CMP Journal 2025-01-27
Statistics
Nature Materials: 2
Physical Review Letters: 8
Physical Review X: 1
arXiv: 58
Nature Materials
Correlated spin-wave generation and domain-wall oscillation in a topologically textured magnetic film
Original Paper | Electronic and spintronic devices | 2025-01-26 19:00 EST
Chuhang Liu, Fangzhou Ai, Spencer Reisbick, Alfred Zong, Alexandre Pofelski, Myung-Geun Han, Fernando Camino, Chunguang Jing, Vitaliy Lomakin, Yimei Zhu
Spin waves, or magnons, are essential for next-generation energy-efficient spintronics and magnonics. Yet, visualizing spin-wave dynamics at nanoscale and microwave frequencies remains a formidable challenge due to the lack of spin-sensitive, time-resolved microscopy. Here we report a breakthrough in imaging dipole-exchange spin waves in a ferromagnetic film owing to the development of laser-free ultrafast Lorentz electron microscopy, which is equipped with a microwave-mediated electron pulser for high spatiotemporal resolution. Using topological spin textures, we captured the emission, propagation, reflection and interference of spin waves from spin anti-vortices under radio-frequency excitations. Remarkably, we show that spin-wave generation is closely tied to the oscillatory motion of specific magnetic domain walls, providing the missing link between wave emission and wall dynamics near magnetic singularities. This work opens new possibilities in magnonics, offering a nanoscopic view of spin dynamics via transmission electron microscopy and enabling controlled excitation via radio-frequency fields for exploring non-equilibrium states in magnetic and multiferroic systems.
Electronic and spintronic devices, Ferromagnetism, Imaging techniques, Magnetic properties and materials, Spintronics
Cryogenic in-memory computing using magnetic topological insulators
Original Paper | Electrical and electronic engineering | 2025-01-26 19:00 EST
Yuting Liu, Albert Lee, Kun Qian, Peng Zhang, Zhihua Xiao, Haoran He, Zheyu Ren, Shun Kong Cheung, Ruizi Liu, Yaoyin Li, Xu Zhang, Zichao Ma, Jianyuan Zhao, Weiwei Zhao, Guoqiang Yu, Xin Wang, Junwei Liu, Zhongrui Wang, Kang L. Wang, Qiming Shao
Machine learning algorithms have proven to be effective for essential quantum computation tasks such as quantum error correction and quantum control. Efficient hardware implementation of these algorithms at cryogenic temperatures is essential. Here we utilize magnetic topological insulators as memristors (termed magnetic topological memristors) and introduce a cryogenic in-memory computing scheme based on the coexistence of a chiral edge state and a topological surface state. The memristive switching and reading of the giant anomalous Hall effect exhibit high energy efficiency, high stability and low stochasticity. We achieve high accuracy in a proof-of-concept classification task using four magnetic topological memristors. Furthermore, our algorithm-level and circuit-level simulations of large-scale neural networks demonstrate software-level accuracy and lower energy consumption for image recognition and quantum state preparation compared with existing magnetic memristor and complementary metal-oxide-semiconductor technologies. Our results not only showcase a new application of chiral edge states but also may inspire further topological quantum-physics-based novel computing schemes.
Electrical and electronic engineering, Electronic devices, Information storage
Physical Review Letters
Multiparticle Flux-Tube S-matrix Bootstrap
Research article | Quantum field theory | 2025-01-27 05:00 EST
Andrea Guerrieri, Alexandre Homrich, and Pedro Vieira
We introduce the notion of jets, states of collinear flux-tube excitations. We argue for the analyticity, crossing, and unitarity of the multiparticle scattering of these jets and, through the S-matrix bootstrap, place bounds on a set of finite-energy multiparticle sum rules. Such bounds define a matrioska with a smaller and smaller allowed regions as we impose more constraints. The Yang-Mills flux tube, as well as other interesting flux-tube theories recently studied through lattice simulations, lie inside a tiny island hundreds of times smaller than the most general space of allowed theories.
Phys. Rev. Lett. 134, 041601 (2025)
Quantum field theory, Scattering amplitudes
Prominent Bump in the Two-Neutron Separation Energies of Neutron-Rich Lanthanum Isotopes Revealed by High-Precision Mass Spectrometry
Research article | Binding energy & masses | 2025-01-27 05:00 EST
A. Jaries, M. Stryjczyk, A. Kankainen, T. Eronen, O. Beliuskina, T. Dickel, M. Flayol, Z. Ge, M. Hukkanen, M. Mougeot, S. Nikas, I. Pohjalainen, A. Raggio, M. Reponen, J. Ruotsalainen, and V. Virtanen
We report on high-precision atomic mass measurements of \(^{148--153}\mathrm{La}\) and \(^{151}\mathrm{Ce}\) performed with the JYFLTRAP double Penning trap using the phase-imaging ion-cyclotron-resonance technique. The masses of \(^{152,153}\mathrm{La}\) were experimentally determined for the first time. We confirm the sharp kink in the two-neutron separation energies at the neutron number \(N=93\) in the cerium (\(Z=58\)) isotopic chain. Our precision mass measurements of the most exotic neutron-rich lanthanum (\(Z=57\)) isotopes reveal a unexpected sudden increase in two-neutron separation energies from \(N=92\) to \(N=93\). Unlike in the cerium isotopic chain, the kink is not sharp but extends to \(N=94\) forming a prominent bump. The gain in energy is about 0.4 MeV, making it one of the strongest changes in two-neutron separation energies over the whole chart of nuclides, away from nuclear shell closures. The results, correlated with a predicted onset of quadrupole deformation for \(N\ge 92\), call for further studies to elucidate the structure of neutron-rich lanthanum isotopes.
Phys. Rev. Lett. 134, 042501 (2025)
Binding energy & masses, 150 ≤ A ≤ 189, 90 ≤ A ≤ 149
Cold Beam Optical Clock with Multifrequency Spectroscopy
Research article | Atomic, optical & lattice clocks | 2025-01-27 05:00 EST
William G. Tobias, Bryan Hemingway, and Steven Peil
Multifrequency spectroscopy of a cold beam optical clock improves the long-term stability while decreasing several sources of systematic time-keeping errors.
Phys. Rev. Lett. 134, 043401 (2025)
Atomic, optical & lattice clocks, Laser spectroscopy, Atomic & molecular beams, Atom & ion cooling
Demonstration of Similarity Laws and Scaling Networks for Radio-Frequency Plasmas
Research article | High-frequency & RF discharges in plasmas | 2025-01-27 05:00 EST
Dong Yang, John P. Verboncoeur, and Yangyang Fu
We experimentally demonstrate similarity laws for capacitive radio-frequency (rf) plasmas, showing that two rf discharges are scale-invariant in geometrically similar systems in which the gas pressure, gap dimension, and driving frequency are proportionally tuned. Spatiotemporal distributions of the excitation rate are measured based on phase-resolved optical emission spectroscopy, and the tendencies of the excitation dynamics scaling with control parameters are presented and agree well with particle-in-cell simulations. Furthermore, similarity-based scaling networks are established, which extensively correlate the discharge states (i.e., the initial, intermediate, and similarity states), enabling an effective strategy for determining scaling relations with fewer experiments. The framework of the scaling networks is interpreted based on the kinetic Boltzmann equation coupled with Poisson's equation. The present work reveals the nature of discharge similarity and provides an additional knob for the exploration of upscaled rf plasma sources for industrial applications, such as large-area etching facilities.
Phys. Rev. Lett. 134, 045301 (2025)
High-frequency & RF discharges in plasmas, Plasma discharges, Low-temperature plasma, Particle-in-cell methods, Plasma spectroscopy, Scaling methods
Epitaxially Defined Luttinger Liquids on \({\mathrm{MoS}}_{2}\) Bicrystals
Research article | Coulomb blockade | 2025-01-27 05:00 EST
Bingchen Deng, Heonsu Ahn, Jue Wang, Gunho Moon, Cheolhee Han, Ninad Dongre, Chao Lei, Giovanni Scuri, Jiho Sung, Elise Brutschea, Kenji Watanabe, Takashi Taniguchi, Fan Zhang, Moon-Ho Jo, and Hongkun Park
Conductance measurement demonstrate that mirror twin boundaries in transition metal dichalcogenides can serve as a platform for studying the interplay between electronic interactions and topology.
Phys. Rev. Lett. 134, 046301 (2025)
Coulomb blockade, Crystal growth, Electrical conductivity, Grain boundaries, Symmetry protected topological states, Valleytronics, 1-dimensional systems, Luttinger liquid model
Magnetic Exciton of EuS Revealed by Resonant Inelastic X-Ray Scattering
Research article | Density of states | 2025-01-27 05:00 EST
Lucia Amidani, Jonas J. Joos, Pieter Glatzel, and Jindřich Kolorenč
Resonant inelastic x-ray scattering measurements on EuS identify two narrow peaks in the optical absorption spectra as magnetic excitons.
Phys. Rev. Lett. 134, 046401 (2025)
Density of states, Excitons, Magnetic semiconductors, Rare-earth magnetic materials, Density functional calculations, Dynamical mean field theory, Optical absorption spectroscopy, Resonant inelastic x-ray scattering, X-ray emission spectroscopy
Exciton Condensation in Landau Levels of Quantum Spin Hall Insulators
Research article | Excitons | 2025-01-27 05:00 EST
Hong-Mao Peng, Zhan Wang, and Long Zhang
We theoretically study the quantum spin Hall insulator (QSHI) in a perpendicular magnetic field. In the noninteracting case, the QSHI with space inversion and/or uniaxial spin rotation symmetry undergoes a topological transition into a normal insulator phase at a critical magnetic field \({B}_{\mathrm{c}}\). The exciton condensation in the lowest Landau levels is triggered by Coulomb interactions in the vicinity of \({B}_{\mathrm{c}}\) at low temperature and spontaneously breaks the inversion and the spin rotation symmetries. We propose that the electron spin resonance spectroscopy with the ac magnetic field also aligned in the perpendicular direction can directly probe the exciton condensation order. Our results should apply to QSHIs such as the \(\mathrm{InAs}/\mathrm{GaSb}\) quantum wells and monolayer transition-metal dichalcogenides.
