Found 60 papers in cond-mat
Date of feed: Tue, 30 Jan 2024 01:30:00 GMT

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A Collision Operator for Describing Dissipation in Noncanonical Phase Space. (arXiv:2401.15086v1 [cond-mat.stat-mech])
Naoki Sato, Philip J. Morrison

The phase space of a noncanonical Hamiltonian system is partially inaccessible due to dynamical constraints (Casimir invariants) arising from the kernel of the Poisson tensor. When an ensemble of noncanonical Hamiltonian systems is allowed to interact, dissipative processes eventually break the phase space constraints, resulting in an equilibrium described by a Maxwell-Boltzmann distribution. However, the time scale required to reach Maxwell-Boltzmann statistics is often much longer than the time scale over which a given system achieves a state of thermal equilibrium. Examples include diffusion in rigid mechanical systems, as well as collisionless relaxation in magnetized plasmas and stellar systems, where the interval between binary Coulomb or gravitational collisions can be longer than the time scale over which stable structures are self-organized. Here, we focus on self-organizing phenomena over spacetime scales such that particle interactions respect the noncanonical Hamiltonian structure, but yet act to create a state of thermodynamic equilibrium. We derive a collision operator for general noncanonical Hamiltonian systems, applicable to fast, localized interactions. This collision operator depends on the interaction exchanged by colliding particles and on the Poisson tensor encoding the noncanonical phase space structure, is consistent with entropy growth and conservation of particle number and energy, preserves the interior Casimir invariants, reduces to the Landau collision operator in the limit of grazing binary Coulomb collisions in canonical phase space, and exhibits a metriplectic structure. We further show how thermodynamic equilibria depart from Maxwell-Boltzmann statistics due to the noncanonical phase space structure, and how self-organization and collisionless relaxation in magnetized plasmas and stellar systems can be described through the derived collision operator.

First-principles Methodology for studying magnetotransport in magnetic materials. (arXiv:2401.15146v1 [cond-mat.mtrl-sci])
Zhihao Liu, Shengnan Zhang, Zhong Fang, Hongming Weng, Quansheng Wu

Unusual magnetotransport behaviors such as temperature dependent negative magnetoresistance(MR) and bowtie-shaped MR have puzzled us for a long time. Although several mechanisms have been proposed to explain them, the absence of comprehensive quantitative calculations has made these explanations less convincing. In our work, we introduce a methodology to study the magnetotransport behaviors in magnetic materials. This approach integrates anomalous Hall conductivity induced by Berry curvature, with a multi-band ordinary conductivity tensor, employing a combination of first-principles calculations and semi-classical Boltzmann transport theory. Our method incorporates both the temperature dependency of relaxation time and anomalous Hall conductivity, as well as the field dependency of anomalous Hall conductivity. We initially test this approach on two-band models and then apply it to a Weyl semimetal \CSS. The results, which align well with experimental observations in terms of magnetic field and temperature dependencies, demonstrate the efficacy of our approach. Additionally, we have investigated the distinct behaviors of magnetoresistance (MR) and Hall resistivities across various types of magnetic materials. This methodology provides a comprehensive and efficient means to understand the underlying mechanisms of the unusual behaviors observed in magneto-transport measurements in magnetic materials.

New perspectives of Hall effects from first-principles calculations. (arXiv:2401.15150v1 [cond-mat.mtrl-sci])
ShengNan Zhang, Hanqi Pi, Zhong Fang, Hongming Weng, QuanSheng Wu

The Hall effect has been a fascinating topic ever since its discovery, resulting in exploration of entire family of this intriguing phenomena. As the field of topology develops and novel materials emerge endlessly over the past few decades, researchers have been passionately debating the origins of various Hall effects. Differentiating between the ordinary Hall effect and extraordinary transport properties, like the anomalous Hall effect, can be quite challenging, especially in high-conductivity materials, including those with topological origins. In this study, we conduct a systematic and comprehensive analysis of Hall effects by combining the semiclassical Boltzmann transport theory with first principles calculations within the relaxation time approximation. We first highlight some striking similarities between the ordinary Hall effect and certain anomalous Hall effects, such as nonlinear dependency on magnetic field and potential sign reversal of the Hall resistivity. We then demonstrate that the Hall resistivity can be scaled with temperature and magnetic field as well, analogue to the Kohler's rule which scales the longitudinal resistivity under the relaxation time approximation. We then apply this Kohler's rule for Hall resistivity to two representative materials: ZrSiS and PtTe$_2$ with reasonable agreement with experimental measurement. Moreover, our methodology has been proven to be applicable to the planar Hall effects of bismuth, of perfect agreements with experimental observations. Our research on the scaling behavior of Hall resistivity addresses a significant gap in this field and provides a comprehensive framework for a deeper understanding of the Hall resistance family, and thus has potential to propel the field forward and spark further investigations into the fascinating world of Hall effects.

First-principles methodology for studying magnetotransport in narrow-gap semiconductors: an application to Zirconium Pentatelluride ZrTe5. (arXiv:2401.15151v1 [cond-mat.mtrl-sci])
Hanqi Pi, Shengnan Zhang, Yang Xu, Zhong Fang, Hongming Weng, Quansheng Wu

The origin of anomalous resistivity peak and accompanied sign reversal of Hall resistivity of ZrTe$_5$ has been under debate for a long time. Although various theoretical models have been proposed to account for these intriguing transport properties, a systematic study from first principles view is still lacking. In this work, we present a first principles calculation combined with Boltzmann transport theory to investigate the transport properties in narrow-gap semiconductors at different temperatures and doping densities within the relaxation time approximation. Regarding the sensitive temperature-dependent chemical potential and relaxation time of semiconductors, we take proper approximation to simulate these two variables, and then comprehensively study the transport properties of ZrTe$_5$ both in the absence and presence of an applied magnetic field. Without introducing topological phases and correlation interactions, we qualitatively reproduced crucial features observed in experiments, including zero-field resistivity anomaly, nonlinear Hall resistivity with sign reversal, and non-saturating magnetoresistance at high temperatures. Our calculation allows a systematic interpretation of the observed properties in terms of multi-carrier and Fermi surface geometry. Our method can be extended to other narrow-gap semiconductors and further pave the way to explore interesting and novel transport properties of this field.

Polaron spectra and edge singularities for correlated flat bands. (arXiv:2401.15155v1 [cond-mat.str-el])
Dimitri Pimenov

Single- and two-particle spectra of a single immobile impurity immersed in a fermionic bath can be computed exactly and are characterized by divergent power laws (edge singularities). Here, we present the leading lattice correction to this canonical problem, by embedding both impurity and bath fermions in bands with non-vanishing Bloch band geometry, with the impurity band being flat. By analyzing generic Feynman diagrams, we pinpoint how the band geometry reduces the effective interaction which enters the power laws; we find that for weak lattice effects or small Fermi momenta, the leading correction is proportional to the Fermi energy times the sum of the quantum metrics of the bands. When only the bath fermion geometry is important, the results can be extended to large Fermi momenta and strong lattice effects. We numerically illustrate our results on the Lieb lattice and draw connections to ultracold gas experiments.

Soft spots of net negative topological charge directly cause the plasticity of 3D glasses. (arXiv:2401.15359v1 [cond-mat.soft])
Arabinda Bera, Matteo Baggioli, Timothy C. Petersen, Timothy W. Sirk, Amelia C. Y. Liu, Alessio Zaccone

The deformation mechanism in amorphous solids subjected to external shear remains poorly understood because of the absence of well-defined topological defects mediating the plastic deformation. The notion of soft spots has emerged as a useful tool to characterize the onset of irreversible rearrangements and plastic flow, but these entities are not well-defined in terms of geometry and topology. In this study, we unveil the phenomenology of recently discovered, well-defined topological defects governing the microscopic mechanical and yielding behavior of a model 3D glass under shear deformation. We identify the existence of vortex-like and anti-vortex-like topological defects within the 3D non-affine displacement field. The number density of these defects exhibits a significant (inverse) correlation with the plastic events, with defect proliferation-annihilation cycles matching the alternation of elastic-like segments and catastrophic plastic drops, respectively. Furthermore, we observe collective annihilation of these point-like defects via plastic events, with large local topological charge fluctuations in the vicinity of regions that feature strong non-affine displacements. We unveil that plastic yielding is driven by very few, but very large, clusters of net negative topological charge, the massive annihilation of which triggers the onset of plastic flow. These findings suggest a geometric and topological characterization of soft spots and pave the way for the mechanistic understanding of topological defects as mediators of plastic deformation in glassy materials.

Multistable localized states in highly photonic polariton rings with a quasiperiodic modulation. (arXiv:2401.15396v1 [cond-mat.mes-hall])
Andrei V. Nikitin, Dmitry A. Zezyulin

We present a theoretical study of an exciton-polariton annular microcavity with an additional quasiperiodic structure along the ring which is implemented in the form of a bicosine dependence. We demonstrate that for a sufficiently strong quasiperiodic modulation, the microcavity features a sharp mobility edge separating a cluster of localized states from the rest of the spectrum consisting of states extended over the whole ring. Localized modes can be excited using a resonant pump whose topological charge determines the phase distribution of excited patterns. Repulsive polariton interactions make the resonance peaks distinctively asymmetric and enable the formation of multistable states which feature the attractor-like dynamical behavior \rev{and hysteresis}. We also demonstrate that the localized states can be realized in a biannular cavity that consists of two rings, each having periodic modulation, such that the periods of two modulations are different.

Corrosion resistance of a water-borne resin doped with graphene derivatives applied on galvanized steel. (arXiv:2401.15410v1 [cond-mat.mtrl-sci])
A. Collazo, B. Díaz, R. Figueroa, X.R. Nóvoa, C. Pérez

The present work reports the effect of adding Graphene Oxide (GO) and reduced Graphene Oxide (rGO) in the corrosion protection provided by a water-borne resin applied on a galvanized steel substrate. Three concentrations, 0.05, 0.1 and 0.15 (all wt%) were tested. The results were markedly affected not only by the concentration of particles but also by their nature. Although the zeta potential values suggested good dispersibility of the particles in the resin, certain aggregation was observed, mainly in rGO 0.1 wt% and rGO 0.15 wt% formulations. The electrochemical impedance spectroscopy (EIS) technique characterised the free films' transport properties. The results suggested that the aggregation strongly influenced the film morphology. The rGO 0.1 wt% and rGO 0.15 wt% formulations exhibited percolating pores that facilitated the electrolyte uptake through the films. The EIS technique was also used to study the protective performance of the films when applied to the metallic substrate. The results confirmed the harmful effect of the particle's aggregation. The results were interesting for the rGO 0.05 wt% system, which displayed long-lasting protection properties. This performance was explained considering its good barrier properties and the zinc surface passivation by the generation of zincite, ZnO.

