Found 23 papers in cond-mat
Date of feed: Thu, 25 Jan 2024 01:30:00 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)

Twisted Lattice Gauge Theory: Membrane Operators, Three-loop Braiding and Topological Charge. (arXiv:2401.13042v1 [cond-mat.str-el])
Joe Huxford, Yong Baek Kim, Dung Xuan Nguyen

3+1 dimensional topological phases can support loop-like excitations in addition to point-like ones, allowing for non-trivial loop-loop and point-loop braiding statistics not permitted to point-like excitations alone. Furthermore, these loop-like excitations can be linked together, changing their properties. In particular, this can lead to distinct three-loop braiding, involving two loops undergoing an exchange process while linked to a third loop. In this work, we investigate the loop-like excitations in a 3+1d Hamiltonian realization of Dijkgraaf-Witten theory through direct construction of their membrane operators, for a general finite Abelian group and 4-cocycle twist. Using these membrane operators, we find the braiding relations and fusion rules for the loop-like excitations, including those linked to another loop-like excitation. Furthermore, we use these membrane operators to construct projection operators that measure the topological charge and show that the number of distinct topological charges measured by the 2-torus matches the ground state degeneracy of the model on the 3-torus, explicitly confirming a general expectation for topological phases. This direct construction of the membrane operators sheds significant light on the key properties of the loop-like excitations in 3+1 dimensional topological phases.

On the existence of nematic-superconducting states in the Ginzburg-Landau regime. (arXiv:2401.13106v1 [cond-mat.supr-con])
Mariano De Leo, Juan Pablo Borgna, Diego García Ovalle

In this article, we investigate the existence of nematic-superconducting states in the Ginzburg-Landau regime, both analytically and numerically. From the configurations considered, a slab and a cylinder with a circular cross-section, we demonstrate the existence of geometrical thresholds for the obtention of non-zero nematic order parameters. Within the frame of this constraint, the numerical calculations on the slab reveal that the competition or collaboration between nematicity and superconductivity is a complex energy minimization problem, requiring the accommodation of the Ginzburg-Landau parameters of the decoupled individual systems, the sign of the bi-quadratic potential energy relating both order parameters and the magnitude of the applied magnetic field. Specifically, the numerical results show the existence of a parameter regime for which it is possible to find mixed nematic-superconducting states. These regimes depend strongly on both the applied magnetic field and the potential coupling parameter. Since the proposed model corresponds to the weak coupling regime, and since it is a condition on these parameters, we design a test to decide whether this condition is fulfilled.

Spinodal decomposition and domain coarsening in a multi-layer Cahn-Hilliard model for lithium intercalation in graphite. (arXiv:2401.13108v1 [cond-mat.mtrl-sci])
Antoine Cordoba, Marion Chandesris, Mathis Plapp

During the intercalation of lithium in layered host materials such as graphite, lithium atoms can move within the plane between two neighboring graphene sheets, but cannot cross the sheets. Repulsive interactions between atoms in different layers lead to the existence of ordered phases called "stages", with stage $n$ consisting of one filled layer out of $n$, the others being empty. Such systems can be conveniently described by a multi-layer Cahn-Hilliard model, which can be seen as a mean-field approximation of a lattice-gas model with intra- and interlayer interactions between lithium atoms. In this paper, the dynamics of stage formation after a rapid quench to lower temperature is analyzed, both by a linear stability analysis and by numerical simulation of the full equations. In particular, the competition between stages 2 and 3 is studied in detail. The linear stability analysis predicts that stage 2 always grows the fastest, even in the composition range where stage 3 is the stable equilibrium state. This is borne out by the numerical simulations, which show that stage 3 emerges only during the non-linear coarsening of stage 2. Some consequences of this finding for the charge-discharge dynamics of electrodes in batteries are briefly discussed.