Phys. Rev. Lett. 134, 046601 (2025)
Excitons, Landau levels, Topological insulators, Electron spin resonance, Inversion symmetry, Mean field theory
Targeted Avoidance in Complex Networks
Research article | Attacks on networks | 2025-01-27 05:00 EST
Aobo Zhang, Chi Ho Yeung, Chen Zhao, Ying Fan, and An Zeng
The study of spreading in networks presents a fascinating topic with a wide array of practical applications. Various strategies have been proposed to attack or immunize networks. However, it is often not feasible or necessary to consider the entire network in the context of real-world systems. Here, we focus on a certain group of target nodes with the aim of disconnecting them from the global network structure. For instance, it becomes possible to effectively prevent the transmission of the disease to vulnerable populations, such as infants and the elderly, by isolating some specific nodes such as their caretakers during the epidemic. From this perspective of targeted avoidance, we introduce a series of target centrality indicators and apply them to segment the target nodes from the giant component of the network. Additionally, we propose a more effective iterative graph-segmentation method for targeted immunization. Our experimental findings reveal that our proposed method can substantially reduce the number of nodes required for removal when compared with the methods based on target centrality, which implies a significant cost effectiveness in isolating target nodes from the rest of the network. Finally, we verify our method on a large mobility network in the scenario of the COVID-19 pandemic, and find that our method can effectively protect the elderly by immunizing or isolating a very small group of nodes.
Phys. Rev. Lett. 134, 047401 (2025)
Attacks on networks, Epidemic, Real world networks, Scale free & inhomogeneous networks, Small-world networks
Physical Review X
Long-Range Optomechanical Interactions in SiN Membrane Arrays
Research article | Optical forces | 2025-01-27 05:00 EST
Xiong Yao, Matthijs H. J. de Jong, Jie Li, and Simon Gröblacher
Interactions between light and a vibrating membrane are a cornerstone of many light-matter experiments. A new setup achieves a long-predicted boost to the optomechanical coupling rate with the use of two membranes.
Phys. Rev. X 15, 011014 (2025)
Optical forces, Optomechanics
arXiv
Exact generalized Bethe eigenstates of the non-integrable alternating Heisenberg chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-27 20:00 EST
Ronald Melendrez, Bhaskar Mukherjee, Marcin Szyniszewski, Christopher J. Turner, Arijeet Pal, Hitesh J. Changlani
Exact solutions of quantum lattice models serve as useful guides for interpreting physical phenomena in condensed matter systems. Prominent examples of integrability appear in one dimension, including the Heisenberg chain, where the Bethe ansatz method has been widely successful. Recent work has noted that certain non-integrable models harbor quantum many-body scar states, which form a superspin of regular states hidden in an otherwise chaotic spectrum. Here we consider one of the simplest examples of a non-integrable model, the alternating ferromagnetic-antiferromagnetic (bond-staggered) Heisenberg chain, a close cousin of the spin-1 Haldane chain and a spin analog of the Su-Schrieffer-Heeger model, and show the presence of exponentially many zero-energy states. We highlight features of the alternating chain that allow treatment with the Bethe ansatz (with important modifications) and surprisingly for a non-integrable system, we find simple compact expressions for zero-energy eigenfunctions for a few magnons including solutions with fractionalized particle momentum. We discuss a general numerical recipe to diagnose the existence of such generalized Bethe ansatz (GBA) states and also provide exact analytic expressions for the entanglement of such states. We conclude by conjecturing a picture of magnon pairing which may generalize to multiple magnons. Our work opens the avenue to describe certain eigenstates of partially integrable systems using the GBA.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
22 pages, 8 figures, 4 tables, 3 appendices
Exact quantum many-body scars tunable from volume to area law
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-27 20:00 EST
Bhaskar Mukherjee, Christopher J. Turner, Marcin Szyniszewski, Arijeet Pal
Teleportation of quantum information over long distances requires robust entanglement on the macroscopic scale. The construction of a manifold of highly energetic eigenstates with tunable long-range entanglement can provide a new medium for information transmission. We construct polynomially many exact zero-energy eigenstates in an exponentially degenerate manifold for a class of non-integrable spin-1/2 Hamiltonians with two-body interactions. A symmetric superposition of the triplet basis of antipodal spin pairs provides a rich manifold for the construction of states with extensive, logarithmic, and short-range entanglement by tuning the distribution of triplet states. We show the volume-law entangled states despite being in the middle of the spectrum host non-thermal expectation values of local observables. Certain quasiparticle excitations in this manifold converge to be exact quantum many-body scars in the thermodynamic limit. This framework has a natural extension to higher dimensions, where entangled states controlled by lattice geometry and internal symmetries can result in new classes of correlated out-of-equilibrium quantum matter. Our results provide a new avenue for entanglement control and a novel method of quantum state construction.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
13 pages, 4 figures, 1 table
AtomProNet: Data flow to and from machine learning interatomic potentials in materials science
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Musanna Galib, Mewael Isiet, Mauricio Ponga
As the atomistic simulations of materials science move from traditional potentials to machine learning interatomic potential (MLIP), the field is entering the second phase focused on discovering and explaining new material phenomena. While MLIP development relies on curated data and flexible datasets from ab-initio simulations, transitioning seamlessly between ab-initio workflows and MLIP frameworks remains challenging. A global survey was conducted to understand the current standing (progress and bottleneck) of the machine learning-guided materials science research. The survey responses have been implemented to design an open-source software to reduce the access barriers of MLIP models for the global scientific community. Here, we present AtomProNet, an open-source Python package that automates obtaining atomic structures, prepares and submits ab-initio jobs, and efficiently collects batch-processed data for streamlined neural network (NN) training. Finally, we compared empirical and start-of-the-art machine learning potential, showing the practicality of using MLIPs based on computational time and resources.
Materials Science (cond-mat.mtrl-sci)
Non-Topological Edge-Localized Yu-Shiba-Rusinov States in CrBr\(_3\)/NbSe\(_2\) Heterostructures
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Jan P. Cuperus, Daniel Vanmaekelbergh, Ingmar Swart
Topological superconductivity is predicted to emerge in certain magnet-superconductor hybrid systems. Here, we revisit the heterostructure of insulating monolayer CrBr\(_3\) and NbSe\(_2\), for which different conclusions on the presence of topological superconductivity have been reported. Using low-temperature scanning tunneling microscopy and (shot noise) spectroscopy, we find that the superconducting gap well inside the CrBr3 islands is not affected by magnetism. At the island edges, we observe Yu-Shiba-Rusinov (YSR) states at a variety of in-gap positions, including zero energy. The absence of topological superconductivity is verified by extensive dI/dV measurements at the CrBr\(_3\) island edges. Our results ask for a more detailed understanding of the interaction between magnetic insulators and superconductors.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Effects of electron correlation on resonant Edelstein and inverse-Edelstein effects
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-27 20:00 EST
Mojdeh Saleh, Abhishek Kumar, Dmitrii L. Maslov, Saurabh Maiti
Spin-orbit coupling in systems with broken inversion symmetry gives rise to the Edelstein effect, which is the induced spin polarization in response to an applied electric field or current, and the inverse Edelstein effect, which is the induced electric current in response to an oscillatory magnetic field or spin polarization. At the same time, an interplay between spin-orbit coupling and electron-electron interaction leads to a special type of collective excitations -- chiral-spin modes -- which are oscillations of spin polarization in the absence of a magnetic field. As a result, both Edelstein and inverse Edelstein effects exhibit resonances at the frequencies of spin-chiral collective modes. Here, we present a detailed study of the effect of electron correlation on the Edelstein and inverse Edelstein effects in a single-valley two-dimensional electron gas and a multi-valley Dirac system with proximity-induced spin-orbit coupling. While the chiral-spin modes involve both in-plane and out-of-plane oscillations of spins, we show that only the in-plane modes are responsible for the above resonances. In the multi-valley system, electron correlation splits the in-plane modes into two. We also study the spectral weight distribution between the two resonances over a large parameter space of intra- and inter-valley interactions.
Strongly Correlated Electrons (cond-mat.str-el)
Active bacterial baths in droplets
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-27 20:00 EST
Cristian Villalobos-Concha, Zhengyang Liu, Gabriel Ramos, Martyna Goral, Anke Lindner, Teresa López-León, Eric Clément, Rodrigo Soto, María Luisa Cordero
Suspensions of self-propelled objects represent a novel paradigm in colloidal science. In such active baths traditional concepts, such as Brownian motion, fluctuation-dissipation relations, and work extraction from heat reservoirs, must be extended beyond the conventional framework of thermal baths. Unlike thermal baths, which are characterized by a single parameter, the temperature, the fundamental descriptors of an active bath remain elusive, especially in confined environments. In this study, buoyant, passive tracers are employed as generalized probes to investigate an active bath comprising motile bacteria confined within a droplet. We demonstrate that momentum transfer from the bath to the tracer can be effectively described as colored noise, characterized by temporal memory and an enhanced effective diffusivity significantly larger compared to thermal Brownian motion values. Using a stochastic analytical framework, we extract the temporal memory and diffusivity parameters that define such an active bath. Notably, the diffusivity scales linearly with bacterial concentration, modulated by a factor representing the role of confinement, expressed as the ratio of the confining radius to the probe radius. This finding, while still awaiting a complete theoretical explanation, offers new insights into the transport properties of confined active baths and paves the way for a deeper understanding of active emulsions driven by confined active matter.