Hometronics: Accessible production of graphene suspensions for health sensing applications using only household items. (arXiv:2401.15418v1 [cond-mat.mtrl-sci])
Adel K.A. Aljarid, Jasper Winder, Cencen Wei, Arvind Venkatraman, Oliver Tomes, Aaron Soul, Dimitrios G. Papageorgiou, Matthias E. Möbius, Conor S. Boland

Nanoscience at times can seem out of reach to the developing world and the general public, with much of the equipment expensive and knowledge seemingly esoteric to nonexperts. Using only cheap, everyday household items, accessible research with real applications can be shown. Here, graphene suspensions were produced using pencil lead, tap water, kitchen appliances, soaps and coffee filters, with a childrens glue based graphene nanocomposite for highly sensitive pulse measurements demonstrated.

All-electrical driving and probing of dressed states in a single spin. (arXiv:2401.15440v1 [cond-mat.mes-hall])
Hong T. Bui, Christoph Wolf, Yu Wang, Masahiro Haze, Arzhang Ardavan, Andreas J. Heinrich, Soo-hyon Phark

The sub-nanometer distance between tip and sample in a scanning tunneling microscope (STM) enables the application of very large electric fields with a strength as high as ~ 1 GV/m. This has allowed for efficient electrical driving of Rabi oscillations of a single spin on a surface at a moderate radio-frequency (RF) voltage of the order of tens of millivolts. Here, we demonstrate the creation of dressed states of a single electron spin localized in the STM tunnel junction by using resonant RF driving voltages. The read-out of these dressed states was achieved all-electrical by a weakly coupled probe spin. Our work highlights the strength of the atomic-scale geometry inherent to the STM that facilitates creation and control of dressed states, which are promising for a design of atomically well-defined single spin quantum devices on surfaces.

Electronic structure and physical properties of candidate topological material GdAgGe. (arXiv:2401.15464v1 [cond-mat.str-el])
D. Ram, J. Singh, M. K. Hooda, O. Pavlosiuk, V. Kanchana, Z. Hossain, D. Kaczorowski

We grew needle-shaped single crystals of GdAgGe, which crystallizes in a noncentrosymmetric hexagonal crystal structure with space group P$\overline{6}$2$m$ (189). The magnetic susceptibility data for $H \perp c$ reveal two pronounced antiferromagnetic transitions at $T_{N1}$ = 20 K and $T_{N2}$ = 14.5 K. The magnetic susceptibility anomalies are less prominent for $H \parallel c$. The transition at $T_{N1}$ is accompanied by a pronounced heat capacity anomaly confirming the bulk nature of the magnetic transition. Below $T_{N1}$, the electrical resistivity data follows a $T^{3/2}$ dependence. In the magnetically ordered state, GdAgGe shows positive transverse magnetoresistance, which increases with decreasing temperature and increasing field, reaching a value of $\sim$ 27% at 9 T and 10 K. The Hall resistivity data and electronic band structure calculations suggest that both the hole and electron charge carriers contribute to the transport properties. The electronic band structure displays linear band crossings near the Fermi level. The calculations reveal that GdAgGe has a nodal line with drumhead surface states coupled with a nonzero Berry phase, making it a nontrivial nodal-line semimetal.

Challenges and Opportunities in Searching for Rashba-Dresselhaus Materials for Efficient Spin-Charge Interconversion at Room Temperature. (arXiv:2401.15524v1 [cond-mat.mtrl-sci])
Zixu Wang, Zhizhong Chen, Rui Xu, Hanyu Zhu, Ravishankar Sundararaman, Jian Shi

Spintronic logic devices require efficient spin-charge interconversion: converting charge current to spin current and spin current to charge current. In spin-orbit materials that are regarded as the most promising candidate for spintronic logic devices, one mechanism that is responsible for spin-charge interconversion is Edelstein and inverse Edelstein effects based on spin-momentum locking in materials with Rashba-type spin-orbit coupling. Over last decade, there has been rapid progresses for increasing interconversion efficiencies due to the Edelstein effect in a few Rashba-Dresselhaus materials and topological insulators, making Rashba spin-momentum locking a promising technological solution for spin-orbit logic devices. However, despite the rapid progress that leads to high spin-charge interconversion efficiency at cryogenic temperatures, the room-temperature efficiency needed for technological applications is still low. This paper presents our understanding on the challenges and opportunities in searching for Rashba-Dresselhaus materials for efficient spin-charge interconversion at room temperature by focusing on materials properties such as Rashba coefficients, momentum relaxation times, spin-momentum locking relations and electrical conductivities.

Dirac mass induced by optical gain and loss. (arXiv:2401.15528v1 [cond-mat.mes-hall])
Letian Yu, Haoran Xue, Ruixiang Guo, Eng Aik Chan, Yun Yong Terh, Cesare Soci, Baile Zhang, Y. D. Chong

Mass is commonly regarded as an intrinsic property of matter, but modern physics shows that particle masses have complex origins . Elementary particles acquire mass from couplings to other fields: most fermions and bosons receive mass from the Higgs field, as well as other interactions (e.g., quarks gain mass from interactions with gluons). In low-energy physics, quasiparticles behaving like fundamental particles can arise in crystalline lattices, such as relativistic Dirac quasiparticles in graphene. Mass can be imparted to these quasiparticles by various lattice perturbations. By tailoring lattice properties, we can explore otherwise-inacessible phenomena, such as how particles behave when Hermiticity, the symmetry responsible for energy conservation, is violated. Non-Hermiticity has long seemed incompatible with mass generation; when Dirac points are subjected to energy-nonconserving perturbations, they typically become exceptional points instead of opening a mass gap. Here, we show experimentally that Dirac masses can be generated via non-Hermiticity. We implement a photonic synthetic lattice with gain and loss engineered to produce Dirac quasiparticles with real mass. By tuning this mass, we demonstrate a crossover from conical to non-conical diffraction , topological boundary states between domains of opposite Dirac mass, and anomalous tunneling into potential barriers.

Magnetic interactions and excitations in SrMnSb$_2$. (arXiv:2401.15572v1 [cond-mat.mtrl-sci])
Zhenhua Ning, Bing Li, Arnab Banerjee, Victor Fanelli, Doug Abernathy, Yong Liu, Benjamin G Ueland, Robert J. McQueeney, Liqin Ke

The magnetic interactions in the antiferromagnetic (AFM) Dirac semimetal candidate SrMnSb$_2$ are investigated using \textit{ab initio} linear response theory and inelastic neutron scattering (INS). Our calculations reveal that the first two nearest in-plane couplings ($J_1$ and $J_2$) are both AFM in nature, indicating a significant degree of spin frustration, which aligns with experimental observations. The orbital resolution of exchange interactions shows that $J_1$ and $J_2$ are dominated by direct and superexchange, respectively. In a broader context, a rigid-band model suggests that electron doping fills the minority spin channel and results in a decrease in the AFM coupling strength for both $J_1$ and $J_2$. To better compare with INS experiments, we calculate the spin wave spectra within a linear spin wave theory framework, utilizing the computed exchange parameters. The calculated spin wave spectra exhibit overall good agreement with measurements from INS experiments, although with a larger magnon bandwidth. Introducing additional electron correlation within the Mn-$3d$ orbitals can promote electron localization and reduce the magnetic coupling, further improving the agreement with experiments.

Predicting Novel Properties in Two-Dimensional Janus Transition Metal Hydrosulfides with 2H and 1T Phases: Electrodes, Charge Density Waves, and Superconductivity. (arXiv:2401.15577v1 [cond-mat.mtrl-sci])
Dawei Zhoua, Zhuo Wangb, Pan Zhanga, Chunying Pua

Inspired by recent experimental synthesis of the two-dimensional Janus material MoSH, we performed extensive first-principles calculations to investigate the characteristics of all possible Janus two-dimensional transition metal hydrosulfides (JTMSHs) in both the 2H and 1T phases. Our investigations revealed that the JTMSHs can form a unique family of two-dimensional materials with novel physical and chemical properties. We found that JTMSHs can exist in different crystal states, exhibiting metallic, semiconducting, and magnetic behaviors. One particularly intriguing finding is the identification of two-dimensional electrodes with distinct bonding characteristics in the 2H-JTMSHs (TM=V, Nb, Ta, Mo, W and Tc). Additionally, we observed evidence of charge density wave (CDW) materials in 1T-JTMSH (TM=Tc, Re, and W) and 2H-JTMSH (TM = Tc). Importantly, by applying a compressive strain to these materials, the CDW can be completely suppressed and superconductivities is hence induced. Specially, we shown that when subjected to a compressive strain within 10%, the superconducting transition temperature (Tc) of 1T-WSH, 1T-TcSH and 2H-TcSH can achieve maximum values of 13.8, 16.2 and 24.2 K respectively. Additionally, our investigation also unveiled two intrinsic phonon-mediated superconductors 2H-WSH and 1T-RuSH with Tc of 17.0 K and 8K, respectively. Overall, our results demonstrate that the family of two-dimensional JTMSHs is full of surprises and holds great potential for future exploration.

In-plane Antiferromagnetism in Ferromagnetic Kagome Semimetal Co3Sn2S2. (arXiv:2401.15602v1 [cond-mat.mtrl-sci])
Sandy Adhitia Ekahana, Satoshi Okamoto, Jan Dreiser, Loïc Roduit, Gawryluk Dariusz Jakub, Andrew Hunter, Anna Tamai, Y. Soh

Co3Sn2S2 has been reported to be a Weyl semimetal with broken time-reversal symmetry with c axis ferromagnetism (FM) below a Curie temperature of 177 K. Despite the large interest in Co3Sn2S2, the magnetic structure is still under debate and recent studies have challenged our understanding of the magnetic phase diagram of Co3Sn2S2 by reporting unusual magnetic phases including the presence of exchange bias. Understanding the magnetism of Co3Sn2S2 is important since its electronic band structure including the much-celebrated flat bands and Weyl nodes depend on the magnetic phase. In this work, using X-ray Magnetic Circular Dichroism (XMCD), we establish that the magnetic moment in Co arises from the spin, with negligible orbital moment. In addition, we detect an in-plane AFM minority phase in the sea of a FM phase using spatially-resolved angle-resolved photoemission spectroscopy ({\mu}-ARPES) combined with density functional theory (DFT) calculation. Separately, we detect a sharp flat band precisely at the Fermi level (EF) at some regions in the sample, which we attribute to a surface state. The AFM phase survives even to the low temperature of 6 K. This example of entirely different magnetic ground states in a stoichiometric intermetallic invites further efforts to explore the observed AFM phase and understand the origin and nature of the magnetic and electronic inhomogeneity on the mesoscale and the interface between the AFM and FM phases.