Persistent homology and topological statistics of hyperuniform point clouds. (arXiv:2401.13123v1 [cond-mat.stat-mech])
Marco Salvalaglio, Dominic J. Skinner, Jörn Dunkel, Axel Voigt

Hyperuniformity, the suppression of density fluctuations at large length scales, is observed across a wide variety of domains, from cosmology to condensed matter and biological systems. Although the standard definition of hyperuniformity only utilizes information at the largest scales, hyperuniform configurations have distinctive local characteristics. However, the influence of global hyperuniformity on local structure has remained largely unexplored; establishing this connection can help uncover long-range interaction mechanisms and detect hyperuniform traits in finite-size systems. Here, we study the topological properties of hyperuniform point clouds by characterizing their persistent homology and the statistics of local graph neighborhoods. We find that varying the structure factor results in configurations with systematically different topological properties. Moreover, these topological properties are conserved for subsets of hyperuniform point clouds, establishing a connection between finite-sized systems and idealized reference arrangements. Comparing distributions of local topological neighborhoods reveals that the hyperuniform arrangements lie along a primarily one-dimensional manifold reflecting an order-to-disorder transition via hyperuniform configurations. The results presented here complement existing characterizations of hyperuniform phases of matter, and they show how local topological features can be used to detect hyperuniformity in size-limited simulations and experiments.

Tunable Topological Phase Transitions in a Piezoelectric Janus Monolayer. (arXiv:2401.13124v1 [cond-mat.mtrl-sci])
Tanshia Tahreen Tanisha (1), Md. Shafayat Hossain (2), Nishat Tasnim Hiramony (1), Ashiqur Rasul (1), M. Zahid Hasan (2), Quazi D. M. Khosru (1) ((1) Department of Electrical and Electronic Engineering, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh, (2) Department of Physics, Princeton University, Princeton, NJ, USA)

Quantum Spin Hall (QSH) insulators represent a quintessential example of a topological phase of matter, characterized by a conducting edge mode within a bulk energy gap. The pursuit of a tunable QSH state stands as a pivotal objective in the development of QSH-based topological devices. In this study, we employ first-principles calculations to identify three strain-tunable QSH insulators based on monolayer MAlGaTe4 (where M represents Mg, Ca, or Sr). These monolayers exhibit dynamic stability, with no imaginary modes detected in their phonon dispersion. Additionally, they possess piezoelectric properties, rendering them amenable to strain-induced tuning. While MgAlGaTe4 is a normal insulator under zero strain, it transitions into the QSH phase when subjected to external strain. Conversely, CaAlGaTe4 and SrAlGaTe4 already exhibit the QSH phase at zero strain. Intriguingly, upon the application of biaxial strain, these two compounds undergo phase transitions, encompassing metallic (M), normal/trivial insulator (NI), and topological insulator (TI) phases, thereby illustrating their strain-tunable electronic and topological properties. (Ca, Sr)AlGaTe4, in particular, undergo M-TI/TI-M transitions under applied strain, while MgAlGaTe4 additionally experiences an M-NI/NI-M transition, signifying it as a material featuring a metal-insulator transition (MIT). Remarkably, the observation of metal-trivial insulator-topological insulator transitions in MgAlGaTe4 introduces it as a unique material platform in which both MIT and topological phase transitions can be controlled through the same physical parameter. Our study thus introduces a novel material platform distinguished by highly strain-tunable electronic and topological properties, offering promising prospects for the development of next-generation, low-power topological devices.

Dynamical Chiral Nernst Effect in Twisted Van der Waals Few Layers. (arXiv:2401.13278v1 [cond-mat.mes-hall])
Juncheng Li, Dawei Zhai, Cong Xiao, Wang Yao

The Nernst effect is a fundamental thermoelectric conversion phenomenon that was deemed to be possible only in systems with magnetic field or magnetization. In this work, we propose a novel dynamical chiral Nernst effect that can appear in two-dimensional van der Waals materials with chiral structural symmetry in the absence of any magnetic degree of freedom. This unconventional effect is triggered by time variation of an out-of-plane electric field, and has an intrinsic quantum geometric origin linked to not only the intralayer center-of-mass motion but also the interlayer coherence of electronic states. We demonstrate the effect in twisted homobilayer and homotrilayer transition metal dichalcogenides, where the strong twisted interlayer coupling leads to sizable intrinsic Nernst conductivities well within the experimental capacity. This work suggests a new route for electric control of thermoelectric conversion.

