the dynamic density structure factor, acquire a minimum gap at finite momentum that can go soft with increasing interaction and give rise to a charge density wave (CDW) at the same wavevector. The sharper and more concentrated spectral weight of the roton mode is observed when approaching the FCI-CDW transition while the single-particle gap remains intact. We also resolve the graviton mode around point of the Brillouin zone by measuring the dynamic quadrupolar density correlations. Interestingly, we not only reveal the graviton response is chiral for a certain FCI, but also show the different chiralities of the graviton of opposite-sign Hall conductance for the first time. Our results offer the clear spectral observations of magnetoroton and chiral graviton in a lattice model of FCI and will have relevance towards the on-going experiments of tunable FCIs in quantum moiré materials.

arXiv:2501.00247 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)

5+5pages, 4+8 figures

Pairing correlation of the Kagome-lattice Hubbard model with the nearest-neighbor interaction

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Chen Yang, Chao Chen, Runyu Ma, Ying Liang, Tianxing Ma

A recently discovered family of Kagome lattice materials, (= ), has attracted great interest, especially in the debate over its dominant superconducting pairing symmetry. To explore this issue, we study the superconducting pairing behavior within the Kagome-Hubbard model through the constrained path Monte Carlo method. It is found that doping around the Dirac point generates a dominant next-nearest-neighbour- pairing symmetry driven by on-site Coulomb interaction . However, when considering the nearest-neighbor interaction , it may induce nearest-neighbor- pairing to become the preferred pairing symmetry. Our results provide useful information to identify the dominant superconducting pairing symmetry in family.

arXiv:2501.00251 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

Chinese Phys. B 33, 107404(2024)

Two-dimensional moir'{e} phonon polaritons

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Hao Shi, Chu Li, Ding Pan, Xi Dai

Phonon polaritons are hybrid modes combining lattice dynamics and electromagnetic waves. Their behavior at long wavelengths is effectively described by Huang's equations. Here, we investigate phonon polaritons within 2D materials featuring twisted moiré structures. The interaction between electromagnetic waves and phonons of varying wavelengths gives rise to rich polaritons with moiré characteristics. We observe the polariton dividing into multiple branches, akin to coupled oscillators. Through numerical simulations based on realistic lattice models, we confirm the existence of these intriguing modes. A distinctive trait of moiré polar crystals is their spatially varying near-field response, offering robust signals for the experimental confirmation.

arXiv:2501.00313 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)

27 pages, 7 figures

Magneto-optical response of Dynes superconductors

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-03 00:00 EST

Michal Šindler, František Herman, Filip Kadlec, Christelle Kadlec

We investigate the terahertz conductivity of conventional superconductors in Voigt and Faraday magneto-optical configurations. In the Voigt geometry, an ultrathin superconducting film is fully penetrated by the magnetic field which interacts with the spin, thus modifying the magnitudes of the optical gap and of the density of the condensate. We provide an alternative interpretation of the recent experiments showing the gapless conductivity of a Nb film measured by Lee et al. [1] which describes better their data for magnetic field above 1 T. In the Faraday geometry, we analyze the terahertz conductivity of three NbN films with varying thicknesses using the Maxwell-Garnett model, treating vortices as normal-state inclusions within a superconducting matrix. Moreover, we effectively account for ubiquitous pair-conserving and magnetic-field-dependent pair-breaking disorder scattering processes using the model of Herman and Hlubina [2].

arXiv:2501.00325 (2025)

Superconductivity (cond-mat.supr-con)

7 pages, 5 figures

Spin waves in magnetic nanodisks, nanorings, and 3D nanovolcanoes

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Oleksandr Dobrovolskiy, Gleb Kakazei

Patterned magnetic nanostructures are advanced materials characterized by their unique magnetic properties at the nanoscale, which are the result of tailored geometric configurations and compositional engineering. As interest in nanotechnology continues to grow exponentially, the exploration of patterned magnetic nanostructures turns into a vibrant and critical area of study for both industry professionals and academic researchers. Here, we review investigations of standing spin waves (collective spin precessions) in magnetic elements by the technique of ferromagnetic resonance (FMR). The presentation encompasses earlier studies of arrays of magnetic nanodisks and nanoringes by cavity-based FMR as well as more recent studies of individual nanodisks and 3D nanovolcanoes by a broadband FMR method which implies the use of a coplanar waveguide. Overall, the manuscript outlines the development of FMR studies along the two major lines: (i) downscaling from multiple to individual magnetic nanoelements and (ii) extending planar nanomagnets into the third dimension.

arXiv:2501.00333 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)

20 pages, 7 figures, 150 references

The simplest spin glass revisited: finite-size effects of the energy landscape can modify aging dynamics in the thermodynamic limit

New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-03 00:00 EST

Bin Li, Yuliang Jin

The random energy model is one of the few glass models whose asymptotic activated aging dynamics are solvable. However, the existing aging theory, i.e., Bouchaud's trap model, does not agree with dynamical simulation results obtained in finite-sized systems. Here we show that this discrepancy originates from non-negligible finite-size corrections in the energy barrier distributions. The finite-size effects add a logarithmic decay term in the time-correlation aging function, which destroys the asymptotic large-time plateau predicted by Bouchaud's trap model in the spin glass phase. Surprisingly, the finite-size effects also give corrections, preserved even in the thermodynamic limit, to the value of the asymptotic plateau. It results in an unexpected dynamical transition where weak ergodicity breaking occurs, at a temperature above the thermodynamic spin-glass transition temperature . Based on the barrier distributions obtained by a numerical barrier-tree method and an expansion theory, we propose a generalized trap model to incorporate such finite-size effects. The theoretically derived aging behavior of the generalized trap model explains the Monte-Carlo dynamical simulation data of random energy models with Gaussian and exponential random energies. Our results suggest that the double limits of large system size and long time are not interchangeable for the activated aging dynamics.

arXiv:2501.00338 (2025)

Disordered Systems and Neural Networks (cond-mat.dis-nn)

19 pages, 20 figures

Density of electronic states in density-wave compounds with imperfect nesting

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

A. V. Tsvetkova, Ya. I. Rodionov, P. D. Grigoriev

We study the effects of imperfect nesting in a simple 2D tight-binding model on the electronic properties in the density-wave (DW) state. The discussed model reflects the main features of quasi-1D metals, where the DW emerges. We show that an imperfect nesting leads to unusual singularities in the quasi-particle density of states, leading to a strong renormalization of the superconducting critical temperature. We also compute the conductivity tensor of the normal state and obtain a satisfactory agreement with the experimental data on rare-earth tritellurides and many other DW materials.

arXiv:2501.00341 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Observation of nonreciprocal transverse localization of light

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Shun Liang, Changchang Li, Wenqing Yu, Zhenzhi Liu, Changbiao Li, Yanpeng Zhang, Guillaume Malpuech, Dmitry Solnyshkov, Hui Jing, Zhaoyang Zhang

Magnetic-free nonreciprocal optical devices that can prevent backscattering of signals are essential for integrated optical information processing. The achieved nonreciprocal behaviors mostly rely on various dispersive effects in optical media, which give rise to dispersive modulations of the transverse beam profile, such as spatial broadening and discretization, of the incident signals. Such deformation inevitably reduces the matching with subsequent components for information processing. Here we experimentally demonstrate the nonreciprocal transverse localization of light in a moiré photonic lattice induced in atomic vapors. When the probe field is set to co- or counter-propagate with the coupling field formed by superposing two identical honeycomb beams in a certain rotation angle, the output pattern can exhibit localized or dispersive behavior. The localization in the forward case is derived from the moiré structure, and the nonreciprocal behaviors (in both beam size and transmitted intensity) are introduced by the thermal motion of atoms. The thermal-motion-induced Doppler effect can destroy the coherent condition for electromagnetically induced transparency in the backward case, because of which the probe beam becomes immune to the modulation of the coupling field. The current work provides an approach to control the transverse beam profile in one-way transmission.

arXiv:2501.00347 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)

Topic Review: Hatsugai-Kohmoto models: Exactly solvable playground for Mottness and Non-Fermi Liquid

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Miaomiao Zhao, Wei-Wei Yang, Yin Zhong

This pedagogic review aims to give a gentle introduction to an exactly solvable model, the Hatsugai-Kohmoto (HK) model, which has infinite-ranged interaction but conserves the center of mass. Although this model is invented in 1992, intensive studies on its properties ranging from unconventional superconductivity, topological ordered states to non-Fermi liquid behaviors are made since 2020. We focus on its emergent non-Fermi liquid behavior and provide discussion on its thermodynamics, single-particle and two-particle correlation functions. Perturbation around solvable limit has also been explored with the help of perturbation theory, renormalization group and exact diagonalization calculation. We hope the present review will be helpful for graduate students or researchers interested in HK-like models or more generic strongly correlated electron systems.

arXiv:2501.00388 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

Alternative harmonic detection approach for quantitative determination of spin and orbital torques

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Y. Xu, B. Bony, S. Krishnia, R. Torrão Victor, S. Collin, A. Fert, J.-M. George, V. Cros, H. Jaffrès

In this study, the spin-orbit torque (SOT) in light metal oxide systems is investigated using an experimental approach based on harmonic Hall voltage techniques in out-of-plane (OOP) angular geometry for samples with in-plane magnetic anisotropy. In parallel, an analytical derivation of this alternative OOP harmonic Hall detection geometry has been developed, followed by experimental validation to extract SOT effective fields. In addition, to accurately quantifying SOT, this method allows complete characterization of thermoelectric effects, opening promising avenues for accurate SOT characterization in related systems. In particular, this study corroborates the critical role of naturally oxidized copper interfaced with metallic Cu in the generation of orbital current in Co(2)|Pt(4)|CuOx(3), demonstrating a two-fold increase in damping-like torques compared to a reference sample with an oxidized Al capping layer. These findings offer promising directions for future research on the application aspect of non-equilibrium orbital angular momentum.

arXiv:2501.00403 (2025)

Materials Science (cond-mat.mtrl-sci)

15 pages, 4 figures, 44 references

Nematic liquid crystal flow driven by time-varying active surface anchoring

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Seyed Reza Seyednejad, Miha Ravnik

We demonstrate the generation of diverse material flow regimes in nematic liquid cells as driven by time-variable active surface anchoring, including no-net flow, oscillatory flow, steady flow, and pulsating flow. Specifically, we numerically simulate a passive nematic fluid inside a cell bounded with two flat solid boundaries at which the time-dependent anchoring is applied with the dynamically variable surface anchoring easy axis. We show that different flow regimes emerge as the result of different anchoring driving directions (i.e. co-rotating or counter-rotating) and relative phase of anchoring driving. The flow magnitude is tunable by cell thickness and anchoring driving frequency. More generally, this work aims towards possible applications of responsive time-variable surfaces, including photonics or synthetic active matter.

arXiv:2501.00407 (2025)

Soft Condensed Matter (cond-mat.soft)

Majorana Flat Bands in the Vortex Line of Superconducting Weyl Semimetals

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-03 00:00 EST

Zhicheng Zhang, Kou-Han Ma

We find that there exist Majorana flat bands (MFBs) in the vortex line of superconducting (SC) Weyl semimetals which break time reversal symmetry. Since a Weyl semimetal can be regarded as Chern insulators stacked along one (z) direction, so we decompose the vortex bound states of SC Weyl semimetals into the vortex bound states of SC Chern insulators labelled by kz. After calculating the topological phase diagram of the SC Chern insulators both analytically and numerically, we can explain the appearance of MFBs and determine the exact boundaries of them in SC Weyl semimetals. What's more, tuning the chemical potential or the pairing strength can result in the MFBs along the whole kz axis. Based on the above understanding, we propose a kz-dependent Z2 Chern-Simons invariant to characterize the MFBs. Finally, if we further consider an attractive Hubbard interaction, the aforementioned SC Weyl semimetal and MFBs can be realized under appropriate parameters.

arXiv:2501.00410 (2025)

Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

12 pages, 4+2 figures

Clifford circuits Augmented Matrix Product States for fermion systems

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Jiale Huang, Xiangjian Qian, Mingpu Qin

Clifford circuits Augmented Matrix Product States (CAMPS) was recently proposed to leverage the advantages of both Clifford circuits and Matrix Product States (MPS). Clifford circuits can support large entanglement and can be efficiently simulated classically according to the Gottesman-Knill theorem. So in CAMPS, MPS needs only to handle the so-called Non-stabilizerness Entanglement Entropy which significantly improves the simulation accuracy for a given bond dimension. In this work, we generalize CAMPS to study the Fermion system by taking advantage of the Jordan-Wigner transformation which can map the studied Fermion system to a spin system. We benchmark the method on both the spinless model and the spinful Hubbard model. Our test results show significant improvement of the accuracy of CAMPS over MPS, especially when the interactions are strong. Fermionic CAMPS provides a useful tool for the accurate study of many-body fermion systems in the future and has the potential to help resolve long-standing issues.

arXiv:2501.00413 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)

Cavity-mediated hybridization of several molecules in the strong coupling regime

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Jahangir Nobakht, André Pscherer, Jan Renger, Stephan Götzinger, Vahid Sandoghdar

Molecular complexes are held together via a variety of bonds, but they all share the common feature that their individual entities are in contact. In this work, we introduce and demonstrate the concept of a , resulting from the far-field electromagnetic coupling of several molecules via a shared mode of an optical microcavity. We discuss a collective enhancement of the vacuum Rabi splitting and study super- and sub-radiant states that arise from the cavity-mediated coupling both in the resonant and dispersive regimes. Moreover, we demonstrate a two-photon transition that emerges between the ground and excited states of the new optical compound. Our experimental data are in excellent agreement with the predictions of the Tavis-Cummings Hamiltonian and open the door to the realization of hybrid light-matter materials.