Aperiodic-quasiperiodic-periodic characteristics in twisted nested Moir\'e patterns and topological transitions. (arXiv:2401.15849v1 [cond-mat.mes-hall])
Peng Peng, Yuchen Peng, Aoqian Shi, Xiaogen Yi, Yizhou Wei, Jianjun Liu

The Moir\'e patterns generated by altering the structural parameters in a two or more layers of periodic materials, including single-layer structure, interlayer stacking, and twisting parameters, exhibit prosperous topological physical properties. However, the intricate characteristics of these Moir\'e patterns and their relationship with topological transitions remain unclear. In this Letter, based on the proposed twisted nested photonic crystal (TNPC), we derive its spatial geometric functions (SGFs), aperiodic-quasiperiodic-periodic characteristics of Moir\'e patterns, and the SSH{\phi} Hamiltonian. We reveal the intrinsic correlation between Moir\'e patterns and topological transitions, obtaining higher-order topological states (HOTSs) with C2z symmetry. This work will provide theoretical references for the design and application of twisted topological PC and their devices.

Topological magnon-polarons in honeycomb antiferromagnets with spin-flop transition. (arXiv:2401.15888v1 [cond-mat.mes-hall])
Gyungchoon Go, Heejun Yang, Je-Geun Park, Se Kwon Kim

We theoretically investigate the thermal Hall transport of magnon-polarons in a two-dimensional honeycomb antiferromagnetic insulator under the influence of a perpendicular magnetic field, varying in strength. The application of a perpendicular magnetic field induces a magnetic phase transition from the collinear antiferromagnetic phase to the spin-flop phase, leading to a significant alteration in Hall transport across the transition point. In this paper, our focus is on the intrinsic contribution to thermal Hall transport arising from the magnetoelastic interaction. To facilitate experimental verification of our theoretical results, we present the dependence of thermal Hall conductivity on magnetic field strength and temperature.

Fast renormalizing the structures and dynamics of ultra-large systems via random renormalization group. (arXiv:2401.15899v1 [cond-mat.stat-mech])
Yang Tian, Yizhou Xu, Pei Sun

Criticality and symmetry, studied by the renormalization groups, lie at the heart of modern physics theories of matters and complex systems. However, surveying these properties with massive experimental data is bottlenecked by the intolerable costs of computing renormalization groups on real systems. Here, we develop a time- and memory-efficient framework, termed as the random renormalization group, for renormalizing ultra-large systems (e.g., with millions of units) within minutes. This framework is based on random projections, hashing techniques, and kernel representations, which support the renormalization governed by linear and non-linear correlations. For system structures, it exploits the correlations among local topology in kernel spaces to unfold the connectivity of units, identify intrinsic system scales, and verify the existences of symmetries under scale transformation. For system dynamics, it renormalizes units into correlated clusters to analyze scaling behaviours, validate scaling relations, and investigate potential criticality. Benefiting from hashing-function-based designs, our framework significantly reduces computational complexity compared with classic renormalization groups, realizing a single-step acceleration of two orders of magnitude. Meanwhile, the efficient representation of different kinds of correlations in kernel spaces realized by random projections ensures the capacity of our framework to capture diverse unit relations. As shown by our experiments, the random renormalization group helps identify non-equilibrium phase transitions, criticality, and symmetry in diverse large-scale genetic, neural, material, social, and cosmological systems.

Energy Localization and Topological Defect in Spherical Non-Hermitian Topolectrical Circuits. (arXiv:2401.15908v1 [])
Xizhou Shen, Xiumei Wang, Haotian Guo, Xingping Zhou

This work delves into the energy localization in non-Hermitian systems, particularly focusing on the effects of topological defects in spherical models. We analyze the mode distribution changes in non-Hermitian Su-Schrieffer-Heeger (SSH) chains impacted by defects, utilizing the Maximum Skin Corner Weight (MaxWSC). By introducing an innovative spherical model, conceptualized through bisecting spheres into one-dimensional chain structures, we investigate the non-Hermitian skin effect (NHSE) in a new dimensional context, venturing into the realm of non-Euclidean geometry. Our experimental validations on Printed Circuit Boards (PCBs) confirm the theoretical findings. Collectively, these results not only validate our theoretical framework but also demonstrate the potential of engineered circuit systems to emulate complex non-Hermitian phenomena, showcasing the applicability of non-Euclidean geometries in studying NHSE and topological phenomena in non-Hermitian systems.

Tunable vortex bound states in multiband CsV3Sb5-derived kagome superconductors. (arXiv:2401.15918v1 [cond-mat.supr-con])
Zihao Huang, Xianghe Han, Zhen Zhao, Jinjin Liu, Pengfei Li, Hengxin Tan, Zhiwei Wang, Yugui Yao, Haitao Yang, Binghai Yan, Kun Jiang, Jiangping Hu, Ziqiang Wang, Hui Chen, Hong-Jun Gao

Vortices and bound states offer an effective means of comprehending the electronic properties of superconductors. Recently, surface dependent vortex core states have been observed in the newly discovered kagome superconductors CsV3Sb5. Although the spatial distribution of the sharp zero energy conductance peak appears similar to Majorana bound states arising from the superconducting Dirac surface states, its origin remains elusive. In this study, we present observations of tunable vortex bound states (VBSs) in two chemically doped kagome superconductors Cs(V1-xTrx)3Sb5 (Tr=Ta or Ti), using low temperature scanning tunneling microscopy/spectroscopy. The CsV3Sb5-derived kagome superconductors exhibit full gap pairing superconductivity accompanied by the absence of long range charge orders, in contrast to pristine CsV3Sb5. Zero energy conductance maps demonstrate a field-driven continuous reorientation transition of the vortex lattice, suggesting multiband superconductivity. The Ta doped CsV3Sb5 displays the conventional cross shaped spatial evolution of Caroli de Gennes Matricon bound states, while the Ti doped CsV3Sb5 exhibits a sharp, non split zero bias conductance peak (ZBCP) that persists over a long distance across the vortex. The spatial evolution of the non split ZBCP is robust against surface effects and external magnetic field but is related to the doping concentrations. Our study reveals the tunable VBSs in multiband chemically doped CsV3Sb5 system and offers fresh insights into previously reported Y shaped ZBCP in a non quantum limit condition at the surface of kagome superconductor.

AdvNF: Reducing Mode Collapse in Conditional Normalising Flows using Adversarial Learning. (arXiv:2401.15948v1 [cs.LG])
Vikas Kanaujia, Mathias S. Scheurer, Vipul Arora

Deep generative models complement Markov-chain-Monte-Carlo methods for efficiently sampling from high-dimensional distributions. Among these methods, explicit generators, such as Normalising Flows (NFs), in combination with the Metropolis Hastings algorithm have been extensively applied to get unbiased samples from target distributions. We systematically study central problems in conditional NFs, such as high variance, mode collapse and data efficiency. We propose adversarial training for NFs to ameliorate these problems. Experiments are conducted with low-dimensional synthetic datasets and XY spin models in two spatial dimensions.

Measurement of the Chern Number for Non-Hermitian Chern Insulators. (arXiv:2401.15991v1 [cond-mat.mes-hall])
Hongfang Liu, Ming Lu, Shengdu Chai, Zhi-Qiang Zhang, Hua Jiang

The identification of the topological invariant of a topological system is crucial in experiments. However, due to the inherent non-Hermitian features, such determination is notably challenging in non-Hermitian systems. Here, we propose that the magnetic effect can be utilized to measure the Chern number of the non-Hermitian Chern insulator. We find that the splitting of non-Hermitian bands under the magnetic field is Chern number dependent. Consequently, one can easily identify the Chern number by analyzing these splitting sub-bands. From the experimental perspective, the measurement of non-Hermitian bands is demonstrated in LC electric circuits. Furthermore, we find that the non-Hermiticity can drive open (closed) orbits of sub-bands in the Hermitian limit closed (open), which can also be identified by our proposal. These phenomena highlight the distinctive capabilities of non-Hermitian systems. Our results facilitate the detection of Chern numbers for non-Hermitian systems and may motivate further studies of their topological properties.

Resonant helical multi-edge transport in Sierpi\'nski carpets. (arXiv:2401.16014v1 [cond-mat.mtrl-sci])
M. A. Toloza Sandoval, A. L. Araújo, F. Crasto de Lima, A. Fazzio

In recent years, synthesis and experimental research of fractalized materials has evolved in a paradigmatic crossover with topological phases of matter. We present here a theoretical investigation of the helical edge transport in Sierpinski carpets (SCs), combining the Bernevig-Hughes-Zhang (BHZ) model and the Landauer approach. Starting from a pristine two-dimensional topological insulator (2DTI), according to the BHZ model, our results reveal resonant transport modes when the SC fractal generation reaches the same scale as the space discretization; these modes are analyzed within a contour plot mapping of the local spin-polarized currents, shown spanned and assisted by inner-edge channels. From such a deeply fractalized SC building block, we introduce a rich tapestry formed by superior SC hierarchies, enlightening intricate patterns and unique fingerprints that offer valuable insights into how helical edge transport occurs in these fractal dimensions.

Temperature-dependent local structure and lattice dynamics of 1T-TiSe$_2$ and 1T-VSe$_2$ probed by X-ray absorption spectroscopy. (arXiv:2401.16118v1 [cond-mat.mtrl-sci])
Inga Pudza, Boris Polyakov, Kaspars Pudzs, Edmund Welter, Alexei Kuzmin

The local atomic structure and lattice dynamics of two isostructural layered transition metal dichalcogenides (TMDs), 1T-TiSe$_2$ and 1T-VSe$_2$, were studied using temperature-dependent X-ray absorption spectroscopy at the Ti, V, and Se K-edges. Analysis of the extended X-ray absorption fine structure (EXAFS) spectra, employing reverse Monte Carlo (RMC) simulations, enabled tracking the temperature evolution of the local environment in the range of 10-300 K. The atomic coordinates derived from the final atomic configurations were used to calculate the partial radial distribution functions (RDFs) and the mean-square relative displacement (MSRD) factors for the first ten coordination shells around the absorbing atoms. Characteristic Einstein frequencies and effective force constants were determined for Ti-Se, Ti-Ti, V-Se, V-V, and Se-Se atom pairs from the temperature dependencies of MSRDs. The obtained results reveal differences in the temperature evolution of lattice dynamics and the strengths of intralayer and interlayer interactions in TiSe$_2$ and VSe$_2$.