Influence of resonant plasmonic nanoparticles on optically accessing the valley degree of freedom in 2D semiconductors. (arXiv:2401.13372v1 [physics.optics])
Tobias Bucher (1, 2, 3), Zlata Fedorova (1, 2, 3), Mostafa Abasifard (2, 1, 3), Rajeshkumar Mupparapu (2), Matthias J. Wurdack (4, 1, 2, 3), Emad Najafidehaghani (5), Ziyang Gan (5), Heiko Knopf (6, 2, 3), Antony George (5, 3), Falk Eilenberger (6, 2, 3, 7), Thomas Pertsch (2, 3, 6, 7), Andrey Turchanin (5, 3, 8), Isabelle Staude (1, 2, 3, 7) ((1) Institute of Solid State Physics, Friedrich Schiller University Jena, Germany (2) Institute of Applied Physics, Friedrich Schiller University Jena, Germany (3) Abbe Center of Photonics, Friedrich Schiller University Jena, Germany (4) ARC Centre of Excellence in Future Low-Energy Electronics Technologies and Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, Australia (5) Institute of Physical Chemistry, Friedrich Schiller University Jena, Germany (6) Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Jena, Germany (7) Max Planck School of Photonics, Germany (8) Jena Center for Soft Matter (JCSM), Jena, Germany)

The valley degree of freedom is one of the most intriguing properties of atomically thin transition metal dichalcogenides. Together with the possibility to address this degree of freedom by valley-contrasting optical selection rules, it has the potential to enable a completely new class of future electronic and optoelectronic devices. Resonant optical nanostructures emerge as promising tools for controlling the valley degree of freedom at the nanoscale. However, a critical understanding gap remains in how nanostructures and their nearfields affect the polarization properties of valley-selective chiral emission hindering further developments in this field. In order to address this issue, our study delves into the experimental investigation of a hybrid model system where valley-specific chiral emission from monolayer molybdenum disulfide is interacting with a resonant plasmonic nanosphere. Contrary to the intuition suggesting that a centrosymmetric nanoresonator preserves the degree of circular polarization in the farfield, our cryogenic photoluminescence microscopy reveals almost complete depolarization. We rigorously study the nature of this phenomenon numerically considering the monolayer-nanoparticle interaction at different levels including excitation and emission. We find that the farfield degree of polarization strongly reduces in the hybrid system when including excitons emitting from outside of the system's symmetry point, which in combination with depolarisation at the excitation level causes the observed effect. Our results highlight the importance of considering spatially distributed chiral emitters for precise predictions of polarization responses in these hybrid systems. This finding advances our fundamental knowledge of the light-valley interactions at the nanoscale but also unveils a serious impediment of the practical fabrication of resonant valleytronic nanostructures.

Layer-Dependent Quantum Anomalous Hall Effect in Rhombohedral Graphene. (arXiv:2401.13413v1 [cond-mat.mes-hall])
Zhaochen Liu, Jing Wang

The quantum anomalous Hall (QAH) effect, first proposed by the Haldane model, has become a paradigmatic example of application of band topology to condensed matter physics. The recent experimental discoveries of high Chern number QAH effect in pentalayer and tetralayer rhombohedral graphene highlights the intriguing interplay between strong interactions and spin-orbit coupling (SOC). Here we propose a minimal interacting model for spin-orbit coupled rhombohedral graphene and use the Hartree-Fock analysis to explore the phase diagram at charge neutrality. We find that with Ising SOC on one outmost graphene layer, the in-plane layer-antiferromagnetic order is the insulating ground state without displacement field. Upon increasing the gate displacement field, we find that the QAH state with Chern number being equal to the layer number emerges between layer-antiferromagentic state and layer-polarized state, which is consistent with experimental observations. We further study phase diagram for different thickness and find pentalayer is optimal for the QAH effect. Finally, we predict that QAH state is enlarged by engineering opposite Ising SOC on the opposite outmost layers of rhombohedral graphene.