arXiv:2501.00414 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Defect-mediated electron-phonon coupling in halide double perovskite

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Aprajita Joshi, Sajid Saikia, Shalini Badola, Angshuman Nag, Surajit Saha

Optically active defects often play a crucial role in governing the light emission as well as the electronic properties of materials. Moreover, defect-mediated states in the mid-gap region can trap electrons, thus opening a path for the recombination of electrons and holes in lower energy states that may require phonons in the process. Considering this, we have probed electron-phonon interaction in halide perovskite systems with the introduction of defects and investigated the thermal effect on this interaction. Here, we report Raman spectroscopy study of the thermal evolution of electron-phonon coupling, which is tunable with the crystal growth conditions, in the halide perovskite systems Cs2AgInCl6 and Cs2NaInCl6. The signature of electron-phonon coupling is observed as a Fano anomaly in the lowest frequency phonon mode (51 cm-1) which evolves with temperature. In addition, we observe a broad band in the photoluminescence (PL) measurements for the defect-mediated systems, which is otherwise absent in defect-free halide perovskite. The simultaneous observation of the Fano anomaly in the Raman spectrum and the emergence of the PL band suggests the defect-mediated mid-gap states and the consequent existence of electron-phonon coupling in the double perovskite.

arXiv:2501.00423 (2025)

Materials Science (cond-mat.mtrl-sci)

16 pages, 9 figures, Accepted in Applied Physics Letters

The Physics of Quantum 2.0: Challenges in understanding Quantum Matter

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Siddhartha Lal, Mayank Shreshtha

Almost a century on from the culmination of the first revolution in quantum physics, we are poised for another. Even as we engage in the creation of impactful quantum technologies, it is imperative for us to face the challenges in understanding the phenomenology of various emergent forms of quantum matter. This will involve building on decades of progress in quantum condensed matter physics, and going beyond the well-established Ginzburg-Landau-Wilson paradigm for quantum matter. We outline and discuss several outstanding challenges, including the need to explore and identify the organisational principles that can guide the development of theories, key experimental phenomenologies that continue to confound, and the formulation of methods that enable progress. These efforts will enable the prediction of new quantum materials whose properties facilitate the creation of next generation technologies.

arXiv:2501.00447 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)

9 pages, 3 figures, 27 references

Nano Futures 8 (2024) 042502

Deterministic role of chemical bonding in the formation of altermagnetism: Reflection from correlated electron system NiS

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Arijit Mandal, Arindom Das, B.R.K. Nanda

Altermagnetism, a new collinear magnetic state that has traits of both ferromagnetism and antiferromagnetism, has gained significant attention in the last few years and the underlying mechanisms driving this quantum phase are still evolving. Going beyond the phenomenological models and group theoretical analyses, which focus on providing a binary explanation of the presence or absence of the altermagnetic state, in this work, we explored the role of crystal chemical bonding. As the latter successfully integrates the crystal and orbital symmetries and is tunable, it provides a quantitative and more realistic mechanism to explain the formation of altermagnetism. From the first principle calculations and tight-binding models within the framework of the linear combination of atomic orbitals on NiS, belonging to the hexagonal NiAs family (e.g. CrSb, MnTe, etc.), we reveal that the second neighbor interaction between the orbitals of the non-magnetic atoms is the most deterministic in inducing altermagnetism. These second-neighbor bondings modulate the intra-sublattice interactions differently for the opposite spin sublattices. As a consequence, the antiferromagnetic sublattice band degeneracy is lifted and it results in momentum dependent altermagnetic spin split (ASS). We further reveal that the strong altermagnetism is observed in these materials due to the participation of multiple and selective orbitals, both from Ni and S, in the chemical bonding. We proposed twelve antinodal regions in the NiAs type hexagonal crystals, where ASS split is maximum. Specific to NiS, ASS increases with correlation, and for the edge valence and conduction bands it can go beyond 1eV, which makes this compound ideal for carrying out altermagnetic experiments and for exploring non-trivial quantum transport through electron and hole doping. The present study opens up new pathways to tailor tunable altermagnetism.

arXiv:2501.00453 (2025)

Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)

12 pages, 10 figures, and 6 tables

Non-perturbative self-consistent electron-phonon spectral functions and transport

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Jae-Mo Lihm, Samuel Poncé

Electron-phonon coupling often dominates the electron spectral functions and carrier transport properties. However, studies of this effect in real materials have largely relied on perturbative one-shot methods due to the lack of a first-principles theoretical and computational framework. Here, we present a self-consistent theory and implementation for the non-perturbative calculations of spectral functions and conductivity due to electron-phonon coupling. Applying this method to monolayer InSe, we demonstrate that self-consistency qualitatively affects the spectral function and transport properties compared to state-of-the-art one-shot calculations and allow one to reconcile experimental angle-resolved photoemission experiments. The developed method can be widely applied to materials with dominant electron-phonon coupling at moderate computational cost.

arXiv:2501.00468 (2025)

Materials Science (cond-mat.mtrl-sci)

On the Wiedemann-Franz law violation in Graphene and quark-gluon plasma systems

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Ashutosh Dwibedi, Subhalaxmi Nayak, Sathe Subodh Kiran, Sabyasachi Ghosh, Sesha Vempati

A comparative study of the thermodynamic and transport properties of the ultra-relativistic quark-gluon plasma (QGP) produced in Heavy ion collisions (HIC) with the "quasi-relativistic" massless electron-hole plasma in graphene sample has been performed. We observe that the enthalpy per net carrier density emerges as a useful physical quantity determining the hydrodynamic domain's transport variables. Lorenz ratio is defined as thermal to electrical conductivity ratio, normalized by temperature. In searching whether the Wiedemann-Franz (WF) law is obeyed or violated by checking the Lorenz ratio as one or deviated from one, we find that the Lorenz ratio determined from the fluid-based framework will always be responsible for the violation of the WF law. The reason is the proportional relation between Lorenz ratio and enthalpy per particle in the fluid. Based on the experimental observation, graphene, and QGP, both systems at low net charge density, exhibit WF law violation due to their fluid nature. However, graphene at high net charge density obeys the WF law, followed by metals with high Fermi energy or density. It indicates a fluid to the non-fluid transition of the graphene system from low to high-density domain. In this regard, the fluid or non-fluid aspect of QGP at high density is yet to be explored by future facilities like Compressed Baryonic matter (CBM) and Nuclotron-based Ion Collider fAcility (NICA) experiments.

arXiv:2501.00490 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Nuclear Theory (nucl-th)

Angle-resolved photoemission of topological materials

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Jaime Sánchez-Barriga, Oliver J. Clark, Oliver Rader

Topological materials have gained significant attention in condensed matter physics due to their unique electronic and transport properties. Three-dimensional (3D) topological materials are characterized by robust electronic states that are protected by symmetries and exhibit peculiar spin textures. They offer a rich platform for for future information technology including spintronics and topological quantum computing. Here, we review the investigation by angle-resolved photoelectron spectroscopy (ARPES) of topological phases such as strong topological insulators, topological crystalline insulators, magnetic topological insulators, and 3D Dirac, Weyl, nodal, and chiral semimetals and address the status of correlated topological insulators and topological superconductors. A special emphasis is laid on examples from the transition metal dichalcogenide family. Moreover, insights from ultrafast pump-probe experiments are reviewed and a brief outlook is provided.

arXiv:2501.00497 (2025)

Materials Science (cond-mat.mtrl-sci)

In T. Chakraborty (Ed.), Encyclopedia of Condensed Matter Physics, 2nd ed., Vol. 4, pp. 334-369. Elsevier, Amsterdam (2024)

Thick liquid crystalline cholesteric shells

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Arda Bulut, Yusuf Sariyar, Giuseppe Negro, Livio Nicola Carenza

We numerically investigate the phase behavior of thick shells of cholesteric liquid crystals with tangential anchoring at the shell boundary. For achiral liquid crystal, we demonstrate a thickness-dependent transition from a configuration featuring four disclination line connecting the inner and outer surfaces to a state free of defect in the bulk, where each surface is topologically isolated and features two boojums. Incorporating chirality stabilizes novel defect arrangements, including a mixed state combining boojums and disclination lines and blue phases at high chirality and we demonstrate that shell thickness strongly modulates these transitions. Finally, we exploit the metastability features of the observed phases to obtain an elastically induced rearrangement of the shell surfaces during a cholesteric hysteresis cycle, stabilizing an alternative configuration that minimizes the free energy at low chirality. Our work paves the way for exploring dynamic behaviors under external fields, mixed anchoring conditions, or active flows.

arXiv:2501.00516 (2025)

Soft Condensed Matter (cond-mat.soft)

Thermal Induced Structural Competitiveness and Metastability of Body-centered Cubic Iron under Non-Equilibrium Conditions

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Shuai Zhang, Aliza Panjwani, Penghao Xiao, Maitrayee Ghosh, Tadashi Ogitsu, Yuan Ping, S. X. Hu

The structure and stability of iron near melting at multi-megabar pressures are of significant interest in high pressure physics and earth and planetary sciences. While the body-centered cubic (BCC) phase is generally recognized as unstable at lower temperatures, its stability relative to the hexagonal close-packed (HCP) phase at high temperatures (approximately 0.5 eV) in the Earth's inner core (IC) remains a topic of ongoing theoretical and experimental debate. Our ab initio calculations show a significant drop in energy, the emergence of a plateau and a local minimum in the potential energy surface, and stabilization of all phonon modes at elevated electron temperatures (>1-1.5 eV). These effects increase the competition among the BCC, HCP, and the face-centered cubic (FCC) phases and lead to the metastability of the BCC structure. Furthermore, the thermodynamic stability of BCC iron is enhanced by its substantial lattice vibration entropy. This thermally induced structural competitiveness and metastability under non-equilibrium conditions provide a clear theoretical framework for understanding iron phase relations and solidification processes, both experimentally and in the IC.

arXiv:2501.00524 (2025)

Materials Science (cond-mat.mtrl-sci), Geophysics (physics.geo-ph)

5 pages, 4 figures

Non-reciprocal neutral ferroelectric domain walls in BiFeO3

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

M. A. P. Goncalves, M. Graf, M. Pasciak, J. Hlinka

This paper analyzes a peculiar phenomenon of non-reciprocal domain wall pairs and illustrate the implications in ab-initio-based atomistic computational experiments with (112)-oriented planar R180 domain walls within the canonical multiferroic ferroelectric crystal of BiFeO3. Results show that parallel walls on the opposite sides of a given domain within a simply twinned lamellar domain structure can have considerably different polarization and oxygen octahedra tilt profiles, different thickness and energy densities. The spontaneous formation of zigzag walls and triangular domains suggests that these domain walls are actually the lowest energy planar R180 walls in pure insulating BiFeO3 crystals and films.

arXiv:2501.00534 (2025)

Materials Science (cond-mat.mtrl-sci)

5 pages, 4 figures

Phase behavior of Cacio and Pepe sauce

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Giacomo Bartolucci, Daniel Maria Busiello, Matteo Ciarchi, Alberto Corticelli, Ivan Di Terlizzi, Fabrizio Olmeda, Davide Revignas, Vincenzo Maria Schimmenti

"Pasta alla Cacio e pepe" is a traditional Italian dish made with pasta, pecorino cheese, and pepper. Despite its simple ingredient list, achieving the perfect texture and creaminess of the sauce can be challenging. In this study, we systematically explore the phase behavior of Cacio and pepe sauce, focusing on its stability at increasing temperatures for various proportions of cheese, water, and starch. We identify starch concentration as the key factor influencing sauce stability, with direct implications for practical cooking. Specifically, we delineate a regime where starch concentrations below 1% (relative to cheese mass) lead to the formation of system-wide clumps, a condition determining what we term the "Mozzarella Phase" and corresponding to an unpleasant and separated sauce. Additionally, we examine the impact of cheese concentration relative to water at a fixed starch level, observing a lower critical solution temperature that we theoretically rationalized by means of a minimal effective free-energy model. Finally, we present a scientifically optimized recipe based on our findings, enabling a consistently flawless execution of this classic dish.

arXiv:2501.00536 (2025)

Soft Condensed Matter (cond-mat.soft)

Measurement-Induced Phase Transition in State Estimation of Chaotic Systems and the Directed Polymer

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-03 00:00 EST

Federico Gerbino, Guido Giachetti, Pierre Le Doussal, Andrea De Luca

We introduce a solvable model of a measurement-induced phase transition (MIPT) in a deterministic but chaotic dynamical system with a positive Lyapunov exponent. In this setup, an observer only has a probabilistic description of the system but mitigates chaos-induced uncertainty through repeated measurements. Using a minimal representation via a branching tree, we map this problem to the directed polymer (DP) model on the Cayley tree, although in a regime dominated by rare events. By studying the Shannon entropy of the probability distribution estimated by the observer, we demonstrate a phase transition distinguishing a chaotic phase with reduced Lyapunov exponent from a strong-measurement phase where uncertainty remains bounded. Remarkably, the location of the MIPT transition coincides with the freezing transition of the DP, although the critical properties differ. We provide an exact universal scaling function describing entropy growth in the critical regime. Numerical simulations confirm our theoretical predictions, highlighting a simple yet powerful framework to explore measurement-induced transitions in classical chaotic systems.

arXiv:2501.00547 (2025)

Statistical Mechanics (cond-mat.stat-mech)