Sliding ferroelectric memories and synapses. (arXiv:2401.16150v1 [cond-mat.mes-hall])
Xiuzhen Li, Biao Qin, Yaxian Wang, Yue Xi, Zhiheng Huang, Mengze Zhao, Yalin Peng, Zitao Chen, Zitian Pan, Jundong Zhu, Chenyang Cui, Rong Yang, Wei Yang, Sheng Meng, Dongxia Shi, Xuedong Bai, Can Liu, Na Li, Jianshi Tang, Kaihui Liu, Luojun Du, Guangyu Zhang

Ferroelectric materials with switchable electric polarization hold great promise for a plethora of emergent applications, such as post-Moore's law nanoelectronics, beyond-Boltzmann transistors, non-volatile memories, and above-bandgap photovoltaic devices. Recent advances have uncovered an exotic sliding ferroelectric mechanism, which endows to design atomically thin ferroelectrics from non-ferroelectric parent monolayers. Although notable progress has been witnessed in understanding its fundamental properties, functional devices based on sliding ferroelectrics, the key touchstone toward applications, remain elusive. Here, we demonstrate the rewritable, non-volatile memory devices at room-temperature utilizing a two-dimensional (2D) sliding ferroelectric semiconductor of rhombohedral-stacked bilayer molybdenum disulfide. The 2D sliding ferroelectric memories (SFeMs) show superior performances with a large memory window of >8V, a high conductance ratio of above 106, a long retention time of >10 years, and a programming endurance greater than 104 cycles. Remarkably, flexible SFeMs are achieved with state-of-the-art performances competitive to their rigid counterparts and maintain their performances post bending over 103 cycles. Furthermore, synapse-specific Hebbian forms of plasticity and image recognition with a high accuracy of 97.81% are demonstrated based on flexible SFeMs. Our work demonstrates the sliding ferroelectric memories and synaptic plasticity on both rigid and flexible substrates, highlighting the great potential of sliding ferroelectrics for emerging technological applications in brain-inspired in-memory computing, edge intelligence and energy-efficient wearable electronics.

Macroscopic electro-optical modulation of solution-processed molybdenum disulfide. (arXiv:2401.16194v1 [cond-mat.mtrl-sci])
Songwei Liu, Yingyi Wen, Jingfang Pei, Xiaoyue Fan, Yongheng Zhou, Yang Liu, Ling-Kiu Ng, Yue Lin, Teng Ma, Panpan Zhang, Xiaolong Chen, Gang Wang, Guohua Hu

Molybdenum disulfide (MoS2) has drawn great interest for tunable photonics and optoelectronics advancement. Its solution processing, though scalable, results in randomly networked ensembles of discrete nanosheets with compromised properties for tunable device fabrication. Here, we show via density-functional theory calculations that the electronic structure of the individual solution-processed nanosheets can be modulated by external electric fields collectively. Particularly, the nanosheets can form Stark ladders, leading to variations in the underlying optical transition processes and thus, tunable macroscopic optical properties of the ensembles. We experimentally confirm the macroscopic electro-optical modulation employing solution-processed thin-films of MoS2 and ferroelectric P(VDF-TrFE), and prove that the localized polarization fields of P(VDF-TrFE) can modulate the optical properties of MoS2, specifically, the optical absorption and photoluminescence on a macroscopic scale. Given the scalability of solution processing, our results underpin the potential of electro-optical modulation of solution-processed MoS2 for scalable tunable photonics and optoelectronics. As an illustrative example, we successfully demonstrate solution-processed electro-absorption modulators.

Competing magnetic states on the surface of multilayer ABC-stacked graphene. (arXiv:2401.16345v1 [cond-mat.mes-hall])
Lauro B. Braz, Tanay Nag, Annica M. Black-Schaffer

We study interaction-mediated magnetism on the surface of ABC-multilayer graphene driven by its zero-energy topological flat bands. Using the random-phase approximation we treat onsite Hubbard repulsion and find multiple competing magnetic states, due to both intra- and inter-valley scattering, with the latter causing an enlarged magnetic unit cell. At half-filling and when the Hubbard repulsion is weak, we observe two different ferromagnetic orders. Once the Hubbard repulsion becomes more realistic, new ferrimagnetic orders arise with distinct incommensurate intra- or inter-valley scattering vectors depending on interaction strength and doping, leading to a multitude of competing magnetic states.

Three-band extension for the Glashow-Weinberg-Salam model. (arXiv:2401.16346v1 [cond-mat.supr-con])
Konstantin V. Grigorishin

By analogy with the Ginzburg-Landau theory of multi-band superconductors with inner (interband) Josephson couplings we formulate the three-band Glashow-Weinberg-Salam model with weak Josephson couplings between strongly asymmetrical condensates of scalar (Higgs) fields. Unlike usual single-band model, we found three Higgs bosons corresponding to three generations of particles, moreover the heaviest of them corresponds to the already discovered H-boson from the single-band theory and decay into fermions of only the third generation. The other two decay into fermions of the first and second generations accordingly, but they are difficult to observe due to very poor conditions for production. We found two sterile ultra-light Leggett bosons, the Bose condensates of which form the dark halos of galaxies and their clusters (i.e so called "dark matter"). The masses of the Leggett bosons are determined by the coefficient of the interband coupling and can be arbitrarily small ($\sim 10^{-20}\mathrm{eV}$) due to non-perturbativeness of the interband coupling. Since propagation of Leggett bosons is not accompanied by current, these bosons are not absorbed by gauge fields unlike the common-mode Goldstone bosons. Three coupled condensates of the scalar fields causes the existence of three generations of leptons, where each generation interacts with the corresponding condensate getting mass. The interflavour mixing between the generations of active neutrinos and sterile right-handed neutrinos in the three-band system causes the existence of mass states of neutrino without interaction with the Higgs condensates.

Theory of intrinsic acoustic plasmons in twisted bilayer graphene. (arXiv:2401.16384v1 [cond-mat.mes-hall])
Lorenzo Cavicchi, Iacopo Torre, Pablo Jarillo-Herrero, Frank H. L. Koppens, Marco Polini

We present a theoretical study of the intrinsic plasmonic properties of twisted bilayer graphene (TBG) as a function of the twist angle $\theta$ (and other microscopic parameters such as temperature and filling factor). Our calculations, which rely on the random phase approximation, take into account four crucially important effects, which are treated on equal footing: i) the layer-pseudospin degree of freedom, ii) spatial non-locality of the density-density response function, iii) crystalline local field effects, and iv) Hartree self-consistency. We show that the plasmonic spectrum of TBG displays a smooth transition from a strongly-coupled regime (at twist angles $\theta \lesssim 2^{\circ}$), where the low-energy spectrum is dominated by a weakly dispersive intra-band plasmon, to a weakly-coupled regime (for twist angles $\theta \gtrsim 2^{\circ}$) where an acoustic plasmon clearly emerges. This crossover offers the possibility of realizing tunable mid-infrared sub-wavelength cavities, whose vacuum fluctuations may be used to manipulate the ground state of strongly correlated electron systems.

Quantized Hall conductance in 3D topological nodal-line semimetals without chiral symmetry. (arXiv:2004.01386v2 [cond-mat.mes-hall] UPDATED)
Guang-Qi Zhao, W. B. Rui, C. M. Wang, Hai-Zhou Lu, X. C. Xie

A quantized Hall conductance (not conductivity) in three dimensions has been searched for more than 30 years. Here we explore it in 3D topological nodal-line semimetals, by using a model capable of describing all essential physics of a semimetal, in particular the drumhead surface states protected by a momentum-dependent winding number. We develop a microscopic theory to demonstrate that the drumhead surface states can host quantized Hall conductance in this 3D material. We stress that breaking chiral symmetry is necessary for the quantum Hall effect of the drumhead surface states. The analytic theory can be verified numerically by the Kubo formula. There may also be trivial quantum Hall effects from the bulk states. We propose an experimental setup to distinguish the surface and bulk quantum Hall effects. The theory will be useful for ongoing explorations on nodal-line semimetals.

Topological Spectral Bands with Frieze Groups. (arXiv:2209.12306v2 [cond-mat.mtrl-sci] UPDATED)
Fabian R. Lux, Tom Stoiber, Shaoyun Wang, Guoliang Huang, Emil Prodan

Frieze groups are discrete subgroups of the full group of isometries of a flat strip. We investigate here the dynamics of specific architected materials generated by acting with a frieze group on a collection of self-coupling seed resonators. We demonstrate that, under unrestricted reconfigurations of the internal structures of the seed resonators, the dynamical matrices of the materials generate the full self-adjoint sector of the stabilized group $C^\ast$-algebra of the frieze group. As a consequence, in applications where the positions, orientations and internal structures of the seed resonators are adiabatically modified, the spectral bands of the dynamical matrices carry a complete set of topological invariants that are fully accounted by the K-theory of the mentioned algebra. By resolving the generators of the K-theory, we produce the model dynamical matrices that carry the elementary topological charges, which we implement with systems of plate resonators to showcase several applications in spectral engineering. The paper is written in an expository style.

Non-Invertible Duality Transformation Between SPT and SSB Phases. (arXiv:2301.07899v3 [cond-mat.str-el] UPDATED)
Linhao Li, Masaki Oshikawa, Yunqin Zheng

In 1992, Kennedy and Tasaki constructed a non-local unitary transformation that maps between a $\mathbb{Z}_2\times \mathbb{Z}_2$ spontaneously symmetry breaking phase and the Haldane gap phase, which is a prototypical Symmetry-Protected Topological phase in modern framework, on an open spin chain. In this work, we propose a way to define it on a closed chain, by sacrificing unitarity. The operator realizing such a non-unitary transformation satisfies non-invertible fusion rule, and implements a generalized gauging of the $\mathbb{Z}_2\times \mathbb{Z}_2$ global symmetry. These findings connect the Kennedy-Tasaki transformation to numerous other concepts developed for SPT phases, and opens a way to construct SPT phases systematically using the duality mapping.

The bosonic skin effect: boundary condensation in asymmetric transport. (arXiv:2301.11339v2 [quant-ph] UPDATED)
Louis Garbe, Yuri Minoguchi, Julian Huber, Peter Rabl

We study the incoherent transport of bosonic particles through a one dimensional lattice with different left and right hopping rates, as modelled by the asymmetric simple inclusion process (ASIP). Specifically, we show that as the current passing through this system increases, a transition occurs, which is signified by the appearance of a characteristic zigzag pattern in the stationary density profile near the boundary. In this highly unusual transport phase, the local particle distribution alternates on every site between a thermal distribution and a Bose-condensed state with broken U(1)-symmetry. Furthermore, we show that the onset of this phase is closely related to the so-called non-Hermitian skin effect and coincides with an exceptional point in the spectrum of density fluctuations. Therefore, this effect establishes a direct connection between quantum transport, non-equilibrium condensation phenomena and non-Hermitian topology, which can be probed in cold-atom experiments or in systems with long-lived photonic, polaritonic and plasmonic excitations.

Hinge Majorana Flat Band in Type-II Dirac Semimetals. (arXiv:2303.11729v3 [cond-mat.supr-con] UPDATED)
Yue Xie, Xianxin Wu, Zhong Fang, Zhijun Wang

Type-II Dirac semimetals (DSMs) have a distinct Fermi surface topology, which allows them to host novel topological superconductivity (TSC) different from type-I DSMs. Depending on the relationship between intra- and inter-orbital electron-electron interactions, the phase diagram of superconductivity is obtained in type-II DSMs. We find that when the inter-orbital attraction is dominant, an unconventional inter-orbital intra-spin superconducting (SC) state ($B_{1u}$ and $B_{2u}$ pairing channels of $D_{4h}$ point group) is realized, yielding hybrid TSC, i.e., first- and second-order TSC exists at the same time. Further analysis reveals the Majorana flat bands on the $z$-directed hinges, which penetrate through the whole hinge Brillouin zone and link the projections of the surface helical Majorana cones at time-reversal-invariant momenta. These higher-order hinge modes are symmetry-protected and can even host strong stability against finite $C_{4z}$ rotation symmetry-breaking order. We suggest that experimental realization of these findings can be explored in transition metal dichalcogenides.