Soft Condensed Matter (cond-mat.soft)
An Approach to Use Depletion Charges for Modifying Band Profiles for Field-Effect Transistors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
We present the study of using depletion charges for tailoring lateral band profiles and applying it to the promising gate-all-around field-effect transistors (GAAFET). Specifically, we introduce heavily p-type doped Si next to the channel, but outside the channel, of a transistor. They are connected to the heavily n-type doped source and drain for generating the depletion charges. The finite difference method was used for simulations and the results show significant modifications of the conduction band along the channel. The depletion charges act as built-in electrodes capable of significantly modifying the band profiles of field-effect transistors. Quantum confinement within the channel has been attempted with different approaches, such as additional electrodes and point contacts. The results presented show two aspects of this approach, namely, realizing quantum confinement in an all-Si structure and tailoring band profiles within channels to modify their transport properties.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Selective enhancement of Coulomb interactions in planar Weyl fermions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Vadym Apalkov, Wenchen Luo, Tapash Chakraborty
We report on our study of the electron interaction effects in topological two-dimensional (2D) materials placed in a quantizing magnetic field. Taking our cue from a recent experimental report, we consider a particular case of bismuthene monolayer with a strong spin-orbit interaction which can be a Weyl semimetal when placed on a specially tuned substrate. Interestingly, we observe that in some Landau levels of this material, the interaction effects are strongly enhanced compared to those for a conventional 2D system. Such an enhancement of electron-electron interactions in these materials is largely due to an anisotropy present in the materials. Additionally, the interaction effects can be tuned by changing the coupling to the substrate and the strongest inter-electron interactions are observed when the system is a Weyl semimental. The observed enhancement of the interaction effects can therefore be an important signature of the 2D Weyl fermions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
4 pages, 4 figures
Time-reversal symmetry breaking, collective modes, and Raman spectrum in pair-density-wave states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-27 20:00 EST
Yi-Ming Wu, Andrey V. Chubukov, Yuxuan Wang, Steven A. Kivelson
Inspired by empirical evidence of the existence of pair-density-wave (PDW) order in certain underdoped cuprates, we investigate the collective modes in systems with unidirectional PDW order with momenta \(\pm {Q}\) and a \(d\)-wave form-factor with special focus on the amplitude (Higgs) modes. In the pure PDW state, there are two overdamped Higgs modes. We show that a phase with co-existing PDW and uniform (\(d\)-wave) superconducting (SC) order, PDW/SC, spontaneously breaks time-reversal symmetry - and thus is distinct from a simpler phase, SC/CDW, with coexisting SC and charge-density-wave (CDW) order. The PDW/SC phase exhibits three Higgs modes, one of which is sharply peaked and is predominantly a PDW fluctuation, symmetric between \({Q}\) and -\({Q}\), whose damping rate is strongly reduced by SC. This sharp mode should be visible in Raman experiments.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
main text: 5 pages + 3 figures; Supplementary Material: 26 pages + 9 figures
Topolectrical space-time circuits
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Weixuan Zhang, Wenhui Cao, Long Qian, Hao Yuan, Xiangdong Zhang
Topolectrical circuits have emerged as a pivotal platform for realizing static topological states that are challenging to construct in other systems, facilitating the design of robust circuit devices. In addition to spatial dimensionality, synergistic engineering of both temporal and spatial degrees in circuit networks holds tremendous potential across diverse technologies, such as wireless communications, non-reciprocal electronics and dynamic signal controls with exotic space-time topology. However, the realization of space-time modulated circuit networks is still lacking due to the necessity for flexible modulation of node connections in both spatial and temporal domains. Here, we propose a new class of topolectrical circuits, referred to as topolectrical space-time circuits, to bridge this gap. By designing and applying a novel time-varying circuit element controlled by external voltages, we can construct circuit networks exhibiting discrete space-time translational symmetries in any dimensionality, where the circuit dynamical equation is in the same form with time-dependent Schrodinger equation. Through the implementation of topolectrical space-time circuits, three distinct types of topological space-time crystals are experimentally demonstrated, including the (1+1)-dimensional topological space-time crystal with midgap edge modes, (2+1)-dimensional topological space-time crystal with chiral edge states, and (3+1)-dimensional Weyl space-time semimetals. Our work establishes a solid foundation for the exploration of intricate space-time topological phenomena and holds potential applications in the field of dynamically manipulating electronic signals with unique space-time topology
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Nat. Commun. 16, 198 (2025)
Topological Influence of Sextets on Graphene Oxide Nanostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Musiri M Balakrishnarajan, Gaurav Jhaa, Pattath D Pancharatna
Graphene Oxide (GO) remains a perennial chemical enigma despite its utility in preparing graphene and its functionalization. Epoxides and tertiary alcohols are construed as primary functional groups, but the structural motifs, spectra, and physicochemical properties remain largely inexplicable. Our graph theoretic perturbational analysis of introducing defects (sp3 carbons) on graphene shows the induction of sextets that topologically force 1, 4-quinoidal channels. Edge defects minimize these, whose propagation is halted by vertex anti-defects. Molecular models show that epoxidation creates a diradical centered on two cove-end carbons due to close-lying frontier orbitals. This drives the cascade addition of hydroxides, yielding the 1:2 ratio of epoxides and hydroxides. This nanostructure accounts for the cation exchange, acidity, anionic nature of GO, and topological conditions that break its sigma framework. The simulated spectra of a 2D sheet with this nanostructure correlate pleasantly with experiments, emphasizing the dominant role of sextet topology on the surface chemistry of graphene.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 7 figures
Nonlinear optical response in a ferromagnetic insulating manganite: Pr\(_{0.8}\)Ca\(_{0.2}\)MnO\(_{3}\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-27 20:00 EST
A. Nakano, K. Uchida, Y. Tomioka, M. Takaya, Y. Okimoto, K. Tanaka
High harmonic generation from Pr\(_{0.8}\)Ca\(_{0.2}\)MnO\(_{3}\) was investigated across a high-temperature paramagnetic phase and a low-temperature ferromagnetic phase. As the temperature decreases, the harmonic intensity gradually increases in the paramagnetic phase like that in different composition material Pr\(_{0.6}\)Ca\(_{0.4}\)MnO\(_{3}\). However, it turns to a decrease in the ferromagnetic phase. We propose a possible interpretation of the anomaly around the ferromagnetic transition temperature considering the thermal fluctuation of orbital order and the metal-insulator phase separation in the ferromagnetic insulating phase.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 5 figures
Field Theory of Birhythmicity
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-27 20:00 EST
Sergei Shmakov, Peter B. Littlewood
Non-equilibrium dynamics are present in many aspects of our lives, ranging from microscopic physical systems to the functioning of the brain. What characterizes stochastic models of non-equilibrium processes is the breaking of the fluctuation-dissipation relations as well as the existence of non-static stable states, or phases. A prototypical example is a dynamical phase characterized by a limit cycle - the order parameter of finite magnitude rotating or oscillating at a fixed frequency. Consequently, birhythmicity, where two stable limit cycles coexist, is a natural extension of the simpler single limit cycle phase. Both the abundance of real systems exhibiting such states as well as their relevance for building our understanding of non-equilibrium phases and phase transitions are strong motivations to build and study models of such behavior. Field theoretic tools can be used to provide insights into either phase and the transition between them. In this work we explore a simple linear model of the single limit cycle phase with phase-amplitude coupling. We demonstrate how such non-equilibrium coupling affects the fluctuation spectrum of the theory. We then extend this model to include a continuous transition to a two-cycle phase. We give various results, such as an appearance of a critical exceptional point, the destruction of the transition, enhancement of noise for the phase and the presence of KPZ dynamics. Finally, we qualitatively demonstrate these results with numerics and discuss future directions.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
11 pages, 7 figures
Enhancing Unconventional Spin-Orbit Torque Efficiency: First Numerical Study on the Influence of Crystallographic Texture and Polycrystalline Effects on Low-Symmetry Materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Spin-orbit torque (SOT) has been extensively studied as a key mechanism in spintronics applications. However, conventional SOT materials limit the spin polarization direction to the in-plane orientation, which is suboptimal for efficient magnetization switching. Recently, spins currents with spin polarization along multiple directions have been observed in low-symmetry materials, offering a promising energy-efficient strategy for the field-free switching of magnetic materials with perpendicular magnetic anisotropy. However, the efficiency of this mechanism is highly dependent on the crystallographic texture of the SOT materials, a critical factor that, to date, has not been quantitatively investigated. In this study, we present the first comprehensive numerical investigation into the impact of both in-plane and out-of-plane crystallographic textures of SOT materials on the unconventional SOT generated by Dresselhaus-like and out-of-plane spin polarizations. By employing a theoretical orientation distribution function, we calculate the effective unconventional SOT values for SOT materials with tunable crystallographic texture. This analysis provides a framework for the synthesis and optimization of future low-symmetry SOT materials for the first time, which can enhance operational efficiency for spintronics applications in magnetoresistive random-access memory and spin logic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
This work has been submitted to the IEEE for possible publication
First-principles Study of Metallic-atom Diffusion in Thermoelectric Material Mg\(_3\)Sb\(_2\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Masayuki Ochi, Kazutaka Nishiguchi, Chul-Ho Lee, Kazuhiko Kuroki
Mg\(_3\)Sb\(_2\) is a promising thermoelectric material that consists of nontoxic and earth-abundant elements. We investigate metallic-atom diffusion in Mg\(_3\)Sb\(_2\) by calculating the defect formation energy and the diffusion energy barrier for several kinds of metallic-atom impurities. We find that early transition metals, including \(4d\) elements, with a large atomic radius have a high defect formation energy, whereas Mg and late transition metals such as Ni, Cu, and Zn have relatively low formation energies as interstitial impurities. Interstitial Ni, which is found to have a very low defect formation energy, might diffuse in the \(ab\) plane at high temperatures with the energy barrier of 0.7 eV, while it seems difficult to diffuse in the \(c\) direction. Interstitial Cu has a higher defect formation energy than Ni but has a low energy barrier of $$0.4 eV for diffusion in the \(ab\) plane. This study will offer important knowledge for developing a thermoelectric device of Mg\(_3\)Sb\(_2\).