14 pages, 5 figures

Quantum many-body dynamics for fermionic t-J model simulated with atom arrays

New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-03 00:00 EST

Ye-bing Zhang, Xin-Chi Zhou, Bao-Zong Wang, Xiong-Jun Liu

The fermionic t-J model has been widely recognized as a canonical model in understanding various strongly correlated phases like cuprate high-Tc superconductivity. Simulating this model with controllable quantum platforms offers new possibilities to probe high-Tc physics, yet suffering challenges. Here we propose a novel scheme to realize the t-J model in a programmable Rydberg-dressed tweezer array. By properly engineering the Rydberg-dressed dipole-dipole interaction and inter-tweezer couplings, a highly tunable fermionic t-J model with next-nearest-neighbour hopping terms is achieved. We particularly explore quantum many-body dynamics in the large J/t limit, a regime far beyond the conventional optical lattices and cuprates. Notably, we predict a nontrivial self-pinning effect enforced by local quantum entanglement that characterizes a novel type of Hilbert space fragmentation. This effect leads to the breakdown of Krylov restricted thermalization. Our prediction opens a new horizon in exploring exotic quantum many-body dynamics with t-J model in tweezer arrays, and shall also make a step towards simulating the high-Tc physics in cold atom systems.

arXiv:2501.00552 (2025)

Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)

8 pages, 4 figures

Observation of superconductivity in a nontrivial approximant quasicrystal

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-03 00:00 EST

Pavan Kumar Meena, Rahul Verma, Arushi, Sonika Jangid, Roshan Kumar Kushwaha, Rhea Stewart, Adrian D. Hillier, Bahadur Singh, Ravi Prakash Singh

Superconductivity and nontrivial topology are highly sought-after phenomena in quantum materials. While many topological crystalline materials have been found to exhibit superconductivity, their presence in quasicrystals - materials with a unique aperiodic yet ordered structure - has remained largely unexplored. In this work, we report the discovery of superconductivity in a monoclinic approximant to the decagonal quasicrystal AlOs, that exhibits a high superconducting transition temperature and a nontrivial electronic structure. The resistivity, magnetization, specific heat, and SR measurements confirm superconductivity with a critical temperature of K. Detailed electronic structure and symmetry analysis reveal nontrivial state with and spin-polarized conducting surface states. Importantly, we identify three-dimensional saddle point van Hove singularities with substantial flat energy dispersion at the Fermi level, which can enhance superconductivity. Our results highlight a rich interplay between superconductivity and nontrivial electronic states in AlOs, demonstrating it as a unique platform for exploring unconventional superconducting states in quasicrystalline materials.

arXiv:2501.00554 (2025)

Superconductivity (cond-mat.supr-con)

17 pages, 3 figures

Characterization of Chromium Impurities in -GaO

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Mark E. Turiansky, Sai Mu, Lukas Razinkovas, Kamyar Parto, Sahil D. Patel, Sean Doan, Ganesh Pokharel, Steven J. Gomez Alvarado, Stephen D. Wilson, Galan Moody, Chris G. Van de Walle

Chromium is a common transition-metal impurity that is easily incorporated during crystal growth. It is perhaps best known for giving rise to the 694.3 nm (1.786 eV) emission in Cr-doped AlO, exploited in ruby lasers. Chromium has also been found in monoclinic gallium oxide, a wide-bandgap semiconductor being pursued for power electronics. In this work, we thoroughly characterize the behavior of Cr in GaO through theoretical and experimental techniques. -GaO samples are grown with the floating zone method and show evidence of a sharp photoluminescence signal, reminiscent of ruby. We calculate the energetics of formation of Cr from first principles, demonstrating that Cr preferentially incorporates as a neutral impurity on the octahedral site. Cr possesses a quartet ground-state spin and has an internal transition with a zero-phonon line near 1.8 eV. By comparing the calculated and experimentally measured luminescence lineshape function, we elucidate the role of coupling to phonons and uncover features beyond the Franck-Condon approximation. The combination of strong emission with a small Huang-Rhys factor of 0.05 and a technologically relevant host material render Cr in GaO attractive as a quantum defect.

arXiv:2501.00561 (2025)

Materials Science (cond-mat.mtrl-sci)

Large Language Model-Driven Database for Thermoelectric Materials

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Suman Itani, Yibo Zhang, Jiadong Zang

Thermoelectric materials provide a sustainable way to convert waste heat into electricity. However, data-driven discovery and optimization of these materials are challenging because of a lack of a reliable database. Here we developed a comprehensive database of 7,123 thermoelectric compounds, containing key information such as chemical composition, structural detail, seebeck coefficient, electrical and thermal conductivity, power factor, and figure of merit (ZT). We used the GPTArticleExtractor workflow, powered by large language models (LLM), to extract and curate data automatically from the scientific literature published in Elsevier journals. This process enabled the creation of a structured database that addresses the challenges of manual data collection. The open access database could stimulate data-driven research and advance thermoelectric material analysis and discovery.

arXiv:2501.00564 (2025)

Materials Science (cond-mat.mtrl-sci), Digital Libraries (cs.DL)

Intrinsic (Axion) Statistical Topological Insulator

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Xi Chen, Fa-Jie Wang, Zhen Bi, Zhi-Da Song

Ensembles that respect symmetries on average exhibit richer topological states than those in pure states with exact symmetries, leading to the concept of average symmetry-protected topological states (ASPTs). The free-fermion counterpart of ASPT is the so-called statistical topological insulator (STI) in disordered ensembles. In this work, we demonstrate the existence of intrinsic STI - which has no band insulator correspondence - characterized by the half-quantized magneto-electric polarization . A symmetry reverses the sign of angle, hence seems to protect a classification of . However, we prove that, if , the topological state with cannot be realized in band insulators where is exact. Surprisingly, using a real space construction (topological crystal), we find that an STI with can arise in Anderson insulators with disorders respecting on average. To illustrate this state, we construct a lattice model and examine its phase diagram using the transfer matrix method up to the largest numerically accessible system size. An STI phase is identified through delocalized surface states and a half-quantized magneto-electric polarization in the bulk. As expected, an unavoidable gapless phase separates the STI from both clean insulators and trivial Anderson insulators, revealing the intrinsic nature of the STI. Moreover, we argue that the intrinsic STI is robust against electron-electron interactions, i.e., interactions cannot open an adiabatic path connecting the STI to a gapped clean system. Thus, our work provides the first intrinsic crystalline ASPT and its lattice realization. We also generalize the discussion to other crystalline symmetries.

arXiv:2501.00572 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn)

Efficient training of machine learning potentials for metallic glasses: CuZrAl validation

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Antoni Wadowski, Anshul D.S. Parmar, Jesper Jesper Byggmästar, Jan S. Wróbel, Mikko J. Alava, Silvia Bonfanti

Interatomic potentials play a vital role in revealing microscopic details and structure-property relations, which are fundamental for multiscale simulations and to assist high-throughput experiments. For metallic glasses, developing these potentials is challenging due to the complexity of their unique disordered structure. As a result, chemistry-specific interaction potentials for this important class of materials are often missing. Here, we solve this gap by implementing an efficient methodology for designing machine learning interatomic potentials (MLIPs) for metallic glasses, and we benchmark it with the widely studied CuZrAl system. By combining a Lennard-Jones surrogate model with swap-Monte Carlo sampling and Density Functional Theory (DFT) corrections, we capture diverse amorphous structures from 14 decades of supercooling. These distinct structures provide robust and efficient training of the model and applicability to the wider spectrum of energies. This approach reduces the need for extensive DFT and ab initio optimization datasets, while maintaining high accuracy. Our MLIP shows results comparable to the classical Embedded Atom Method (EAM) available for CuZrAl, in predicting structural, energetic, and mechanical properties. This work paves the way for the development of new MLIPs for complex metallic glasses, including emerging multicomponent and high entropy metallic glasses.

arXiv:2501.00589 (2025)

Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)

9 pages, 5 figures

Coexistence of Commensurate and Incommensurate Antiferromagnetic Groundstates in CoNbSe Single Crystal

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

H. Cein Mandujano, Peter Y. Zavalij, Alicia Manjón-Sanz, Huibo Cao, Efrain E. Rodriguez

In CoNbSe, crystal symmetry, and cobalt site occupation drive the formation of two distinct magnetic phases. At , the centrosymmetric structure ($P_3mmc$) promotes Co-Co interactions leading to the formation of an -type antiferromagnetic structure phase with a transition temperature of = 169 K. At , the non-centrosymmetric structure ($P_3$22) induces a lower-temperature magnetic phase with = 28 K. We report the coexistence of both substructures within a superlattice, with a nuclear propagation vector of (1/3, 1/3, 0) relative to the host lattice. Single crystals of CoNbSe exhibit both magnetic transitions, with corresponding to the phase and corresponding to the phase. Magnetic susceptibility and specific heat measurements confirm these transitions, although only the high-temperature phase significantly affects resistivity. We successfully isolate each phase in powder samples, while single crystals with an intercalation ratio of display the coexistence of both phases in a single sample. Using single-crystal neutron diffraction, we solved the magnetic structure of the high-temperature centrosymmetric phase (), and neutron powder diffraction revealed the double- magnetic structure of the low-temperature noncentrosymmetric phase ()

arXiv:2501.00591 (2025)

Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)

Constriction and contact impedance of ceramic solid electrolytes

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Md Salman Rabbi Limon, Curtis Duffee, Zeeshan Ahmad

The development of solid-state batteries is hindered by the degradation of the solid-solid interface during cycling which can cause void formation and contact loss. Here, we systematically investigate the effect of unrecoverable and real interfacial contact area at the electrode/LiPSCl interface on the impedance spectrum. By varying applied stack pressures and controlling contact geometries, we identify their distinct signatures in the impedance spectrum and quantify their influence on the interfacial resistance and effective ionic conductivity of the solid electrolyte. Experimental results demonstrate that higher pressures and improved contact areas significantly reduce interfacial resistance. The interfacial resistance scales with pressure according to power law with exponent of -0.5, providing insights into the variation of real contact area. Further, distributed contacts lead to lower impedance compared to concentrated contacts due to smaller potential gradients and a more uniform potential distribution. Our simulations predict interfacial resistances of the contact geometries in agreement with experiments. Our work emphasizes the distinct roles of unrecoverable and recoverable contact losses in controlling the impedance of solid-state batteries.

arXiv:2501.00600 (2025)

Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)

19 pages, 6 figures + 16 pages of Supporting Information

A Novel Velocity Discretization for Lattice Boltzmann Method: Application to Compressible Flow

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Navid Afrasiabian, Colin Denniston

The Lattice Boltzmann Method (LBM) has emerged as a powerful tool in computational fluid dynamics and material science. However, standard LBM formulation imposes some limitations on the applications of the method, particularly compressible fluids. In this paper, we introduce a new velocity discretization method to overcome some of these challenges. In this new formulation, the particle populations are discretized using a bump function that has a mean and a variance. This introduces enough independent degrees of freedom to set the equilibrium moments to the moments of Maxwell-Boltzmann distribution up to and including the third moments. Consequently, the correct macroscopic fluid dynamics equations for compressible fluids are recovered. We validate our method using several benchmark simulations.

arXiv:2501.00620 (2025)

Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Fluid Dynamics (physics.flu-dyn)

33 pages, 10 figures

Inhomogeneous evolution of a dense ensemble of optically pumped excitons to the excitonic insulator state

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Natasha Kirova, Serguei Brazovskii

Phase transformations induced by short optical pulses is a mainstream in studies of of dynamics of cooperative electronic states. We present a semi-phenomenological modeling of spacio-temporal effects expected when optical excitons are intricate with the order parameter as it happens e.g. in organic compounds with neutral-ionic ferroelectric phase transitions. A conceptual complication appears here, where both the excitation and the ground syate ordering are built from the intermolecular electronic transfer. To describe both thermodynamic and dynamic effects on the same root, we adopt for the phase transition a view of the Excitonic Insulator - a hypothetical phase of a semiconductor which appears if the exciton energy becomes negative. After the initial pumping pulse, a quasi-condensate of excitons can appear as a macroscopic quantum state which then evolves interacting with other degrees of freedom prone to an instability. The self-trapping of excitons enhances their density which can locally surpass a critical value to trigger the phase transformation. The system is stratified in domains which evolve through dynamical phase transitions and may persist even after the initiating excitons have recombined.

arXiv:2501.00635 (2025)

Strongly Correlated Electrons (cond-mat.str-el), Pattern Formation and Solitons (nlin.PS), Optics (physics.optics)

Gating and tunable confinement of active colloids within patterned environments

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Carolina van Baalen, Stefania Ketzetzi, Anushka Tintor, Lucio Isa

Active colloidal particles typically exhibit a pronounced affinity for accumulating and being captured at boundaries. Here, we engineer long-range repulsive interactions between colloids that self-propel under an electric field and patterned obstacles. As a result of these interactions, particles turn away from obstacles and avoid accumulation. We show that by tuning the applied field frequency, we precisely and rapidly control the effective size of the obstacles and therefore modulate the particle approach distance. This feature allows us to achieve gating and tunable confinement of our active particles whereby they can access regions between obstacles depending on the applied field. Our work provides a versatile means to directly control confinement and organization, paving the way towards applications such as sorting particles based on motility or localizing active particles on demand.

arXiv:2501.00660 (2025)

Soft Condensed Matter (cond-mat.soft)

Measuring the effective stress parameter using the multiphase lattice Boltzmann method and investigating the source of its hysteresis

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Reihaneh Hosseini, Krishna Kumar

The effective stress parameter, , is essential for calculating the effective stress in unsaturated soils. Experimental measurements have captured different relationships between and the degree of saturation, ; however, they have not been able to justify the particular shapes of the - curves. Theoretical solutions express as a function of and the air-water interfacial area, ; however, is difficult to predict, limiting further investigation of variation. We seek an alternative approach for studying by simulating the pore-scale distribution of the two fluid phases in unsaturated soils using the multiphase lattice Boltzmann method (LBM). We develop an algorithm for measuring based on the suction and surface tension forces applied to each grain. Using this algorithm, we simulate the - curve over a full hydraulic cycle for a synthetic 3D granular soil column with immobile grains. We find that at and at , while for all other saturations. The maximum divergence of from happens at the transition from/to the pendular regime. We also observe that the - curve is hysteretic; is larger during wetting (imbibition) compared to drying (drainage) due to larger contribution of surface tension forces.

