Found 59 papers in cond-mat
Date of feed: Tue, 21 Nov 2023 01:30:00 GMT

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Probing the tunable multi-cone bandstructure in Bernal bilayer graphene. (arXiv:2311.10816v1 [cond-mat.mes-hall])
Anna M. Seiler, Nils Jacobsen, Martin Statz, Noelia Fernandez, Francesca Falorsi, Kenji Watanabe, Takashi Taniguchi, Zhiyu Dong, Leonid S. Levitov, R. Thomas Weitz

Controlling the bandstructure of Dirac materials is of wide interest in current research but has remained an outstanding challenge for systems such as monolayer graphene. In contrast, Bernal bilayer graphene (BLG) offers a highly flexible platform for tuning the bandstructure, featuring two distinct regimes. In one regime, which is well established and widely used, a tunable bandgap is induced by a large enough transverse displacement field. Another is a gapless metallic band occurring near charge neutrality and at not too strong fields, featuring rich 'fine structure' consisting of four linearly-dispersing Dirac cones with opposite chiralities in each valley and van Hove singularities. Even though BLG was extensively studied experimentally in the last two decades, the evidence of this exotic bandstructure is still elusive, likely due to insufficient energy resolution. Here, rather than probing the bandstructure by direct spectroscopy, we use Landau levels as markers of the energy dispersion and carefully analyze the Landau level spectrum in a regime where the cyclotron orbits of electrons or holes in momentum space are small enough to resolve the distinct mini Dirac cones. We identify the presence of four distinct Dirac cones and map out complex topological transitions induced by electric displacement field. These findings introduce a valuable addition to the toolkit for graphene electronics.


Fractional Hall physics from large $N$ interacting fermions. (arXiv:2311.10818v1 [hep-th])
Kristan Jensen, Amir Raz

We solve models of $N$ species of fermions in the lowest Landau level with $U(N)$-invariant interactions in the $N\gg 1$ limit. We find saddles of the second quantized path integral at fixed chemical potential corresponding to fractional Hall states with filling $ \frac{p}{q}$ where the integers $p$ and $q$ depend on the chemical potential and interactions. On a long torus there are $q$ such states related by translation symmetry, and $SU(N)$-invariant excitations of fractional charge. Remarkably, these saddles and their filling persist as extrema of the second-quantized action at $N=1$. Our construction gives a first-principles derivation of fractional Hall states from strongly interacting fermions.


Scaling laws of failure dynamics on complex networks. (arXiv:2311.10850v1 [cond-mat.dis-nn])
G. Pál, Zs. Danku, A. Batool, V. Kádár, N. Yoshioka, N. Ito, G. Ódor, F. Kun

The topology of the network of load transmitting connections plays an essential role in the cascading failure dynamics of complex systems driven by the redistribution of load after local breakdown events. In particular, as the network structure is gradually tuned from regular to completely random a transition occurs from the localized to mean field behavior of failure spreading. Based on finite size scaling in the fiber bundle model of failure phenomena, here we demonstrate that outside the localized regime, the load bearing capacity and damage tolerance on the macro-scale, and the statistics of clusters of failed nodes on the micro-scale obey scaling laws with exponents which depend on the topology of the load transmission network and on the degree of disorder of the strength of nodes. Most notably, we show that the spatial structure of damage governs the emergence of the localized to mean field transition: as the network gets gradually randomized failed clusters formed on locally regular patches merge through long range links generating a percolation like transition which reduces the load concentration on the network. The results may help to design network structures with an improved robustness against cascading failure.


Wave function propagation in a two-dimensional paramagnetic semiconductor from an impurity. (arXiv:2311.10853v1 [cond-mat.mes-hall])
Josh Wanninger, Gonzalo Ordonez

We simulated modifications to a model of a two-dimensional paramagnetic semiconductor called the half-BHZ model, also known as the QWZ model, and simulated a modified full BHZ model, where a time reversal pair is introduced. Our modifications to the models include adding single and multiple impurities connected to the lattices or as a connection between the time-reversal pairs. We employed the Julia programming language to show how to speed up calculations for time evolutions. By simulating the time evolutions, we could observe the differences in the effects of these modifications. Our simulations showed the presence of scattering behavior associated with the infinite QWZ model topological states. Moreover, we observed scattering and absorption behavior related to the parameters and placements of impurities and Hamiltonian imaginary component's symmetry or anti-symmetry. These tools and early results lay the foundations for developing electronic devices that use the models' unique scattering and absorption behaviors and explore more complex and physically accurate modifications to the models.


Research on solitons interactions' in one-dimensional indium chains on Si(111) surfaces. (arXiv:2311.10860v1 [cond-mat.mtrl-sci])
Yu Yao, Chaojie Luo, Xiuxia Wang, Hui Zhang

Solitons have garnered significant attention across various fields, yet a contentious debate persists regarding the precise structure of solitons on indium chains. Currently, multiple forms of solitons in one-dimensional atomic chains have been reported. STM provides an effective means to study the precise atomic structure of solitons, particularly their dynamics and interactions. However, limited research has been conducted on soliton interactions and soliton-chain interactions, despite their profound impact on relative soliton motions and the overall physical properties of the system. In this work, we characterized the structures of the soliton dimer and trimer, observed the displacements induced by the soliton entity and statisticized the dynamic behaviors of soliton dimers over time evolution or temperature. To reveal the soliton mechanism, we further utilized STM to investigate the CDWs between two solitons when two monomers were encountered. Additionally, we achieved the manipulation of the monomer on the indium chain by the STM tip. Our work serves as an important approach to elucidate interactions in correlated electronic systems and advance the development of potential topological soliton computers.


Graphene-like nanoribbons connected by four-/five- membered rings on pentacene/picene precursors, Au(110) surface. (arXiv:2311.10889v1 [cond-mat.mes-hall])
Yu Yao, Shuangxiang Wu, Hui Zhang

The rapid development of functional graphene-like nanoribbons with high-quality has become increasingly reliant on multiple nanofabrication platforms while traditional methods are facing mounting limitations in this regard. Consequently, the demand for novel techniques to explore and manipulate graphene-like nanoribbons has surged. Herein, we report an on-surface synthesis of graphene-like nanoribbons on pentacene/picene monomers via a series of self-assembly and annealing on the one-dimensional(1D) Au(110) substrate. Our scanning tunneling microscope(STM) research reveals that four-/eight- membered rings are formed between adjacent molecules. Furthermore, we demonstrate the technique to manipulate the pentacene dimer without breaking its structure by operating an STM tip. Our results exhibit a possible platform for developing next generation graphene-based quantum computing designs and a technique to obtain multiple functional graphene-like nanoribbons with high-precision.


Structural and magnetic properties of molecular beam epitaxy (MnSb2Te4)x(Sb2Te3)1-x topological materials with exceedingly high Curie temperature. (arXiv:2311.10891v1 [cond-mat.mtrl-sci])
Candice R. Forrester, Christophe Testelin, Kaushini Wickramasinghe, Ido Levy, Dominique Demaille, David Hrabovski, Xiaxin Ding, Lia Krusin-Elbaum, Gustavo E. Lopez, Maria C. Tamargo

Tuning magnetic properties of magnetic topological materials is of interest to realize elusive physical phenomena such as quantum anomalous hall effect (QAHE) at higher temperatures and design topological spintronic devices. However, current topological materials exhibit Curie temperature (TC) values far below room temperature. In recent years, significant progress has been made to control and optimize TC, particularly through defect engineering of these structures. Most recently we showed evidence of TC values up to 80K for (MnSb2Te4)x(Sb2Te3)1-x, where x is greater than or equal to 0.7 and less than or equal to 0.85, by controlling the compositions and Mn content in these structures. Here we show further enhancement of the TC, as high as 100K, by maintaining high Mn content and reducing the growth rate from 0.9 nm/min to 0.5 nm/min. Derivative curves reveal the presence of two TC components contributing to the overall value and propose TC1 and TC2 have distinct origins: excess Mn in SLs and Mn in Sb2-yMnyTe3QLs alloys, respectively. In pursuit of elucidating the mechanisms promoting higher Curie temperature values in this system, we show evidence of structural disorder where Mn is occupying not only Sb sites but also Te sites, providing evidence of significant excess Mn and a new crystal structure:(Mn1+ySb2-yTe4)x(Sb2-yMnyTe3)1-x. Our work shows progress in understanding how to control magnetic defects to enhance desired magnetic properties and the mechanism promoting these high TC in magnetic topological materials such as (Mn1+ySb2-yTe4)x(Sb2-yMnyTe3)1-x.


Hydrogen Doping Induced $p_x\pm ip_y$ Triplet Superconductivity in Quasi-One-Dimensional K$_2$Cr$_3$As$_3$. (arXiv:2311.10942v1 [cond-mat.supr-con])
Ming Zhang, Chen Lu, Yajiang Chen, Yunbo Zhang, Fan Yang

Quasi-one-dimensional (Q1D) Cr-based pnictide K$_2$Cr$_3$As$_3$ has aroused great research interest due to its possible triplet superconducting pairing symmetry. Recent experiments have shown that incorporating hydrogen atoms into K$_2$Cr$_3$As$_3$ would significantly change its electronic and magnetic properties. Hence, it's necessary to investigate the impact of hydrogen doping in superconducting pairing symmetry of this material. Employing the hydrogen as an non-trivial electron-doping, our calculates show that, different from the $p_z$-wave obtained without hydrogen, the system exhibits $p_x\pm ip_y$ pairing superconductivity under specific hydrogen doping. Specifically, we adopt the random-phase-approximation approach based on a six-band tight-binding model equipped with multi-orbital Hubbard interactions to study the hydrogen-doping dependence of the pairing symmetry and superconducting $T_c$. Under the rigid-band approximation, our pairing phase diagram shows the spin-triplet pairing states is dominated through out the hydrogen-doping regime $x\in (0,0.7)$. Particularly, the $T_c\sim x$ curve shows a peak at the 3D-quasi-1D Lifshitz transition point, and the pairing symmetry around this doping level is $p_x\pm ip_y$. The physical origin of this pairing symmetry is that the density of states is mainly concentrated at $k_x(k_y)$ with large momentum. Due to the three-dimensional character of the real material, this $p_x\pm ip_y$-wave superconducting state possesses point gap nodes. We further provide experiment prediction to identify this triplet $p_x\pm ip_y$-wave superconductivity.


Observation of a Topological Phase Transition in Random Coaxial Cable Structures with Chiral Symmetry. (arXiv:2311.11040v1 [cond-mat.dis-nn])
D. M. Whittaker, Maxine M. McCarthy, Qingqing Duan

We report an experimental study of the disordered Su-Schrieffer-Heeger (SSH) model, implemented in a system of coaxial cables, whose radio frequency properties map on to the SSH Hamiltonian. By measuring multiple chains with random hopping terms, we demonstrate the presence of a topologically protected state, with frequency variation of less than 0.2% over the ensemble. Connecting the ends of the chains to form loops, we observe a topological phase transition, characterised by the closure of the band gap and the appearance of states which are delocalised, despite the strong disorder.