Disorder-induced phase transitions in higher-order nodal line semimetals. (arXiv:2401.13443v1 [cond-mat.dis-nn])
Yue-Ran Ding, Dong-Hui Xu, Chui-Zhen Chen

Higher-order nodal line semimetals represent a recently proposed topological semimetal class that harbors bulk nodal lines and features gapless hinge Fermi arc excitations, governed by the bulk-hinge correspondence. In this study, we investigate the disorder effect on a higher-order nodal line semimetal and the consequent phase transitions. Within the pristine higher-order nodal line semimetal model, we unveil three distinct phases: higher-order nodal line semimetal, conventional nodal line semimetal, and normal insulator. The higher-order nodal line semimetal is characterized by one-dimensional hinge Fermi arc states connecting a pair of nodal rings, contrasting with conventional nodal line semimetals that exhibit two-dimensional drumhead surface states. We demonstrate that disorder can trigger multiple phase transitions within this system. Significantly, intermediate disorder can induce higher-order topology in an initial conventional nodal line semimetal or even an initial normal insulator. Further increase in disorder drives the system through a diffusive metallic phase before ultimately reaching the Anderson insulator regime. Employing a combination of finite-size scaling analysis and an effective medium theory, we construct a comprehensive phase diagram, elucidating the intricate interplay between disorder and topology.

In-plane magnetization orientation driven topological phase transition in OsCl$_3$ monolayer. (arXiv:2401.13449v1 [cond-mat.str-el])
Ritwik Das, Subhadeep Bandyopadhyay, Indra Dasgupta

The quantum anomalous Hall effect resulting from the in-plane magnetization in the OsCl$_3$ monolayer is shown to exhibit different electronic topological phases determined by the crystal symmetries and magnetism. In this Chern insulator, the Os-atoms form a two dimensional planar honeycomb structure with an easy-plane ferromagnetic configuration and the required non-adiabatic paths to tune the topology of electronic structure exist for specific magnetic orientations based on mirror symmetries of the system. Using density functional theory (DFT) calculations, these tunable phases are identified by changing the orientation of the magnetic moments. We argue that in contrast to the buckled system, here the Cl-ligands bring non-trivial topology into the system by breaking the in-plane mirror symmetry. The interplay between the magnetic anisotropy and electronic band-topology changes the Chern number and hence the topological phases. Our DFT study is corroborated with comprehensive analysis of relevant symmetries as well as a detailed explanation of topological phase transitions using a generic tight binding model.

Ordering kinetics in the active Ising model. (arXiv:2401.13471v1 [cond-mat.stat-mech])
Sayam Bandyopadhyay, Swarnajit Chatterjee, Aditya Kumar Dutta, Mintu Karmakar, Heiko Rieger, Raja Paul

We undertake a numerical study of the ordering kinetics in the two-dimensional $(2d)$ active Ising model (AIM), a discrete flocking model with a non-conserved scalar order parameter. We find that for a quench into the liquid-gas coexistence region and in the ordered liquid region, the characteristic length scale of both the density and magnetization domains follows the Lifshitz-Cahn-Allen (LCA) growth law: $R(t) \sim t^{1/2}$, consistent with the growth law of passive systems with scalar order parameter and non-conserved dynamics. The system morphology is analyzed with the two-point correlation function and its Fourier transform, the structure factor, which conforms to the well-known Porod's law, a manifestation of the coarsening of compact domains with smooth boundaries. We also find the domain growth exponent unaffected by different noise strengths and self-propulsion velocities of the active particles. However, transverse diffusion is found to play the most significant role in the growth kinetics of the AIM. We extract the same growth exponent by solving the hydrodynamic equations of the AIM.

Intriguing low-temperature phase in the antiferromagnetic kagome metal FeGe. (arXiv:2401.13474v1 [cond-mat.str-el])
M. Wenzel, E. Uykur, A. A. Tsirlin, S. Pal, R. Mathew Roy, C. Yi, C. Shekhar, C. Felser, A. V. Pronin, M. Dressel

The properties of kagome metals are governed by the interdependence of band topology and electronic correlations resulting in remarkably rich phase diagrams. Here, we study the temperature evolution of the bulk electronic structure of the antiferromagnetic kagome metal FeGe using infrared spectroscopy. We uncover drastic changes in the low-energy interband absorption at the 100 K structural phase transition that has been linked to a charge-density-wave (CDW) instability. We explain this effect by the minuscule Fe displacement in the kagome plane, which results in parallel bands in the vicinity of the Fermi level. In contrast to conventional CDW materials, however, the spectral weight shifts to low energies, ruling out the opening of a CDW gap in FeGe.