arXiv:2501.00661 (2025)

Soft Condensed Matter (cond-mat.soft)

Self-reconfiguring colloidal active matter

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Stefania Ketzetzi, Lorenzo Caprini, Vivien Willems, Laura Alvarez, Hartmut Löwen, Lucio Isa

Cells and microorganisms employ dynamic shape changes to enable steering and avoidance for efficient spatial exploration and collective organization. In contrast, active colloids, their synthetic counterparts, currently lack similar abilities and strategies. Through physical interactions alone, here we create active colloidal molecules that spontaneously reconfigure their structure, unlike traditional active particles. We find that self-reconfiguration decouples reorientational dynamics from rotational diffusivity and bestows our active molecules additional reorientation capabilities. During encounters with neighbors, rapid conformational changes lead to self-steering and avoidance. At higher area fractions, reconfiguration-induced avoidance fully inhibits characteristic dynamic clustering, motility-induced phase separation and flocking; instead, the system retains a homogeneous structure comprising well-separated active units. Self-reconfiguring systems therefore present an exciting path towards autonomous motion beyond that of classical synthetic active matter.

arXiv:2501.00672 (2025)

Soft Condensed Matter (cond-mat.soft)

Exploiting Parallelism for Fast Feynman Diagrammatics

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

John Sturt, Evgeny Kozik

Diagrammatic expansions are a paradigmatic and powerful tool of quantum many-body theory. Their evaluation to high order, e.g., by the Diagrammatic Monte Carlo technique, can provide unbiased results in strongly correlated and challenging regimes. However, calculating a factorial number of terms to acceptable precision remains very costly even for state-of-the-art methods. We achieve a dramatic acceleration of evaluating Feynman's diagrammatic series by use of specialised hardware architecture within the recently introduced combinatorial summation (CoS) framework. We present how exploiting the massive parallelism and concurrency available from GPUs leads to orders of magnitude improvement in computation time even on consumer-grade hardware. This provides a platform for making probes of novel phenomena of strong correlations much more accessible.

arXiv:2501.00675 (2025)

Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph), Quantum Physics (quant-ph)

11 pages, 7 figures

Theory of Transient Heat Conduction

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

David E. Crawford, Yi Zeng, Judith Vidal, Jianjun Dong

Ultrafast and nanoscale heat conduction demands a unified theoretical framework that rigorously bridges macroscopic transport equations with microscopic material properties derived from statistical this http URL empirical generalizations of Fourier's law often lack a solid microscopic foundation, failing to connect observed non-Fourier behavior with underlying atomic scale mechanisms. In this work, we present a time-domain theory of transient heat conduction rooted in Zwanzig's statistical theory of irreversible processes. Central to this framework is the time-domain transport function, Z(t), defined through equilibrium time-correlation functions of heat fluxes. This function generalizes the conventional concept of steady-state thermal conductivity, governing the transition of conduction dynamics from onset second sound type wave propagation at finite speeds to diffusion-dominated behavior across broad temporal and spatial scales. Unlike phonon hydrodynamic models that rely on mesoscopic constructs such as phonon drift velocity, our approach provides a quantitative and microscopic description of intrinsic memory effects in transient heat fluxes and applies universally to bulk materials at any temperature or length scale. By integrating atomistic-scale first-principles calculations with continuum-level macroscopic equations, this framework offers a robust foundation for numerical simulations of transient temperature fields. Furthermore, it facilitates the interpretation and design of transient thermal grating experiments using nanometer-scale heat sources and ultrafast laser systems in the extreme ultraviolet and x-ray wavelength ranges, advancing our understanding of heat dissipation dynamics.

arXiv:2501.00679 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)

38 pages, 4 figures

BiFeO nanoparticles at low-temperature using atomistic simulations -- surface charge distribution and terminations

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Mauro A. P. Goncalves, Monica Graf, Marek Pasciak, Jiri Hlinka

This paper analyzes how the ferroelectric properties of cubic-like BiFeO nanoparticles are affected by different terminations and charge distributions at the surface using ab-initio-based atomistic computational experiments. Our findings unveil multiple multidomain configurations and illustrate how the different order parameters evolve towards the surface. Interestingly, for neutral terminations, a non-rhombohedral phase of BiFeO with a stripe-like polarization arrangement was stabilized. We evaluate the polarization, oxygen octahedra rotation, and volume variation for all the configurations obtained, taking advantage of the atomic-scale details provided by the methods used in this study.

arXiv:2501.00680 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

11 pages, 5 figures

Unconventional Coherence Peak in Cuprate Superconductors

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-03 00:00 EST

Zheng Li, Chao Mu, Pengfei Li, Wei Wu, Jiangping Hu, Tao Xiang, Kun Jiang, Jianlin Luo

The Hebel-Slichter coherence peak, observed in the spin-lattice relaxation rate just below the critical temperature , serves as a crucial experimental validation of the Bardeen-Cooper-Schrieffer pairing symmetry in conventional superconductors. However, no coherence peak in has been observed in unconventional superconductors like cuprates. In this study, an unconventional coherence peak is identified for the first time using nuclear quadrupole resonance on YBaCuO, pointing to a distinctive pairing symmetry. The spin-lattice relaxation rate in nuclear quadrupole resonance and nuclear magnetic resonance with nuclear spin comprises the magnetic relaxation rate , which probes magnetic fluctuations, and the quadrupole relaxation rate , which probes charge fluctuations. By utilizing Cu and Cu isotopes, we successfully distinguish and of YBaCuO and reveal the presence of the coherence peak in but not in , in contrast to conventional superconductors. Our finding demonstrates that unconventional superconductors do not exhibit a coherence peak in when the relaxation is due to fluctuations of the hyperfine field. Conversely, a coherence peak is expected when the relaxation is caused by electric field gradient fluctuations, due to the different coherence factors between charge and magnetic fluctuations. Our successful measurements of for the chains of YBaCuO suggest that, should the conditions for predominant quadrupole relaxation be satisfied, this phenomenon could provide a novel approach to exploring the unconventional nature of the pairing mechanism in other superconductors.

arXiv:2501.00699 (2025)

Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)

Phys. Rev. X 14, 041072(2024)

Essentially degenerate hidden nodal lines in two-dimensional magnetic layer groups

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Xiao-Ping Li, Chaoxi Cui, Lei Wang, Weikang Wu, Zeying Zhang, Zhi-Ming Yu, Yugui Yao

According to the theory of group representations, the types of band degeneracy can be divided into accidental degeneracy and essential degeneracy. The essentially degenerate nodal lines (NLs) are typically resided on the high-symmetry lines of the Brillouin zone. Here, we propose a type of NL in two dimension that is essentially degenerate but is hidden within the high-symmetry planes, making it less observable, dubbed a hidden-essential nodal line (HENL). The existence of HENL is guaranteed as long as the system hosts a horizontal glide-mirror symmetry, hence such NLs can be widely found in both non-magnetic and magnetic systems. We perform an exhaustive search over all 528 magnetic layer groups (MLGs) for HENL that can be enforced by glide-mirror symmetry with both spinless and spinfull systems. We find that 122 candidate MLGs host spinless HENL, while 63 candidate MLGs demonstrate spinful HENL. In addition, we reveal that horizontal mirror and time-reversal symmetry in type-II and type-IV MLGs with spin-orbital coupling can enforce HENL formed. The 15 corresponding candidate MLGs have also been presented. Furthemore, we derive a few typical lattice models to characterize the existence for the HENL. For specific electronic fillings in real materials, namely 4+2 in spinless systems (and 2+1 in spinful systems), the presence of the HENLs in candidate MLGs is required regardless of the details of the systems. Using calculations, we further identify possible material candidates that realize spinless and spinful HENL. Moreover, spinful HENLs exhibit a novel persistent spin texture wih the characteristic of momentum-independent spin configuration. Our findings uncover a new type of topological semimetal state and offer an ideal platform to study the related physics of HENLs.

arXiv:2501.00706 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Spin Hall effect in 3d ferromagnetic metals for field-free switching of perpendicular magnetization: A first-principles investigation

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Fanxing Zheng, Jianting Dong, Yizhuo Song, Meng Zhu, Xinlu Li, Jia Zhang

Ferromagnetic metals, with the potential to generate spin current with unconventional spin polarization via the spin Hall effect, offer promising opportunities for field-free switching of perpendicular magnetization and for the spin-orbit torque devices. In this study, we investigate two distinct spin Hall mechanisms in 3d ferromagnetic metals including spin-orbit coupling driven spin Hall effect in Fe, Co, Ni and their alloys, and non-relativistic spin Hall effect arising from anisotropic spin-polarized transport by taking L10-MnAl as an example. By employing first-principles calculations, we examine the temperature and alloy composition dependence of spin Hall conductivity in Fe, Co, Ni and their alloys. Our results reveal that the spin Hall conductivities with out-of-plane spin polarization in 3d ferromagnetic metals are at the order of 1000 ( , )^{-1} at 300 K, but with a relatively low spin Hall angles around 0.01~0.02 due to the large longitudinal conductivity. For L10-MnAl(101), the non-relativistic spin Hall conductivity can reach up to 10000 ( , )^{-1}, with a giant spin Hall angle around 0.25 at room temperature. By analyzing the magnetization switching process, we demonstrate deterministic switching of perpendicular magnetization without an external magnetic field by using 3d ferromagnetic metals as spin current sources. Our work may provide an unambiguous understanding on spin Hall effect in ferromagnetic metals and pave the way for their potential applications in related spintronic devices.

arXiv:2501.00737 (2025)

Materials Science (cond-mat.mtrl-sci)

Braiding rule of boundary Majorana-like zero mode

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Qiyun Ma, Hailong He, Meng Xiao, Zhengyou Liu

The study of topological states has become an important topic in both solid-state systems and artificial structures such as photonic crystals and phononic crystals. Among them, Majorana zero modes, which exhibit nontrivial braiding process, have attracted extensive research interest. The analog of Majorana zero modes in classical waves, or the Majorana-like zero modes (MLZMs), have also got a lot of attention recently. However, the vast majority of previous works concerned with MLZMs that were bounded to vortexes inside the bulk. Here in this work, we unveil the braiding rule of MLZMs that are tunable around the boundary of a vortex-texture Kekule modulated graphene. We show that the existence of these zero-dimensional boundary MLZMs is protected by the Zak phase of 1D boundary states. As such, we are able to construct multiple MLZMs and analyze the corresponding braiding process. In addition, we also provide an implementation scheme of the boundary MLZMs in acoustic crystals. The tunability of the boundary MLZMs proposed herein offer new freedom for topological states braiding in both solid-state systems and artificial structures.

arXiv:2501.00749 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Genuine and Robust Magnetoelectric Coupling Effect in van der Waals Multiferroic Tunnel Junctions

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Zhi Yan, Xujin Zhang, Jianhua Xiao, Cheng Fang, Xiaohong Xu

Van der Waals multiferroic tunnel junctions (vdW-MFTJs) are promising candidates for data storage devices due to their tunable thickness and capability to exhibit multiple nonvolatile resistance states. However, existing vdW-MFTJs utilize ferroelectricity and ferromagnetism independently, failing to achieve true magnetoelectric coupling, which leads to unnecessary energy dissipation. Here, we propose an innovative vdW-MFTJ design based on a CrBr/MnPSe/CrBr vertical heterostructure, enabling genuine magnetoelectric coupling without relying on atomic migration induced by inversion symmetry breaking for ferroelectric polarization reversal. Using first-principles calculations, we investigate the spin-polarized quantum transport properties of the proposed structure. By integrating asymmetric PtTe/alkali-metal (Li/Na/K)-doped/intercalated CrBr electrodes, the device demonstrates exceptional performance, with a maximum tunneling magnetoresistance (TMR) exceeding % and tunneling electroresistance (TER) reaching 2499%, while the spin-filtering channels can be flexibly controlled by the magnetization direction of the magnetic free layer, achieving perfect spin-filtering over a broad bias voltage range. Applying an external bias voltage further enhances these metrics, increasing TMR to % and TER to 9990%. Notably, a pronounced negative differential resistance (NDR) effect is observed, yielding an unprecedented peak-to-valley ratio (PVR) of %, the highest value reported to date. These extraordinary characteristics highlight the potential of vdW-MFTJs for ultra-efficient electronic switching, a key feature for next-generation spintronic devices. Our findings provide a solid theoretical foundation for designing and developing high-performance magnetic storage and logic technologies.

arXiv:2501.00761 (2025)

Materials Science (cond-mat.mtrl-sci)

7 pages, 4 figures

Longitudinal Spin Hall Magnetoresistance from Spin Fluctuations

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Ping Tang

Spin Hall magnetoresistance (SMR), the variation in resistance in a heavy metal (HM) with the magnetization orientation of an adjacent ferromagnet (FM), has been extensively studied as a powerful tool for probing surface magnetic moments in a variety of magnetic materials. However, the conventional SMR theory assumes rigid magnetization of a fixed magnitude, an assumption that breaks down close to the FM's Curie temperature (T_c), where the magnetic susceptibility diverges. Here, we report an unconventional SMR effect arising from the magnetic-field modulation of spin fluctuations in the FM, while its magnetization remaining collinear to the spin Hall accumulation in the HM. In contrast to the conventional SMR, which scales with the magnetization and vanishes near , such ``longitudinal" SMR (LSMR), though suppressed at low temperatures, becomes critically enhanced at (T_c), reaching a magnitude comparable to conventional SMR amplitudes. Our findings suggest a promising method for electrically detecting enhanced spin fluctuations in magnetic systems.