Exotic Symmetry Breaking Properties of Self-Dual Fracton Spin Models. (arXiv:2311.11066v1 [quant-ph])
Giovanni Canossa, Lode Pollet, Miguel A. Martin-Delgado, Hao Song, Ke Liu

Fracton codes host unconventional topological states of matter and are promising for fault-tolerant quantum computation due to their large coding space and strong resilience against decoherence and noise. In this work, we investigate the ground-state properties and phase transitions of two prototypical self-dual fracton spin models -- the tetrahedral Ising model and the fractal Ising model -- which correspond to error-correction procedures for the representative fracton codes of type-I and type-II, the checkerboard code and the Haah's code, respectively, in the error-free limit. They are endowed with exotic symmetry-breaking properties that contrast sharply with the spontaneous breaking of global symmetries and deconfinement transition of gauge theories. To show these unconventional behaviors, which are associated with sub-dimensional symmetries, we construct and analyze the order parameters, correlators, and symmetry generators for both models. Notably, the tetrahedral Ising model acquires an extended semi-local ordering moment, while the fractal Ising model fits into a polynomial ring representation and leads to a fractal order parameter. Numerical studies combined with analytical tools show that both models experience a strong first-order phase transition with an anomalous $L^{-(D-1)}$ scaling, despite the fractal symmetry of the latter. Our work provides new understanding of sub-dimensional symmetry breaking and makes an important step for studying quantum-error-correction properties of the checkerboard and Haah's codes.


Design of spin-orbital-textures in ferromagnetic/topological insulator interfaces. (arXiv:2311.11084v1 [cond-mat.mes-hall])
A. L. Araújo, F. Crasto de Lima, C. H. Lewenkopf, A. Fazzio

Spin-orbital textures in topological insulators due to the spin locking with the electron momentum, play an important role in spintronic phenomena that arise from the interplay between charge and spin degrees of freedom. We have explored interfaces between a ferromagnetic system (CrI$_3$) and a topological insulator (Bi$_2$Se$_3$) that allow the manipulation of spin-orbital textures. Within an {\it ab initio} approach we have extracted the spin-orbital-textures dependence of experimentally achievable interface designs. The presence of the ferromagnetic system introduces anisotropic transport of the electronic spin and charge. From a parameterized Hamiltonian model we capture the anisotropic backscattering behavior, showing its extension to other ferromagnetic/topological insulator interfaces. We verified that the van der Waals TI/MI interface is an excellent platform for controlling the spin degree of freedom arising from topological states, providing a rich family of unconventional spin texture configurations.


Quantum defects in 2D transition metal dichalcogenides for THz-technologies. (arXiv:2311.11092v1 [cond-mat.mtrl-sci])
Jingda Zhang, Su Ying Quek

Terahertz technologies are important for a number of emerging applications, such as for next generation communications. We predict that transition metal substitutional defects in two-dimensional transition metal dichalcogenides (TMDs) can serve as quantum defects for terahertz technologies. Central to this prediction is the finding that the zero field splittings between spin sublevels in such defects are typically in the sub-terahertz to terahertz range due to the large spin-orbit coupling in these systems. As a proof of concept, we consider different transition metal impurities from across the periodic table, in prototypical TMDs, MoS2 and WSe2. Using first principles calculations, we demonstrate that selected spin triplet defects can potentially serve as qubits operating in the terahertz regime. We also propose defects that can potentially be quantum sources of terahertz radiation. Our research broadens the scope of advancements in quantum information science and lays a foundation for their integration with THz technologies.


A hybrid pulsed laser deposition approach to grow thin films of chalcogenides. (arXiv:2311.11146v1 [cond-mat.mtrl-sci])
Mythili Surendran, Shantanu Singh, Huandong Chen, Claire Wu, Amir Avishai, Yu-Tsun Shao, Jayakanth Ravichandran

Vapor-pressure mismatched materials such as transition metal chalcogenides have emerged as electronic, photonic, and quantum materials with scientific and technological importance. However, epitaxial growth of vapor-pressure mismatched materials are challenging due to differences in the reactivity, sticking coefficient, and surface adatom mobility of the mismatched species constituting the material, especially sulfur containing compounds. Here, we report a novel approach to grow chalcogenides - hybrid pulsed laser deposition - wherein an organosulfur precursor is used as a sulfur source in conjunction with pulsed laser deposition to regulate the stoichiometry of the deposited films. Epitaxial or textured thin films of sulfides with variety of structure and chemistry such as alkaline metal chalcogenides, main group chalcogenides, transition metal chalcogenides and chalcogenide perovskites are demonstrated, and structural characterization reveal improvement in thin film crystallinity, and surface and interface roughness compared to the state-of-the-art. The growth method can be broadened to other vapor-pressure mismatched chalcogenides such as selenides and tellurides. Our work opens up opportunities for broader epitaxial growth of chalcogenides, especially sulfide-based thin film technological applications.


Atomistic mechanism of friction force independence on the normal load and other friction laws for dynamic structural superlubricity. (arXiv:2311.11173v1 [physics.comp-ph])
Nikolay V. Brilliantov, Alexey A. Tsukanov, Artem K. Grebenko, Albert G. Nasibulin, Igor A. Ostanin

We explore dynamic structural superlubricity for the case of a relatively large contact area, where the friction force is proportional to the area (exceeding $\sim 100\,nm^2$) experimentally, numerically, and theoretically. We use a setup comprised of two molecular smooth incommensurate surfaces -- graphene-covered tip and substrate. The experiments and MD simulations demonstrate independence of the friction force on the normal load, for a wide range of normal loads and relative surface velocities. We propose an atomistic mechanism of this phenomenon, associated with synchronic out-of-plane surface fluctuations of thermal origin, and confirm it by numerical experiments. Based on this mechanism, we develop a theory for this type of superlubricity and show that friction force increases linearly with increasing temperature and relative velocity, for velocities, larger than a threshold velocity. The MD results are in a fair agreement with predictions of the theory.


Non-Hermitian effect to the ballistic transport and quantized Hall conductivity in an operable experimental platform. (arXiv:2311.11276v1 [cond-mat.mes-hall])
Chen-Huan Wu, Yida Li

By designing a multi-channel millimeter Hall measurement configuration, we realize the carrier-density (locally) controllable measurement on the transport property in 2H MoS$_{2}$. We observe a linearly increased Hall conductivity and exponentially decreased resistivity as the increase of dc current. The intrinsically large band gap does not exhibit too much effect on our measurement, as far as the magnetic field is above the critical value, which is $B=6$ T for 2H-MoS$_{2}$. Instead, the edge effect which emerge as a result of one-dimensional channels. This is different from the Corbino geometry which is widely applied on semiconductors, where the edges are absent. At room temperature, we observe that the emergent quantized quantum Hall plateaus are at the same value for both the two measurements, which implies that the quantized conductivity does not depends on the non-Hermitian interactions, but the number of partially filled Landau levels, and this is in consistent with the previous theoretical works\cite{Siddiki}. At low-temperature limit, the Hall plateaus are destroyed due to the filtered contribution from the electrons above fermi energy, and in this case, the two measuremens exhibits stronger distinction, where we observe stronger fluctuations (of voltage, conductivity, and resistivity) at the currents between where there are Hall plateaus at higher temperature.


Fermi surface topology and electronic transport properties of a chiral crystal NbGe$_2$ with strong electron-phonon interaction. (arXiv:2311.11341v1 [cond-mat.str-el])
Yoshiki J. Sato, Ai Nakamura, Rei Nishinakayama, Ryuji Okazaki, Hisatomo Harima, Dai Aoki

We report the electronic structures and transport properties of a chiral crystal NbGe$_2$, which is a candidate for a coupled electron-phonon liquid. The electrical resistivity and thermoelectric power of NbGe$_2$ exhibit clear differences compared to those of NbSi2 even though both niobium ditetrelides are isostructural and isoelectronic. We discuss the intriguing transport properties of NbGe$_2$ based on a van Hove-type singularity in the density of states. The analysis of de Haas-van Alphen oscillations measured by the field modulation and magnetic torque methods reveals the detailed shape of the Fermi surface of NbGe$_2$ by comparison with the results of energy band structure calculations using a local density approximation. The electron and hole Fermi surfaces of NbGe$_2$ split into two because of the anti-symmetric spin-orbit interaction. The temperature dependence of quantum oscillations indicates that the effective mass is isotropically enhanced in NbGe$_2$ due to strong electron-phonon interaction.


Discovery of Superconductivity and Electron-Phonon Drag in the Non-Centrosymmetric Semimetal LaRhGe$_3$. (arXiv:2311.11402v1 [cond-mat.supr-con])
Mohamed Oudah, Hsiang-Hsi Kung, Samikshya Sahu, Niclas Heinsdorf, Armin Schulz, Kai Philippi, Marta-Villa De Toro Sanchez, Yipeng Cai, Kenji Kojima, Andreas P. Schnyder, Hidenori Takagi, Bernhard Keimer, Doug A. Bonn, Alannah M. Hallas

We present a comprehensive study of the non-centrosymmetric semimetal LaRhGe$_3$. Our transport measurements reveal evidence for electron-hole compensation at low temperatures, resulting in a large magnetoresistance of 3000% at 1.8 K and 14 T. The carrier concentration is on the order of $10^{21}\rm{/cm}^3$, higher than typical semimetals. We predict theoretically the existence of $\textit{almost movable}$ Weyl nodal lines that are protected by the tetragonal space group. We discover superconductivity for the first time in this compound with a $T_{\text c}$ of 0.39(1) K and $B_{\rm{c}}(0)$ of 2.1(1) mT, with evidence from specific heat and transverse-field muon spin relaxation ($\mu \rm{SR}$). LaRhGe$_3$ is a weakly-coupled type-I superconductor, and we find no evidence for time-reversal symmetry breaking in our zero-field $\mu \rm{SR}$. We study the electrical transport in the normal state and find an unusual $\sim T^{3}$ dependence at low temperature while Seebeck coefficient and thermal conductivity measurements reveal a peak in the same temperature range. We conclude that the transport properties of LaRhGe$_3$ in its normal state are strongly influenced by electron-phonon interactions. Furthermore, we examine the temperature dependent Raman spectra of LaRhGe$_3$ and find that the lifetime of the lowest energy $A_1$ phonon is dominated by phonon-electron scattering instead of anharmonic decay.


The fate of high winding number topological phases in the disordered extended Su-Schrieffer-Heeger model. (arXiv:2311.11405v1 [cond-mat.str-el])
Emmanuele G. Cinnirella, Andrea Nava, Gabriele Campagnano, Domenico Giuliano

We use the Lindblad equation approach to investigate topological phases hosting more than one localized state at each side of a disordered SSH chain with properly tuned long range hoppings. Inducing a non equilibrium steady state across the chain, we probe the robustness of each phase and the fate of the edge modes looking at the distribution of electrons along the chain and the corresponding standard deviation in presence of different kinds of disorder either preserving, or not, the symmetries of the Hamiltonian.