Visualization of alternating triangular domains of charge density waves in 2H-NbSe$_2$ by scanning tunneling microscopy. (arXiv:2304.00846v2 [cond-mat.str-el] UPDATED)
Shunsuke Yoshizawa, Keisuke Sagisaka, Hideaki Sakata

The charge density wave (CDW) state of 2H-NbSe$_2$ features commensurate domains separated by domain boundaries accompanied by phase slips known as discommensurations. We have unambiguously visualized the structure of CDW domains using a displacement-field measurement algorithm on a scanning tunneling microscopy image. Each CDW domain is delimited by three vertices and three edges of discommensurations and is designated by a triplet of integers whose sum identifies the types of commensurate structure. The observed structure is consistent with the alternating triangular tiling pattern predicted by a phenomenological Landau theory. The domain shape is affected by crystal defects and also by topological defects in the CDW phase factor. Our results provide a foundation for a complete understanding of the CDW state and its relation to the superconducting state.

Fracton-elasticity duality on curved manifolds. (arXiv:2304.12242v2 [hep-th] UPDATED)
Lazaros Tsaloukidis, José J. Fernández-Melgarejo, Javier Molina-Vilaplana, Piotr Surówka

Mechanical properties of crystals on curved substrates mix elastic, geometric and topological degrees of freedom. In order to elucidate properties of such crystals we formulate the low-energy effective action that combines metric degrees of freedom with displacement fields and defects. We propose new dualities for elasticity coupled to curved geometry formulated in terms of tensor gauge theories. We show that the metric degrees of freedom, evolving akin to linearized gravity are mapped to tensors with three indices. When coupled to crystals these degrees of freedom become gapped and, in the presence of dislocations and disclinations, multivalued. The elastic degrees of freedom remain gapless and mapped to symmetric gauge fields with two indices. In analogy with elasticity on flat space formulation we assume that the trace of the total quadrupole moment is conserved. In the dual formulation, topological defects, which act as sources for the gauge fields, are fractons or excitations with restricted mobility. This leads to a generalized glide constraints that restrict both displacement and gravitational defects.

2D triangular Ising model with bond phonons: An entropic simulation study. (arXiv:2305.03127v2 [cond-mat.stat-mech] UPDATED)
R. M. L. Nascimento, Claudio J. DaSilva, L. S. Ferreira, A. A. Caparica

In this work, we study and evaluate the impact of a periodic spin-lattice coupling in an Ising-like system on a 2D triangular lattice. Our proposed simple Hamiltonian considers this additional interaction as an effect of preferential phonon propagation direction augmented by the symmetry ofthe underline lattice. The simplified analytical description of this new model brought us consistent information about its ground state and thermal behavior, and allowed us to highlight a singularity where the model behaves as several decoupled one-dimensional Ising systems. A thorough analysis was obtained via entropic simulations based in the Wang-Landau method that estimates the density of states g(E) to explore the phase diagram and other thermodynamic properties of interest. Also, we used the finite size scaling technique to characterize the critical exponents and the nature of the phase transitions that, despite the strong influence of the spin-lattice coupling, turned out to be within the same universality class as the original 2D Ising model.

A new microscopic representation of the spin dynamics in quantum systems with the Coulomb exchange interactions. (arXiv:2305.03826v3 [cond-mat.mtrl-sci] UPDATED)
Mariya Iv. Trukhanova, Pavel Andreev

There is a version of the Landau-Lifshitz equation that takes into account the Coulomb exchange interactions between atoms, expressed by the term $\sim\bm{s}\times\triangle\bm{s}$. On the other hand, ions in the magnetic materials have several valence electrons on the $d$-shell, and therefore the Hamiltonian of many-electron atoms with spins $S>1$ should include a biquadratic exchange interaction. We first propose a new fundamental microscopic derivation of the spin density evolution equation with an explicit form of biquadratic exchange interaction using the method of many-particle quantum hydrodynamics. The equation for the evolution of the spin density is obtained from the many-particle Schrodinger-Pauli equation and contains the contributions of the usual Coulomb exchange interaction and the biquadratic exchange. Furthermore, the derived biquadratic exchange torque in the spin density evolution equation is proportional to the nematic tensor for the medium of atoms with spin $\textit{S = 1}$. Our method may be very attractive for further studies of the magnetoelectric effect in multiferroics.

Magnetostriction-Driven Muon Localization in an Antiferromagnetic Oxide. (arXiv:2305.12237v3 [cond-mat.str-el] UPDATED)
Pietro Bonfà, Ifeanyi John Onuorah, Franz Lang, Iurii Timrov, Lorenzo Monacelli, Chennan Wang, Xiao Sun, Oleg Petracic, Giovanni Pizzi, Nicola Marzari, Stephen J. Blundell, Roberto De Renzi

Magnetostriction drives a rhombohedral distortion in the cubic rock salt antiferromagnet MnO at the N\'eel temperature $T_{N}=118$ K. As an unexpected consequence we show that this distortion acts to localize the site of an implanted muon due to the accompanying redistribution of electron density. This lifts the degeneracy between equivalent sites, resulting in a single observed muon precession frequency. Above $T_{N}$, the muon instead becomes delocalized around a network of equivalent sites. Our first-principles simulations based on Hubbard-corrected density-functional theory and molecular dynamics are consistent with our experimental data and help to resolve a long-standing puzzle regarding muon data on MnO, as well as having wider applicability to other magnetic oxides.

Quantum impurity with 2/3 local moment in 1D quantum wires: an NRG study. (arXiv:2305.18121v2 [cond-mat.str-el] UPDATED)
P. A. Almeida, M. A. Manya, M. S. Figueira, S. E. Ulloa, E. V. Anda, G. B. Martins

We study a Kondo state that is strongly influenced by its proximity to an w^-1/2 singularity in the metallic host density of states. This singularity occurs at the bottom of the band of a 1D chain, for example. We first analyze the non-interacting system: A resonant state e_d, located close to the band singularity, suffers a strong `renormalization', such that a bound state is created below the bottom of the band in addition to a resonance in the continuum. When e_d is positioned right at the singularity, the spectral weight of the bound state is 2/3, irrespective of its coupling to the conduction electrons. The interacting system is modeled using the Single Impurity Anderson Model, which is then solved using the Numerical Renormalization Group method. We observe that the Hubbard interaction causes the bound state to suffer a series of transformations, including level splitting, transfer of spectral weight, appearance of a spectral discontinuity, changes in binding energy (the lowest state moves farther away from the bottom of the band), and development of a finite width. When e_d is away from the singularity and in the intermediate valence regime, the impurity occupancy is lower. As e_d moves closer to the singularity, the system partially recovers Kondo regime properties, i.e., higher occupancy and lower Kondo temperature T_K. The impurity thermodynamic properties show that the local moment fixed point is also strongly affected by the existence of the bound state. When e_d is close to the singularity, the local moment fixed point becomes impervious to charge fluctuations (caused by bringing e_d close to the Fermi energy), in contrast to the local moment suppression that occurs when e_d is away from the singularity. We also discuss an experimental implementation that shows similar results to the quantum wire, if the impurity's metallic host is an armchair graphene nanoribbon.

Non-coplanar helimagnetism in the layered van-der-Waals metal DyTe$_3$. (arXiv:2306.04854v2 [cond-mat.mtrl-sci] UPDATED)
Shun Akatsuka, Sebastian Esser, Shun Okumura, Ryota Yambe, Rinsuke Yamada, Moritz M. Hirschmann, Seno Aji, Jonathan S. White, Shang Gao, Yoshichika Onuki, Taka-hisa Arima, Taro Nakajima, Max Hirschberger

Magnetic materials with highly anisotropic chemical bonding can be exfoliated to realize ultrathin sheets or interfaces with highly controllable optical or spintronics responses, while also promising novel cross-correlation phenomena between electric polarization and the magnetic texture. The vast majority of these van-der-Waals magnets are collinear ferro-, ferri-, or antiferromagnets, with a particular scarcity of lattice-incommensurate helimagnets of defined left- or right-handed rotation sense, or helicity. Here we use polarized neutron scattering to reveal cycloidal, or conical, magnetic structures in DyTe$_3$, with coupled commensurate and incommensurate order parameters, where covalently bonded double-slabs of dysprosium square nets are separated by highly metallic tellurium layers. Based on this ground state and its evolution in a magnetic field as probed by small-angle neutron scattering (SANS), we establish a one-dimensional spin model with off-diagonal on-site terms, spatially modulated by the unconventional charge order in DyTe$_3$. The CDW-driven term couples to antiferromagnetism, or to the net magnetization in applied magnetic field, and creates a complex magnetic phase diagram indicative of competing interactions in an easily cleavable helimagnet. Our work paves the way for twistronics research, where helimagnetic layers can be combined to form complex spin textures on-demand, using the vast family of rare earth chalcogenides and beyond.

The $\mathrm{SO}(5)$ Deconfined Phase Transition under the Fuzzy Sphere Microscope: Approximate Conformal Symmetry, Pseudo-Criticality, and Operator Spectrum. (arXiv:2306.16435v3 [cond-mat.str-el] UPDATED)
Zheng Zhou, Liangdong Hu, W. Zhu, Yin-Chen He

The deconfined quantum critical point (DQCP) is an example of phase transitions beyond the Landau symmetry breaking paradigm that attracts wide interest. However, its nature has not been settled after decades of study. In this paper, we apply the recently proposed fuzzy sphere regularization to study the $\mathrm{SO}(5)$ non-linear sigma model (NL$\sigma$M) with a topological Wess-Zumino-Witten term, which serves as a dual description of the DQCP with an exact $\mathrm{SO}(5)$ symmetry. We demonstrate that the fuzzy sphere functions as a powerful microscope, magnifying and revealing a wealth of crucial information about the DQCP, ultimately paving the way towards its final answer. In particular, through exact diagonalization, we provide clear evidence that the DQCP exhibits approximate conformal symmetry. The evidence includes the existence of a conserved $\mathrm{SO}(5)$ symmetry current, a stress tensor, and integer-spaced levels between conformal primaries and their descendants. Most remarkably, we have identified 23 primaries and 76 conformal descendants. Furthermore, by examining the renormalization group flow of the lowest symmetry singlet as well as other primaries, we provide numerical evidence in favour of DQCP being pseudo-critical, with the approximate conformal symmetry plausibly emerging from nearby complex fixed points. The primary spectrum we compute also has important implications, including the conclusion that the $\mathrm{SO}(5)$ DQCP cannot describe a direct transition from the N\'eel to valence bond solid phase on the honeycomb lattice.