arXiv:2501.00768 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Chiral induced Spin Polarized Electron Current: Origin of the Chiral Induced Spin Selectivity Effect

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

J. Fransson

The discovery of the chiral induced spin selectivity effect has provided a novel tool to study how active physical and chemical mechanism may differ in chiral enantiomers, however, the origin of the effect itself is yet an open question. In this article, it is theoretically shown that two aspects have to be fulfilled for the chiral induced spin selectivity effect to arise. First, chirality is a necessary condition for breaking spin-degeneracy in molecular structures that do not comprise heavy elements. Second, dissipation is indispensable for the molecule to develop a non-vanishing spin-polarization. These theoretical conclusions are illustrated in terms of a few examples, showing the necessity of the two aspects to be coordinated for the emergence of the chiral induced spin selectivity effect.

arXiv:2501.00781 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)

6 pages, 4 figures; submitted

Morphogenesis of cheese flowers through scraping

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

J. Zhang, A. Ibarra, B. Roman, M. Ciccotti

The "Tete de moine" Swiss cheese is generally served by scraping the surface of a cylindrical loaf with a sharp tool. This produces thin sheets of cheese that are strongly wrinkled at the edge, resembling frilly flowers and enhancing the tasting experience. In this work we unveil the physical mechanisms at play in this scraping-induced morphogenesis. We measure the deformation of the cheese during scraping and show that plastic deformation occurs everywhere, but find a larger plastic contraction in the inner part of the flower, causing its buckling into shape. We show that it surprisingly derives from the lower friction coefficient evidenced on the cheese close to its crust. Our analysis provides the tools for a better control of chip morphogenesis through plasticity in the shaping of other delicacies, but also in metal cutting.

arXiv:2501.00797 (2025)

Soft Condensed Matter (cond-mat.soft), Popular Physics (physics.pop-ph)

Sputtering Current Driven Growth & Transport Characteristics of Superconducting Ti40V60 Alloy Thin Films

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-03 00:00 EST

Shekhar Chandra Pandey, Shilpam Sharma, K. K. Pandey, Pooja Gupta, Sanjay Rai, Rashmi Singh, M. K. Chattopadhyay

The room temperature growth, characterization, and electrical transport properties of magnetron sputtered superconducting Ti40V60 alloy thin films are presented. The films exhibit low surface roughness and tunable transport properties. As the sputtering current increases, the superconducting transition move towards higher temperatures. Rietveld refinement of two dimensional XRD (2D XRD) pattern reveals the presence of stress in the films, which shifts from tensile to compressive as the sputtering current increases. Additionally, the crystallite size of the films increases with higher sputtering currents. The films exhibit a strong preferential orientation, contributing to their texturing. The crystallite size and texturing are found to be correlated with the superconducting transition temperature (TC) of the films. As the crystallite size and texturing increase, the TC of the films also rises.

arXiv:2501.00812 (2025)

Superconductivity (cond-mat.supr-con)

Role of Chalcogen atoms in In Situ Exfoliation for Large-Area 2D Semiconducting Transition Metal Dichalcogenides

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Zhiying Dan, Ronak Sarmasti Emami, Giovanna Feraco, Melina Vavali, Dominic Gerlach, Petra Rudolf, Antonija Grubišić-Čabo

Two-dimensional (2D) transition metal dichalcogenides have emerged as a promising platform for next-generation optoelectronic and spintronic devices. Mechanical exfoliation using adhesive tape remains the dominant method for preparing 2D materials of highest quality, including transition metal dichalcogenides, but always results in small-sized flakes. This limitation poses a significant challenge for investigations and applications where large scale flakes are needed. To overcome these constraints, we explored the preparation of 2D WS2 and WSe2 using a recently developed kinetic in situ single-layer synthesis method (KISS). In particular, we focused on the influence of different substrates, Au and Ag, and chalcogen atoms, S and Se, on the yield and quality of the 2D films. The crystallinity and spatial morphology of the 2D films were characterized using optical microscopy and atomic force microscopy, providing a comprehensive assessment of exfoliation quality. Low-energy electron diffraction verified that there is no preferential orientation between the 2D film and the substrate, while optical microscopy revealed that WSe2 consistently outperformed WS2 in producing large monolayers, regardless of the substrate used. Finally, X-ray diffraction and X-ray photoelectron spectroscopy demonstrate that no covalent bonds are formed between the 2D material and the underlying substrate. These results identify KISS method as a non-destructive approach for a more scalable approach of high-quality 2D transition metal dichalcogenides.

arXiv:2501.00815 (2025)

Materials Science (cond-mat.mtrl-sci)

Article (13 pages, 5 figures) and supporting information (5 pages, 6 figures)

Current-induced re-entrant superconductivity and extreme nonreciprocal superconducting diode effect in valley-polarized systems

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-03 00:00 EST

Yu-Chen Zhuang, Qing-Feng Sun

The superconducting diode effect (SDE) refers to the nonreciprocity of superconducting critical currents for the metal-superconductor transition. Generally, the SDE has a positive and a negative critical current corresponding to two opposite directions whose amplitudes are unequal. It is demonstrated that an extreme nonreciprocity where two critical currents can become both positive (or negative) has been observed in a recent experiment. In this work, we theoretically propose a possible mechanism to realize an extreme nonreciprocal SDE. Based on a microscopic theory and a simple valley-polarized model, we demonstrate that depairing currents required to dissolve Cooper pairs can be remodulated under the interplay between the valley polarization and the applied current. Near the disappearance of the superconductivity, the remodulation is shown to induce the extreme nonreciprocity and also the current-induced re-entrant superconductivity where the system has two different critical current intervals. Our study may provide new horizons for understanding the coexistence of superconductivity and spontaneous ferromagnetism and pave a new way to designing the SDE with 100% efficiency.

arXiv:2501.00835 (2025)

Superconductivity (cond-mat.supr-con)

14 pages, 8 figures, This manusrcipt was submitted to Phys. Rev. Lett. on December 4, 2023

Extended Landauer-B"{u}ttiker Formula for Current through Open Quantum Systems with Gain or Loss

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Chao Yang, Yucheng Wang

The Landauer-Büttiker formula, which characterizes the current flowing through a finite region connected to leads, has significantly advanced our understanding of transport. We extend this formula to describe particle and energy currents with gain or loss in the intermediate region by using the Lindblad-Keldysh formalism. Based on the derived formula, several novel effects induced by gain or loss in the current are discussed: the breaking of inversion symmetry in the gain and loss terms or in the system can lead to current generation; the anomalous phenomenon that disorder can induce current generation; the presence of gain and loss makes the thermal and electrical conductances continuous and ensures they follow the Wiedemann-Franz law even outside the energy band; the effect of bond loss-induced skin effect on current. This work deepens and extends our understanding of transport phenomena in open systems.

arXiv:2501.00844 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 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)

Robustness of quantum many-body scars in the presence of Markovian bath

New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-03 00:00 EST

Xiang-Ping Jiang, Mingdi Xu, Xuanpu Yang, Yucheng Wang, Lei Pan

A generic closed quantum many-body system will inevitably tend to thermalization, whose local information encoded in the initial state eventually scrambles into the full space, known as quantum ergodicity. A paradigmatic exception in closed quantum systems for strong ergodicity breaking is known as many-body localization, where strong disorder-induced localization prevents the occurrence of thermalization. It is generally recognized that a localized quantum system would be delocalized under dissipation induced by the environment. However, this consequence recently has received challenges where an exotic dissipation-induced localization mechanism is proposed, and transitions between localized and extended phases are found. In this Letter, we promote this mechanism to systems for weak ergodicity breaking hosting quantum many-body scars (QMBS). We find that the system relaxes to a steady state dominated by QMBS, and the dissipative dynamics exhibit dynamic revivals by suitably preparing an initial state. We point out an experimental realization of the controlled dissipation with a cold atomic setup. This makes the signature of ergodicity breaking visible over dissipative dynamics and offers potential possibilities for experimentally preparing stable QMBS with associated coherent dynamics.

arXiv:2501.00886 (2025)

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)

7+1 pages, 4+1 figures. Comments are welcome

Is a phonon excitation of a superfluid Bose gas a Goldstone boson?

New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-03 00:00 EST

Maksim Tomchenko

It is generally accepted that phonons in a superfluid Bose gas are Goldstone bosons. This is justified by spontaneous symmetry breaking (SSB), which is usually defined as follows: the Hamiltonian of the system is invariant under the transformation , whereas the order parameter is not. However, the strict definition of SSB is different: the Hamiltonian and the boundary conditions are invariant under a symmetry transformation, while the is not. Based on the latter criterion, we study a finite system of spinless, weakly interacting bosons using three approaches: the standard Bogoliubov method, the particle-number-conserving Bogoliubov method, and the approach based on the exact ground-state wave function. Our results show that the answer to the question in the title is no. Thus, phonons in a real-world (finite) superfluid Bose gas are similar to sound in a classical gas: they are not Goldstone bosons, but quantised collective vibrational modes arising from the interaction between atoms. In the case of an infinite Bose gas, however, the picture becomes paradoxical: the ground state can be regarded as either infinitely degenerate or non-degenerate, making the phonon both similar to a Goldstone boson and different from it.

arXiv:2501.00893 (2025)

Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)

22 pages

Understanding Memristive Behavior: An Atomistic Study of the Influence of Grain Boundaries on Surface and Out-of-Plane Diffusion of Metallic Atoms

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Mohit D. Ganeriwala, Daniel Luque-Jarava, Francisco Pasadas, Juan J. Palacios, Francisco G. Ruiz, Andres Godoy, Enrique G. Marin

Atomic migration from metallic contacts, and subsequent filament formation, is recognised as a prevailing mechanism leading to resistive switching in memristors based on two-dimensional materials (2DMs). This study presents a detailed atomistic examination of the migration of different metal atoms across the grain boundaries (GBs) of 2DMs, employing Density Functional Theory in conjunction with Non-Equilibrium Green's Function transport simulations. Various types of metallic atoms, Au, Cu, Al, Ni, and Ag, are examined, focusing on their migration both in the out-of-plane direction through a MoS layer and along the surface of the MoS layer, pertinent to filament formation in vertical and lateral memristors, respectively. Different types of GBs usually present in MoS are considered to assess their influence on the diffusion of metal atoms. The findings are compared with structures based on pristine MoS and those with mono-sulfur vacancies, aiming to understand the key elements that affect the switching performance of memristors. Furthermore, transport simulations are carried out to evaluate the effects of GBs on both out-of-plane and in-plane electron conductance, providing valuable insights into the resistive switching ratio.

arXiv:2501.00904 (2025)

Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Computational Physics (physics.comp-ph)

Achievable Information-Energy Exchange in a Brownian Information Engine through Potential Profiling

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Rafna Rafeek, Debasish Mondal

The information engine extracts work from a single heat bath using mutual information obtained during the operation cycle. This study investigates the influence of the potential shaping in a Brownian information engine (BIE) in harnessing the information from thermal fluctuations. We have designed a BIE by considering an overdamped Brownian particle inside a confined potential and introducing an appropriate symmetric feedback cycle. We find that the upper bound of the extractable work for a BIE with a monostable centrosymmetric confining potential, with a stable state at the potential centre, depends on the bath temperature and the convexity of the confinement. A concave confinement is more efficient for an information-energy exchange. For a bistable confinement with an unstable centre and two symmetric stable basins, one can find an engine-to-refrigeration transition beyond a certain barrier height related to the energy difference between the energy barrier and the stable basins. Finally, we use the concavity-induced gain in information harnessing to device a BIE in the presence of a multistable potential that can harvest even more energy than monostable confinement.

arXiv:2501.00918 (2025)

Soft Condensed Matter (cond-mat.soft)

Anisotropic Raman scattering and lattice orientation identification of 2M-WS2

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Sabin Gautam, Sougata Mardanya, Joseph McBride, A K M Manjur Hossain, Qian Yang, Wenyong Wang, John Ackerman, Brian M. Leonard, Sugata Chowdhury, Jifa Tian

Anisotropic materials with low symmetries hold significant promise for next-generation electronic and quantum devices. 2M-WS2, a candidate for topological superconductivity, has garnered considerable interest. However, a comprehensive understanding of how its anisotropic features contribute to unconventional superconductivity, along with a simple, reliable method to identify its crystal orientation, remains elusive. Here, we combine theoretical and experimental approaches to investigate angle- and polarization-dependent anisotropic Raman modes of 2M-WS2. Through first-principles calculations, we predict and analyze phonon dispersion and lattice vibrations of all Raman modes in 2M-WS2. We establish a direct correlation between their anisotropic Raman spectra and high-resolution transmission electron microscopy images. Finally, we demonstrate that anisotropic Raman spectroscopy can accurately determine the crystal orientation and twist angle between two stacked 2M-WS2 layers. Our findings provide insights into the electron-phonon coupling and anisotropic properties of 2M-WS2, paving the way for the use of anisotropic materials in advanced electronic and quantum devices.

arXiv:2501.00945 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)

19 pages, 5 figures

Active and transfer learning with partially Bayesian neural networks for materials and chemicals

New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-03 00:00 EST

Sarah I. Allec, Maxim Ziatdinov

Active learning, an iterative process of selecting the most informative data points for exploration, is crucial for efficient characterization of materials and chemicals property space. Neural networks excel at predicting these properties but lack the uncertainty quantification needed for active learning-driven exploration. Fully Bayesian neural networks, in which weights are treated as probability distributions inferred via advanced Markov Chain Monte Carlo methods, offer robust uncertainty quantification but at high computational cost. Here, we show that partially Bayesian neural networks (PBNNs), where only selected layers have probabilistic weights while others remain deterministic, can achieve accuracy and uncertainty estimates on active learning tasks comparable to fully Bayesian networks at lower computational cost. Furthermore, by initializing prior distributions with weights pre-trained on theoretical calculations, we demonstrate that PBNNs can effectively leverage computational predictions to accelerate active learning of experimental data. We validate these approaches on both molecular property prediction and materials science tasks, establishing PBNNs as a practical tool for active learning with limited, complex datasets.