Massive spin-flip excitations in a $\nu = 2$ quantum Hall ferromagnet. (arXiv:2311.11418v1 [cond-mat.str-el])
S. Dickmann, P. S. Berezhnoy

Excitation with a massive spin reversal of the individual skyrmion/antiskyrmion type is theoretically studied in a quantum Hall ferromagnet, where the zero and first Landau levels are completely occupied only by electrons with spins aligned strictly in the direction determined by the magnetic field. The Wigner-Seitz parameter is not necessarily considered to be small. The microscopic model in use is based on a reduced basic set of quantum states [the so-called ''single-mode (single-exciton) approximation''], which allows proper account to be taken for mixing of Landau levels, and substantiating the equations of the classical $O(3)$ nonlinear $\sigma$ model. The calculated ''spin stiffness'' determines the exchange gap for creating a pair of skyrmion and antiskyrmion. This gap is significantly smaller than the doubled cyclotron energy and the characteristic electron-electron correlation energy. Besides, the skyrmion--antiskyrmion creation gap is much smaller than the energy of creation of a separated electron--exchange-hole pair calculated in the limit case of a spin magnetoexciton corresponding to an infinitely large 2D momentum. At a certain magnetic field (related to the 2D electron density in the case of fixed filling factor $\nu$), the gap vanishes, which presumably points to a Stoner transition of the quantum Hall ferromagnet to a paramagnetic phase.


Graphene-perovskite fibre photodetectors. (arXiv:2311.11450v1 [physics.app-ph])
S. Akhavan, A. Taheri Najafabadi, S. Mignuzzi, M. Abdi Jalebi, A. Ruocco, I. Paradisanos, O. Balci, Z. Andaji-Garmaroudi, I. Goykhman, L. G. Occhipinti, E. Lidorikis, S. D. Stranks, A. C. Ferrari

The integration of optoelectronic devices, such as transistors and photodetectors (PDs), into wearables and textiles is of great interest for applications such as healthcare and physiological monitoring. These require flexible/wearable systems adaptable to body motions, thus materials conformable to non-planar surfaces, and able to maintain performance under mechanical distortions. Here, we prepare fibre PDs combining rolled graphene layers and photoactive perovskites. Conductive fibres ($\sim$500$\Omega$/cm) are made by rolling single layer graphene (SLG) around silica fibres, followed by deposition of a dielectric layer (Al$_{2}$O$_{3}$ and parylene C), another rolled SLG as channel, and perovskite as photoactive component. The resulting gate-tunable PDs have response time$\sim$5ms, with an external responsivity$\sim$22kA/W at 488nm for 1V bias. The external responsivity is two orders of magnitude higher and the response time one order of magnitude faster than state-of-the-art wearable fibre based PDs. Under bending at 4mm radius, up to$\sim$80\% photocurrent is maintained. Washability tests show$\sim$72\% of initial photocurrent after 30 cycles, promising for wearable applications.


Observation of multiple van Hove singularities and correlated electronic states in a new topological ferromagnetic kagome metal NdTi3Bi4. (arXiv:2311.11488v1 [cond-mat.mtrl-sci])
Mazharul Islam Mondal, Anup Pradhan Sakhya, Milo Sprague, Brenden R. Ortiz, Matthew Matzelle, Barun Ghosh, Nathan Valadez, Iftakhar Bin Elius, Arun Bansil, Madhab Neupane

Kagome materials have attracted enormous research interest recently owing to its diverse topological phases and manifestation of electronic correlation due to its inherent geometric frustration. Here, we report the electronic structure of a new distorted kagome metal NdTi3Bi4 using a combination of angle resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations. We discover the presence of two at bands which are found to originate from the kagome structure formed by Ti atoms with major contribution from Ti dxy and Ti dx2-y2 orbitals. We also observed multiple van Hove singularities (VHSs) in its electronic structure, with one VHS lying near the Fermi level EF. In addition, the presence of a surface Dirac cone at the G point and a linear Dirac-like state at the K point with its Dirac node lying very close to the EF indicates its topological nature. Our findings reveal NdTi3Bi4 as a potential material to understand the interplay of topology, magnetism, and electron correlation.


Electronic interactions in Dirac fluids visualized by nano-terahertz spacetime mapping. (arXiv:2311.11502v1 [cond-mat.str-el])
Suheng Xu, Yutao Li, Rocco A. Vitalone, Ran Jing, Aaron J. Sternbach, Shuai Zhang, Julian Ingham, Milan Delor, James. W. McIver, Matthew Yankowitz, Raquel Queiroz, Andrew J. Millis, Michael M. Fogler, Cory R. Dean, James Hone, Mengkun Liu, D.N. Basov

Ultraclean graphene at charge neutrality hosts a quantum critical Dirac fluid of interacting electrons and holes. Interactions profoundly affect the charge dynamics of graphene, which is encoded in the properties of its collective modes: surface plasmon polaritons (SPPs). The group velocity and lifetime of SPPs have a direct correspondence with the reactive and dissipative parts of the tera-Hertz (THz) conductivity of the Dirac fluid. We succeeded in tracking the propagation of SPPs over sub-micron distances at femto-second (fs) time scales. Our experiments uncovered prominent departures from the predictions of the conventional Fermi-liquid theory. The deviations are particularly strong when the densities of electrons and holes are approximately equal. Our imaging methodology can be used to probe the electromagnetics of quantum materials other than graphene in order to provide fs-scale diagnostics under near-equilibrium conditions.


Absence of metallicity and bias-dependent resistivity in low-carrier-density EuCd2As2. (arXiv:2311.11515v1 [cond-mat.mes-hall])
Yuxiang Wang, Jianwen Ma, Jian Yuan, Wenbin Wu, Yong Zhang, Yicheng Mou, Jiaming Gu, Peihong Cheng, Wu Shi, Xiang Yuan, Jinglei Zhang, Yanfeng Guo, Cheng Zhang

EuCd2As2 was theoretically predicted to be a minimal model of Weyl semimetals with a single pair of Weyl points in the ferromagnet state. However, the heavily p-doped EuCd2As2 crystals in previous experiments prevent direct identification of the semimetal hypothesis. Here we present a comprehensive magneto-transport study of high-quality EuCd2As2 crystals with ultralow bulk carrier density (10^13 cm-3). In contrast to the general expectation of a Weyl semimetal phase, EuCd2As2 shows insulating behavior in both antiferromagnetic and ferromagnetic states as well as surface-dominated conduction from band bending. Moreover, the application of a dc bias current can dramatically modulate the resistance by over one order of magnitude, and induce a periodic resistance oscillation due to the geometric resonance. Such nonlinear transport results from the highly nonequilibrium state induced by electrical field near the band edge. Our results suggest an insulating phase in EuCd2As2 and put a strong constraint on the underlying mechanism of anomalous transport properties in this system.


Magnetic-field-induced nonlinear transport in HfTe5. (arXiv:2311.11517v1 [cond-mat.mes-hall])
Cheng Zhang, Jinshan Yang, Zhongbo Yan, Xiang Yuan, Yanwen Liu, Minhao Zhao, Alexey Suslov, Jinglei Zhang, Li Pi, Zhong Wang, Faxian Xiu

The interplay of electron correlations and topological phases gives rise to various exotic phenomena including fractionalization, excitonic instability, and axionic excitation. Recently-discovered transition-metal pentatellurides can reach the ultra-quantum limit in low magnetic fields and serve as good candidates for achieving such a combination. Here, we report evidences of density wave and metal-insulator transition in HfTe5 induced by intense magnetic fields. Using the nonlinear transport technique, we detect a distinct nonlinear conduction behavior in the longitudinal resistivity within the a-c plane, corresponding to the formation of a density wave induced by magnetic fields. In high fields, the onset of the nonlinear conduction in the Hall resistivity indicates an impurity-pinned magnetic freeze-out as the possible origin of the insulating behavior. These frozen electrons can be gradually re-activated into mobile states above a threshold electric field. These experimental evidences call for further investigations into the underlying mechanism for the bulk quantum Hall effect and field-induced phase transtions in pentatellurides.


Thermal Hall effects due to topological spin fluctuations in YMnO$_3$. (arXiv:2311.11527v1 [cond-mat.str-el])
Ha-Leem Kim, Takuma Saito, Heejun Yang, Hiroaki Ishizuka, Matthew John Coak, Jun Han Lee, Hasung Sim, Yoon Seok Oh, Naoto Nagaosa, Je-Geun Park

The thermal Hall effect in magnetic insulators has been considered a powerful method for examining the topological nature of charge-neutral quasiparticles such as magnons. Yet, unlike the kagome system, the triangular lattice has received less attention for studying the thermal Hall effect because the scalar spin chirality cancels out between adjacent triangles. However, such cancellation cannot be perfect if the triangular lattice is distorted, which could open the possibility of a non-zero thermal Hall effect. Here, we report that the trimerized triangular lattice of multiferroic hexagonal manganite YMnO$_3$ produces a highly unusual thermal Hall effect due to topological spin fluctuations with the additional intricacy of a Dzyaloshinskii-Moriya interaction under an applied magnetic field. We conclude the thermal Hall conductivity arises from the system's topological nature of spin fluctuations. Our theoretical calculations demonstrate that the thermal Hall conductivity is also related in this material to the splitting of the otherwise degenerate two chiralities, left and right, of its 120$^{\circ}$ magnetic structure. Our result is one of the most unusual cases of topological physics due to this broken $Z_2$ symmetry of the chirality in the supposedly paramagnetic state of YMnO$_3$, with strong topological spin fluctuations. These new mechanisms in this important class of materials are crucial in exploring new thermal Hall physics and exotic excitations.


Interference and switching effect of topological interfacial modes with geometric phase. (arXiv:2311.11556v1 [physics.optics])
Xing-Xiang Wang, Tomohiro Amemiya, Xiao Hu

We investigate interference between topological interfacial modes in a semiconductor photonic crystal platform with Dirac frequency dispersions, which can be exploited for interferometry switch. It is showcased that, in a two-in/two-out structure with four topological waveguides, geometric phases of the two-component spinor wavefunctions of topological photonic modes accumulate at turning points of waveguides, which govern the interferences and split the electromagnetic energy into two output ports with relative power ratio tunable by the relative phase of inputs. We unveil that this brand-new photonic phenomenon is intimately related to the spin-momentum locking property of quantum spin Hall effect, and results from the symphonic contributions of three phase variables: the spinor phase and geometric phase upon design, and the global phase controlled from outside. The present findings open the door for manipulating topological interfacial modes, thus exposing a new facet of topological physics. The topology-driven interference can be incorporated into other devices which is expected to leave far-reaching impacts to advanced photonics, optomechanics and phononics applications.


Quantum geometric bound and ideal condition for Euler band topology. (arXiv:2311.11577v1 [cond-mat.mes-hall])
Soonhyun Kwon, Bohm-Jung Yang

Understanding the relationship between quantum geometry and topological invariants is a central problem in the study of topological states. In this work, we establish the relationship between the quantum metric and the Euler curvature in two-dimensional systems with space-time inversion $I_{ST}$ symmetry satisfying $I^2_{ST}=+1$. As $I_{ST}$ symmetry imposes the reality of the wave function with vanishing Berry curvature, the well-known inequality between the quantum metric and the Berry curvature is not meaningful in this class of systems. We find that the non-abelian quantum geometric tensor of two real bands exhibits an intriguing inequality between the off-diagonal Berry curvature and the quantum metric, which in turn gives the inequality between the quantum volume and the Euler invariant. Moreover, we show that the saturation condition of the inequality is deeply related to the ideal condition for Euler bands, which provides a criterion for the stability of fractional topological phases in interacting Euler bands. Our findings demonstrate the potential of the quantum geometry as a powerful tool for characterizing symmetry-protected topological states and their interaction effect.