Tuning of Charge Order by Uniaxial Stress in a Cuprate Superconductor. (arXiv:2401.13526v1 [cond-mat.supr-con])
Laure Thomarat, Frank Elson, Elisabetta Nocerino, Debarchan Das, Oleh Ivashko, Marek Bartkowiak, Martin Månsson, Yasmine Sassa, Tadashi Adachi, Martin v. Zimmermann, Hubertus Luetkens, Johan Chang, Marc Janoschek, Zurab Guguchia, Gediminas Simutis

Strongly correlated electron materials are often characterized by competition and interplay of multiple quantum states. For example, in high-temperature cuprate superconductors unconventional superconductivity, spin- and charge-density wave orders coexist. A key question is whether competing states coexist on the atomic scale or if they segregate into distinct 'islands'. Using X-ray diffraction, we investigate the competition between charge order and superconductivity in the archetypal cuprate La(2-x)BaxCuO4, around the x = 1/8-doping, where uniaxial stress restores optimal 3D superconductivity at approximately 0.06 GPa. We find that the charge order peaks and the correlation length along the stripe are strongly reduced up to the critical stress, above which they stay constant. Simultaneously, the charge order onset temperature only shows a modest decrease. Our findings suggest that optimal 3D superconductivity is not linked to the absence of charge stripes but instead requires their arrangement into smaller 'islands'. Our results provide insight into the length scales over which the interplay between superconductivity and charge order takes place.

Moving crystal phases of a quantum Wigner solid in an ultra-high-quality 2D electron system. (arXiv:2401.13533v1 [cond-mat.mes-hall])
P. T. Madathil, K. A. Villegas Rosales, Y. J. Chung, K. W. West, K. W. Baldwin, L. N. Pfeiffer, L. W. Engel, M. Shayegan

In low-disorder, two-dimensional electron systems (2DESs), the fractional quantum Hall states at very small Landau level fillings ($\nu$) terminate in a Wigner solid (WS) phase, where electrons arrange themselves in a periodic array. The WS is typically pinned by the residual disorder sites and manifests an insulating behavior, with non-linear current-voltage (\textit{I-V}) and noise characteristics. We report here, measurements on an ultra-low-disorder, dilute 2DES, confined to a GaAs quantum well. In the $\nu < 1/5$ range, superimposed on a highly-insulating longitudinal resistance, the 2DES exhibits a developing fractional quantum Hall state at $\nu=1/7$, attesting to its exceptional high quality, and dominance of electron-electron interaction in the low filling regime. In the nearby insulating phases, we observe remarkable non-linear \textit{I-V} and noise characteristics as a function of increasing current, with current thresholds delineating three distinct phases of the WS: a pinned phase (P1) with very small noise, a second phase (P2) in which $dV/dI$ fluctuates between positive and negative values and is accompanied by very high noise, and a third phase (P3) where $dV/dI$ is nearly constant and small, and noise is about an order of magnitude lower than in P2. In the depinned (P2 and P3) phases, the noise spectrum also reveals well-defined peaks at frequencies that vary linearly with the applied current, suggestive of washboard frequencies. We discuss the data in light of a recent theory that proposes different dynamic phases for a driven WS.

Interfaces of nodal-line semimetals: drum states, transport and refraction. (arXiv:2401.13542v1 [cond-mat.mes-hall])
Mattia Rudi, Alessandro De Martino, Kristof Moors, Domenico Giuliano, Francesco Buccheri

We study transport through interfaces in topological nodal-line semimetals, focusing on two geometries: a single interface between two large samples, one nodal-line semimetal and one metal, and an infinite nodal-line semimetal slab in between two metallic regions. We investigate the dependence of the spectra on the boundary conditions, showing how they affect the surface states and the band dispersion. We find a set of drum states, arising from the hybridization of the drumhead states on opposite surfaces at finite slab width, and describe their signatures in the transport properties of a clean sample. Finally, we compute the electronic trajectories in the ballistic regime and show that there is a series of resonant angles that ensure perfect transmission. We also show how the current density profile acquires an inhomogeneous distribution in the radial direction.