arXiv:2501.00952 (2025)

Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Data Analysis, Statistics and Probability (physics.data-an)

New Insights into the Dependence of Glass Transition Temperature and Dynamic Fragility on Molecular Weight in Oligomers and Polymers

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Valeriy V. Ginzburg, Oleg V. Gendelman, Riccardo Casalini, Alessio Zaccone

In an earlier preprint (V. V. Ginzburg, O. V. Gendelman, R. Casalini, and A. Zaccone, arXiv:2409.17291), we demonstrated that the dynamic (relaxation time) and volume equations of state for many amorphous polymers are near-universal -- each material is characterized by two governing parameters -- the glass transition temperature, T_{g}, and the elementary relaxation time, /tau_{el}. The dynamic fragility, m, is uniquely related to /tau_{el}. The earlier analysis was based on the data for high polymers (degree of polymerization, N > 200, and molecular weight, Mw > 20,000 g/mol). Here, we investigate the dependence of T_{g} and /tau_{el} on N (or, equivalently, on the molecular weight, M). We consider the dielectric spectroscopy data for homologous series of four polymers: polystyrene (PS), poly-(2-vinylpyridine) (P2VP), poly(dimethylsiloxane) (PDMS), and polybutadiene (PB). It is shown that the relaxation time curves for various oligomers can be successfully collapsed onto the same master curve as the high polymers. The glass transition temperature and the dynamic fragility are found to be linear functions of 1/M, in agreement with the Fox-Flory equation. The scaling results are interpreted based on the SL-TS2 theory, ensuring that the model description is consistent with the Boyer rules for the coefficients of thermal expansion above and below T_{g}, as well as the thermodynamical scaling for the pressure dependence of the relaxation time.

arXiv:2501.00956 (2025)

Soft Condensed Matter (cond-mat.soft)

14 pages, 3 figures, 1 table

Optical signatures of Euler superconductors

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-03 00:00 EST

Chun Wang Chau, Wojciech J. Jankowski, Robert-Jan Slager

We study optical manifestations of multigap band topology in multiband superconductors with a non-trivial topological Euler class. We introduce a set of lattice models for non-Abelian superconductors with the Euler invariant signified by a non-trivial quantum geometry. We then demonstrate that the topological Bogoliubov excitations realized in these models provide for a characteristic first-order optical response distinct from those of the other known topological superconductors. We find that the spectral distribution of the optical conductivity universally admits a topologically quantized jump and naturally differs from the features induced by the quantum geometry in the non-interacting bands without pairing terms. Further to uncovering observable signatures in first-order optical conductivities, we showcase that the higher-order nonlinear optical responses of the non-Abelian Euler superconductor can result in enhanced steady dc currents that fingerprint the exotic topological invariant. Finally, by employing a diagrammatic approach, we generalize our findings beyond the specific models of Euler superconductors.

arXiv:2501.00960 (2025)

Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)

10+14 pages, 6+3 figures

Strain Mediated Voltage Control of Magnetic Anisotropy and Magnetization Reversal in Bismuth Substituted Yttrium Iron Garnet Films and Meso-structures

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Walid Al Misba, Miela Josephine Gross, Kensuke Hayashi, Daniel B. Gopman, Caroline A. Ross, Jayasimha Atulasimha

We report on magnetic anisotropy modulation in Bismuth substituted Yttrium Iron Garnet (Bi-YIG) thin films and mesoscale patterned structures deposited on a PMN-PT substrate with the application of voltage-induced strain. The Bi content is selected for low coercivity and higher magnetostriction than that of YIG, yielding significant changes in the hysteresis loops through the magnetoelastic effect. The piezoelectric substrate is poled along its thickness, which is the [011] direction, by applying a voltage across the PMN-PT/SiO2/Bi-YIG/Pt heterostructure. In-situ magneto-optical Kerr effect microscopy (MOKE) shows the modulation of magnetic anisotropy with voltage-induced strain. Furthermore, voltage control of the magnetic domain state of the Bi-YIG film at a fixed magnetic field produces a 90° switching of the magnetization easy axis above a threshold voltage. The magnetoelectric coefficient of the heterostructure is 1.05x10^(-7)s/m which is competitive with that of other ferromagnetic oxide films on ferroelectric substrates such as La0.67Sr0.33MnO3/PMNPT and YIG/PMN-PZT. Voltage-control of magnetization reversal fields in 5-30 microns wide dots and racetracks of Bi-YIG show potential for energy efficient non-volatile memory and neuromorphic computing devices.

arXiv:2501.00980 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Critical Dynamics and Cyclic Memory Retrieval in Non-reciprocal Hopfield Networks

New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-03 00:00 EST

Shuyue Xue, Mohammad Maghrebi, George I. Mias, Carlo Piermarocchi

We study Hopfield networks with non-reciprocal coupling inducing switches between memory patterns. Dynamical phase transitions occur between phases of no memory retrieval, retrieval of multiple point-attractors, and limit-cycle attractors. The limit cycle phase is bounded by two critical regions: a Hopf bifurcation line and a fold bifurcation line, each with unique dynamical critical exponents and sensitivity to perturbations. A Master Equation approach numerically verifies the critical behavior predicted analytically. We discuss how these networks could model biological processes near a critical threshold of cyclic instability evolving through multi-step transitions.

arXiv:2501.00983 (2025)

Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph), Molecular Networks (q-bio.MN)

Kagome Metal GdNbSn: A 4d Playground for Topological Magnetism and Electron Correlations

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Yusen Xiao, Qingchen Duan, Zhaoyi Li, Shu Guo, Hengxin Tan, Ruidan Zhong

Magnetic kagome metals have garnered considerable attention as an ideal platform for investigating intrinsic topological structures, frustrated magnetism, and electron correlation effects. In this work, we present the synthesis and detailed characterization of GdNbSn, a metal that features a niobium-based kagome lattice and a frustrated triangular gadolinium network. The compound adopts the HfFeGe-type crystal structure, with lattice parameters of a = b = 5.765(4) Å and c = 9.536(8) Å. Magnetic susceptibility and specific heat measurements reveal a magnetic transition near 2.3 K. Electrical transport data confirm metallic behavior, unsaturated positive magnetoresistance, and a hole-dominated multiband Hall effect. Furthermore, first-principles calculations indicate that Nb-4d orbitals predominantly contribute to the electronic states near the Fermi energy, with the band structure showing multiple topologically nontrivial crossings around the Fermi surface. This study also compares GdNbSn with GdVSn, highlighting their similarities and differences. Our findings pave the way for exploring RNbSn (R = rare earth) with customized substitutions of R sites to fine-tune their properties.

arXiv:2501.00996 (2025)

Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)

7 pages, 7 figures

Spatial Correlation Unifies Nonequilibrium Response Theory for Arbitrary Markov Jump Processes

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-03 00:00 EST

Jiming Zheng, Zhiyue Lu

Understanding how systems respond to external perturbations is a fundamental challenge in physics, particularly for non-equilibrium and non-stationary processes. The fluctuation-dissipation theorem provides a complete framework for near-equilibrium systems, and various bounds are recently reported for specific non-equilibrium regimes. Here, we present an exact response equality for arbitrary Markov processes that decompose system response into spatial correlations of local dynamical events. This decomposition reveals that response properties are encoded in correlations between transitions and dwelling times across the network, providing a natural generalization of the fluctuation-dissipation theorem to generic non-equilibrium processes. Our theory unifies existing response bounds, extends them to time-dependent processes, and reveals fundamental monotonicity properties of the tightness of multi-parameter response inequalities. Beyond its theoretical significance, this framework enables efficient numerical evaluation of response properties from unperturbed trajectory data, offering practical advantages for studying complex networks and biological systems far from equilibrium.

arXiv:2501.01050 (2025)

Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)

Fluctuations of topological charges in two-dimensional classical Heisenberg model

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-03 00:00 EST

Shan-Chang Tang, Yu Shi

Binding and unbinding of vortices drives Kosterlitz-Thouless phase transition in two-dimensional XY model. Here we investigate whether similar mechanism works in two-dimensional Heisenberg model, by using the fluctuation of the topological charge inside a loop to characterize the nature of binding versus unbinding of defects. Through Monte Carlo simulations, we find that the fluctuation is proportional to the perimeter of the loop at low temperatures while to the area of the loop at high temperatures, implying binding of the defects at low temperatures and unbinding at high temperatures.

arXiv:2501.01051 (2025)

Statistical Mechanics (cond-mat.stat-mech)

13 pages, preprint

Is there Kibble-Zurek scaling of topological defects in first-order phase transitions?

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-03 00:00 EST

Fan Zhong

Kibble-Zurek scaling is the scaling of the density of the topological defects formed via the Kibble-Zurek mechanism with respect to the rate at which a system is cooled across a continuous phase transition. Recently, the density of the topological defects formed via the Kibble-Zurek mechanism was computed for a system cooled through a first-order phase transition instead of the usual continuous transitions. Here we address the problem of whether such defects generated across a first-order phase transition exhibit Kibble-Zurek scaling similar to the case in continuous phase transitions. We show that any possible Kibble-Zurek scaling for the topological defects can only be a very rough approximation due to an intrinsic field for the scaling. However, complete universal scaling for other properties does exist.

arXiv:2501.01064 (2025)

Statistical Mechanics (cond-mat.stat-mech)

6 pages, 2 figures

Machine Learning-Driven Insights into Excitonic Effects in 2D Materials

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Ahsan Javed, Sajid Ali

Understanding excitonic effects in two-dimensional (2D) materials is critical for advancing their potential in next-generation electronic and photonic devices. In this study, we introduce a machine learning (ML)-based framework to predict exciton binding energies in 2D materials, offering a computationally efficient alternative to traditional methods such as many-body perturbation theory (GW) and the Bethe-Salpeter equation. Leveraging data from the Computational 2D Materials Database (C2DB), our ML models establish connections between cheaply available material descriptors and complex excitonic properties, significantly accelerating the screening process for materials with pronounced excitonic effects. Additionally, Bayesian optimization with Gaussian process regression was employed to efficiently filter materials with largest exciton binding energies, further enhancing the discovery process. Although developed for 2D systems, this approach is versatile and can be extended to three-dimensional materials, broadening its applicability in materials discovery.

arXiv:2501.01092 (2025)

Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)

Tensor network method for solving the Ising model with a magnetic field

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-03 00:00 EST

Myung-Hoon Chung

We study the two-dimensional square lattice Ising ferromagnet and antiferromagnet with a magnetic field by using tensor network method. Focusing on the role of guage fixing, we present the partition function in terms of a tensor network. The tensor has a different symmetry property for ferromagnets and antiferromagnets. The tensor network of the partition function is interpreted as a multiple product of the one-dimensional quantum Hamiltonian. We perform infinite density matrix renormalization group to contract the two-dimensional tensor network. We present the numerical result of magnetization and entanglement entropy for the Ising ferromagnet and antiferromagnet side by side. In order to determine the critical line in the parameter space of temperature and magnetic field, we use the half-chain entanglement entropy of the one-dimensional quantum state. The entanglement entropy precisely indicates the critical line forming the parabolic shape for the antiferromagnetic case, but shows the critical point for the ferromagnetic case.

arXiv:2501.01098 (2025)

Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)

6 pages, 7 figures

On Computational Complexity of 3D Ising Spin Glass: Lessons from D-Wave Annealer

New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-03 00:00 EST

Hao Zhang, Alex Kamenev

Finding an exact ground state of a 3D Ising spin glass is proven to be an NP-hard problem. There is a widespread belief that this statement implies an exponential scaling, , of necessary computational efforts (classical or quantum), with the number of spins, . Yet, what is a factor here and are there any fundamental limits on how large it can be? Here we report results of extensive experimentation with D-Wave 3D annealer with . We found exact ground states (in a probabilistic sense) for typical realizations of 3D spin glasses with the efficiency, characterized by . We argue that with a further improvement of annealing protocols, post-processing algorithms and device noise reduction, can be increased even further. We provide a theoretical argumentation for this observation based on statistical analysis of low energy states.

arXiv:2501.01107 (2025)

Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Physics (quant-ph)

9 pages, 6 figures

Native antisite defects in h-BN

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Song Li, Pei Li, Adam Gali

Hexagonal boron nitride (hBN) is an excellent host for solid-state single phonon emitters. Experimental observed emission ranges from infrared to ultraviolet. The emission centers are generally attributed to either intrinsic or extrinsic point defects embedded into hBN. Nevertheless, the microscopic structure of most of these defect emitters is uncertain. Here, through density-functional theory calculations we studied the native antisite defects in hBN. We find that the neutral boron antisite might be a nonmagnetic single photon source with zero-phonon-line (ZPL) at 1.58 eV and such a lineshape that is often observed in experiments. Furthermore, the positively charged nitrogen antisite might be associated with a dim color center recently observed as a blue emitter with ZPL at 2.63 eV. These simple single substitution defects indicate the existence of out-of-plane phonon mode which significantly affects the optical properties. Our results could provide useful information for identification of quantum emitters in hBN.

arXiv:2501.01133 (2025)

Materials Science (cond-mat.mtrl-sci)

Partial versus total resetting for L'evy flights in d dimensions: similarities and discrepancies