Getting topological invariants from snapshots: a protocol for defining and calculating topological invariants of systems with discrete parameter space. (arXiv:2311.11618v1 [cond-mat.mes-hall])
Youjiang Xu, Walter Hofstetter

Topological invariants, including the Chern numbers, can topologically classify parameterized Hamiltonians. We find that topological invariants can be properly defined and calculated even if the parameter space is discrete, which is done by geodesic interpolation in the classifying space. We specifically present the interpolation protocol for the Chern numbers, which can be directly generalized to other topological invariants. The protocol generates a highly efficient algorithm for numerical calculation of the second and higher Chern numbers, by which arbitrary precision can be achieved given the values of the parameterized Hamiltonians on a coarse grid with a fixed resolution in the parameter space. Our findings also open up opportunities to study topology in finite-size systems where the parameter space can be naturally discrete.


Antiferromagnetic topological insulator with selectively gapped Dirac cones. (arXiv:2311.11620v1 [cond-mat.mes-hall])
A. Honma, D. Takane, S. Souma, K. Yamauchi, Y. Wang, K. Nakayama, K. Sugawara, M. Kitamura, K. Horiba, H. Kumigashira, K. Tanaka, T. K. Kim, C. Cacho, T. Oguchi, T. Takahashi, Yoichi Ando, T. Sato

Antiferromagnetic (AF) topological materials offer a fertile ground to explore a variety of quantum phenomena such as axion magnetoelectric dynamics and chiral Majorana fermions. To realize such intriguing states, it is essential to establish a direct link between electronic states and topology in the AF phase, whereas this has been challenging because of the lack of a suitable materials platform. Here we report the experimental realization of the AF topological-insulator phase in NdBi. By using micro-focused angle-resolved photoemission spectroscopy, we discovered contrasting surface electronic states for two types of AF domains; the surface having the out-of-plane component in the AF-ordering vector displays Dirac-cone states with a gigantic energy gap, whereas the surface parallel to the AF-ordering vector hosts gapless Dirac states despite the time-reversal-symmetry breaking. The present results establish an essential role of combined symmetry to protect massless Dirac fermions under the presence of AF order and widen opportunities to realize exotic phenomena utilizing AF topological materials.


Nonequilibrium protection effect and spatial localization of noise-induced fluctuations under gas flow scattering on partially penetrable obstacle. (arXiv:2311.11658v1 [cond-mat.stat-mech])
S.P. Lukyanets, O.V. Kliushnichenko

We consider a nonequilibrium transition that leads to the formation of nonlinear steady-state structures due to the gas flow scattering on a partially penetrable obstacle. The resulting nonequilibrium steady state (NESS) corresponds to a two-domain gas structure attained at certain critical parameters. We use a simple mean-field model of the driven lattice gas with ring topology to demonstrate that this transition is accompanied by the emergence of local invariants related to a complex composed of the obstacle and its nearest gas surrounding, which we refer to as obstacle edges. These invariants are independent of the main system parameters and behave as local first integrals, at least qualitatively. As a result, the complex becomes insensitive to the noise of external driving field within the overcritical domain. The emerged invariants describe the conservation of the number of particles inside the obstacle and strong temporal synchronization or correlation of gas states at obstacle edges. Such synchronization guarantees the equality to zero of the total edge current at any time. The robustness against external drive fluctuations is shown to be accompanied by strong spatial localization of induced gas fluctuations near the domain wall separating the depleted and dense gas phases. Such a behavior can be associated with nonequilibrium protection effect and synchronization of edges. The transition rates between different NESSs are shown to be different. The relaxation rates from one NESS to another take complex and real values in the sub- and overcritical regimes, respectively. The mechanism of these transitions is governed by the generation of shock waves at the back side of the obstacle. In the subcritical regime, these solitary waves are generated sequentially many times, while only a single excitation is sufficient to rearrange the system state in the overcritical regime.


Precursors to Topological Phase Transition in Topological Ladders. (arXiv:2311.11673v1 [cond-mat.mes-hall])
Seungju Han, Mahn-Soo Choi

We study the coupling of two topologcal subsystems in distinct topological states, and show that it leads to a precursor behavior of the topological phase transition in the overall system. This behavior is solely determined by the symmetry classes of the subsystem Hamiltonians and coupling terms, and is marked by the persistent existence of subgap states within the bulk energy gap. By investigating the critical current of Josephson junctions involving topological superconductors, we also illustrate that such subgap states play crucial roles in physical properties of nanoscale devices or materials.


Emergence of new topological gapless phases in the modified square-lattice Kitaev model. (arXiv:2311.11684v1 [cond-mat.str-el])
Jihyeon Park, Gun Sang Jeon

We investigate emergent topological gapless phases in the square-lattice Kitaev model with additional hopping terms. In the presence of nearest-neighbor hopping only, the model is known to exhibit gapless phases with two topological gapless points. When the strength of the newly added next-nearest-neighbor hopping is smaller than a certain value, qualitatively the same phase diagram persists. We find that further increase of the extra hopping results in a new topological phase with four gapless points. We construct a phase diagram to clarify the regions of emergent topological gapless phases as well as topologically trivial ones in the space of the chemical potential and the next-nearest-neighbor hopping strength. We examine the evolution of the gapless phases in the energy dispersions of the bulk as the chemical potential varies. The topological properties of the gapless phases are characterized by the winding numbers of the present gapless points. We also consider the ribbon geometry to examine the corresponding topological edge states. It is revealed that Majorana-fermion edge modes exist as flat bands in topological gapless phases. We also perform the analytical calculation as to Majorana-fermion zero-energy modes and discuss its implications on the numerical results.


Tailored Perdew-Burke-Ernzerhof functionals for improved band gap predictions in Zn monochalcogenides. (arXiv:2311.11702v1 [cond-mat.mtrl-sci])
Satadeep Bhattacharjee, Namitha Anna Koshi, Seung-Cheol Lee

Zinc monochalcogenides, including ZnO, ZnS and ZnSe, are crucial for various applications in optoelectronics and catalysis due to their exceptional optoelectronic properties. However, accurately predicting their electronic structures, especially the band gap and energy levels of Zn 3d states, remains a challenge. Traditional density functional theory (DFT) approaches, including local density and gradient-corrected approximations (LDA or GGA), often significantly underestimate these properties compared to experimental values. Advanced methods such as the GW approximation and DFT+U have been used to resolve these discrepancies, but they involve high computational costs or require seemingly unphysical parameters. This study focuses on a modified Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional with the aim of more efficient prediction of the band gaps in zinc monochalcogenides. Unlike previous approaches that require large negative U values for O p orbitals, our method provides a more transparent solution by directly changing the PBE functional. We demonstrate improved predictions of the electronic and optical properties of zinc monochalcogenides that closely align with experimental data, addressing a significant challenge in the computational study of these materials.


Interlayer electric multipoles induced by in-plane field from quantum geometric origins. (arXiv:2311.11710v1 [cond-mat.mes-hall])
Huiyuan Zheng, Dawei Zhai, Cong Xiao, Wang Yao

We show that interlayer charge transfer in 2D materials can be driven by an in-plane electric field, giving rise to electrical multipole generation in linear and second order of in-plane field. The linear and nonlinear effects have quantum geometric origins in the Berry curvature and quantum metric respectively, defined in extended parameter spaces characteristic of layered materials. We elucidate their symmetry characters, and demonstrate sizable dipole and quadrupole polarizations respectively in twisted bilayers and trilayers of transition metal dichalcogenides. Furthermore, we show that the effect is strongly enhanced during the topological phase transition tuned by interlayer translation. The effects point to a new electric control on layer quantum degree of freedom.


Orbital Hall effect and topology on a two-dimensional triangular lattice: from bulk to edge. (arXiv:2311.11715v1 [cond-mat.mes-hall])
Anderson L. R. Barbosa, Luis M. Canonico, Jose H. Garía, Tatiana G. Rappoport

We investigate a generalized multi-orbital tight-binding model on a triangular lattice, a system prevalent in a wide range of two-dimensional materials, and particularly relevant for simulating transition metal dichalcogenide monolayers. We show that the interplay between spin-orbit coupling and different symmetry-breaking mechanisms leads to the emergence of four distinct topological phases [Eck, P., \textit{et al.}, Phys. Rev. B, 107 (11), 115130 (2023)]. Remarkably, this interplay also triggers the orbital Hall effect with distinguished characteristics. Furthermore, by employing the Landauer-B\"uttiker formula, we establish that in the orbital Hall insulating phase, the orbital angular momentum is carried by edge states present in nanoribbons with specific terminations. We also show that, as expected, they do not have topological protection against the disorder of the edge states belonging to a first-order topological insulator.


Effective Hamiltonian of topologically protected qubit in a helical crystal. (arXiv:2311.11748v1 [cond-mat.mes-hall])
R. A. Niyazov, D. N. Aristov, V. Yu. Kachorovskii

We study a superlattice formed by tunnel-coupled identical antidots periodically situated in a two-dimensional topological insulator placed in a magnetic field. The superlattice spectrum can be controlled by gate electrodes or by changing the magnetic flux through the antidots. We demonstrate that a topologically protected qubit appears at the boundary between two regions with different fluxes. The qubit properties depend on the value of the flux jump on the boundary and can be controlled by the gate voltage. We derive the effective Hamiltonian of such a qubit and analyze the dependence of its properties on the main parameters of the superlattice: the tunnel coupling between antidots, and the probability of jumps with the spin flip.


Surface spin polarization in the magnetic response of GeTe Rashba ferroelectric. (arXiv:2311.11831v1 [cond-mat.mes-hall])
A.A. Avakyants, N.N. Orlova, A.V. Timonina, N.N. Kolesnikov, E.V. Deviatov

We experimentally investigate magnetization reversal curves for a GeTe topological semimetal. In addition to the known lattice diamagnetic response, we observe narrow magnetization loop in low fields, which should not be expected for non-magnetic GeTe. The hysteresis is unusual, so the saturation level is negative in positive fields, and the loop is passed clockwise, in contrast to standard ferromagnetic behavior. The experimental hysteresis curves can not be obtained from usual ferromagnetic ones by adding/subtracting of any linear dependence, or even by considering several interacting magnetic phases. The possibility of several phases is also eliminated by the remanence plots technique (Henkel or {\delta}M plots). We explain our results as a direct consequence of the correlation between ferroelectricity and spin-polarized surface states in GeTe, similarly to magnetoelectric structures.


Quantum dots on the InAs(110) cleavage surface created by atom manipulation. (arXiv:2311.11848v1 [cond-mat.mes-hall])
Van Dong Pham, Yi Pan, Steven C. Erwin, Stefan Fölsch

Cryogenic scanning tunneling microscopy was employed in combination with density-functional theory calculations to explore quantum dots made of In adatoms on the InAs(110) surface. Each adatom adsorbs at a surface site coordinated by one cation and two anions, and transfers one electron to the substrate, creating an attractive quantum well for electrons in surface states. We used the scanning-probe tip to assemble the positively charged adatoms into precisely defined quantum dots exhibiting a bound state roughly 0.1 eV below the Fermi level at an intrinsic linewidth of only ~4 meV, as revealed by scanning tunneling spectroscopy. For quantum-dot dimers, we observed the emergence of a bonding and an antibonding state with even and odd wave-function character, respectively, demonstrating the capability to engineer quasi-molecular electronic states. InAs(110) constitutes a promising platform in this respect because highly perfect surfaces can be readily prepared by cleavage and charged adatoms can be generated in-situ by the scanning-probe tip.