Signature of nodal topology in nonlinear quantum transport across junctions in Weyl and multi-Weyl semimetals. (arXiv:2307.11737v3 [cond-mat.mes-hall] UPDATED)
Suvendu Ghosh, Snehasish Nandy, Jian-Xin Zhu, A. Taraphder

We investigate quantum transport through a rectangular potential barrier in Weyl semimetals (WSMs) and multi-Weyl semimetals (MSMs), within the framework of Landauer-B\"uttiker formalism. Our study uncovers the role of nodal topology imprinted in the electric current and the shot noise. We find that, in contrast to the finite odd-order conductance and noise power, the even-order contributions vanish at the nodes. Additionally, depending on the topological charge ($J$), the linear conductance ($G_1$) scales with the Fermi energy ($E_F$) as $G_1^{E_F>U}\propto E_F^{2/J}$. We demonstrate that the $E_F$-dependence of the second-order conductance and shot noise power could quite remarkably distinguish an MSM from a WSM depending on the band topology, and may induce several smoking gun experiments in nanostructures made out of WSMs and MSMs. Analyzing shot noise and Fano factor, we show that the transport across the rectangular barrier follows the sub-Poissonian statistics. Interestingly, we obtain universal values of Fano factor at the nodes unique to their topological charges. The universality for a fixed $J$, however, indicates that only a fixed number of open channels participate in the transport through evanescent waves at the nodes. The proposed results can serve as a potential diagnostic tool to identify different topological systems in experiments.

Electronic Structure and Vibrational Stability of Copper-substituted Lead Apatite (LK-99). (arXiv:2308.01135v3 [cond-mat.supr-con] UPDATED)
J. Cabezas-Escares, N. F. Barrera, R. H. Lavroff, A. N. Alexandrova, C. Cardenas, F. Munoz

Two recent preprints in the physics archive (arXiv) have called attention as they claim experimental evidence that a Cu-substituted apatite material (dubbed LK-99) exhibits superconductivity at room temperature and pressure. If this proves to be true, LK-99 will be a "holy grail" of superconductors. In this work, we used Density Functional Theory (DFT+U) calculations to elucidate some key features of the electronic structure of LK-99. We find two different phases of this material: (i) a hexagonal lattice featuring metallic half-filled and spin-split bands, an {apparent nesting} of the Fermi surface, a remarkably large electron-phonon coupling, but this lattice is vibrationally unstable. (ii) A triclinic lattice, with the Cu and surrounding O distorted. This lattice is vibrationally stable and its bands correspond to an insulator. In a crystal, the Cu atoms should oscillate between equivalent triclinic positions, with an average close to the hexagonal positions. We discuss the electronic structure expected from these fluctuations and if it is compatible with superconductivity.

Optimization Algorithms for Multi-Species Spherical Spin Glasses. (arXiv:2308.09672v3 [math.PR] UPDATED)
Brice Huang, Mark Sellke

This paper develops approximate message passing algorithms to optimize multi-species spherical spin glasses. We first show how to efficiently achieve the algorithmic threshold energy identified in our companion work, thus confirming that the Lipschitz hardness result proved therein is tight. Next we give two generalized algorithms which produce multiple outputs and show all of them are approximate critical points. Namely, in an $r$-species model we construct $2^r$ approximate critical points when the external field is stronger than a "topological trivialization" phase boundary, and exponentially many such points in the complementary regime. We also compute the local behavior of the Hamiltonian around each. These extensions are relevant for another companion work on topological trivialization of the landscape.

Second-order topological superconductor via noncollinear magnetic texture. (arXiv:2308.12703v2 [cond-mat.mes-hall] UPDATED)
Pritam Chatterjee, Arnob Kumar Ghosh, Ashis K. Nandy, Arijit Saha

We put forth a theoretical framework for engineering a two-dimensional (2D) second-order topological superconductor (SOTSC) by utilizing a heterostructure: incorporating noncollinear magnetic textures between an $s$-wave superconductor and a 2D quantum spin Hall insulator. It stabilizes the higher order topological superconducting phase, resulting in Majorana corner modes (MCMs) at four corners of a 2D domain. The calculated non-zero quadrupole moment characterizes the bulk topology. Subsequently, through a unitary transformation, an effective low-energy Hamiltonian reveals the effects of magnetic textures, resulting in an effective in-plane Zeeman field and spin-orbit coupling. This approach provides a qualitative depiction of the topological phase, substantiated by numerical validation within exact real-space model. Analytically calculated effective pairings in the bulk illuminate the microscopic behavior of the SOTSC. The comprehension of MCM emergence is supported by a low-energy edge theory, which is attributed to the interplay between effective pairings of $(p_x + p_y)$-type and $(p_x + i p_y)$-type. Our extensive study paves the way for practically attaining the SOTSC phase by integrating noncollinear magnetic textures.

Energetics of twisted elastic filament pairs. (arXiv:2309.11344v2 [cond-mat.soft] UPDATED)
Julien Chopin, Animesh Biswas, Arshad Kudrolli

We investigate the elastic energy stored in a filament pair as a function of applied twist by measuring torque under prescribed end-to-end separation conditions. We show that the torque increases rapidly to a peak with applied twist when the filaments are initially separate, then decreases to a minimum as the filaments cross and come into contact. The torque then increases again while the filaments form a double helix with increasing twist. A nonlinear elasto-geometric model that combines the effect of geometrical nonlinearities with large stretching and self-twist is shown to capture the evolution of the helical geometry, the torque profile, and the stored energy with twist. We find that a large fraction of the total energy is stored in stretching the filaments, which increases with separation distance and applied tension. We find that only a small fraction of energy is stored in the form of bending energy, and that the contribution due to contact energy is negligible. Our study highlights the consequences of stretchablility on filament twisting which is a fundamental topological transformation relevant to making ropes, tying shoelaces, actuating robots, and the physical properties of entangled polymers.

Matter-wave collimation to picokelvin energies with scattering length and potential shape control. (arXiv:2310.04383v2 [physics.atom-ph] UPDATED)
Alexander Herbst, Timothé Estrampes, Henning Albers, Robin Corgier, Knut Stolzenberg, Sebastian Bode, Eric Charron, Ernst M. Rasel, Naceur Gaaloul, Dennis Schlippert

We study the impact of atomic interactions on an in-situ collimation method for matter-waves. Building upon an earlier study with $^{87}$Rb, we apply a lensing protocol to $^{39}$K where the atomic scattering length can be tailored by means of magnetic Feshbach resonances. Minimizing interactions, we show an enhancement of the collimation compared to the strong interaction regime observing a one-dimensional expansion corresponding to (340 $\pm$ 12) pK in our experiment. Our results are supported by an accurate simulation, describing the ensemble dynamics, which allows us to extrapolate a 2D ballistic expansion energy of (438 $\pm$ 77) pK from our measurements. We further use the simulation to study the behavior of various trap configurations for different interaction strengths. Based on our findings we propose an advanced scenario which allows for 3D expansion energies below 16 pK by implementing an additional pulsed delta-kick collimation directly after release from the trapping potential. Our results pave the way to realize ensembles with hundreds of thousands of particles and 3D expansion energies in the two-digit pK range in typical dipole trap setups required to perform ultra-precise measurements without the need of complex micro-gravity or long-baseline environments.

Active Solids Model: Rigid Body Motion and Shape-changing Mechanisms. (arXiv:2310.12879v2 [cond-mat.soft] UPDATED)
Claudio Hernández-López (1 and 4), Paul Baconnier (2), Corentin Coulais (3), Olivier Dauchot (2), Gustavo Düring (4) ((1) École Normale Supérieure Paris, (2) Gulliver ESPCI Paris, (3) Institute of Physics Universiteit van Amsterdam, (4) Instituto de Física Pontificia Universidad Católica de Chile)

Active solids such as cell collectives, colloidal clusters, and active metamaterials exhibit diverse collective phenomena, ranging from rigid body motion to shape-changing mechanisms. The nonlinear dynamics of such active materials remains however poorly understood when they host zero-energy deformation modes and when noise is present. Here, we show that stress propagation in a model of active solids induces the spontaneous actuation of multiple soft floppy modes, even without exciting vibrational modes. By introducing an adiabatic approximation, we map the dynamics onto an effective Landau free energy, predicting mode selection and the onset of collective dynamics. These results open new ways to study and design living and robotic materials with multiple modes of locomotion and shape-change.

Trions in two-dimensional monolayers within the hyperspherical harmonics method. Application to transition metal dichalcogenides. (arXiv:2310.19196v2 [cond-mat.mes-hall] UPDATED)
Roman Ya. Kezerashvili, Shalva M.Tsiklauri, Andrew Dublin

We develop the theoretical formalism and study the formation of valley trions in transition metal dichalcogenide (TMDC) monolayers within the framework of a nonrelativistic potential model using the method of hyperspherical harmonics (HH) in four-dimensional space. We present the solution of the three-body Schr\"{o}dinger equation with the Rytova-Keldysh (RK) potential by expanding the wave function of a trion in terms of the HH. The antisymmetrization of trions wave function is based on the electron and hole spin and valley indices.

We consider a long-range approximation when the RK potential is approximated by the Coulomb potential and a short-range limit when this potential is approximated by the logarithmic potential. In a diagonal approximation, the coupled system of differential equations for the hyperradial functions is decoupled in both limits. Our approach yields the analytical solution for binding energy and wave function of trions in the diagonal approximation for these two limiting cases: the Coulomb and logarithmic potentials. We obtain exact analytical expressions for eigenvalues and eigenfunctions for negatively and positively charged trions. The corresponding energy eigenvalues can be considered as the lower and upper limits for the trions binding energies.

The proposed theoretical approach can describe trions in TMDCs and address the energy difference between the binding energies of $X^{-}$ and $X^{+}$ in TMDC. Results of numerical calculations for the ground state energies with the RK potential are in good agreement with similar calculations and in reasonable agreement with experimental measurements of trion binding energies.

Temperature upper bound of an ideal gas. (arXiv:2311.06994v3 [cond-mat.stat-mech] UPDATED)
Hyeong-Chan Kim

We study thermodynamics of a heat-conducting ideal gas system, incorporating a model that has a temperature upper bound. We construct the model based on i) the first law of thermodynamics from action formulation which shows heat-dependence of energy density and ii) the existence condition of a (local) Lorentz boost between an Eckart observer and a Landau-Lifschitz observer--a condition that extends the stability criterion of thermal equilibrium. The implications of these conditions include: i) Heat contributes to the energy density through the combination $q/n\Theta^2$ where $q$, $n$, and $\Theta$ represent heat, the number density, and the temperature, respectively. ii) The energy density has a unique minimum at $q=0$. iii) The temperature upper bound suppresses the heat dependence of the energy density inverse quadratically. This result explains why the expected heat dependence of energy density is difficult to observe in ordinary situation thermodynamics.