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-03 00:00 EST

Costantino Di Bello, Aleksei Chechkin, Tomasz Grzywny, Karol Szczypkowski, Bartosz Trojan, Zbigniew Palmowski

While stochastic resetting (or total resetting) is less young and more established concept in stochastic processes, partial stochastic resetting (PSR) is a relatively new field. PSR means that, at random moments in time, a stochastic process gets multiplied by a factor between 0 and 1, thus approaching but not reaching the resetting position. In this paper, we present new results on PSR highlighting the main similarities and discrepancies with total resetting. Specifically, we consider both symmetric -stable Lévy processes (Lévy flights) and Brownian motion with PSR in arbitrary d dimensions. We derive explicit expressions for the propagator and its stationary measure, and discuss in detail their asymptotic behavior. Interestingly, while approaching to stationarity, a dynamical phase transition occurs for the Brownian motion, but not for Lévy flights. We also analyze the behavior of the process around the resetting position and find significant differences between PSR and total resetting.

arXiv:2501.01139 (2025)

Statistical Mechanics (cond-mat.stat-mech)

Terahertz Magnon Excitations and Switching in Non-Collinear Antiferromagnets

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Durga Prasad Goli, Se Kwon Kim

We investigate how spatiotemporal spin polarized current can lead to terahertz frequency excitations in non-collinear antiferromagnets. By solving the Landau-Lifshitz-Gilbert equation numerically for non-collinear antiferromagnet, we show that the magnon frequency spectrum exhibits standing spin wave modes and depends on the thickness of MnGe in heterostructure Fe|Au|MnGe. Also, we analyze the switching process of ground state as a function of a spin current. We show a switching phase diagram, which contains switching and non-switching regions. Our work suggests non-collinear antiferromagnets as an efficient platform for terahertz magnonics and ultrafast memory devices.

arXiv:2501.01150 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Characteristic oscillations in frequency-resolved heat dissipation of linear time-delayed Langevin systems: Approach from the violation of the fluctuation-dissipation relation

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-03 00:00 EST

Xin Wang, Ruicheng Bao, Naruo Ohga

Time-delayed effects are widely present in nature, often accompanied by distinctive nonequilibrium features such as negative apparent heat dissipation. To elucidate detailed structures of the dissipation, we study the frequency decompositions of the heat dissipation in linear time-delayed Langevin systems. We analytically solve Langevin equations with a single linear time-delayed feedback force and calculate the spectrum of the heat dissipation in the frequency domain using the Harada-Sasa equality, which relates the heat dissipation to the violation of the fluctuation-dissipation relation (FDR). We find a characteristic oscillatory behavior in the spectrum, which asymptotically oscillates sinusoidally with a decaying envelope proportional to the strength of the time-delayed force and the inverse of the frequency. We confirm the generality of the results by extending our analysis to systems with multiple delay times and continuously distributed delay times. Since the violation of FDR is experimentally accessible, our results suggest an experimental direction for detecting and analyzing detailed characteristics of dissipation in time-delayed systems.

arXiv:2501.01151 (2025)

Statistical Mechanics (cond-mat.stat-mech)

10 pages, 4 figures

Revisiting Impurity Induced In-gap Bound States In Unconventional Superconductors

New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-03 00:00 EST

Junkang Huang, Z. D. Wang, Tao Zhou

This study revisits the effects of single impurity scattering in unconventional superconductors, with a specific emphasis on intralayer -wave pairing and interlayer -wave pairing. We reveal that in the context of a square lattice near half-filling doping, there exists an intrinsic connection between the -wave pairing symmetry and the appearance of mid-gap states. This relationship is determined by the rotational symmetry of both the -wave gap amplitude and the square lattice itself. Furthermore, we identify an intrinsic link between the in-gap states and the sign change of the order parameter. In systems with interlayer pairing, strong resonant peaks are observed, despite the absence of sign-reversal characteristics in the pairing order parameter. By utilizing the -matrix approach, we elucidate the mechanisms underlying these impurity-induced states. Our theoretical framework is pertinent to the analysis of newly discovered nickel-based high-temperature superconductors, providing a powerful tool for distinguishing their pairing properties. The results of this study shed light on the complex interplay between pairing symmetries and impurity effects in unconventional superconductors, paving the way for future investigations into the unique properties of these emerging materials.

arXiv:2501.01155 (2025)

Superconductivity (cond-mat.supr-con)

8 pages, 6 figures, including the supplemental material

Simultaneous Spin and Point-Group Adaptation in Exact Diagonalization of Spin Clusters

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Shadan Ghassemi Tabrizi, Thomas D. Kühne

While either spin or point-group adaptation is straightforward when considered independently, the standard technique for factoring isotropic spin Hamiltonians by the total spin S and the irreducible representation of the point-group is limited by the complexity of transformations between different coupling-schemes that are related by site-permutations. To overcome these challenges, we apply projection-operators directly to uncoupled basis-states, enabling the simultaneous treatment of spin and point-group symmetry without the need for recoupling-transformations. This provides a simple and efficient approach for the exact diagonalization of isotropic spin-models that we illustrate with applications to Heisenberg spin-rings and polyhedra, including systems that are computationally inaccessible with conventional coupling-techniques.

arXiv:2501.01160 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

21 pages, 12 figures

Atomic-scale observation of -- spin coupling in coordination structures

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Xue Zhang, Xin Li, Jie Li, Haoyang Pan, Minghui Yu, Yajie Zhang, Gui-Lin Zhu, Zhen Xu, Ziyong Shen, Shimin Hou, Yaping Zang, Bingwu Wang, Kai Wu, Shang-Da Jiang, Ivano E. Castelli, Lianmao Peng, Per Hedegård, Song Gao, Jing-Tao Lü, Yongfeng Wang

Spin coupling between magnetic metal atoms and organic radicals plays a pivotal role in high-performance magnetic materials. The complex interaction involving multi-spin centers in bulk materials makes it challenging to study spin coupling at the atomic scale. Here, we investigate the -- spin interaction in well-defined metal-organic coordinated structures composed of two iron (Fe) atoms and four all-trans retinoic acid (ReA) molecules, using low-temperature scanning tunneling microscopy and atomic force microscopy. The ReA molecule is turned into a spin- radical state by dehydrogenation, facilitating strong magnetic coupling with the coordinated Fe atoms. Comprehensive theoretical analysis, based on density functional theory and valence bond theory, further elucidates the intrinsic mechanism of ferrimagnetic spin coupling in the coordination structure. Specifically, simultaneous antiferromagnetic coupling of Fe dimer to ReA radicals parallelizes the dimer spin orientation. This work contributes to the fundamental understanding of spin interaction in metal-organic coordination structures and provides microscopic insights for designing advanced magnetic materials.

arXiv:2501.01162 (2025)

Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Formation of Magnonic Waveguides via Surface Anisotropy-Induced Bragg Mirrors

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Grzegorz Centała, Jarosław W. Kłos

Waveguides are fundamental components for signal transmission in integrated wave-based processing systems. In this paper, we address the challenges associated with designing magnonic waveguides and propose a novel type with promising properties. Specifically, we study a magnonic waveguide formed within a uniform ferromagnetic layer (CoFeB) through surface anisotropy applied in stripe regions, creating Bragg mirror structures. The proposed waveguide enables the propagation of high-frequency spin waves with high velocities in the ferromagnetic layer while avoiding static demagnetizing effects. Using finite element simulations, we calculate the dispersion relation of the waveguide modes and analyze their spatial profiles. Additionally, we evaluate the group velocity and localization characteristics, providing a comprehensive understanding of the waveguide's performance.

arXiv:2501.01169 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

On modeling global grain boundary energy functions

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Adam Morawiec

Grain boundaries affect properties of polycrystalline materials. The influence of a boundary is largely determined by its energy. Grain boundary energy is often portrayed as a function of macroscopic boundary parameters representing grain misorientation and boundary plane inclination. In grain boundary simulation and modeling, many studies neglect structural multiplicity of boundaries, i.e., existence of metastable states, and focus on minimum energy. The minimum energy function restricted to constant misorientation should satisfy Herring's condition for interface stability. This requirement has been ignored in recent works on grain boundary energy functions. Example violations of the stability condition are shown. Moreover, a simple and natural procedure for constructing a continuous function satisfying the condition is described. Cusps in the energy as a function of boundary plane inclinations arise because of the imposition of the stability condition, and their locations and shapes result from properties of input data. An example of applying the procedure to simulated data is presented.

arXiv:2501.01175 (2025)

Materials Science (cond-mat.mtrl-sci)

19 pages, 8 figures, 34 references

Pyramidal charged domain walls in ferroelectric BiFeO

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Pavel Marton, Marek Paściak, Mauro Gonçalves, Ondřej Novák, Jiří Hlinka, Richard Beanland, Marin Alexe

Domain structures play a crucial role in the electric, mechanical and other properties of ferroelectric materials. In this study, we uncover the physical origins of the enigmatic zigzag domain structure in the prototypical multiferroic material BiFeO. Using phase-field simulations within the Landau-Ginzburg-Devonshire framework, we demonstrate that spatially-homogeneous defect charges result in domain structures that closely resemble those observed experimentally. The acquired understanding of the underlying physics of pyramidal-domain formation may enable the engineering of new materials with self-assembled domain structures exhibiting defined domain periodicity at the nanometre scale, opening avenues for advanced applications.

arXiv:2501.01190 (2025)

Materials Science (cond-mat.mtrl-sci)

A Magnon Band Analysis of GdRu2Si2 in the Field-Polarized State

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

G. D. A. Wood, J. R. Stewart, D. A. Mayoh, J. A. M. Paddison, J. Bouaziz, S. M. Tobin, O. A. Petrenko, M. R. Lees, P. Manuel, J. B. Staunton, G. Balakrishnan

Understanding the formation of skyrmions in centrosymmetric materials is a problem of fundamental and technological interest. GdRu2Si2 is one such candidate material which has been shown to host a variety of multi-Q magnetic structures, including in zero-field. Here, inelastic neutron scattering is used to measure the spin excitations in the field-polarized phase of GdRu2Si2. Linear spin wave theory and a method of interaction invariant path analysis are used to derive a Hamiltonian accounting for the observed spectra, and comparisons to calculations are made. No evidence for anisotropic or higher order-exchange terms beyond bilinear Heisenberg exchange is found. This is discussed in the context of the multi-Q states existing at lower fields, for which these types of terms have previously been conceived to be significant in the formation of multi-Q ground states.

arXiv:2501.01201 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

Many-Body Dissipative Particle Dynamics Simulations of Lipid Bilayers with the MDPD-MARTINI Force-Field

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Natalia Kramarz, Luís H. Carnevale, Panagiotis E. Theodorakis

Many-body dissipative particle dynamics (MDPD) offers a significant speed-up in the simulation of various systems, including soft matter, in comparison with molecular dynamics (MD) simulations based on Lennard-Jones nteractions, which is crucial for describing phenomena characterized by large time and length scales. Moreover, it has recently been shown that the MARTINI force-field coarse-graining approach is applicable in MDPD, thus rendering feasible the simulation of complex systems as in MD MARTINI for ever larger systems for longer physical times. Here, simulations of various lipid membranes were performed by using the MDPD-MARTINI coarse-grained (CG) force-field, relevant properties were calculated, and comparison with standard MD MARTINI CG simulations and experimental data was made. Thus insights into structural properties of these bilayer systems and further evidence regarding the transferability of the MDPD-MARTINI models are provided. In this regard, this is a natural next step in the development of the general-purpose MDPD-MARTINI CG force-field, which generally provides significant speed-ups in both computational and physical simulated times, in comparison with standard CG MD simulations.

arXiv:2501.01225 (2025)

Soft Condensed Matter (cond-mat.soft)

16 pages, 5 figures

Revealing diatom-inspired materials multifunctionality

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Ludovico Musenich, Daniele Origo, Filippo Gallina, Markus J. Buehler, Flavia Libonati

Diatoms have been described as nanometer-born lithographers because of their ability to create sophisticated three-dimensional amorphous silica exoskeletons. The hierarchical architecture of these structures provides diatoms with mechanical protection and the ability to filter, float, and manipulate light. Therefore, they emerge as an extraordinary model of multifunctional materials from which to draw inspiration. In this paper, we use numerical simulations, analytical models, and experimental tests to unveil the structural and fluid dynamic efficiency of the Coscinodiscus species diatom. Then we propose a novel 3D printable multifunctional biomimetic material for applications such as porous filters, heat exchangers, drug delivery systems, lightweight structures, and robotics. Our results demonstrate the role of Nature as a material designer for efficient and tunable systems and highlight the potential of diatoms for engineering materials innovation. Additionally, the results reported in this paper lay the foundation to extend the structure-property characterization of diatoms.

arXiv:2501.01229 (2025)

Materials Science (cond-mat.mtrl-sci)

Self-diffusive dynamics of active Brownian particles at moderate densities

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Rodrigo Soto

The Active Brownian Particle (ABP) model has become a prototype of self-propelled particles. ABPs move persistently at a constant speed along a direction that changes slowly by rotational diffusion, characterized by a coefficient . Persistent motion plus random reorientations generate a random walk at long times with a diffusion coefficient that, for isolated ABPs in two dimensions, is given by . Here we study the density effects on the self-diffusive dynamics using a recently proposed kinetic theory for ABPs, in which persistent collisions are described as producing a net displacement on the particles. On intermediate timescales, where many collisions have taken place but the director of the tagged particle has not yet changed, an effective stochastic dynamics emerges, characterized by an effective reduced streaming velocity and anisotropic diffusion, with coefficients explicitly depending on density. Based on this result, an effective theoretical and numerical approach is proposed in which the particles follow stochastic dynamics with mean-field interactions based on the local density. Finally, on time scales larger than , the tagged particle shows an effective diffusive motion with a coefficient . The dependence of on density indicates that the kinetic theory is limited to are fractions smaller than 0.42, and beyond this limit unphysical results appear.