Materials Science (cond-mat.mtrl-sci)
7 pages, 5 figures
J. Phys. Soc. Jpn. 94, 024704 (2025)
Prerequisite of superconductivity: SDW rather than tetragonal structure in double-layer La3Ni2O7-x
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Mengzhu Shi, Di Peng, Yikang Li, Zhenfang Xing, Yuzhu Wang, Kaibao Fan, Houpu Li, Rongqi Wu, Zhidan Zeng, Qiaoshi Zeng, Jianjun Ying, Tao Wu, Xianhui Chen
The pressure-induced high-temperature superconductivity(Tc) in nickelates La3Ni2O7-x has sparked significant interest to explore its superconductivity at ambient this http URL+1NinO3n+1(n=2,3)adopts an orthorhombic structure with tilted NiO6 octahedra and undergoes a spin-density-wave(SDW) transition at ambient pressure, while the octahedral tilting and the SDW are suppressed by pressure, and high pressure induces a structural transition from orthorhombic to tetragonal, and the high-Tc superconductivity is achieved in the tetragonal structure. This tetragonal structure is widely believed to be crucial for the pressure-induced superconductivity. Whether the pressure-stabilized tetragonal structure is a prerequisite for achieving nickelate superconductivity at ambient pressure is under hot debate. Here, by post-annealing of the orthorhombic La3Ni2O7-x as grown microcrystals with noticeable oxygen defects in high oxygen pressure environment, tetragonal La3Ni2O6.96 single crystals are successfully obtained at ambient pressure. In contrast to the orthorhombic La3Ni2O7-x, the tetragonal La3Ni2O7-x exhibits metallic behavior without a SDW transition at ambient pressure. Moreover, no superconductivity is observed at high pressure up to ~ 70 GPa. On the other hand, by utilizing Helium as the pressure medium, we have revisited the superconducting structure in pressurized orthorhombic La3Ni2O6.93. Our results indicate that the orthorhombic structure is quite robust against pressure, and no structural transition from orthorhombic to tetragonal happens, and the superconductivity under high pressure is achieved in orthorhombic structure rather than tetragonal structure claimed previously. All these results suggest that tetragonal structure is not prerequisite for achieving superconductivity in La3Ni2O7-x.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
20 pages, 4 figures
Probing \(k\)-Space Alternating Spin Polarization via the Anomalous Hall Effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Rui Chen, Zi-Ming Wang, Hai-Peng Sun, Bin Zhou, Dong-Hui Xu
Altermagnets represent a recently discovered class of collinear magnets, characterized by antiparallel neighboring magnetic moments and alternating-sign spin polarization in momentum-space(\(k\)-space). However, experimental methods for probing the \(k\)-space spin polarization in altermagnets remain limited. In this work, we propose an approach to address this challenge by interfacing an altermagnet with the surface of a topological insulator. The massless Dirac fermions on the topological insulator surface acquire a mass due to the time-reversal symmetry breaking. The local \(k\)-space magnetic moment at the Dirac point directly determines both the sign and magnitude of this Dirac mass, resulting in an anomalous Hall effect. By measuring the Hall conductance, we can extract the local \(k\)-space magnetic moment. Moreover, we can map the global magnetic moment distribution by tuning the Dirac point position using an in-plane magnetic field, thereby revealing the \(k\)-space spin density of the altermagnet. This work establishes the Dirac fermion on the topological insulator surface as a sensitive probe for unveiling spin characters of altermagnets and those of other unconventional antiferromagnets.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Out-of-time-order correlator computation based on discrete truncated Wigner approximation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-27 20:00 EST
Tatsuhiko Shirai, Takashi Mori
We propose a method based on the discrete truncated Wigner approximation (DTWA) for computing out-of-time-order correlators. This method is applied to long-range interacting quantum spin systems where the interactions decay as a power law with distance. As a demonstration, we use a squared commutator of local operators and its higher-order extensions that describe quantum information scrambling under Hamilton dynamics. Our results reveal that the DTWA method accurately reproduces the exact dynamics of the average spreading of quantum information (i.e., the squared commutator) across all time regimes in strongly long-range interacting systems. We also identify limitations in the DTWA method when capturing dynamics in weakly long-range interacting systems and the fastest spreading of quantum information. This work provides a new technique to study scrambling dynamics in long-range interacting quantum spin systems.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
8 pages, 3 captioned figures
On the multi-\(\mathbf{q}\) characteristics of magnetic ground states of honeycomb cobalt oxides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-27 20:00 EST
Yuchen Gu, Xianghong Jin, Yuan Li
The Kitaev honeycomb model has received significant attention for its exactly solvable quantum spin liquid ground states and fractionalized excitations. For realizing the model, layered cobalt oxides have been considered a promising platform. Yet, in contrast to the conventional wisdom about single-\(\mathbf{q}\) zigzag magnetic order inferred from previous studies of the Na\(_2\)IrO\(_3\) and \(\alpha\)-RuCl\(_3\) candidate materials, recent experiments on two of the representative honeycomb cobalt oxides, hexagonal Na\(_2\)Co\(_2\)TeO\(_6\) and monoclinic Na\(_3\)Co\(_2\)SbO\(_6\), have uncovered evidence for more complex multi-\(\mathbf{q}\) variants of the zigzag order. This review surveys on experimental strategies to distinguish between single- and multi-\(\mathbf{q}\) orders, along with the crystallographic symmetries of the cobalt oxides in comparison to the previously studied systems. General formation mechanism of multi-\(\mathbf{q}\) order is also briefly discussed. The goal is to provide some rationales for examining the relevance of multi-\(\mathbf{q}\) order in the honeycomb cobalt oxides, along with its implications on the microscopic model of these intriguing quantum magnets.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 6 figures; invited mini-review article
Chin. Phys. Lett. (2025)
Observation of Giant Orbital Hall Effect in Si
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
R. Matsumoto (1), R. Ohshima (1,2), Y. Ando (1,2), D. Go (3,4), Y. Mokrousov (3,4), M. Shiraishi (1,2) ((1) Kyoto Univ., (2) CSRN, (3) FZ Jülich, (4) Uni. Mainz)
Controlling/storing information carriers, such as electron charge and spin, is key for modern information society, and significant efforts have been paid made to establish novel technologies at the nanoscale. The rise of Si-based semiconductor technology and magnetism-based technology has been motivated by the aforementioned demands. However, both technologies have been individually developed, with little effort in fusing them. Hence, establishing a technology to bridge semiconductor and magnetism-based technologies that would allow realization of a novel information device is strongly awaited. In line with this research strategy, the creation of a magnetic device using semiconductors would enable fundamental innovation. Here, we show that a mother material for modern electronics, Si, gives rise to a giant room-temperature orbital Hall effect (OHE), enabling the creation of novel energy-efficient magnetic memory via efficient torque generation. The orbital torque efficiency largely exceeds that of the archetypal metallic materials used in the OHE. Our achievement overtures the conventional understanding that nonmagnetic semiconductors cannot play a pivotal role in magnetic devices and paves a new avenue for creating novel information devices through the fusion of semiconductor and magnetism-based technologies.
Materials Science (cond-mat.mtrl-sci)
24 pages, 5 figures
Efficient method for calculating magnon-phonon coupling from first principles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Wuzhang Fang, Jacopo Simoni, Yuan Ping
Linear magnon-phonon coupling hybridizes magnon and phonon bands at the same energy and momentum, resulting in an anticrossing this http URL hybrid quasiparticle benefits from a long phonon lifetime and efficient magnon transport, showing great potential for spintronics and quantum information science this http URL this paper, we present an efficient and accurate first-principles approach for calculating linear magnon-phonon this http URL first calculate the magnon spectra from linear spin wave theory with spin Hamiltonian and first-principles exchange constants, which compared well with time-dependent density-functional this http URL then obtain the magnon-phonon coupling from the derivative of off-diagonal exchange constants in real space, calculated from the Hellmann-Feynman forces of the spin-constrained configurations, avoiding the use of cumbersome finite-difference this http URL implementation allows calculating coupling coefficients at an arbitrary wave vector in the Brillouin zone in a single step, through Fourier interpolation of real-space supercell calculations. We verify our implementation through two-dimensional magnetic systems, monolayer \(\mathrm{CrI_3}\), in agreement with experiments, and extend its application to monolayer \(\mathrm{CrTe_2}\). We emphasize the role of nonmagnetic atoms in superexchange interactions and magnon-phonon coupling, which have been overlooked previously. We suggest effective tuning of magnon-phonon coupling through strain, doping, and terahertz excitations, for spintronics and quantum magnonics applications.
Materials Science (cond-mat.mtrl-sci)
Thermal and dimensional stability of photocatalytic material ZnPS\(_3\) under extreme environmental conditions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Abhishek Mukherjee, Vivian J. Santamaría-García, Damian Wlodarczyk, Ajeesh K. Somakumar, Piotr Sybilski, Ryan Siebenaller, Emmanuel Rowe, Saranya Narayanan, Michael A. Susner, L. Marcelo Lozano-Sanchez, Andrzej Suchocki, Julio L. Palma, Svetlana V. Boriskina
Zinc phosphorus trisulfide (ZnPS\(_3\)), a promising material for photocatalysis and energy storage, is shown in this study to exhibit remarkable stability under extreme conditions. We explore its optical and structural properties under high pressure and cryogenic temperatures using photoluminescence (PL) spectroscopy, Raman scattering, and density functional theory (DFT). Our results identify a pressure-induced phase transition starting at 6.75 GPa and stabilizing by 12.5 GPa, after which ZnPS\(_3\) demonstrates robust stability across a broad pressure range of 15 to 100 GPa. DFT calculations predict a semiconductor-to-semimetal transition at 100 GPa, while PL measurements reveal defect-assisted emissions that quench under pressure due to enhanced non-radiative recombination. At cryogenic temperatures, PL quenching intensifies as non-radiative processes dominate, driven by a rising Grüneisen parameter and reduced phonon population. Cryogenic X-ray diffraction (XRD) also reveals a high mean thermal expansion coefficient (TEC) of (4.369 \(\pm\) 0.393) \(\times\) 10\(^{-5}\) K\(^{-1}\), among the highest reported for 2D materials. This unique combination of tunable electronic properties under low pressure and high thermal sensitivity makes ZnPS\(_3\) a strong candidate for sensing applications in extreme environments.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Optical Response of Multi-orbital Superconductors: Role of Fermi Surface Topology and Geometry
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Meghdad Yazdani-Hamid, Mehdi Biderang, Alireza Akbari
Motivated by the possibility of shifting the nearest peak in the density of states relative to the Fermi level leading to a Lifshitz transition, such as through strain in Sr\(^{}_2\)RuO\(^{}_4\), this study examines the consequent effects on Hall transport and the polar Kerr angle. Using a three-orbital model, variations in the chemical potential and \(z\)-direction hopping reveal \(d+ig\)- and \(d_{x^2-y^2}\)-wave pairings as leading candidates for pairing symmetry in the quasi-2D orbital within the weak-coupling regime. The Lifshitz transition is further analyzed for its impact on coherence factors and the density of states, both of which are crucial to response functions. Interactions with van Hove points and nearby degenerate electronic states emerge as key contributors to Hall-type responses, while electron transfer between quasi-1D and quasi-2D orbitals significantly modifies these transport properties.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 4 figures, 1 table
Natural and Intrinsic Vacancies in two-dimensional g-C\(_3\)N\(_4\) for Trapping Isolated B and C Atoms as Color Centers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Manqi You, Chaoyu He, Gencai Guo, Jianxin Zhong
Color centers are vital for quantum information processing, but traditional ones often suffer from instability, difficulty in realization, and precise control of locations. In contrast, natural intrinsic vacancy-based color centers in two-dimensional systems offer enhanced stability and tunability. In this work, we demonstrate that g-C\(_3\)N\(_4\) with natural intrinsic vacancies is highly suitable for trapping B/C atoms to form stable color centers as qubits. With easily identifiable vacancies, B/C atoms are expectable to be placed at the vacancy sites in g-C\(_3\)N\(_4\) through STM manipulation. The vacancy sites are confirmed as the most stable adsorption positions, and once atoms are adsorbed, they are protected by diffusion barriers from thermal diffusions. The most stable charge states are C\(_V^{+2}\)/B\(_V^{+2}\), C\(_V^{+1}\)/B\(_V^{+1}\), and C\(_V^0\)/B\(_V^0\) in turn, with charge transition levels of 0.39 eV and 2.49 eV, respectively. Specifically, the defect levels and net spin of C\(_V\)/B\(_V\) can be adjusted by charge states. C\(_V\), C\(_V^{+1}\), C\(_V^{+2}\), B\(_V^{+1}\), and B\(_V^{+2}\) exhibit optically allowable defect transition levels. The zero-phonon lines suggest fluorescence wavelengths fall within the mid-infrared band, ideal for qubit operations of stable initialization and readout. Furthermore, the Zero-field splitting (ZFS) parameter and the characteristic hyperfine tensor are provided as potential fingerprints for electron paramagnetic resonance (EPR) experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
11 pages, 4 figures and 1 table
Microscopic study of 3D Potts phase transition via Fuzzy Sphere Regularization
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-27 20:00 EST
Shuai Yang, Yan-Guang Yue, Yin Tang, Chao Han, W. Zhu, Yan Chen
The Potts model describes interacting spins with \(Q\) different components, which is a direct generalization of the Ising model (\(Q=2\)). Compared to the existing exact solutions in 2D, the phase transitions and critical phenomena in the 3D Potts model have been less explored. Here, we systematically investigate a quantum \((2+1)\)-D Potts model with \(Q=3\) using a fuzzy sphere regularization scheme. We first construct a microscopic model capable of achieving a magnetic phase transition that separates a spin \(S_3\) permutationally symmetric paramagnet and a spontaneous symmetry-breaking ferromagnet. Importantly, the energy spectrum at the phase transition point exhibits an approximately conformal symmetry, implying that an underlying conformal field theory may govern this transition. Moreover, when tuning along the phase transition line in the mapped phase diagram, we find that the dimension of the subleading \(S_3\) singlet operator flows and drifts around the critical value \(\sim 3\), which is believed to be crucial for understanding this phase transition, although determining its precise value remains challenging due to the limitations of our finite-size calculations. These findings suggest a discontinuous transition in the 3D 3-state Potts model, characterized by pseudo-critical behavior, which we argue results from a nearby multicritical or complex fixed point.