Solid-that-flows picture of glass-forming liquids. (arXiv:2311.14460v4 [cond-mat.soft] UPDATED)
Jeppe C. Dyre

This perspective article reviews arguments that glass-forming liquids are different from those of standard liquid-state theory, which typically have a viscosity in the mPa$\cdot$s range and relaxation times of order picoseconds. These numbers grow dramatically and become $10^{12}-10^{15}$ times larger for liquids cooled toward the glass transition. This translates into a qualitative difference, and below the ``solidity length'' which is of order one micron at the glass transition, a glass-forming liquid behaves much like a solid. Recent numerical evidence for the solidity of ultraviscous liquids is reviewed, and experimental consequences are discussed in relation to dynamic heterogeneity, frequency-dependent linear-response functions, and the temperature dependence of the average relaxation time.

Pairwise annihilation of Weyl nodes induced by magnetic fields in the Hofstadter regime. (arXiv:2312.02463v2 [cond-mat.mes-hall] UPDATED)
Faruk Abdulla

Weyl semimetal, which does not require any symmetry except translation for protection, is a robust gapless state of quantum matters in three dimensions. When translation symmetry is preserved, the only way to destroy a Weyl semimetal state is to bring two Weyl nodes of opposite chirality close to each other to annihilate pairwise. An external magnetic field can destroy a pair of Weyl nodes (which are separated by a momentum space distance $2k_0$) of opposite chirality, when the magnetic length $l_B$ becomes close to or smaller than the inverse separation $1/2k_0$. In this work, we investigate pairwise annihilation of Weyl nodes induced by external magnetic field which ranges all the way from small to a very large value in the Hofstadter regime $l_B \sim a$. We show that this pairwise annihilation in a WSM featuring two Weyl nodes leads to the emergence of either a normal insulator or a layered Chern insulator. In the case of a Weyl semimetal with multiple Weyl nodes, the potential for generating a variety of states through external magnetic fields emerges. Our study introduces a straightforward and intuitive representation of the pairwise annihilation process induced by magnetic fields, enabling accurate predictions of the phases that may appear after pairwise annihilation of Weyl nodes.

Accelerated adiabatic passage of a single electron spin qubit in quantum dots. (arXiv:2312.13135v2 [cond-mat.mes-hall] UPDATED)
Xiao-Fei Liu, Yuta Matsumoto, Takafumi Fujita, Arne Ludwig, Andreas D. Wieck, Akira Oiwa

Adiabatic processes can keep the quantum system in its instantaneous eigenstate, which is robust to noises and dissipation. However, it is limited by sufficiently slow evolution. Here, we experimentally demonstrate the transitionless quantum driving (TLQD) of the shortcuts to adiabaticity in gate-defined semiconductor quantum dots (QDs) to greatly accelerate the conventional adiabatic passage for the first time. For a given efficiency of quantum state transfer, the acceleration can be more than twofold. The dynamic properties also prove that the TLQD can guarantee fast and high-fidelity quantum state transfer. In order to compensate for the diabatic errors caused by dephasing noises, the modified TLQD is proposed and demonstrated in experiment by enlarging the width of the counter-diabatic drivings. The benchmarking shows that the state transfer fidelity of 97.8% can be achieved. This work will greatly promote researches and applications about quantum simulations and adiabatic quantum computation based on the gate-defined QDs.

Dipole coupling of a bilayer graphene quantum dot to a high-impedance microwave resonator. (arXiv:2312.14629v2 [cond-mat.mes-hall] UPDATED)
Max J. Ruckriegel, Lisa M. Gächter, David Kealhofer, Mohsen Bahrami Panah, Chuyao Tong, Christoph Adam, Michele Masseroni, Hadrien Duprez, Rebekka Garreis, Kenji Watanabe, Takashi Taniguchi, Andreas Wallraff, Thomas Ihn, Klaus Ensslin, Wei Wister Huang

We implement circuit quantum electrodynamics (cQED) with quantum dots in bilayer graphene, a maturing material platform for semiconductor qubits that can host long-lived spin and valley states. The presented device combines a high-impedance ($Z_\mathrm{r} \approx 1 \mathrm{k{\Omega}}$) superconducting microwave resonator with a double quantum dot electrostatically defined in a graphene-based van der Waals heterostructure. Electric dipole coupling between the subsystems allows the resonator to sense the electric susceptibility of the double quantum dot from which we reconstruct its charge stability diagram. We achieve sensitive and fast detection with a signal-to-noise ratio of 3.5 within 1 ${\mu}\mathrm{s}$ integration time. The charge-photon interaction is quantified in the dispersive and resonant regimes by comparing the coupling-induced change in the resonator response to input-output theory, yielding a maximal coupling strength of $g/2{\pi} = 49.7 \mathrm{MHz}$. Our results introduce cQED as a probe for quantum dots in van der Waals materials and indicate a path toward coherent charge-photon coupling with bilayer graphene quantum dots.

Higher-Order Cellular Automata Generated Symmetry-Protected Topological Phases and Detection Through Multi-Point Strange Correlators. (arXiv:2401.00505v2 [cond-mat.str-el] UPDATED)
Jie-Yu Zhang, Meng-Yuan Li, Peng Ye

In computer and system sciences, higher-order cellular automata (HOCA) are a type of cellular automata that evolve over multiple time steps and generate complex patterns, which have various applications such as secret sharing schemes, data compression, and image encryption. In this paper, we introduce HOCA to quantum many-body physics and construct a series of symmetry-protected topological (SPT) phases of matter, in which symmetries are supported on a great variety of subsystems embbeded in the SPT bulk. We call these phases HOCA-generated SPT (HGSPT) phases. Specifically, we show that HOCA can generate not only well-understood SPTs with symmetries supported on either regular (e.g., line-like subsystems in the 2D cluster model) or fractal subsystems, but also a large class of unexplored SPTs with symmetries supported on more choices of subsystems. One example is mixed-subsystem SPT that has either fractal and line-like subsystem symmetries simultaneously or two distinct types of fractal symmetries simultaneously. Another example is chaotic SPT in which chaotic-looking symmetries are significantly different from and thus cannot reduce to fractal or regular subsystem symmetries. We also introduce a new notation system to characterize HGSPTs. As the usual two-point strange correlators are trivial in most HGSPTs, we find that the nontrivial SPT orders can be detected by what we call multi-point strange correlators. We propose a universal procedure to design the spatial configuration of the multi-point strange correlators for a given HGSPT phase. Our HOCA programs and multi-point strange correlators pave the way for a unified paradigm to design, classify, and detect phases of matter with symmetries supported on a great variety of subsystems, and also provide potential useful perspective in surpassing the computational irreducibility of HOCA in a quantum mechanical way.

Spectral signatures of non-trivial topology in a superconducting circuit. (arXiv:2401.10876v2 [cond-mat.mes-hall] UPDATED)
L. Peyruchat (1 and 2), R. H. Rodriguez (1 and 2), J.-L. Smirr (2), R. Leone (3), Ç. Ö. Girit (1 and 2) ((1) Quantronics Group, Université Paris Saclay, CEA, CNRS, SPEC, (2) JEIP, USR 3573 CNRS, Collège de France, PSL University, (3) Laboratoire de Physique et Chimie Théoriques, Université de Lorraine, CNRS)

Topology, like symmetry, is a fundamental concept in understanding general properties of physical systems. In condensed matter systems, non-trivial topology may manifest itself as singular features in the energy spectrum or the quantization of observable quantities such as electrical conductance and magnetic flux. Using microwave spectroscopy, we show that a superconducting circuit with three Josephson tunnel junctions in parallel can possess energy degeneracies indicative of $\textrm{\emph{intrinsic}}$ non-trivial topology. We identify three topological invariants, one of which is related to a hidden quantum mechanical supersymmetry. Depending on fabrication parameters, devices are gapless or not, and fall on a simple phase diagram which is shown to be robust to perturbations including junction imperfections, asymmetry, and inductance. Josephson tunnel junction circuits, which are readily fabricated with conventional microlithography techniques, allow access to a wide range of topological systems which have no condensed matter analog. Notable spectral features of these circuits, such as degeneracies and flat bands, may be leveraged for quantum information applications, whereas quantized transport properties could be useful for metrology applications.

Hybridized magnonic materials for THz frequency applications. (arXiv:2401.11010v2 [cond-mat.mtrl-sci] UPDATED)
D.-Q. To, A. Rai, J. M. O. Zide, S. Law, J. Q. Xiao, M. B. Jungfleisch, M. F. Doty

The capability of magnons to hybridize and strongly couple with diverse excitations offers a promising avenue for realizing and controlling emergent properties that hold significant potential for applications in devices, circuits, and information processing. In this letter, we present recent theoretical and experimental developments in magnon-based hybrid systems, focusing on the combination of magnon excitation in an antiferromagnet with other excitations, namely plasmons in a topological insulator, phonons in a 2D AFM, and photons. The existence of THz frequency magnons, plasmons, and phonons makes magnon-based hybrid systems particularly appealing for high-operating-speed devices. In this context, we explore several directions to advance magnon hybrid systems, including strong coupling between a surface plasmon and magnon polariton in a TI/AFM bilayer, a giant spin Nernst effect induced by magnon phonon coupling in 2D AFMs, and control of magnon-photon coupling using spin torque.

Universal collective Larmor-Silin mode emerging in magnetized correlated Dirac fermions. (arXiv:2401.14358v2 [cond-mat.str-el] UPDATED)
Chuang Chen, Yuan Da Liao, Chengkang Zhou, Gaopei Pan, Zi Yang Meng, Yang Qi

Employing large-scale quantum Monte Carlo simulations, we find in magnetized interacting Dirac fermion model, there emerges a new and universal collective Larmor-Silin spin wave mode in the transverse dynamical spin susceptibility. Such mode purely originates from the interaction among Dirac fermions and distinguishes itself from the usual particle-hole continuum with finite lifetime and clear dispersion, both at small and large momenta in a large portion of the Brillouin zone. Our unbiased numerical results offer the dynamic signature of this new collective excitations in interacting Dirac fermion systems, and provide experimental guidance for inelastic neutron scattering, electron spin resonance and other spectroscopic approaches in the investigation of such universal collective modes in quantum Moire materials, topological insulators and quantum spin liquid materials under magnetic field, with quintessential interaction nature beyond the commonly assumed noninteracting Dirac fermion or spinon approximations.