Orbital Kerr effect and terahertz detection via the nonlinear Hall effect. (arXiv:2311.11889v1 [cond-mat.mtrl-sci])
Diego Garcia Ovalle, Armando Pezo, Aurélien Manchon

We investigate the optical response induced by a d.c. current flowing in a nonmagnetic material that lacks inversion symmetry. In this class of materials, the flowing current experiences a nonlinear Hall effect and induces a nonequilibrium orbital magnetization, even in the absence of spin-orbit coupling. As a result, an orbital-driven Kerr effect arises that can be used to probe not only the orbital magnetization, but also the nonlinear Hall effect. In addition, in the long wavelength limit, the nonlinear Hall effect leads to a rectification current that can be used to detect terahertz radiation. We apply the theory to selected model systems, such as WTe$_2$ bilayer, as well as to realistic materials, i.e., bulk Te and metallic superlattices. The nonequilibrium orbital Kerr efficiencies obtained in these systems are comparable to the largest values reported experimentally in GaAs and MoS$_2$, exceeding the values reported in metals and suggesting a large terahertz current responsivity.


Novel implementations for reservoir computing -- from spin to charge. (arXiv:2311.11929v1 [physics.app-ph])
Karin Everschor-Sitte, Atreya Majumdar, Katharina Wolk, Dennis Meier

Topological textures in magnetic and electric materials are considered to be promising candidates for next-generation information technology and unconventional computing. Here, we discuss how the physical properties of topological nanoscale systems, such as skyrmions and domain walls, can be leveraged for reservoir computing, translating non-linear problems into linearly solvable ones. In addition to the necessary requirements of physical reservoirs, the topological textures give new opportunities for the downscaling of devices, enhanced complexity, and versatile input and readout options. Our perspective article presents topological magnetic and electric defects as an intriguing platform for non-linear signal conversion, giving a new dimension to reservoir computing and in-materio computing in general.


Spin Hall conductivity in Bi$_{1-x}$Sb$_x$ as an experimental test of bulk-boundary correspondence. (arXiv:2311.11933v1 [cond-mat.mes-hall])
Yongxi Ou, Wilson Yanez-Parreño, Yu-sheng Huang, Supriya Ghosh, Cüneyt Şahin, Max Stanley, Sandra Santhosh, Saurav Islam, Anthony Richardella, K. Andre Mkhoyan, Michael E. Flatté, Nitin Samarth

Bulk-boundary correspondence is a foundational principle underlying the electronic band structure and physical behavior of topological quantum materials. Although it has been rigorously tested in topological systems where the physical properties involve charge currents, it remains unclear whether bulk-boundary correspondence should also hold for non-conserved spin currents. We study charge-to-spin conversion in a canonical topological insulator, Bi$_{1-x}$Sb$_x$, to address this fundamentally unresolved question. We use spin-torque ferromagnetic resonance measurements to accurately probe the charge-to-spin conversion efficiency in epitaxial Bi$_{1-x}$Sb$_x$~thin films of high structural quality spanning the entire range of composition, including both trivial and topological band structures, as verified using {\it in vacuo} angle-resolved photoemission spectroscopy. From these measurements, we deduce the effective spin Hall conductivity (SHC) and find excellent agreement with the values predicted by tight-binding calculations for the intrinsic SHC of the bulk bands. These results provide strong evidence that the strong spin-orbit entanglement of bulk states well below the Fermi energy connects directly to the SHC in epitaxial Bi$_{1-x}$Sb$_x$~films interfaced with a metallic ferromagnet. The excellent agreement between theory and experiment points to the generic value of analyses focused entirely on bulk properties, even for topological systems involving non-conserved spin currents.


An on-chip platform for multi-degree-of-freedom control of two-dimensional quantum and nonlinear materials. (arXiv:2311.12030v1 [cond-mat.mes-hall])
Haoning Tang, Yiting Wang, Xueqi Ni, Kenji Watanabe, Takashi Taniguchi, Shanhui Fan, Eric Mazur, Amir Yacoby, Yuan Cao

Two-dimensional materials (2DM) and their derived heterostructures have electrical and optical properties that are widely tunable via several approaches, most notably electrostatic gating and interfacial engineering such as twisting. While electrostatic gating is simple and has been ubiquitously employed on 2DM, being able to tailor the interfacial properties in a similar real-time manner represents the next leap in our ability to modulate the underlying physics and build exotic devices with 2DM. However, all existing approaches rely on external machinery such as scanning microscopes, which often limit their scope of applications, and there is currently no means of tuning a 2D interface that has the same accessibility and scalability as electrostatic gating. Here, we demonstrate the first on-chip platform designed for 2D materials with in situ tunable interfacial properties, utilizing a microelectromechanical system (MEMS). Each compact, cost-effective, and versatile device is a standalone micromachine that allows voltage-controlled approaching, twisting, and pressurizing of 2DM with high accuracy. As a demonstration, we engineer synthetic topological singularities, known as merons, in the nonlinear optical susceptibility of twisted hexagonal boron nitride (h-BN), via simultaneous control of twist angle and interlayer separation. The chirality of the resulting moire pattern further induces a strong circular dichroism in the second-harmonic generation. A potential application of this topological nonlinear susceptibility is to create integrated classical and quantum light sources that have widely and real-time tunable polarization. Our invention pushes the boundary of available technologies for manipulating low-dimensional quantum materials, which in turn opens up the gateway for designing future hybrid 2D-3D devices for condensed-matter physics, quantum optics, and beyond.


Topological Diagnosis of Strongly Correlated Electron Systems. (arXiv:2311.12031v1 [cond-mat.str-el])
Chandan Setty, Fang Xie, Shouvik Sur, Lei Chen, Silke Paschen, Maia G. Vergniory, Jennifer Cano, Qimiao Si

The intersection of electronic topology and strong correlations offers a rich platform to discover exotic quantum phases of matter and unusual materials. An overarching challenge that impedes the discovery is how to diagnose strongly correlated electronic topology. Here, we develop a framework to address this outstanding question, and illustrate its power in the setting of electronic topology in Mott insulators. Based on single-particle Green's functions, the concept of a Green's function Berry curvature -- which is frequency dependent -- is introduced. We apply this notion in a system that contains symmetry-protected nodes in its noninteracting bandstructure; strong correlations drive the system into a Mott insulating state, creating contours in frequency-momentum space where the Green's function vanishes. The Green's function Berry flux of such zeros is found to be quantized, and is as such direct probe of the system's topology. Our framework allows for a systematic search of strongly correlated topological materials with Green's function topology.


Bridging the gap between numerics and experiment in free standing graphene. (arXiv:2104.09655v2 [cond-mat.str-el] UPDATED)
Maksim Ulybyshev, Savvas Zafeiropoulos, Christopher Winterowd, Fakher Assaad

We report results of large-scale quantum Monte Carlo (QMC) simulations of graphene. Using cutting-edge algorithmic improvements, we are able to consider spatial volumes, corresponding to 20808 electrons, that allow us to access energy scales of direct relevance to experiments. Using constrained random phase approximation (cRPA) estimates of short-ranged interactions combined with a Coulomb tail, we are able to successfully confront numerical and experimental estimates of the Fermi velocity renormalization. These results and their comparison with perturbation theory not only show the non-Fermi liquid character of graphene, but also prove the importance of lattice-scale physics and higher-order perturbative corrections beyond RPA for the quantitative description of the experimental data for the Fermi velocity renormalization in suspended graphene.


Valence fluctuation in Ce$_2$Re$_3$Si$_5$ and Ising-type magnetic ordering in Pr$_2$Re$_3$Si$_5$ single crystals. (arXiv:2111.12597v2 [cond-mat.str-el] UPDATED)
Suman Sanki, Vikash Sharma, Souvik Sasmal, Vikas Saini, Gaurav dwari, Bishal Baran Maity, Ruta Kulkarni, A. Thamizhavel

Single crystals of ${\rm Ce_2Re_3Si_5}$ and ${\rm Pr_2Re_3Si_5}$ have been grown by Czochralski method in a tetra-arc furnace. Powder x-ray diffraction confirmed that these compounds crystallize in the ${\rm U_2Mn_3Si_5}$-type tetragonal crystal structure with space group $P4/mnc$ (No. 128). The anisotropic physical properties have been studied comprehensively by measuring the magnetic susceptibility, isothermal magnetization, electrical transport and specific heat. The low value of magnetic susceptibility together with no magnetic transition down to $2$~K gives evidence that the Ce-ions are in the intermediate valence state in ${\rm Ce_2Re_3Si_5}$. On the other hand ${\rm Pr_2Re_3Si_5}$ revealed a magnetic ordering at $9$~K. The sharp drop in the magnetic susceptibility and a spin flip like metamagnetic transition, for $H~\parallel~[001]$ in the magnetization plot of ${\rm Pr_2Re_3Si_5}$ suggest an Ising-type antiferromagnetic ordering. Based on magnetic susceptibility and isothermal magnetization data, a detailed crystal electric field (CEF) analysis shows that degenerate ${J} = 4$ Hund's rule derived ground state of ${\rm Pr^{3+}}$ ion splits into nine singlets with an overall splitting of $1179$~K. The magnetic ordering in ${\rm Pr_2Re_3Si_5}$ is due to the exchange-generated admixture of the lowest lying CEF energy levels. Heat capacity data reveal a sharp peak at $9$~K, that confirms the bulk nature of the magnetic ordering in ${\rm Pr_2Re_3Si_5}$.


A new phase pentlandite. (arXiv:2210.13348v3 [physics.chem-ph] UPDATED)
Y Liu, SH Mei, LP Wang

The search for new phases is an important direction in materials science. The phase transition of sulfides results in significant changes in catalytic performance, such as MoS$_2$ and WS$_2$. Cubic pentlandite [cPn, (Fe, Ni, Co)$_9$S$_8$] can be a functional material in batteries, solar cells, and catalytic fields. However, no report about the material properties of other phases of pentlandite exists. The newly-discovered hexagonal pentlandite in this research can be a new mineral material for the energy industry and different catalytic field.


Light-Induced Transitions of Polar State and Domain Morphology of Photo-Ferroelectric Nanoparticles. (arXiv:2303.04904v3 [cond-mat.mtrl-sci] UPDATED)
Eugene A. Eliseev, Anna N. Morozovska, Yulian M. Vysochanskii, Lesya P. Yurchenko, Venkatraman Gopalan, Long-Qing Chen

Using the Landau-Ginzburg-Devonshire approach, we study light-induced phase transitions, evolution of polar state and domain morphology in photo-ferroelectric nanoparticles (NPs). Light exposure increases the free carrier density near the NP surface and may in turn induce phase transitions from the nonpolar paraelectric to the polar ferroelectric phase. Using the uniaxial photo-ferroelectric Sn2P2S6 as an example, we show that visible light exposure induces the appearance and vanishing of striped, labyrinthine or curled domains and changes in the polarization switching hysteresis loop shape from paraelectric curves to double, pinched and single loops, as well as the shifting in the position of the tricritical point. Furthermore, we demonstrate that an ensemble of non-interacting photo-ferroelectric NPs may exhibit superparaelectric-like features at the tricritical point, such as strongly frequency-dependent giant piezoelectric and dielectric responses, which can potentially be exploited for piezoelectric applications.