Multi-Dirac and Weyl physics in heavy-fermion systems. (arXiv:2401.13607v1 [cond-mat.str-el])
Joelson F. Silva, E. Miranda

We have studied multi-Dirac/Weyl systems with arbitrary topological charge n in the presence of a lattice of local magnetic moments. To do so, we propose a multi-Dirac/Weyl Kondo lattice model which is analyzed through a mean-field approach appropriate to the paramagnetic phase. We study both the broken time-reversal and the broken inversion-symmetry Weyl cases. The multi- Dirac and broken-time reversal multi-Weyl cases have similar behavior, which is in contrast to the broken-parity case. For the former, low-energy particle-hole symmetry leads to the emergence of a critical coupling constant below which there is no Kondo quenching, reminiscent of the pseudogap Kondo impurity problem. Away from particle-hole symmetry, there is always Kondo quenching. For the broken inversion symmetry, there is no critical coupling. Depending on the conduction electron filling, Kondo insulator, heavy fermion metal or semimetal phases can be realized. In the last two cases, quasiparticle renormalizations can differ widely between opposite chirality sectors, with characteristic dependences on microscopic parameters that could in principle be detected experimentally.

Kibble-Zurek mechanism and errors of gapped quantum phases. (arXiv:2401.13625v1 [quant-ph])
Amit Jamadagni, Javad Kazemi, Arpan Bhattacharyya

Kibble-Zurek mechanism relates the domain of non-equilibrium dynamics with the critical properties at equilibrium. It establishes a power law connection between non-equilibrium defects quenched through a continuous phase transition and the quench rate via the scaling exponent. We present a novel numerical scheme to estimate the scaling exponent wherein the notion of defects is mapped to errors, previously introduced to quantify a variety of gapped quantum phases. To demonstrate the versatility of our method we conduct numerical experiments across a broad spectrum of spin-half models hosting local and symmetry protected topological order. Furthermore, an implementation of the quench dynamics featuring a topological phase transition on a digital quantum computer is proposed to quantify the associated criticality.

Frustrated superconductivity and sextetting order. (arXiv:2209.13745v2 [cond-mat.supr-con] UPDATED)
Zhiming Pan, Chen Lu, Fan Yang, Congjun Wu

Superconducting phase typically favors a uniform spatial distribution like ferromagnet. Nevertheless, the pair-density-wave state exhibits sign changes in the pairing order, and thus frustrations can occur in phase coherence. We propose a mechanism to the sextetting order arising from the frustrations in the phase coherence of a pair-density-wave state, whose spatial modulation manifests a vortex-antivortex honeycomb lattice. The classical ground state configurations are mapped to Baxter's three-coloring model, exhibiting a macroscopic degeneracy and extensive entropy. The phase coherence problem couples the U(1) phases and the vorticity variables together. The resultant color and phase fluctuations suppress the pair-density-wave order but maintain the sextetting order above the superconducting $T_c$. The $1/3$-fractional vortex emerges as the fundamental topological defect in the sextetting order. This novel frustrated superconductivity provides an alternative explanation for the experimental observation of fractional oscillation in CsV$_3$Sb$_5$.

Theory of Fractional Quantum Hall States of the $\mathcal{A}$ phase in the Second Landau Level. (arXiv:2301.00850v2 [cond-mat.mes-hall] UPDATED)
Sudipto Das, Sahana Das, Sudhansu S. Mandal

A proposal of the existence of an {\em Anomalous} phase ($\mathcal{A}$ phase) [ Das et al., Phys. Rev. Lett. 131, 056202 (2023)] at the experimental range of moderate Landau-level-mixing strength has recently been made for $5/2$ state. We here report that the gapped $\mathcal{A}$ phase is generic to the sequence of spin-polarized fractional quantum Hall states with filling fractions $\nu = n/(nm-1)$ and $\nu = 1-n/(nm-1)$, $(n \geqslant 1,\,m\geqslant 3)$, that exhausts almost all the observed states and also predicts some states in the second Landau level for GaAs systems. Our proposed trial wavefunctions for all these states have remarkably high overlaps with the corresponding exact ground states and can support non-Abelian quasiparticle excitations with charge $e/[2(nm-1)]$. By analyzing edge modes, we predict experimentally verifiable thermal Hall conductance $2.5(\pi^2 k_B^2T/3h)$ for all the states in these sequences.