Found 12 papers in prb
Date of feed: Tue, 30 Jan 2024 04:17:04 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Qubit dynamics beyond Lindblad: Non-Markovianity versus rotating wave approximation
Kiyoto Nakamura and Joachim Ankerhold
Author(s): Kiyoto Nakamura and Joachim Ankerhold

With increasing performance of actual qubit devices, even subtle effects in the interaction between qubits and environmental degrees of freedom become progressively relevant and experimentally visible. This applies particularly to the timescale separations that are at the basis of the most commonly …

[Phys. Rev. B 109, 014315] Published Mon Jan 29, 2024

Intrinsic origin and enhancement of topological responses in ferrimagnetic antiperovskite ${\mathrm{Mn}}_{4}\mathrm{N}$
Temuujin Bayaraa, Vsevolod Ivanov, Liang Z. Tan, and Sinéad M. Griffin
Author(s): Temuujin Bayaraa, Vsevolod Ivanov, Liang Z. Tan, and Sinéad M. Griffin

Using first-principles calculations we investigate the intrinsic origins of the anomalous Hall effect (AHE) and the anomalous Nernst effect (ANE) in antiperovskite ferrimagnet ${\mathrm{Mn}}_{4}\mathrm{N}$. We predict that the AHE is significantly enhanced under both compressive and tensile strain; …

[Phys. Rev. B 109, 014430] Published Mon Jan 29, 2024

Noncollinear $2\mathrm{k}$ antiferromagnetism in the Zintl semiconductor ${\mathrm{Eu}}_{5}{\mathrm{In}}_{2}{\mathrm{Sb}}_{6}$
Vincent C. Morano, Jonathan Gaudet, Nicodemos Varnava, Tanya Berry, Thomas Halloran, Chris J. Lygouras, Xiaoping Wang, Christina M. Hoffman, Guangyong Xu, Jeffrey W. Lynn, Tyrel M. McQueen, David Vanderbilt, and Collin L. Broholm
Author(s): Vincent C. Morano, Jonathan Gaudet, Nicodemos Varnava, Tanya Berry, Thomas Halloran, Chris J. Lygouras, Xiaoping Wang, Christina M. Hoffman, Guangyong Xu, Jeffrey W. Lynn, Tyrel M. McQueen, David Vanderbilt, and Collin L. Broholm

${\mathrm{Eu}}_{5}{\mathrm{In}}_{2}{\mathrm{Sb}}_{6}$ is an orthorhombic nonsymmorphic small band gap semiconductor with three distinct ${\mathrm{Eu}}^{2+}$ sites and two low-temperature magnetic phase transitions. The material displays one of the greatest (negative) magnetoresistances of known stoi…

[Phys. Rev. B 109, 014432] Published Mon Jan 29, 2024

Microscopic origin of the spin-reorientation transition in the kagome topological magnet ${\mathrm{TbMn}}_{6}{\mathrm{Sn}}_{6}$
Zhentao Huang, Wei Wang, Huiqing Ye, Song Bao, Yanyan Shangguan, Junbo Liao, Saizheng Cao, Ryoichi Kajimoto, Kazuhiko Ikeuchi, Guochu Deng, Michael Smidman, Yu Song, Shun-Li Yu, Jian-Xin Li, and Jinsheng Wen
Author(s): Zhentao Huang, Wei Wang, Huiqing Ye, Song Bao, Yanyan Shangguan, Junbo Liao, Saizheng Cao, Ryoichi Kajimoto, Kazuhiko Ikeuchi, Guochu Deng, Michael Smidman, Yu Song, Shun-Li Yu, Jian-Xin Li, and Jinsheng Wen

${\mathrm{TbMn}}_{6}{\mathrm{Sn}}_{6}$ is a correlated topological magnet with a Mn-based kagome lattice, in which a Chern gap opens at the Dirac point at low temperatures. The magnetic moment direction of the ferrimagnetic order changes from in the kagome plane to out-of-plane upon cooling, which i…

[Phys. Rev. B 109, 014434] Published Mon Jan 29, 2024

Characterization of zero-energy corner states in higher-order topological systems with chiral symmetry
Wen-Jie Yang, Shi-Feng Li, Xin-Ye Zou, and Jian-Chun Cheng
Author(s): Wen-Jie Yang, Shi-Feng Li, Xin-Ye Zou, and Jian-Chun Cheng

Corner-localized states represent intriguing aspects of higher-order topological systems. Despite their importance, the topological invariant that distinguishes between zero-energy and non-zero-energy corner states has received limited attention in the literature. Therefore, we introduce “modified m…

[Phys. Rev. B 109, 024114] Published Mon Jan 29, 2024

Electron irradiation reveals robust fully gapped superconductivity in ${\mathrm{LaNiGa}}_{2}$
S. Ghimire, K. R. Joshi, E. H. Krenkel, M. A. Tanatar, Yunshu Shi, M. Kończykowski, R. Grasset, V. Taufour, P. P. Orth, M. S. Scheurer, and R. Prozorov
Author(s): S. Ghimire, K. R. Joshi, E. H. Krenkel, M. A. Tanatar, Yunshu Shi, M. Kończykowski, R. Grasset, V. Taufour, P. P. Orth, M. S. Scheurer, and R. Prozorov

The effects of 2.5-MeV electron irradiation were studied in the superconducting phase of single crystals of ${\mathrm{LaNiGa}}_{2}$, using measurements of electrical transport and radio-frequency magnetic susceptibility. The London penetration depth is found to vary exponentially with temperature, s…

[Phys. Rev. B 109, 024515] Published Mon Jan 29, 2024

Creation and annihilation of reflection shift vortices on the interface between multifold Weyl semimetals
Qiao He, Rui-Qiang Wang, Ming-Xun Deng, and Mou Yang
Author(s): Qiao He, Rui-Qiang Wang, Ming-Xun Deng, and Mou Yang

When an electron beam hits an interface at a point, the reflection beam comes back from another interface point and a reflection shift occurs in real space. We investigate the reflection shift evolution and Fermi arcs on the interface between two Multifold Weyl semimetals by changing the system para…

[Phys. Rev. B 109, 035434] Published Mon Jan 29, 2024

Continuum contact model for friction between graphene sheets that accounts for surface anisotropy and curvature
Aningi Mokhalingam, Shakti S. Gupta, and Roger A. Sauer
Author(s): Aningi Mokhalingam, Shakti S. Gupta, and Roger A. Sauer

Understanding the interaction mechanics between graphene layers and coaxial carbon nanotubes (CNTs) is essential for modeling graphene and CNT-based nanoelectromechanical systems. This work proposes a new continuum contact model to study interlayer interactions between curved graphene sheets. The co…

[Phys. Rev. B 109, 035435] Published Mon Jan 29, 2024

Fractional Chern insulators versus nonmagnetic states in twisted bilayer ${\mathrm{MoTe}}_{2}$
Jiabin Yu, Jonah Herzog-Arbeitman, Minxuan Wang, Oskar Vafek, B. Andrei Bernevig, and Nicolas Regnault
Author(s): Jiabin Yu, Jonah Herzog-Arbeitman, Minxuan Wang, Oskar Vafek, B. Andrei Bernevig, and Nicolas Regnault

Fractionally filled Chern bands with strong interactions may give rise to fractional Chern insulator (FCI) states, the zero-field analog of the fractional quantum Hall effect. Recent experiments have demonstrated the existence of FCIs in twisted bilayer ${\mathrm{MoTe}}_{2}$ without external magneti…

[Phys. Rev. B 109, 045147] Published Mon Jan 29, 2024

Origin of the extreme and anisotropic magnetoresistance in the Weyl semimetal NbP
F. Balduini, A. Molinari, L. Rocchino, V. Hasse, C. Felser, C. Zota, H. Schmid, and B. Gotsmann
Author(s): F. Balduini, A. Molinari, L. Rocchino, V. Hasse, C. Felser, C. Zota, H. Schmid, and B. Gotsmann

The fascination with semimetals, especially Dirac and Weyl semimetals, is given by their surprisingly strong response to magnetic fields. In particular, the extremely large magnetoresistance (XMR), i.e., the change in electrical resistivity as a function of the applied magnetic field, has attracted …

[Phys. Rev. B 109, 045148] Published Mon Jan 29, 2024

Effect of electron-phonon scattering on the electronic transport of Weyl semimetal ${\mathrm{WP}}_{2}$
Kai-Cheng Zhang, Chen Shen, Hong-Bin Zhang, Yong-Feng Li, and Yong Liu
Author(s): Kai-Cheng Zhang, Chen Shen, Hong-Bin Zhang, Yong-Feng Li, and Yong Liu

Although the topological properties of type-II Weyl semimetal ${\mathrm{WP}}_{2}$ have been widely studied by both the experiments and the theoretical calculations, the dominant electron-phonon scattering and the effect of Fermi pockets on the electronic transport still remain elusive. In this work,…

[Phys. Rev. B 109, 045149] Published Mon Jan 29, 2024

Ultrafast all-electrical universal nanoqubits
David T. S. Perkins and Aires Ferreira
Author(s): David T. S. Perkins and Aires Ferreira

We propose how to create, control, and read out real-space localized spin qubits in proximitized finite graphene nanoribbon (GNR) systems using purely electrical methods. Our proposed nanoqubits are formed of in-gap singlet-triplet states that emerge through the interplay of Coulomb and relativistic…

[Phys. Rev. B 109, L041411] Published Mon Jan 29, 2024

Found 2 papers in prl
Date of feed: Tue, 30 Jan 2024 04:17:01 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Visualization of Alternating Triangular Domains of Charge Density Waves in $2H\text{−}{\mathrm{NbSe}}_{2}$ by Scanning Tunneling Microscopy
Shunsuke Yoshizawa, Keisuke Sagisaka, and Hideaki Sakata
Author(s): Shunsuke Yoshizawa, Keisuke Sagisaka, and Hideaki Sakata

The charge density wave (CDW) state of $2H\text{−}{\mathrm{NbSe}}_{2}$ features commensurate domains separated by domain boundaries accompanied by phase slips known as discommensurations. We have unambiguously visualized the structure of CDW domains using a displacement-field measurement algorithm o…

[Phys. Rev. Lett. 132, 056401] Published Mon Jan 29, 2024

Interaction-Induced ac Stark Shift of Exciton-Polaron Resonances
T. Uto, B. Evrard, K. Watanabe, T. Taniguchi, M. Kroner, and A. İmamoğlu
Author(s): T. Uto, B. Evrard, K. Watanabe, T. Taniguchi, M. Kroner, and A. İmamoğlu

Laser-induced shift of atomic states due to the ac Stark effect has played a central role in cold-atom physics and facilitated their emergence as analog quantum simulators. Here, we explore this phenomenon in an atomically thin layer of semiconductor ${\mathrm{MoSe}}_{2}$, which we embedded in a het…

[Phys. Rev. Lett. 132, 056901] Published Mon Jan 29, 2024

Found 2 papers in acs-nano
Date of feed: Mon, 29 Jan 2024 14:03:52 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

[ASAP] Graphene Magnetoresistance Control by Photoferroelectric Substrate
Krishna Maity, Jean-François Dayen, Bernard Doudin, Roman Gumeniuk, and Bohdan Kundys

TOC Graphic

ACS Nano
DOI: 10.1021/acsnano.3c07277

[ASAP] Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide
Hyun Jeong, Komla Nomenyo, Hye Min Oh, Agnieszka Gwiazda, Seok Joon Yun, Clotaire Chevalier César, Rafael Salas-Montiel, Sibiri Wourè-Nadiri Bayor, Mun Seok Jeong, Young Hee Lee, and Gilles Lérondel

TOC Graphic

ACS Nano
DOI: 10.1021/acsnano.3c10721

Found 1 papers in nat-comm

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Supercurrent mediated by helical edge modes in bilayer graphene
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