Scanning Tunneling Microscopy Study of Epitaxial Fe3GeTe2 Monolayers on Bi2Te3. (arXiv:2303.10113v2 [cond-mat.mtrl-sci] UPDATED)
Brad M. Goff, Alexander J. Bishop, Wenyi Zhou, Ryan Bailey-Crandell, Katherine Robinson, Roland K. Kawakami, Jay A. Gupta

Introducing magnetism to the surface state of topological insulators, such as Bi2Te3, can lead to a variety of interesting phenomena. We use scanning tunneling microscopy (STM) to study a single quintuple layer (QL) of the van der Waals magnet Fe3GeTe2 (FGT) that is grown on Bi2Te3 via molecular beam epitaxy. STM topographic images show that the FGT grows as free-standing islands on Bi2Te3 and outwards from Bi2Te3 steps. Atomic resolution imaging shows atomic lattices of 390 +- 10 pm for FGT and 430 +- 10 pm for Bi2Te3, consistent with the respective bulk crystals. A moir\'e pattern is observed on FGT regions with a periodicity of 4.3 +- 0.4 nm that can be attributed solely to this lattice mismatch and thus indicates zero rotational misalignments. While most of the surface is covered by a single QL of the FGT, there are small double QL regions, as well as regions with distinct chemical terminations due to an incomplete QL. The most common partial QL surface termination is the FeGe layer, in which the top two atomic layers are missing. This termination has a distinctive electronic structure and a (sqrt3 x sqrt3)R30 reconstruction overlaid on the moir\'e pattern in STM images. Magnetic circular dichroism (MCD) measurements confirm these thin FGT films are ferromagnetic with TC ~190 K.


GlassNet: a multitask deep neural network for predicting many glass properties. (arXiv:2303.15538v3 [cond-mat.soft] UPDATED)
Daniel R. Cassar

A multitask deep neural network model was trained on more than 218k different glass compositions. This model, called GlassNet, can predict 85 different properties (such as optical, electrical, dielectric, mechanical, and thermal properties, as well as density, viscosity/relaxation, crystallization, surface tension, and liquidus temperature) of glasses and glass-forming liquids of different chemistries (such as oxides, chalcogenides, halides, and others). The model and the data used to train it are available in the GlassPy Python module as free and open source software for the community to use and build upon. As a proof of concept, GlassNet was used with the MYEGA viscosity equation to predict the temperature dependence of viscosity and outperformed another general purpose viscosity model available in the literature (ViscNet) on unseen data. An explainable AI algorithm (SHAP) was used to extract knowledge correlating the input (physicochemical information) and output (glass properties) of the model, providing valuable insights for glass manufacturing and design. It is hoped that GlassNet, with its free and open source nature, can be used to enable faster and better computer-aided design of new technological glasses.


Tunable helical crystals. (arXiv:2305.08242v2 [cond-mat.mes-hall] UPDATED)
R. A. Niyazov, D. N. Aristov, V. Yu. Kachorovskii

We consider a superlattice formed by tunnel-connected identical holes, periodically placed in a two-dimensional topological insulator. We study tunneling transport through helical edges of these holes and demonstrate that the band structure of such helical crystal can be controlled by both gate electrodes and external magnetic filed. For integer and half-integer values of dimensionless magnetic flux through the holes, the spectrum possesses Dirac points whose positions and velocities can be tuned by gates. The deviation of magnetic flux from these special values by $\delta \phi$ makes the Dirac cones massive, with the gap value $\Delta \propto |\delta \phi|$. At certain gate-dependent values of $\delta \phi$ different Dirac points converge to a double Dirac point and then disappear with further increase of $\delta \phi.$ Interaction between carriers may lead to strong renormalization of parameters $\alpha$ and $\beta$ controlling total tunnel coupling between holes and spin flip tunneling processes, respectively. We plot the renormalization flow in the plane $(\alpha,\beta)$ and demonstrate multicritical behavior of the crystal -- there is a multicritical fully unstable fixed point separating three different phases: independent rings, independent shoulders, and perfect spin-flip channels. We also find that defects in the crystal may lead to a formation of topologically protected qubits which are not destroyed by temperature and can be also manipulated both by gates and by magnetic field. The possibility of purely electrical high-temperature control of the qubits opens a wide avenue for applications in the area of quantum computing.


Quantum Fisher Information and multipartite entanglement in spin-1 chains. (arXiv:2307.02407v2 [quant-ph] UPDATED)
Federico Dell'Anna, Sunny Pradhan, Cristian Degli Esposti Boschi, Elisa Ercolessi

In this paper, we study the ground state Quantum Fisher Information (QFI) in one-dimensional spin-1 models, as witness to Multipartite Entanglement. The models addressed are the Bilinear-Biquadratic model, the most general isotropic SU(2)-invariant spin-1 chain, and the XXZ spin-1 chain, both with nearest-neighbor interactions and open boundary conditions. We show that the scaling of the QFI of strictly non-local observables can be used for characterizing the phase diagrams and, in particular, for studying topological phases, where it scales maximally. Analysing its behavior at the critical phases we are also able to recover the scaling dimensions of the order parameters both for local and string observables. The numerical results have been obtained by exploiting the Density Matrix Renormalization Group algorithm and Tensor Network techniques.


Spin waves in bilayers of transition-metal dichalcogenides. (arXiv:2307.13414v2 [cond-mat.mes-hall] UPDATED)
Wojciech Rudziński, Józef Barnaś, Anna Dyrdał

Van der Waals magnetic materials are currently of great interest as materials for applications in future ultrathin nanoelectronics and nanospintronics. Due to weak coupling between individual monolayers, these materials can be easily obtained in the monolayer and bilayer forms. The latter are of specific interest as they may be considered as natural two-dimensional spin valves. In this paper, we study theoretically spin waves in bilayers of transition metal dichalcogenides. The considerations are carried within the general spin wave theory based on effective spin Hamiltonian and Hollstein-Primakoff-Bogolubov transformation. The spin Hamiltonian includes intra-layer as well as inter-layer nearest-neighbour exchange interactions, easy-plane anisotropy, and additionally a weak in-plane easy-axis anisotropy. The bilayer systems consist of two ferromagnetic (in-plane magnetization) monolayers that are coupled either ferromagnetically or antiferromagnetically. In the latter case, we analyse the spin wave spectra in all magnetic phases, i.e. in the antiferromagnetic, spin-flop, and ferromagnetic ones.


Critical fates induced by interaction competition in the three-dimensional tilted Dirac semimetals. (arXiv:2307.13436v3 [cond-mat.str-el] UPDATED)
Jing Wang, Jie-Qiong Li, Wen-Hao Bian, Qiao-Chu Zhang, Xiao-Yue Ren

The interplay between Coulomb interaction, electron-phonon coupling, and phonon-phonon coupling has a significant impact on the low-energy behavior of three-dimensional type-I tilted Dirac semimetals. To investigate this phenomenon, we construct an effective theory, calculate one-loop corrections contributed by all these interactions, and establish the coupled energy-dependent flows of all associated interaction parameters by adopting the renormalization group approach. Deciphering such coupled evolutions allows us to determine a series of low-energy critical outcomes for these materials. At first, we present the low-energy tendencies of all interaction parameters. The tilting parameter exhibits distinct tendencies that depend heavily upon the initial anisotropy of fermion velocities. In comparison, the latter is mainly dominated by its initial value but less sensitive to the former. With the variance of these two quantities, parts of the interaction parameters are driven towards the strong anisotropy in the low-energy, indicating the screened interaction in certain directions, while others tend to move towards an approximate isotropy. Additionally, we observe that the tendencies of interaction parameters can be qualitatively clustered into three distinct types of fixed points, accompanying the potential instabilities around which certain interaction-driven phase transition is triggered. Furthermore, approaching such fixed points leads to physical quantities, such as the density of states, compressibility, and specific heat, exhibiting behavior that is quite different from their non-interacting counterparts and even deviates slightly from Fermi-liquid behavior. Our investigation sheds light on the intricate relationship between different types of interactions in these semimetals and provides useful insights into their fundamental properties.


Crystal facet orientated Altermagnets for detecting ferromagnetic and antiferromagnetic states by giant tunneling magnetoresistance effect. (arXiv:2309.09561v2 [cond-mat.mtrl-sci] UPDATED)
Boyuan Chi, Leina Jiang, Yu Zhu, Guoqiang Yu, Caihua Wan, Jia Zhang, Xiufeng Han

Emerging altermagnetic materials with vanishing net magnetizations and unique band structures have been envisioned as an ideal electrode to design antiferromagnetic tunnel junctions. Their momentum-resolved spin splitting in band structures defines a spin-polarized Fermi surface, which allows altermagnetic materials to polarize current as a ferromagnet, when the current flows along specific directions relevant to their altermagnetism. Here, we design an Altermagnet/Insulator barrier/Ferromagnet junction, renamed as altermagnetic tunnel junction (ATMTJ), using RuO$_2$/TiO$_2$/CrO$_2$ as a prototype. Through first-principles calculations, we investigate the tunneling properties of the ATMTJ along the [001] and [110] directions, which shows that the tunneling magnetoresistance (TMR) is almost zero when the current flows along the [001] direction, while it can reach as high as 6100\% with current flows along the [110] direction. The spin-resolved conduction channels of the altermagnetic RuO$_2$ electrode are found responsible for this momentum-dependent (or transport-direction-dependent) TMR effect. Furthermore, this ATMTJ can also be used to readout the N\'{e}el vector of the altermagnetic electrode RuO$_2$. Our work promotes the understanding toward the altermagnetic materials and provides an alternative way to design magnetic tunnel junctions with ultrahigh TMR ratios and robustness of the altermagnetic electrode against external disturbance, which broadens the application avenue for antiferromagnetic spintronic devices.


Fractional Quantum Anomalous Hall Effect in a Graphene Moire Superlattice. (arXiv:2309.17436v3 [cond-mat.mes-hall] UPDATED)
Zhengguang Lu, Tonghang Han, Yuxuan Yao, Aidan P. Reddy, Jixiang Yang, Junseok Seo, Kenji Watanabe, Takashi Taniguchi, Liang Fu, Long Ju

The fractional quantum anomalous Hall effect (FQAHE), the analog of the fractional quantum Hall effect1 at zero magnetic field, is predicted to exist in topological flat bands under spontaneous time-reversal-symmetry breaking. The demonstration of FQAHE could lead to non-Abelian anyons which form the basis of topological quantum computation. So far, FQAHE has been observed only in twisted MoTe2 (t-MoTe2) at moire filling factor v > 1/2. Graphene-based moire superlattices are believed to host FQAHE with the potential advantage of superior material quality and higher electron mobility. Here we report the observation of integer and fractional QAH effects in a rhombohedral pentalayer graphene/hBN moire superlattice. At zero magnetic field, we observed plateaus of quantized Hall resistance Rxy = h/(ve^2) at filling factors v = 1, 2/3, 3/5, 4/7, 4/9, 3/7 and 2/5 of the moire superlattice respectively. These features are accompanied by clear dips in the longitudinal resistance Rxx. In addition, at zero magnetic field, Rxy equals 2h/e^2 at v = 1/2 and varies linearly with the filling factor-similar to the composite Fermi liquid (CFL) in the half-filled lowest Landau level at high magnetic fields. By tuning the gate displacement field D and v, we observed phase transitions from CFL and FQAH states to other correlated electron states. Our graphene system provides an ideal platform for exploring charge fractionalization and (non-Abelian) anyonic braiding at zero magnetic field, especially considering a lateral junction between FQAHE and superconducting regions in the same device.