Statistical Mechanics (cond-mat.stat-mech)
Optimal disk packing of chloroplasts in plant cells
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-27 20:00 EST
Nico Schramma, Eric R. Weeks, Maziyar Jalaal
Photosynthesis is vital for the survival of entire ecosystems on Earth. While light is fundamental to this process, excessive exposure can be detrimental to plant cells. Chloroplasts, the photosynthetic organelles, actively move in response to light and self-organize within the cell to tune light absorption. These disk-shaped motile organelles must balance dense packing for enhanced light absorption under dim conditions with spatial rearrangements to avoid damage from excessive light exposure. Here, we reveal that the packing characteristics of chloroplasts within plant cells show signatures of optimality. Combining measurements of chloroplast densities and three-dimensional cell shape in the water plant Elodea densa, we construct an argument for optimal cell shape versus chloroplast size to achieve two targets: dense packing into a two-dimensional monolayer for optimal absorption under dim light conditions and packing at the sidewalls for optimal light avoidance. We formalize these constraints using a model for random close packing matched with packing simulations of polydisperse hard disks confined within rectangular boxes. The optimal cell shape resulting from these models corresponds closely to that measured in the box-like plant cells, highlighting the importance of particle packing in the light adaptation of plants. Understanding the interplay between structure and function sheds light on how plants achieve efficient photo adaptation. It also highlights a broader principle: how cell shape relates to the optimization of packing finite and relatively small numbers of organelles under confinement. This universal challenge in biological systems shares fundamental features with the mechanics of confined granular media and the jamming transitions in dense active and passive systems across various scales and contexts.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Impact of Nonreciprocal Hopping on Localization in Non-Hermitian Quasiperiodic Systems
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-27 20:00 EST
Xianqi Tong, Yiling Zhang, Bin Li, Xiaosen Yang
We study the non-Hermitian Aubry-André-Harper model, incorporating complex phase modulation, unmodulated and modulated nonreciprocal hopping. Using Avila's global theory, we derive analytical phase boundaries and map out the phase diagrams, revealing extended, localized, critical, and skin phases unique to non-Hermitian systems. For complex phase modulation, we determine localization lengths through Lyapunov exponents and show that topological transitions align with localization transitions. In the nonreciprocal case, we use similarity transformations to confirm phase boundaries consistent with Avila's theory and uncover asymmetric localization behaviors. Importantly, modulated nonreciprocal hopping transforms both extended and critical phases into skin phases under open boundary conditions. These results highlight the interplay between topology, localization, and non-Hermitian effects, offering new perspectives on quasiperiodic systems.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
10 pages, 3 figures
Crowding Effects during DNA Translocation in Nanopipettes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Rand A. Al-Waqfi, Cengiz Khan, Oliver J. Irving, Lauren Matthews, Tim Albrecht
Quartz nanopipettes are an important emerging class of electric single-molecule sensors for DNA, proteins, their complexes as well as other biomolecular targets. However, in comparison to other resistive pulse sensors, nanopipettes constitute a highly asymmetric environment and the transport of ions and biopolymers can become strongly direction-dependent. For double-stranded DNA, this can include the characteristic translocation time and its tertiary structure, but as we show here, nanoconfinement can not only lead to unexplored features in the transport characteristics of the sensor, but also unlock new capabilities for biophysical and bioanalytical studies at the single-molecule level. To this end, we show how the accummulation of DNA inside the nanochannel leads to crowding effects, and in some cases reversible blocking of DNA entry, and provide a detailed analysis based on a range of different DNA samples and experimental conditions. Moreover, using biotin-functionalised DNA and streptavidin-modified gold nanoparticles as target, we demonstrate in a proof-of-concept study how the crowding effect, and the resulting increased residence time in nanochannel, can be exploited in a new analytical paradigm, involving DNA injection into the nanochannel, incubation with the nanoparticle target and analysis of the complex by reverse translocation. We thereby integrate elements of sample processing and detection into the nanopipette, as an important conceptual advance, and make a case for the wider applicability of this device concept.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Lower bound of entropy production at short time scales for noise-driven stochastic systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-27 20:00 EST
Mairembam Kelvin Singh, R.K. Brojen Singh, Moirangthem Shubhakanta Singh
The second law of thermodynamics governs that nonequilibrium systems evolve towards states of higher entropy over time. However, it does not specify the rate of this evolution and the role of fluctuations that impact the system's dynamics. Entropy production quantifies how far a system is driven away from equilibrium and provides a measure of irreversibility. In stochastic systems, entropy production becomes essential for understanding the approach to nonequilibrium states. While macroscopic observations provide valuable insights, they often overlook the local behaviors of the system, governed by fluctuations. In this study, we focus on measuring the lower bound of entropy production at short time scales for generalized stochastic systems by calculating the Kullback-Leibler divergence (KLD) between the probability density functions of forward and backward trajectories. By analysing the entropy production across sliding time scales, we uncover patterns that reveal distinctions between local, small-scale dynamics and the global, macroscopic behavior, offering deeper insights into the system's departure from equilibrium. We also analysed the effects of switching to different types of noise or fluctuations and found that the observations at larger time scales provide no distinction between the different forms of noise while at short time scales, the distinction is significant.
Statistical Mechanics (cond-mat.stat-mech)
Conditions for orbital-selective altermagnetism in Sr2RuO4: tight-binding model, similarities with cuprates, and implications for superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Carmine Autieri, Giuseppe Cuono, Debmalya Chakraborty, Paola Gentile, Annica M. Black-Schaffer
The vibrational modes in Sr\(_2\)RuO\(_4\) easily induce octahedral rotations without tilting. Being on the verge of a magnetic instability, such propensity of octahedral rotation may also produce magnetic fluctuations. In this work, we analyze the long-range magnetic phase diagram incorporating such octahedral rotations and demonstrate the possibility of an altermagnetic phase in Sr\(_2\)RuO\(_4\). Using ab-initio calculations, we first study single layer Sr\(_2\)RuO\(_4\) with octahedral rotations, obtaining an orbital-selective \(g\)-wave altermagnetic phase. We further provide an effective \(t_{2g}\) tight-binding model, demonstrating that the \(g\)-wave altermagnetism is primarily a product of second and third nearest neighbor interorbital hybridizations between the \({\gamma}z\) (\(\gamma=x,y\)) orbitals, but only a much longer range intraorbital hybridization in the \(xy\) orbitals, establishing a strong orbital-selectiveness for the altermagnetism. Notably, by replacing the \(xy\) orbital with the \(x^2-y^2\) orbital, a similar tight-biding model may be used to investigate the hole-doped cuprate superconductors. We then study bulk Sr\(_2\)RuO\(_4\), where we find the altermagnetic phase as the magnetic ground state for a range of finite octahedral rotations. In the bulk, interlayer hopping breaks some of the symmetries of the \(g\)-wave altermagnet, resulting in a \(d_{xy}\)-wave altermagnet, still with orbital selectiveness. We also include relativistic effects through spin-orbit coupling and obtain that an effective staggered Dzyaloshinskii-Moriya interaction generates weak ferromagnetism. Finally, we discuss the implications of the altermagnetic order on the intrinsic superconductivity of Sr\(_2\)RuO\(_4\). Assuming in-plane and intraorbital pairing, the altermagnetism favors spin-singlet \(d_{x^2-y^2}\)-wave or \(g\)-wave pairing, or (nematic or chiral) combinations thereof.
Superconductivity (cond-mat.supr-con)
18 pages, 16 figures
Anomalies in the electronic stopping of slow antiprotons in LiF
New Submission | Other Condensed Matter (cond-mat.other) | 2025-01-27 20:00 EST
Guerda Massillon-JL, Alfredo A. Correa, Xavier Andrade, Emilio Artacho
We present first-principles theoretical calculations for the electronic stopping power (SP) of both protons and anti-protons in LiF. Our results show the presence of the Barkas effect: a higher stopping for positively charged particles than their negatively charged antiparticles. In contrast, a previous study has predicted an anti-Barkas effect (higher stopping for negative charges) at low velocity [Qi, Bruneval and Maliyov, Phys. Rev. Lett. 128, 043401 (2022)]. We explain this discrepancy by showing that this anti-Barkas effect appears for highly symmetric trajectories and disappears when considering trajectories that better reproduce the experimental setup. Our low-velocity results show that the SP of both protons and anti-proton vanish for velocities under 0.1 a.u. .
Other Condensed Matter (cond-mat.other)
5 pages, 3 figures
Integrating Deep-Learning-Based Magnetic Model and Non-Collinear Spin-Constrained Method: Methodology, Implementation and Application
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Daye Zheng, Xingliang Peng, Yike Huang, Yinan Wang, Duo Zhang, Zhengtao Huang, Linfeng Zhang, Mohan Chen, Ben Xu, Weiqing Zhou
We propose a non-collinear spin-constrained method that generates training data for deep-learning-based magnetic model, which provides a powerful tool for studying complex magnetic phenomena at the atomic scale. First, we propose a projection method for atomic magnetic moments by applying a radial truncation to the numerical atomic orbitals. We then implement a Lagrange multiplier method that can yield the magnetic torques of atoms by constraining the magnitude and direction of atomic magnetic moments. The method is implemented in ABACUS with both plane wave basis and numerical atomic orbital basis. We benchmark the iron (Fe) systems with the new method and analyze differences from calculations with the plane wave basis and numerical atomic orbitals basis in describing magnetic energy barriers. Based on more than 30,000 first-principles data with the information of magnetic torque, we train a deep-learning-based magnetic model DeePSPIN for the Fe system. By utilizing the model in large-scale molecular dynamics simulations, we successfully predict Curie temperatures of \(\alpha\)-Fe close to experimental values.