arXiv:2501.01251 (2025)

Soft Condensed Matter (cond-mat.soft)

Momentum tunnelling between nanoscale liquid flows

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Baptiste Coquinot, Anna T. Bui, Damien Toquer, Angelos Michaelides, Nikita Kavokine, Stephen J. Cox, Lydéric Bocquet

The world of nanoscales in fluidics is the frontier where the continuum of fluid mechanics meets the atomic, and even quantum, nature of matter. While water dynamics remains largely classical under extreme confinement, several experiments have recently reported coupling between water transport and the electronic degrees of freedom of the confining materials. This avenue prompts us to reconsider nanoscale hydrodynamic flows under the perspective of interacting excitations, akin to condensed matter frameworks. Here we show, using a combination of many-body theory and molecular simulations, that the flow of a liquid can induce the flow of another liquid behind a separating wall, at odds with the prediction of continuum hydrodynamics. We further show that the range of this 'flow tunnelling' can be tuned through the solid's electronic excitations, with a maximum occurring when these are at resonance with the liquid's charge density fluctuations. Flow tunnelling is expected to play a role in global transport across nanoscale fluidic networks, such as lamellar graphene oxide or MXene membranes. It further suggests exploiting the electronic properties of the confining walls for manipulating liquids via their dielectric spectra, beyond the nature and characteristics of individual molecules.

arXiv:2501.01253 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)

Nature Nanotechnology (2025)

Heitler effect and resonance fluorescence in quantum magnonics

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Enes Ilbuğa, V. V. Dobrovitski, Ya. M. Blanter

We consider a coupled system of a qubit and a magnon mode in which the qubit is weakly driven. We demonstrate that the spectral steady-state responses of both the qubit and the magnon show, in addition to two sidebands split by the coupling, also a peak at the driving frequency with virtually zero linewidth. This phenomenon, which persists at both strong and weak coupling, is an analog of the Heitler effect in atomic physics, and shows the path towards building of coherent magnon sources.

arXiv:2501.01254 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)

10 pages including SI

Competing Hexagonal and Square Lattices on a Spherical Surface

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Han Xie, Wenyu Liu, Zhenyue Lu, Jeff Z.Y. Chen, Yao Li

The structural properties of packed soft-core particles provide a platform to understand the cross-pollinated physical concepts in solid-state- and soft-matter physics. Confined on spherical surface, the traditional differential geometry also dictates the overall defect properties in otherwise regular crystal lattices. Using molecular dynamics simulation of the Hertzian model as a tool, we report here the emergence of new types of disclination patterns: domain and counter-domain defects, when hexagonal and square patterns coexist. A new angle is presented to understand the incompatibility between tiling lattice shapes and the available spherical areal shapes, which is common in nature -- from molecular systems in biology to backbone construction in architectures.

arXiv:2501.01270 (2025)

Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)

Authors' version of the article submitted to Nano Letters and accepted

Transport Signatures of Inverted Andreev Bands in Topological Josephson Junctions

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Jonathan Sturm, Raffael L. Klees, Ewelina M. Hankiewicz, Daniel Gresta

We study the thermoelectrical transport transverse to conventional and topological Josephson junctions with a central quantum dot (QD). For that purpose, we derive an effective resonant tunneling model where the QD is renormalized with an induced superconducting gap. By applying Keldysh Green's function technique, we compute the local density of states as well as the transmission functions. In the latter case, we observe that the Andreev bound states forming on the QD are inverted if the junction has -wave symmetry, meaning that electron and hole orbitals switch roles. We calculate the thermoelectric transport coefficients both analytically and numerically and show how the induced gaps and the band inversion are reflected in the electrical and heat conductance as well as the Seebeck coefficient, the latter experiencing a sign change in the topological case.

arXiv:2501.01307 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

12 pages, 6 figures

Launching Focused and Spatially Confined Phonon-Polaritons in Hexagonal Boron Nitride

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Bogdan Borodin, Sergey Lepeshov, Kenji Watanabe, Takashi Taniguchi, Petr Stepanov

Launching and focusing phonon-polaritons present novel opportunities for low-loss guiding of subdiffractionally confined light at the nanoscale. Despite significant efforts to improve control in polaritonic media, focused and spatially confined phonon-polariton waves have only been achieved in the in-plane anisotropic crystals (such as MoO) and remain elusive in the in-plane isotropic crystals (such as hexagonal boron nitride). In this study, we present a previously unexplored approach to launching phonon-polaritons by employing hBN subwavelength resonators coupled to gold nanoantennas. The integration of gold nanoantennas enables efficient coupling to the far-field component of mid-infrared light, while the geometry of the resonators defines the wavefront curvature, spatial confinement, and focusing of the launched polaritons. Using standard lithographic protocols, we achieve strong field enhancement and resonant mode localization, generating phonon-polaritons with precise spatial definition. Scattering-type scanning near-field optical microscopy reveals the real-space optical contrast of these modes. This innovative and practical approach introduces a new paradigm for fabricating nanoresonators that actively launch and focus phonon-polaritons, opening avenues for advanced nanophotonic devices.

arXiv:2501.01319 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

8 pages, 4 figures

Can hydrodynamic interactions destroy travelling waves formed by non-reciprocity?

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Giulia Pisegna, Navdeep Rana, Ramin Golestanian, Suropriya Saha

The collective chasing dynamics of non-reciprocally coupled densities leads to stable travelling waves which can be mapped to a model for emergent flocking. In this work, we couple the non-reciprocal Cahn-Hilliard model (NRCH) to a fluid to minimally describe scalar active mixtures in a suspension, with the aim to explore the stability of the waves, i.e. the emergent flock in the presence of self-generated fluid flows. We show that the emergent polarity is linearly unstable to perturbations for a specific sign of the active stress recalling instabilities of orientational order in a fluid. Using numerical simulations, we find however that non-reciprocity stabilizes the waves against the linear instability in a large region of the phase space.

arXiv:2501.01330 (2025)

Soft Condensed Matter (cond-mat.soft)

Chiral electronic network within skyrmionic lattice on topological insulator surfaces

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Matteo Wilczak, Dmitry K. Efimkin, Victor Gurarie

We consider a proximity effect between Dirac surface states of a topological insulator and the skyrmion phase of an insulating magnet. A single skyrmion results in the surface states having a chiral gapless mode confined to the perimeter of the skyrmion. For the lattice of skyrmions, the tunneling coupling between confined states leads to the formation of low energy bands delocalized across the whole system. We show that the structure of these bands can be investigated with the help of the phenomenological chiral network model with a kagome lattice geometry. While the network model by itself can be in a chiral Floquet phase unattainable without external periodic driving, we show how to use a procedure known as band reconstruction to obtain the low energy bands of the electrons on the surface of the topological insulator for which there is no external driving. We conclude that band reconstruction is essential for the broad class of network models recently introduced to describe the electronic properties of different nanostructures.

arXiv:2501.01337 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Close-contact melting on hydrophobic textured surfaces: Confinement and meniscus effects

New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-03 00:00 EST

Nan Hu, Liwu Fan, Xiang Gao, Howard A. Stone

We investigate the dynamics of close-contact melting (CCM) on gas-trapped hydrophobic surfaces, with specific focus on the effects of geometrical confinement and the liquid-air meniscus below the liquid film. By employing dual-series and perturbation methods, we obtain numerical solutions for the effective slip lengths associated with velocity and temperature fields, across various values of aspect ratio (defined as the ratio of the film thickness to the structure's periodic length ) and gas-liquid fraction . Asymptotic solutions of and for and are derived and summarized for different surface structures, interface shapes and , which reveal a different trend for and and the presence of a meniscus. In the context of constant-pressure CCM, our results indicate that transverse-grooves surfaces consistently reduced the heat transfer. However, longitudinal grooves can enhance heat transfer under the effects of confinement and meniscus when and . For gravity-driven CCM, the parameters of and determine whether the melting rate is enhanced, reduced, or nearly unaffected. We construct a phase diagram based on the parameter matrix to delineate these three regimes. Lastly, we derived two asymptotic solutions for predicting the variation in time of the unmelted solid height.

arXiv:2501.01340 (2025)

Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)

Magnetic frustration and weak Mn magnetic ordering in EuMnP

New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-03 00:00 EST

Sarah Krebber, Jörg Sichelschmidt, Pierre Chailloleau, Asmaa El Mard, Marvin Kopp, Michael Baenitz, Kurt Kummer, Denis V. Vyalikh, Jens Müller, Cornelius Krellner, Kristin Kliemt

We report on the electron spin resonance (ESR), heat capacity, magnetization, nuclear magnetic resonance (NMR), magnetic circular and linear dichroism (XMCD, XMLD), as well as the electrical resistivity of EuMnP single crystals. Antiferromagnetic order of Eu was observed in several quantities at . The temperature dependencies of ESR linewidth and resonance shift show, when approaching the Eu-ordered state, a divergence towards , indicating the growing importance of magnetic correlations and the build-up of internal magnetic fields. An additional temperature scale of has considerable impact on linewidth, resonance field and intensity. This points to the presence of weak Mn-based ordering. The observed ESR line is interpreted as an Eu resonance, which probes the weak magnetic background of the Mn subsystem. Such picture is suggested by the lineshape which keeps to be Lorentzian across the scale and by the ESR intensity which can be described by the same Curie-Weiss temperature above and below . In the same temperature range anomalies were observed at and in the heat capacity data as well as a pronounced broadening of the NMR signal of the EuMnP samples. In XMCD and XMLD measurements, this weak magnetic order could not be detected in the same temperature range which might be due to the small magnetic moment, with a potential -component or frustration.

arXiv:2501.01355 (2025)

Strongly Correlated Electrons (cond-mat.str-el)

Three-dimensional quantum anomalous Hall effect in Weyl semimetals

New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-03 00:00 EST

Zhi-Qiang Zhang, Yu-Hang Li, Ming Lu, Hongfang Liu, Hailong Li, Hua Jiang, X. C. Xie

The quantum anomalous Hall effect (QAHE) is a quantum phenomenon in which a two-dimensional system exhibits a quantized Hall resistance in the absence of magnetic field, where is the Planck constant and is the electron charge. In this work, we extend this novel phase to three dimensions and thus propose a three-dimensional QAHE exhibiting richer and more versatile transport behaviors. We first confirm this three-dimensional QAHE through the quantized Chern number, then establish its bulk-boundary correspondence, and finally reaffirm it via the distinctive transport properties. Remarkably, we find that the three-dimensional QAHE hosts two chiral surface states along one spatial direction while a pair of chiral hinge states along another direction, and the location of the hinge states depends sensitively on the Fermi energy. These two types of boundary states are further connected through a perpendicular chiral surface states, whose chirality is also Fermi energy dependent. Consequently, depending on the transport direction, its Hall resistance can quantize to , , or when the Fermi energy is tuned across the charge neutral point. This three-dimensional QAHE not only fill the gap in the Hall effect family but also holds significant potentials in device applications such as in-memory computing.

arXiv:2501.01399 (2025)

Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)

Sample shape dependence of magnetic noise

New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-03 00:00 EST

Steven T. Bramwell

Zero-field magnetic noise, characterised by the magnetic autocorrelation function , has been observed, perhaps surprisingly, to depend on sample shape . The reasons for this are identified and general expressions are derived that relate the autocorrelation functions for systems of different shape to an underlying `intrinsic' form. Assuming the flcutuatiopn-dissipation theorem, it is shown that, for any noise that relaxes monotonically, the effect of sample shape is to reduce both the noise amplitude and mean relaxation time by a factor of , where is the demagnetizing factor and the intrinsic susceptibility. In frequency space, where Fourier transforms into the power spectrum , the above two factors combine to suppress the zero frequency amplitude of by , while at high frequency, sample shape dependence becomes negligible. These results suggest simple and robust experimental tests of the fluctuation--dissipation theorem in magnetic systems that may be useful in distinguishing bulk from surface effects.

arXiv:2501.01400 (2025)

Statistical Mechanics (cond-mat.stat-mech)

6 pages, 4 figures

Strain-Induced Activation of Symmetry-Forbidden Exciton-Phonon Couplings for Enhanced Phonon-Assisted Photoluminescence in MoS Monolayers

New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-03 00:00 EST

Rishabh Saraswat, Rekha Verma, Sitangshu Bhattacharya

Phonon-assisted photoluminescence (PL) in molybdenum-based two-dimensional dichalcogenides is typically weak due to the dormant phonon coupling with optically inactive momentum-dark (intervalley) excitons, unlike in tungsten-based dichalcogenides where such processes are more prominent. Despite this inefficiency, we revisit excitons in MoS using rigorous finite-momentum Bethe-Salpeter equation calculations to identify ways to enhance phonon-assisted recombination channels. Our ab-initio results, complemented by group-theoretic analyses, reveal that while unstrained MoS exhibits no phonon-assisted PL emissions at cryogenic temperatures due to forbidden A phonon modes, biaxial strain opens a pathway to significantly intensify this emission by activating hole-phonon A-mediated scattering channels. By calculating allowed exciton-phonon matrix elements and scattering rates, we demonstrate how strain redistributes oscillator strengths toward radiative recombination. These findings provide a promising route to improving PL emission efficiency in various metal dichalcogenide monolayers through strain engineering and offer valuable insights for further exploration of exciton-phonon dynamics, including time-resolved spectroscopic studies.

arXiv:2501.01410 (2025)

Materials Science (cond-mat.mtrl-sci)


CMP Journal 2025-01-03
https://liugroupcornell.github.io/2025/01/03/2025-01-03/
Author
Lab Liu
Posted on
January 3, 2025
Licensed under