Theory for Planar Hall Effect in Organic Dirac Fermion System. (arXiv:2310.04066v2 [cond-mat.str-el] UPDATED)
Yuki Nakamura, Takao Morinari

In a recent experiment on the interlayer magnetoresistance in the quasi-two-dimensional organic salt, $\alpha$-(BEDT-TTF)$_2$I$_3$, it has been observed that at low temperatures, interlayer tunneling attains phase coherence, leading to the emergence of a three-dimensional electronic structure. Theoretically and experimentally it has been suggested that the system exhibits characteristics of a three-dimensional Dirac semimetal as a consequence of broken time-reversal symmetry and inversion symmetry. Here, we perform a theoretical calculation of the magnetoconductivity under an in-plane magnetic field and demonstrate that the system displays a planar Hall effect. Our calculations are based on a realistic model for $\alpha$-(BEDT-TTF)$_2$I$_3$ incorporating interlayer tunneling and the tilt of the Dirac cone. Given that the planar Hall effect is anticipated as a consequence of chiral anomaly, our findings provide support for the classification of $\alpha$-(BEDT-TTF)$_2$I$_3$ as a three-dimensional Dirac semimetal.


Mapping of Spin-Wave Transport in Thulium Iron Garnet Thin Films Using Diamond Quantum Microscopy. (arXiv:2310.06188v2 [cond-mat.mes-hall] UPDATED)
Rupak Timalsina, Haohan Wang, Bharat Giri, Adam Erickson, Xiaoshan Xu, Abdelghani Laraoui

Spin waves, collective dynamic magnetic excitations, offer crucial insights into magnetic material properties. Rare-earth iron garnets offer an ideal spin-wave (SW) platform with long propagation length, short wavelength, gigahertz frequency, and applicability to magnon spintronic platforms. Of particular interest, thulium iron garnet (TmIG) has attracted a huge interest recently due to its successful growth down to a few nanometers, observed topological Hall effect and spin orbit torque-induced switching effects. However, there is no direct spatial measurement of its SW properties. This work uses diamond nitrogen vacancy (NV) magnetometry in combination with SW electrical transmission spectroscopy to study SW transport properties in TmIG thin films. NV magnetometry allows probing spin waves at the sub-micrometer scale, seen by the amplification of the local microwave magnetic field due to the coupling of NV spin qubits with the stray magnetic field produced by the microwave-excited spin waves. By monitoring the NV spin resonances, the SW properties in TmIG thin films are measured as function of the applied magnetic field, including their amplitude, decay length (~ 50 um), and wavelength (0.8 - 2 um). These results pave the way for studying spin qubit-magnon interactions in rare-earth magnetic insulators, relevant to quantum magnonics applications.


Electron Interactions in Rashba Materials. (arXiv:2310.20084v2 [cond-mat.supr-con] UPDATED)
Yasha Gindikin, Alex Kamenev

We show that Rashba spin-orbit interaction (RSOI) modifies electron-electron interaction vertex giving rise to a spectrum of novel phenomena. First, the spin-orbit-modified Coulomb interactions induce $p$-wave superconducting order, without any need for other mediators of attraction. Remarkably, two distinct superconducting phases arise in 3D systems, mirroring the $\mathrm{A}$ or $\mathrm{B}$ phases of $^3\mathrm{He}$, depending on the sign of the SOI constant. In contrast, 2D systems exhibit $p^x\pm i p^y$ order parameter, leading to time-reversal-invariant topological superconductivity. Second, a sufficiently strong RSOI induces ferromagnetic ordering. It is associated with a deformation of the Fermi surface, which may lead to a Lifshitz transition from a spherical to a toroidal Fermi surface, with a number of experimentally observable signatures. Finally, in sufficiently clean Rashba materials, ferromagnetism and $p$-wave superconductivity may coexist. This state resembles the $\mathrm{A}_1$ phase of $^3\mathrm{He}$, yet it may avoid nodal points due to the toroidal shape of the Fermi surface.


Nonlinear optical response in multiband Dirac-Electron System. (arXiv:2311.07176v2 [cond-mat.mes-hall] UPDATED)
Keisuke Kitayama, Masao Ogata

We study the dc photocurrent induced by linearly polarized light in a multiband Dirac-electron system, focusing on the organic conductor $\alpha$-(BEDT-TTF)$_2$I$_3$. Utilizing perturbation theory, we predict the dependence of shift current on the frequency of light in photodriven $\alpha$-(BEDT-TTF)$_2$I$_3$. Our findings demonstrate a strong correlation between the frequency of light and both the magnitude and direction of the shift current. Furthermore, we delve into the nonperturbative effects of nonlinear optical responses using Floquet theory and demonstrate how the sign of the optical response changes with increasing light intensity. Our results unveil remarkable optical phenomena in the multiband Dirac-electron system and are anticipated to be observed in future experiments.


Found 10 papers in prb
Date of feed: Tue, 21 Nov 2023 04:17:08 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)

Bulk-edge correspondences for surface plasmon polaritons: A circuit approach
Yosuke Nakata, Toshihiro Nakanishi, Ryo Takahashi, Fumiaki Miyamaru, and Shuichi Murakami
Author(s): Yosuke Nakata, Toshihiro Nakanishi, Ryo Takahashi, Fumiaki Miyamaru, and Shuichi Murakami

In this study, we establish circuit-theoretical bulk-edge correspondences to indicate the existence of surface plasmon polaritons topologically. First, we reveal an essential topological transition in a minimal circuit model of a composite right-/left-handed transmission line. We then demonstrate th…


[Phys. Rev. B 108, 174105] Published Mon Nov 20, 2023

In-plane canted ferromagnetism, intrinsic Weyl fermions, and large anomalous Hall effect in the kagome semimetal ${\mathrm{Rh}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$
Meng-Xin Wu, Yu-Hao Wei, Da-Shuai Ma, Peng Wang, Nan Gao, Shao-Yi Wu, and Min-Quan Kuang
Author(s): Meng-Xin Wu, Yu-Hao Wei, Da-Shuai Ma, Peng Wang, Nan Gao, Shao-Yi Wu, and Min-Quan Kuang

Magnetic Weyl semimetals can reveal a renowned electronic transport phenomenon, i.e., the anomalous Hall effect due to the intrinsic Berry curvature promoted by the Weyl fermions. Here, the layered kagome compound ${\mathrm{Rh}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$ is identified as a ferromagnetic …


[Phys. Rev. B 108, 174430] Published Mon Nov 20, 2023

Magnetic properties of $4f$ adatoms on graphene: Density functional theory investigations
Johanna P. Carbone, Juba Bouaziz, Gustav Bihlmayer, and Stefan Blügel
Author(s): Johanna P. Carbone, Juba Bouaziz, Gustav Bihlmayer, and Stefan Blügel

Rare-earth atoms on top of 2D materials represent an interesting platform with the prospect of tailoring the magnetic anisotropy for practical applications. Here, we investigate the ground state and magnetic properties of selected $4f$ atoms deposited on a graphene substrate in the framework of the …


[Phys. Rev. B 108, 174431] Published Mon Nov 20, 2023

Measurement induced criticality in quasiperiodic modulated random hybrid circuits
Gal Shkolnik, Aidan Zabalo, Romain Vasseur, David A. Huse, J. H. Pixley, and Snir Gazit
Author(s): Gal Shkolnik, Aidan Zabalo, Romain Vasseur, David A. Huse, J. H. Pixley, and Snir Gazit

We study one-dimensional hybrid quantum circuits perturbed by quenched quasiperiodic (QP) modulations across the measurement-induced phase transition (MIPT). Considering non-Pisot QP structures, characterized by unbounded fluctuations, allows us to tune the wandering exponent $β$ to exceed the Luck …


[Phys. Rev. B 108, 184204] Published Mon Nov 20, 2023

Thermal cycle and polaron formation in structured bosonic environments
Angela Riva, Dario Tamascelli, Angus J. Dunnett, and Alex W. Chin
Author(s): Angela Riva, Dario Tamascelli, Angus J. Dunnett, and Alex W. Chin

Chain-mapping techniques combined with the time-dependent density matrix renormalization group are powerful tools for simulating the dynamics of open quantum systems interacting with structured bosonic environments. Most interestingly, they leave the degrees of freedom of the environment open to ins…


[Phys. Rev. B 108, 195138] Published Mon Nov 20, 2023

Flat bands and magnetism in ${\mathrm{Fe}}_{4}{\mathrm{GeTe}}_{2}$ and ${\mathrm{Fe}}_{5}{\mathrm{GeTe}}_{2}$ due to bipartite crystal lattices
Fuyi Wang and Haijun Zhang
Author(s): Fuyi Wang and Haijun Zhang

${\mathrm{Fe}}_{n=4,5}{\mathrm{GeTe}}_{2}$ exhibits quasi-two-dimensional properties as a promising candidate for a near-room-temperature ferromagnet, which has attracted great interest. In this work, we notice that the crystal lattice of ${\mathrm{Fe}}_{n=4,5}{\mathrm{GeTe}}_{2}$ can be approximate…


[Phys. Rev. B 108, 195140] Published Mon Nov 20, 2023

Shaking photons out of a topological material
Mário G. Silveirinha
Author(s): Mário G. Silveirinha

Nontrivial topological phases in electronic materials are often associated with the quantization of the Hall conductivity. Here, the author introduces a photonic analogue of this phenomenon. It is shown that the physical acceleration of a material can induce a photon flow in a direction perpendicular to the acceleration, analogous to the electronic Hall effect. For nonreciprocal materials, the response function linking the induced energy flow with the acceleration is quantized and is determined by the photonic gap Chern number.