Materials Science (cond-mat.mtrl-sci)
Efficiently charting the space of mixed vacancy-ordered perovskites by machine-learning encoded atomic-site information
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Fan Zhang, Li Fu, Weiwei Gao, Peihong Zhang, Jijun Zhao
Vacancy-ordered double perovskites (VODPs) are promising alternatives to three-dimensional lead halide perovskites for optoelectronic and photovoltaic applications. Mixing these materials creates a vast compositional space, allowing for highly tunable electronic and optical properties. However, the extensive chemical landscape poses significant challenges in efficiently screening candidates with target properties. In this study, we illustrate the diversity of electronic and optical characteristics as well as the nonlinear mixing effects on electronic structures within mixed VODPs. For mixed systems with limited local environment options, the information regarding atomic-site occupation in-principle determines both structural configurations and all essential properties. Building upon this concept, we have developed a model that integrates a data-augmentation scheme with a transformer-inspired graph neural network (GNN), which encodes atomic-site information from mixed systems. This approach enables us to accurately predict band gaps and formation energies for test samples, achieving Root Mean Square Errors (RMSE) of 21 meV and 3.9 meV/atom, respectively. Trained with datasets that include (up to) ternary mixed systems and supercells with less than 72 atoms, our model can be generalized to medium- and high-entropy mixed VODPs (with 4 to 6 principal mixing elements) and large supercells containing more than 200 atoms. Furthermore, our model successfully reproduces experimentally observed bandgap bowing in Sn-based mixed VODPs and reveals an unconventional mixing effect that can result in smaller band gaps compared to those found in pristine systems.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Computational Physics (physics.comp-ph)
22 pages, 9 figures
Molecular origins of colossal barocaloric effects in plastic crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Ares Sanuy, Carlos Escorihuela-Sayalero, Pol Lloveras, Josep Lluis Tamarit, Luis Carlos Pardo, Claudio Cazorla
In recent years, orientationally disordered crystals, or plastic crystals, have transformed the field of solid-state cooling due to the significant latent heat and entropy changes associated with their temperature induced molecular order-disorder phase transition, which can produce colossal caloric effects under external field stimuli. However, the molecular mechanisms underlying these huge caloric effects remain inadequately understood, and general principles for enhancing the performance of caloric plastic crystals are lacking. Previous studies have predominantly focused on molecular rotations, overlooking other potentially critical factors, such as lattice vibrations and molecular conformations. In this study, we employ classical molecular dynamics (MD) simulations to both replicate and elucidate the microscopic origins of the experimentally observed colossal barocaloric (BC) effects -- those driven by hydrostatic pressure -- in the archetypal plastic crystal neopentyl glycol (NPG). Our MD simulations demonstrate that in NPG, the combined BC response and phase-transition entropy changes arising from lattice vibrations and molecular conformations are nearly equal to those from molecular reorientations, contributing 45% and 55%, respectively. These findings suggest that, alongside hydrogen bonding -- which directly impacts molecular rotational dynamics -- lattice vibrational and molecular structural features, often overlooked, must be integrated into the rational design and modeling of advanced caloric plastic crystals. These insights are not only of significant fundamental interest but also essential for driving the development of next-generation solid-state refrigeration technologies.
Materials Science (cond-mat.mtrl-sci)
13 pages, 7 figures
Bipartite Current Fluctuations in Quantum Wires through Charge Fractionalization
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Quantum information measures of many-body systems often imply a measure with multi- or two regions such as bipartite charge fluctuations within the ground state revealing the logarithmic profile of the entanglement entropy in a quantum wire. Here, we introduce a new method from the bipartite current fluctuations and the divergence theorem. They reveal the fractional charges related to ground-state energetics and the proximity to Mott physics in the same ballistic quantum wires. This also encodes the behavior of the electron Green's function in space. With metallic gates on both sides of an interface to implement the protocol introducing the two macroscopic domains, bipartite current fluctuations can reveal an additional localized bound state associated to the topological Jackiw-Rebbi model, coexisting with the fractional charges. Through the Density Matrix Renormalization Group (DMRG) algorithm we introduce a quantum spin chain analogue.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
5 pages + bibliography list, 3 Figures
A chemical bonding based descriptor for predicting the impact of quantum nuclear and anharmonic effects on hydrogen-based superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Francesco Belli, Eva Zurek, Ion Errea
Quantum nuclear effects (QNEs) can significantly alter a material's crystal structure and phonon spectra, impacting properties such as thermal conductivity and superconductivity. However, predicting a priori whether these effects will enhance or suppress superconductivity, or destabilize a structure, remains a grand challenge. Herein, we address this unresolved problem by introducing a descriptor, based upon the integrated crystal orbital bonding index (iCOBI), to predict the influence of QNEs on a crystal lattice's dynamic stability, phonon spectra and superconducting properties. We find that structures with atoms in symmetric chemical bonding environments exhibit greater resilience to structural perturbations induced by QNEs, while those with atoms in asymmetric bonding environments are more susceptible to structural alterations, resulting in enhanced superconducting critical temperatures.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Classical and quantum spin liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-27 20:00 EST
When considering magnetic systems in the thermodynamic limit and at low enough temperature, one finds typically magnetically ordered phases. In contrast, in the high-temperature regime, the interactions between the spin degrees of freedom become less relevant and the system loses its order: this is a paramagnet. This phenomenon of phase transition has been well understood using statistical mechanics and simple modelling. In these short lecture notes, we will review the possibility that a many-body magnetic system may remain magnetically disordered down to zero-temperature, both for classical or quantum spins. These exotic phases of matter are known, respectively, as classical and quantum spin liquids. We will address in particular the question of classification of these classical or quantum disordered phases. Indeed, while they have no local order parameter by definition, they can still possess different qualitative features related e.g. to the nature of their correlations or elementary excitations, which could be probed experimentally.
Strongly Correlated Electrons (cond-mat.str-el)
lecture notes from a talk given at the IHP workshop about "Open questions in the quantum many-body problem" organized by Yvan Castin and Carlos S� de Melo
Comptes Rendus. Physique, Volume 26 (2025), pp. 91-111
Electrically-tunable graphene nanomechanical resonators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Yi-Bo Wang, Zhuo-Zhi Zhang, Chen-Xu Wu, Yu-Shi Zhang, Guo-Sheng Lei, Xiang-Xiang Song, Guo-Ping Guo
The excellent mechanical properties make graphene promising for realizing nanomechanical resonators with high resonant frequencies, large quality factors, strong nonlinearities, and the capability to effectively interface with various physical systems. Equipped with gate electrodes, it has been demonstrated that these exceptional device properties can be electrically manipulated, leading to a variety of nanomechanical/acoustic applications. Here, we review the recent progress of graphene nanomechanical resonators with a focus on their electrical tunability. First, we provide an overview of different graphene nanomechanical resonators, including their device structures, fabrication methods, and measurement setups. Then, the key mechanical properties of these devices, for example, resonant frequencies, nonlinearities, dissipations, and mode coupling mechanisms, are discussed, with their behaviors upon electrical gating being highlighted. After that, various potential classical/quantum applications based on these graphene nanomechanical resonators are reviewed. Finally, we briefly discuss challenges and opportunities in this field to offer future prospects of the ongoing studies on graphene nanomechanical resonators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Invited review
Investigating topological in-gap states in non-Hermitian quasicrystal with unconventional \(p\)-wave pairing
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-27 20:00 EST
Shaina Gandhi, Jayendra N. Bandyopadhyay
The interplay of onsite quasiperiodic potential, superconductivity, and non-Hermiticity is explored in a non-Hermitian unconventional superconducting quasicrystal described by Aubry-André-Harper (NHAAH) model with \(p\)-wave pairing. In previous studies, the non-Hermiticity was only considered at the onsite quasiperiodic potential of the NHAAH model, and Majorana zero modes (MZMs) were observed under open boundary conditions (OBC) in this model. In this work, we study an NHAAH model with \(p\)-wave pairing, where non-Hermiticity is considered onsite by introducing complex quasiperiodic potential and asymmetry at the hopping part. Our analysis uncovers triple-phase transitions, where topological, metal-insulator, and unconventional real-to-complex transitions coincide at weak \(p\)-wave pairing strength. Additionally, instead of the MZMs observed in the symmetric hopping case, we observe the emergence of in-gap states under OBC in this model. These in-gap states are robust against disorder, underscoring their topological protection. Therefore, unlike the MZMs, which are very challenging to experimentally realize, these in-gap states can be used in topological quantum computational protocols.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Physics (quant-ph)
11 pages, 11 figures
Chern Vector Protected Three-dimensional Quantized Hall Effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Zhi-Qiang Zhang, Shu-Guang Cheng, Hongfang Liu, Hailong Li, Hua Jiang, X. C. Xie
Recently, Chern vector with arbitrary formula \(\textbf{C}\!=\!(\mathcal{C}_{yz},\mathcal{C}_{xz},\mathcal{C}_{xy})\) in three-dimensional systems has been experimentally realized []. Motivated by these progresses, we propose the Chern vector \(\textbf{C}\!=\!(0,m,n)\)-protected quantized Hall effect in three-dimensional systems. By examining samples with Chern vector \(\textbf{C}\!=\!(0,m,n)\) and dimensions \(L_y\) and \(L_z\) along the \(y\)- and \(z\)-directions, we demonstrate a topologically protected two-terminal response. This response can be reformulated as the sum of the transmission coefficients along the \(x\)- and \(y\)-directions, given by \((mL_y\!+\!nL_z)\). When applied to Hall bar setups, this topological mechanism gives rise to quantized Hall conductances, such as (G_{xy}) and (G_{xz}), which are expressed by \(\pm(mL_y\!+\!nL_z)\). These Hall conductances exhibit a clear dependency on sample dimensions, illuminating the intrinsic three-dimensional nature. Finally, we propse potential candidates for experimental realization. Our findings not only deepen the understanding of the topological nature of Chern vectors but also enlighten the exploration of their transport properties.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Imaging the Meissner Effect and Flux Trapping of Superconductors under High Pressure using N-V Centers
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Cassandra Dailledouze, Antoine Hilberer, Martin Schmidt, Marie-Pierre Adam, Loïc Toraille, Kin On Ho, Anne Forget, Dorothée Colson, Paul Loubeyre, Jean-François Roch
Pressure is a key parameter for tuning or revealing superconductivity in materials and compounds. Many measurements of superconducting phase transition temperatures have been conducted using diamond anvil cells (DACs), which provide a wide pressure range and enable concomitant microscopic structural characterization of the sample. However, the inherently small sample volumes in DACs complicate the unambiguous detection of the Meissner effect, the hallmark of superconductivity. Recently, the Meissner effect in superconductors within a DAC was successfully demonstrated using diamond nitrogen-vacancy (N-V) widefield magnetometry, a non-invasive optical technique. In this work, we show that N-V magnetometry can also map superconductivity with micrometer resolution. We apply this technique to a microcrystal of HgBa\(_2\)Ca\(_2\)Cu\(_3\)O\(_{8+\delta}\) (Hg-1223) mercury-based cuprate superconductor under 4 GPa of pressure. The method is capable to detect the magnetic field expulsion and heterogeneities in the sample, visible in a set of characteristic parameters as the local critical temperature \(T_{c}\). Flux pinning zones are identified through flux trapping maps. This approach could enable detailed investigations of superconductivity of a broad range of materials under high-pressure conditions.
Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
How does heat propagate in Liquids?
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-27 20:00 EST
In this paper, we illustrate the consequences and implications of the Dual Model of Liquids (DML) by applying it to heat propagation.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)
Thermo-Mechanical and Mdchano-Thermal Effects in Liquids Explained by means of the Dual Model of Liquids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-27 20:00 EST
We pursue to illustrate the capabilities of the Dual Model of Liquids showing that it may explain crossed effects notable in Non-Equilibrium Thermodynamics. The aim of the paper is to demonstrate that the DML may correctly model the thermodiffusion, in particular getting formal expressions for positive and negative Soret coefficient, and another unexpected mechano-thermal effect recently discovered in liquids submitted to shear strain, for which the first-ever theoretical interpretation is provided.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)
Scanning gate microscopy detection of Majorana bound states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
We theoretically study scanning gate microscopy of a superconductor-proximitized semiconducting wire focusing on the possibility of detection of Majorana bound states. We exploit the possibility to create local potential perturbation by the scanning gate tip which allows controllable modification of the spatial distribution of the Majorana modes, which is translated into changes in their energy structure. When the tip scans across the system, it effectively divides the wire into two parts with controllable lengths, in which two pairs of Majorana states are created when the system is in the topological regime. For strong values of the tip potential the pairs are decoupled, and the presence of Majorana states can be detected via local tunneling spectroscopy that resolves the energy splittings resulting from the Majorana states wave functions overlap. Importantly, as the system is probed spatially via the tip, this technique can distinguish Majorana bound states from quasi-Majorana states localized on smooth potential barriers. We demonstrate that for weaker tip potentials the two neighboring Majorana states hybridize opening pronounced anticrossings in the energy spectra which are reflected in local conductance maps and which result in non-zero non-local conductance features. Finally, we demonstrate the effect of the disorder on the scanning gate microscopy spectroscopy maps.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Designing edge currents using mesoscopic patterning in chiral d-wave superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Patric Holmvall, Annica M. Black-Schaffer
Chiral superconductors are topological as characterized by a finite Chern number and chiral edge modes. Direct fingerprints of chiral superconductivity is thus often taken to be spontaneous edge currents with associated magnetic signatures. However, a number of recent theoretical studies have shown that the total edge current along semi-infinite edges is greatly reduced or even vanishes in many scenarios for all pairing symmetries except chiral \(p\)-wave, thus impeding experimental detection. We demonstrate how mesoscopic finite-sized samples can be designed to give rise to a shape- and size-dependent strong enhancement of the chiral edge currents and their generated orbital magnetic moment and magnetic fields. In particular, we find that low rotational symmetry systems, such as pentagons and hexagons, give rise to the largest currents, while circular disks also generate large currents but in the opposite direction. The current and magnetic signatures diverge with shrinking system sizes, eventually cut-off by finite-size suppression of chiral superconductivity. We thus also extract the full phase diagram as a function of temperature and system size for different geometries, including competing superconducting orders. Our results are relevant for system sizes on the order of tens to hundreds of coherence lengths, and highlight mesoscopic patterning as a viable route to experimentally identify chiral \(d\)-wave superconductivity.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
19 pages, 12 figures
Ambient pressure growth of bilayer nickelate single crystals with superconductivity over 90 K under high pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Feiyu Li, Di Peng, Jie Dou, Ning Guo, Liang Ma, Chao Liu, Lingzhen Wang, Yulin Zhang, Jun Luo, Jie Yang, Jian Zhang, Weizhao Cai, Jinguang Cheng, Qiang Zheng, Rui Zhou, Qiaoshi Zeng, Xutang Tao, Junjie Zhang
Recently, the Ruddlesden-Popper bilayer nickelate La3Ni2O7 has been discovered as a high temperature superconductor with Tc near 80 K above 14 GPa.[1-3] The search for nickelate superconductors with higher Tc, the preparation of high-quality single crystals, and the removal of high-pressure conditions including single crystal growth under high gas pressure and achievement of high Tc superconductivity under high pressure, are the most challenging tasks. Here, we present ambient pressure flux growth of high-quality bilayer nickelate single crystals with superconductivity up to 91 K under high pressure. Single crystals of bilayer La3-xRxNi2O7-y with dimensions up to 220 um on the edge were successfully grown using flux method at atmosphere conditions. Single crystal X-ray diffraction, nuclear quadrupole resonance, energy dispersion spectroscopy and scanning transmission electron microscopy measurements evidenced high quality of bilayer La2SmNi2O7-y single crystals in average structure and local structure. Superconductivity has been observed in high pressure resistivity measurements of annealed La2SmNi2O7-y single crystals with Tc onset up to 91 K, which is the highest among the known superconducting nickelates. Our results not only demonstrate a new and easy-to-access method for synthesizing high-quality bilayer nickelate single crystals, but also providing a direction for discovering superconducting nickelates with higher Tc.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
4 figures and 1 table
Magnetic and crystal electric field studies of two Yb\(^{3+}\)-based triangular lattice antiferromagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
S. Guchhait, R. Kolay, A. Magar, R. Nath
We present the low-temperature magnetic properties of two Yb\(^{3+}\)-based triangular lattice compounds NaSrYb(BO\(_3\))\(_2\) and K\(_3\)YbSi\(_2\)O\(_7\) via thermodynamic measurements followed by crystal electric field (CEF) calculations. Magnetization and specific heat data as well as the CEF energy levels confirm that the ground state is characterized by the low-lying Kramers' doublet of Yb\(^{3+}\) with effective spin-1/2 (\(J_{\rm eff} = 1/2\)). A small Curie-Weiss temperature and scaling of magnetic isotherms corroborate very weak magnetic correlations among \(J_{\rm eff} = 1/2\) spins. The crystal field parameters are calculated using the point charge model and the CEF Hamiltonian is determined for both the compounds. The simulation using the eigenvalues of the CEF Hamiltonian reproduces the experimental susceptibility, magnetic isotherm, and magnetic specific heat data very well. The large separation between the ground state and first excited state doublets implies that the ground state is a Kramers' doublet with \(J_{\rm eff} = 1/2\) at low temperatures, endorsing the experimental findings.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 9 figures, 6 tables
Phase-controlled minimal Kitaev chain in multiterminal Josephson junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Samuel D. Escribano, Anders Enevold Dahl, Karsten Flensberg, Yuval Oreg
We propose a nanodevice based on multi-terminal Josephson junctions for the creation and detection of poor man's Majorana (PMM) modes. The device consists of a double three-terminal Josephson junction (3TJJ) embedded in a planar semiconductor that engineers a two-site Kitaev chain. We identify the conditions necessary for the emergence of PMM modes by precisely tuning the superconducting phases of the terminals and the inter-junction coupling between the 3TJJs. To validate our findings, we perform numerical simulations that account for disorder in a more general geometry, and test experimentally feasible protocols based on conductance measurements to reliably detect these modes. Unlike traditional approaches that rely on magnetic fields, our design eliminates the need for such fields, potentially increasing the energy-level resolution and significantly expanding the range of compatible semiconductor materials, such as Ge-based heterostructures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
19 pages, 9 figures
New phase space of hardness materials and synergic enhancement of hardness and toughness in superconducting Ti2Co and Ti4Co2X (X = B, C, N, O)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Lifen Shi, Keyuan Ma, Jingyu Hou, Pan Ying, Ningning Wang, Xiaojun Xiang, Pengtao Yang, Xiaohui Yu, Huiyang Gou, Jianping Sun, Yoshiya Uwatoko, Fabian O. von Rohr, Xiang-Feng Zhou, Bosen Wang, Jinguang Cheng
Compared to traditional superhard materials with high electron density and strong covalent bonds, alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness. Breaking through the limits of alloy materials is a preface and long term topic, which is of great significance and value for improving the comprehensive mechanical properties of alloy materials. Here, we report on the discovery of a cubic alloy semiconducting material Ti2Co with large Vickers of hardness Hvexp = 6.7 GPa and low fracture toughness of KICexp =1.51 MPa m0.5. Unexpectedly, the former value is nearly triple of the Hvcal = 2.66 GPa predicted by density functional theory (DFT) calculations and the latter value is about one or two orders of magnitude smaller than that of ordinary titanium alloy materials (KICexp = 30-120 MPa m0.5).These specifications place Ti2Co far from the phase space of the known alloy materials, but close to medium hardness materials such as MgO or TiO2. Upon incorporation of oxygen into structural void positions, both values were simultaneously improved for Ti4Co2O to = 9.7 GPa and 2.19 MPa m0.5, respectively. Further DFT calculations on the electron localization function of Ti4Co2X (X = B, C, N, O) vs. the interstitial elements indicate that these simultaneous improvements originate from the coexistence of Ti-Co metallic bonds, the emergence of newly oriented Ti-X covalent bonds, and the increase of electron concentration. Moreover, the large difference between Hvexp and Hvcal of Ti2Co suggests underlying mechanism concerning the absence of the O(16d) or Ti2-O bonds in the O-(Ti2)6 this http URL discovery expands the phase space of alloy materials and illuminates the path of exploring superconducting materials with excellent mechanical performances.