[Phys. Rev. B 108, 205142] Published Mon Nov 20, 2023

Large power factor, anomalous Nernst effect, and temperature-dependent thermoelectric quantum oscillations in the magnetic Weyl semimetal NdAlSi
Qing-Xin Dong, Jin-Feng Wang, Li-Bo Zhang, Jian-Li Bai, Qiao-Yu Liu, Jing-Wen Cheng, Pin-Yu Liu, Cun-Dong Li, Jun-Sen Xiang, Zhi-An Ren, Pei-Jie Sun, and Gen-Fu Chen
Author(s): Qing-Xin Dong, Jin-Feng Wang, Li-Bo Zhang, Jian-Li Bai, Qiao-Yu Liu, Jing-Wen Cheng, Pin-Yu Liu, Cun-Dong Li, Jun-Sen Xiang, Zhi-An Ren, Pei-Jie Sun, and Gen-Fu Chen

Magnetic topological materials have attracted much attention due to the interplay between magnetism and topological electronic band structure, which may not only generate new exotic quantum states but also bring great potential applications. Here, we present Seebeck and Nernst effects in the magneti…


[Phys. Rev. B 108, 205143] Published Mon Nov 20, 2023

Disorder in the nonlinear anomalous Hall effect of $\mathcal{PT}$-symmetric Dirac fermions
Rhonald Burgos Atencia, Di Xiao, and Dimitrie Culcer
Author(s): Rhonald Burgos Atencia, Di Xiao, and Dimitrie Culcer

The study of the nonlinear anomalous Hall effect (NLAHE) in $\mathcal{P}\mathcal{T}$-symmetric systems has focused on intrinsic mechanisms. Here, we show that disorder contributes substantially to NLAHE and often overwhelms intrinsic terms. We identify terms to zeroth order in the disorder strength …


[Phys. Rev. B 108, L201115] Published Mon Nov 20, 2023

Exciton localization on a magnetic domain wall in ${\mathrm{MoSe}}_{2}\text{−}{\mathrm{CrI}}_{3}$ heterostructures
S. Mikkola, I. Chestnov, I. Iorsh, and V. Shahnazaryan
Author(s): S. Mikkola, I. Chestnov, I. Iorsh, and V. Shahnazaryan

The existence of spontaneous magnetization that fingerprints a ground-state ferromagnetic order was recently observed in two-dimensional (2D) van der Waals materials. Despite progress in the fabrication and manipulation of the atom-thick magnets, investigation of nanoscale magnetization properties i…


[Phys. Rev. B 108, L201403] Published Mon Nov 20, 2023

Found 1 papers in prl
Date of feed: Tue, 21 Nov 2023 04:17:11 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)

AlphaFold2 Can Predict Single-Mutation Effects
John M. McBride, Konstantin Polev, Amirbek Abdirasulov, Vladimir Reinharz, Bartosz A. Grzybowski, and Tsvi Tlusty
Author(s): John M. McBride, Konstantin Polev, Amirbek Abdirasulov, Vladimir Reinharz, Bartosz A. Grzybowski, and Tsvi Tlusty

A new method based on AlphaFold2 improves the precision of single-mutation predictions for protein folding.


[Phys. Rev. Lett. 131, 218401] Published Mon Nov 20, 2023

Found 1 papers in prx
Date of feed: Tue, 21 Nov 2023 04:17:13 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)

Learning Interacting Theories from Data
Claudia Merger, Alexandre René, Kirsten Fischer, Peter Bouss, Sandra Nestler, David Dahmen, Carsten Honerkamp, and Moritz Helias
Author(s): Claudia Merger, Alexandre René, Kirsten Fischer, Peter Bouss, Sandra Nestler, David Dahmen, Carsten Honerkamp, and Moritz Helias

Models of systems in physics usually start with elementary processes. New work with a neural network shows how models can also be built by observing the system as a whole and deducing the underlying interactions.


[Phys. Rev. X 13, 041033] Published Mon Nov 20, 2023

Found 19 papers in nano-lett
Date of feed: Mon, 20 Nov 2023 14:10:31 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] Multistage Filtration Desalination via Ion Self-Rejection Effect in Cation-Controlled Graphene Oxide Membrane under 1 Bar Operating Pressure
Junjie Chen, Xing Liu, Zhoule Ding, Zhenglin He, Huixiong Jiang, Kaiyuan Zhu, Yunzhang Li, and Guosheng Shi

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c03105

[ASAP] High-Performance Complementary Circuits from Two-Dimensional MoTe2
Jun Cai, Zheng Sun, Peng Wu, Rahul Tripathi, Hao-Yu Lan, Jing Kong, Zhihong Chen, and Joerg Appenzeller

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c03184

[ASAP] Phonon Chirality Manipulation Mechanism in Transition-Metal Dichalcogenide Interlayer-Sliding Ferroelectrics
Hao Chen, Qianqian Wang, Xukun Feng, Weikang Wu, and Lifa Zhang

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c03787

[ASAP] Fatigue Response of MoS2 with Controlled Introduction of Atomic Vacancies
Yolanda Manzanares-Negro, Aitor Zambudio, Guillermo López-Polín, Soumya Sarkar, Manish Chhowalla, Julio Gómez-Herrero, and Cristina Gómez-Navarro

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02479

[ASAP] Photoluminescence Enhancement of Monolayer WS2 by n-Doping with an Optically Excited Gold Disk
Bayarjargal N. Tugchin, Nathan Doolaard, Angela I. Barreda, Zifei Zhang, Anastasia Romashkina, Stefan Fasold, Isabelle Staude, Falk Eilenberger, and Thomas Pertsch

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c03053

[ASAP] Magnetotransport Signatures of Superconducting Cooper Pairs Carried by Topological Surface States in Bismuth Selenide
Raj Kumar, Cristian V. Ciobanu, Somilkumar J. Rathi, Joseph E. Brom, Joan M. Redwing, and Frank Hunte

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02795

[ASAP] Giant and Controllable Valley Currents in Graphene by Double Pumped THz Light
Sangeeta Sharma, Deepika Gill, and Samuel Shallcross

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02874

[ASAP] Modulating the Electrochemical Intercalation of Graphene Interfaces with α-RuCl3 as a Solid-State Electron Acceptor
Jonathon Nessralla, Daniel T. Larson, Takashi Taniguchi, Kenji Watanabe, Efthimios Kaxiras, and D. Kwabena Bediako

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02877

[ASAP] Gate-Tuning Hybrid Polaritons in Twisted α-MoO3/Graphene Heterostructures
Zhou Zhou, Renkang Song, Junbo Xu, Xiang Ni, Zijia Dang, Zhichen Zhao, Jiamin Quan, Siyu Dong, Weida Hu, Di Huang, Ke Chen, Zhanshan Wang, Xinbin Cheng, Markus B. Raschke, Andrea Alù, and Tao Jiang

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c03769

[ASAP] Nanoparticle Deep-Subwavelength Dynamics Empowered by Optical Meron–Antimeron Topology
Chengfeng Lu, Bo Wang, Xiang Fang, Din Ping Tsai, Weiming Zhu, Qinghua Song, Xiao Deng, Tao He, Xiaoyun Gong, Hong Luo, Zhanshan Wang, Xinhua Dai, Yuzhi Shi, and Xinbin Cheng

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c03351

[ASAP] Graphene Oxide-Mediated Regulation of Volume Exclusion and Wettability in Biomimetic Phosphorylation-Responsive Ionic Gates
Liu Shi, Beibei Nie, Lingjun Sha, Keqin Ying, Jinlong Li, and Genxi Li

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02924

[ASAP] PZT-Enabled MoS2 Floating Gate Transistors: Overcoming Boltzmann Tyranny and Achieving Ultralow Energy Consumption for High-Accuracy Neuromorphic Computing
Jing Chen, Ye-Qing Zhu, Xue-Chun Zhao, Zheng-Hua Wang, Kai Zhang, Zheng Zhang, Ming-Yuan Sun, Shuai Wang, Yu Zhang, Lin Han, Xiaoming Wu, and Tian-Ling Ren

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02721

[ASAP] Topological Transitions and Surface Umklapp Scattering in Weakly Modulated Periodic Metasurfaces
Kobi Cohen, Shai Tsesses, Shimon Dolev, Yael Blechman, Guy Ankonina, and Guy Bartal

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02759

[ASAP] High-Performance WSe2 Top-Gate Devices with Strong Spacer Doping
Po-Hsun Ho, Yu-Ying Yang, Sui-An Chou, Ren-Hao Cheng, Po-Heng Pao, Chao-Ching Cheng, Iuliana Radu, and Chao-Hsin Chien

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02757

[ASAP] Robustness of Trion State in Gated Monolayer MoSe2 under Pressure
Zeya Li, Feng Qin, Chin Shen Ong, Junwei Huang, Zian Xu, Peng Chen, Caiyu Qiu, Xi Zhang, Caorong Zhang, Xiuxiu Zhang, Olle Eriksson, Angel Rubio, Peizhe Tang, and Hongtao Yuan

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02812

[ASAP] Unveiling Local Optical Properties Using Nanoimaging Phase Mapping in High-Index Topological Insulator Bi2Se3 Resonant Nanostructures
Sukanta Nandi, Shany Z. Cohen, Danveer Singh, Michal Poplinger, Pilkhaz Nanikashvili, Doron Naveh, and Tomer Lewi

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c03128

[ASAP] Electric Potential at the Interface of Membraneless Organelles Gauged by Graphene
Christian Hoffmann, Gennadiy Murastov, Johannes Vincent Tromm, Jean-Baptiste Moog, Muhammad Awais Aslam, Aleksandar Matkovic, and Dragomir Milovanovic

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c02915

[ASAP] Semiconducting Transition Metal Dichalcogenide Heteronanotubes with Controlled Outer-Wall Structures
Yohei Yomogida, Mai Nagano, Zheng Liu, Kan Ueji, Md. Ashiqur Rahman, Abdul Ahad, Akane Ihara, Hiroyuki Nishidome, Takashi Yagi, Yusuke Nakanishi, Yasumitsu Miyata, and Kazuhiro Yanagi

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c01761

[ASAP] Submillimeter-Long WS2 Nanotubes: The Pathway to Inorganic Buckypaper
Vojtěch Kundrát, Rita Rosentsveig, Kristýna Bukvišová, Daniel Citterberg, Miroslav Kolíbal, Shachar Keren, Iddo Pinkas, Omer Yaffe, Alla Zak, and Reshef Tenne

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Nano Letters
DOI: 10.1021/acs.nanolett.3c02783

Found 4 papers in acs-nano
Date of feed: Mon, 20 Nov 2023 14:06:20 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] Spin-Stabilization by Coulomb Blockade in a Vanadium Dimer in WSe2
Samuel Stolz, Bowen Hou, Dan Wang, Azimkhan Kozhakhmetov, Chengye Dong, Oliver Gröning, Joshua A. Robinson, Diana Y. Qiu, and Bruno Schuler

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ACS Nano
DOI: 10.1021/acsnano.3c04841

[ASAP] Analysis of Strain and Defects in Tellurium-WSe2 Moiré Heterostructures Using Scanning Nanodiffraction
Bengisu Sari, Steven E. Zeltmann, Chunsong Zhao, Philipp M. Pelz, Ali Javey, Andrew M. Minor, Colin Ophus, and Mary C. Scott

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ACS Nano
DOI: 10.1021/acsnano.3c04283

[ASAP] Strain-Induced 2H to 1T′ Phase Transition in Suspended MoTe2 Using Electric Double Layer Gating
Shubham Sukumar Awate, Ke Xu, Jierui Liang, Benjamin Katz, Ryan Muzzio, Vincent H. Crespi, Jyoti Katoch, and Susan K. Fullerton-Shirey

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ACS Nano
DOI: 10.1021/acsnano.3c04701

[ASAP] Graphene-In2Se3 van der Waals Heterojunction Neuristor for Optical In-Memory Bimodal Operation
Subhrajit Mukherjee, Debopriya Dutta, Anurag Ghosh, and Elad Koren

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ACS Nano
DOI: 10.1021/acsnano.3c03820

Found 1 papers in comm-phys


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)

An atomically tailored chiral magnet with small skyrmions at room temperature
Roland K. Kawakami

Communications Physics, Published online: 14 November 2023; doi:10.1038/s42005-023-01444-1

Magnetic skyrmions are topological excitations that have attracted great attention recently for their potential applications in low power, ultrahigh density memory. A major challenge has been to find materials that meet the dual requirement of small skyrmions stable at room temperature. Here, the authors further both these goals by developing epitaxial FeGe films with excess Fe using atomic layer molecular beam epitaxy far from thermal equilibrium.