Materials Science (cond-mat.mtrl-sci)
17 pages, 4 figures,
A dressed singlet-triplet qubit in germanium
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Konstantinos Tsoukalas, Uwe von Lüpke, Alexei Orekhov, Bence Hetényi, Inga Seidler, Lisa Sommer, Eoin G. Kelly, Leonardo Massai, Michele Aldeghi, Marta Pita-Vidal, Nico W. Hendrickx, Stephen W. Bedell, Stephan Paredes, Felix J. Schupp, Matthias Mergenthaler, Gian Salis, Andreas Fuhrer, Patrick Harvey-Collard
In semiconductor hole spin qubits, low magnetic field (\(B\)) operation extends the coherence time (\(T_\mathrm{2}^\ast\)) but proportionally reduces the gate speed. In contrast, singlet-triplet (ST) qubits are primarily controlled by the exchange interaction (\(J\)) and can thus maintain high gate speeds even at low \(B\). However, a large \(J\) introduces a significant charge component to the qubit, rendering ST qubits more vulnerable to charge noise when driven. Here, we demonstrate a highly coherent ST hole spin qubit in germanium, operating at both low \(B\) and low \(J\). By modulating \(J\), we achieve resonant driving of the ST qubit, obtaining an average gate fidelity of \(99.68\%\) and a coherence time of \(T_\mathrm{2}^\ast=1.9\,\mu\)s. Moreover, by applying the resonant drive continuously, we realize a dressed ST qubit with a tenfold increase in coherence time (\(T_\mathrm{2\rho}^\ast=20.3\,\mu\)s). Frequency modulation of the driving signal enables universal control, with an average gate fidelity of \(99.64\%\). Our results demonstrate the potential for extending coherence times while preserving high-fidelity control of germanium-based ST qubits, paving the way for more efficient operations in semiconductor-based quantum processors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Machine Learning Inversion from Small-Angle Scattering for Charged Polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-27 20:00 EST
Lijie Ding, Chi-Huan Tung, Jan-Michael Y. Carrillo, Wei-Ren Chen, Changwoo Do
We develop Monte Carlo simulations for uniformly charged polymers and machine learning algorithm to interpret the intra-polymer structure factor of the charged polymer system, which can be obtained from small-angle scattering experiments. The polymer is modeled as a chain of fixed-length bonds, where the connected bonds are subject to bending energy, and there is also a screened Coulomb potential for charge interaction between all joints. The bending energy is determined by the intrinsic bending stiffness, and the charge interaction depends on the interaction strength and screening length. All three contribute to the stiffness of the polymer chain and lead to longer and larger polymer conformations. The screening length also introduces a second length scale for the polymer besides the bending persistence length. To obtain the inverse mapping from the structure factor to these polymer conformation and energy-related parameters, we generate a large data set of structure factors by running simulations for a wide range of polymer energy parameters. We use principal component analysis to investigate the intra-polymer structure factors and determine the feasibility of the inversion using the nearest neighbor distance. We employ Gaussian process regression to achieve the inverse mapping and extract the characteristic parameters of polymers from the structure factor with low relative error.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
8 pages, 8 figures
Terahertz-induced second-harmonic generation in quantum paraelectrics: hot-phonon effect
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
F. Yang, X. J. Li, D. Talbayev, L. Q. Chen
Recent terahertz-pump second-harmonic-generation(SHG)-probe measurements of quantum paraelectrics observed a significant long-lived non-oscillatory SHG component following an ultrafast resonant excitation of the soft mode, which was interpreted as a signature of terahertz-induced transient ferroelectric order. Here we propose a temperature-dependent dynamic model incorporating the hot-phonon effect to simulate the soft-mode behaviors under ultrafast terahertz excitation. Its application to paraelectric KTaO3 produces quantitatively most of the features exhibited in our time-resolved SHG measurements and those in existing literature, including a long-lived non-oscillatory SHG response, SHG oscillations at twice the soft-mode frequency, SHG dampings as well as temperature and field-strength dependencies. We conclude that the observed terahertz-induced non-oscillatory SHG response in quantum paraelectrics is a consequence of the induced nonequilibrium hot-phonon effect, offering an alternative to its existing interpretation as a signature of transient ferroelectric order.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Impact of phonon lifetimes on the single-photon indistinguishability in quantum emitters based on 2D materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-27 20:00 EST
Alexander Steinhoff, Steffen Wilksen, Ivan Solovev, Christian Schneider, Christopher Gies
Localized excitons in two-dimensional (2D) materials are considered as promising sources of single photons on demand. The photon indistinguishability as key figure of merit for quantum information processing is strongly influenced by the coupling of charge excitations to lattice vibrations of the surrounding semiconductor material. Here, we quantify the impact of exciton-acoustic-phonon-interaction and cavity QED effects on photon indistinguishability in a Hong-Ou-Mandel setup by solving fully quantum mechanical equations for the coupled QD-cavity-phonon system including non-Markovian effects. We find a strong reduction of indistinguishability compared to 3D systems due to increased exciton-phonon coupling efficiency. Moreover, we show that the coherence properties of photons are significantly influenced by the finite phonon lifetime in the surrounding material giving rise to pure dephasing. Only if these limitations can be overcome, localized excitons in 2D semiconductors can become a new avenue for quantum light sources.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Landscape of Correlated Orders in Strained Bilayer Nickelate Thin Films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-27 20:00 EST
Congcong Le, Jun Zhan, Xianxin Wu, Jiangping Hu
The discovery of high-temperature superconductivity in bilayer nickelates La\(_3\)Ni\(_2\)O\(_7\) under pressure has sparked significant research interest. This interest has been further fueled by the recent achievement of superconductivity in compressed thin films at ambient pressure, although the origin and underlying mechanism remain elusive. In this work, we explore the electronic structures and instabilities of strained thin films on substrates to identify the key factors for achieving superconductivity, using first-principles and functional renormalization group calculations. Our findings suggest that the compressed NiO\(_2\) bilayer near the interface is unlikely to exhibit superconductivity, despite its electron-doped nature. In contrast, the NiO\(_2\) bilayer away from the interface shows density-wave instability when undoped or slightly hole-doped. However, when this bilayer is hole-doped, leading to the emergence of a hole pocket around the M point, it exhibits robust \(s_{\pm}\)-wave superconductivity, which may account for superconductivity observed in thin films. For the stretched NiO\(_2\) bilayer, robust spin-density-wave instability is observed due to enhanced Fermi surface nesting, despite the presence of a hole pocket around the M point. Potential experimental implications are discussed. Our study highlights the crucial role of fermiology in determining electronic instability and establishes a unified scenario for superconductivity in both pressurized bulk and strained thin films of bilayer nickelates.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 4 figures
Thermomechanical Processing of Pure Magnesium: Hot Extrusion, Hot Rolling and Cold Drawing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Mohamad Amin Kalateh, Naeime Talebi, Soroush Nekoei, Mohamad Mahdi Novini, Farzad Khodabakhshi, Mahmoud Nili-Ahmadabadi
A comprehensive study on thermomechanical processing of pure Mg was conducted through sequential hot extrusion, hot rolling, and cold drawing operations. Three different extrusion ratios (6:1, 25:1, and 39:1) were investigated at 350°C, revealing that 39:1 ratio produced an optimal bimodal grain structure with beneficial twin morphology. Subsequently, hot rolling experiments were performed at varying linear speeds (26- and 130-mm s-1) and interpass annealing times (2.5 and 10 minutes). Results demonstrated that higher rolling speeds led to finer microstructure, while longer interpass annealing times resulted in reduced twin fraction and more inhomogeneous microstructure. The processed material was then subjected to cold drawing with approximately 12% true strain per pass. Different annealing conditions (275°C and 375°C for 2.5-10 minutes) between drawing passes were evaluated. Analysis showed that annealing at 375°C for 2.5-5 minutes provided optimal softening for subsequent deformation. Fracture analysis revealed a mixed ductile-brittle behavior, with twin-matrix interfaces serving as preferred crack propagation paths This study establishes optimal processing parameters for pure Mg wire production, highlighting the critical role of twin characteristics and restoration processes in determining material formability during multi-step thermomechanical processing.
Materials Science (cond-mat.mtrl-sci)
13 International Conference on Materials engineering and Metallurgy-Karaj, Iran
Enhanced Confocal Laser Scanning Microscopy with Adaptive Physics Informed Deep Autoencoders
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Zaheer Ahmad, Junaid Shabeer, Usman Saleem, Tahir Qadeer, Abdul Sami, Zahira El Khalidi, Saad Mehmood
We present a physics-informed deep learning framework to address common limitations in Confocal Laser Scanning Microscopy (CLSM), such as diffraction limited resolution, noise, and undersampling due to low laser power conditions. The optical system's point spread function (PSF) and common CLSM image degradation mechanisms namely photon shot noise, dark current noise, motion blur, speckle noise, and undersampling were modeled and were directly included into model architecture. The model reconstructs high fidelity images from heavily noisy inputs by using convolutional and transposed convolutional layers. Following the advances in compressed sensing, our approach significantly reduces data acquisition requirements without compromising image resolution. The proposed method was extensively evaluated on simulated CLSM images of diverse structures, including lipid droplets, neuronal networks, and fibrillar systems. Comparisons with traditional deconvolution algorithms such as Richardson-Lucy (RL), non-negative least squares (NNLS), and other methods like Total Variation (TV) regularization, Wiener filtering, and Wavelet denoising demonstrate the superiority of the network in restoring fine structural details with high fidelity. Assessment metrics like Structural Similarity Index (SSIM) and Peak Signal to Noise Ratio (PSNR), underlines that the AdaptivePhysicsAutoencoder achieved robust image enhancement across diverse CLSM conditions, helping faster acquisition, reduced photodamage, and reliable performance in low light and sparse sampling scenarios holding promise for applications in live cell imaging, dynamic biological studies, and high throughput material characterization.
Materials Science (cond-mat.mtrl-sci), Computer Vision and Pattern Recognition (cs.CV), Image and Video Processing (eess.IV)
Large Negative Magnetoresistance in Antiferromagnetic Gd2Se3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-27 20:00 EST
Santosh Karki Chhetri, Gokul Acharya, David Graf, Rabindra Basnet, Sumaya Rahman, M.M. Sharma, Dinesh Upreti, Md Rafique Un Nabi, Serhii Kryvyi, Josh Sakon, Mansour Mortazavi, Bo Da, Hugh Churchill, Jin Hu
Rare earth chalcogenides provide a great platform to study exotic quantum phenomena such as superconductivity and charge density waves. Among various interesting properties, the coupling between magnetism and electronic transport has attracted significant attention. Here, we report the investigation of such coupling in {alpha}-Gd2Se3 single crystals through magnetic, calorimetric, and transport property measurements. {alpha}-Gd2Se3 is found to display an antiferromagnetic ground state below 11 K with metamagnetic spin-flop transitions. The magnetic fluctuations remain strong above the transition temperature. Transport measurements reveal an overall metallic transport behavior with a large negative magnetoresistance of ~ 65% near the magnetic transition temperature, together with positive MR near the field-induced spin-flop transitions, which can be understood in terms of the suppression of spin scattering by the magnetic field.
Materials Science (cond-mat.mtrl-sci)
13 Pages, 5 figures, 1 Table
Phys. Rev. B 111, 014431 (2025)
Dualities between 2+1d fusion surface models from braided fusion categories
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-27 20:00 EST
Fusion surface models generalize the concept of anyon chains to 2+1 dimensions, utilizing fusion 2-categories as their input. We investigate bond-algebraic dualities in these systems and show that distinct module tensor categories \(\mathcal{M}\) over the same braided fusion category \(\mathcal{B}\) give rise to dual lattice models. This extends the 1+1d result that dualities in anyon chains are classified by module categories over fusion categories. We analyze two concrete examples: (i) a \(\text{Rep}(S_3)\) model with a constrained Hilbert space, dual to the spin-\(\tfrac{1}{2}\) XXZ model on the honeycomb lattice, and (ii) a bilayer Kitaev honeycomb model, dual to a spin-\(\tfrac{1}{2}\) model with XXZ and Ising interactions. Unlike regular \(\mathcal{M}=\mathcal{B}\) fusion surface models, which conserve only 1-form symmetries, models constructed from \(\mathcal{M} \neq \mathcal{B}\) can exhibit both 1-form and 0-form symmetries, including non-invertible ones.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)