Long-lived valley states in bilayer graphene quantum dots. (arXiv:2304.00980v2 [cond-mat.mes-hall] UPDATED)
Rebekka Garreis, Chuyao Tong, Jocelyn Terle, Max Josef Ruckriegel, Jonas Daniel Gerber, Lisa Maria Gächter, Kenji Watanabe, Takashi Taniguchi, Thomas Ihn, Klaus Ensslin, Wei Wister Huang

Bilayer graphene is a promising platform for electrically controllable qubits in a two-dimensional material. Of particular interest is the ability to encode quantum information in the so-called valley degree of freedom, a two-fold orbital degeneracy that arises from the symmetry of the hexagonal crystal structure. The use of valleys could be advantageous, as known spin- and orbital-mixing mechanisms are unlikely to be at work for valleys, promising more robust qubits. The Berry curvature associated with valley states allows for electrical control of their energies, suggesting routes for coherent qubit manipulation. However, the relaxation time of valley states -- which ultimately limits these qubits' coherence properties and therefore their suitability as practical qubits -- is not yet known. Here, we measure the characteristic relaxation times of these spin and valley states in gate-defined bilayer graphene quantum dot devices. Different valley states can be distinguished from each other with a fidelity of over 99%. The relaxation time between valley triplets and singlets exceeds 500ms, and is more than one order of magnitude longer than for spin states. This work facilitates future measurements on valley-qubit coherence, demonstrating bilayer graphene as a practical platform hosting electrically controlled long-lived valley qubits.

Novel transition dynamics of topological solitons. (arXiv:2304.01264v3 [hep-th] UPDATED)
Kentaro Nishimura, Noriyuki Sogabe

Continuous phase transitions can be classified into ones characterized by local-order parameters and others that need additional topological constraints. The critical dynamics near the former transitions have been extensively studied, but the latter is less understood. We fill this gap in knowledge by studying the transition dynamics to a parity-breaking topological ground state called the chiral soliton lattice in quantum chromodynamics at finite temperature, baryon chemical potential, and external magnetic field. We find a slowing down of the soliton's translational motion as the critical magnetic field approaches while the local dissipation rate remains finite. Therefore, the characteristic time it takes to converge to the stationary state associated with a finite topological number strongly depends on the initial configuration: whether it forms a solitonic structure or not.

Inferring effective couplings with Restricted Boltzmann Machines. (arXiv:2309.02292v3 [cond-mat.dis-nn] UPDATED)
Aurélien Decelle, Cyril Furtlehner, Alfonso De Jesus Navas Gómez, Beatriz Seoane

Generative models offer a direct way of modeling complex data. Energy-based models attempt to encode the statistical correlations observed in the data at the level of the Boltzmann weight associated with an energy function in the form of a neural network. We address here the challenge of understanding the physical interpretation of such models. In this study, we propose a simple solution by implementing a direct mapping between the Restricted Boltzmann Machine and an effective Ising spin Hamiltonian. This mapping includes interactions of all possible orders, going beyond the conventional pairwise interactions typically considered in the inverse Ising (or Boltzmann Machine) approach, and allowing the description of complex datasets. Earlier works attempted to achieve this goal, but the proposed mappings were inaccurate for inference applications, did not properly treat the complexity of the problem, or did not provide precise prescriptions for practical application. To validate our method, we performed several controlled inverse numerical experiments in which we trained the RBMs using equilibrium samples of predefined models with local external fields, 2-body and 3-body interactions in different sparse topologies. The results demonstrate the effectiveness of our proposed approach in learning the correct interaction network and pave the way for its application in modeling interesting binary variable datasets. We also evaluate the quality of the inferred model based on different training methods.

Chirality induced spin selectivity in chiral crystals. (arXiv:2312.04366v2 [cond-mat.mes-hall] UPDATED)
Qun Yang, Yongkang Li, Claudia Felser, Binghai Yan

Chirality is a fundamental property of great importance in physics, chemistry, and biology, and has recently been found to generate unexpected spin polarization for electrons passing through organic molecules, known as chirality-induced spin selectivity (CISS). CISS shows promising application potential in spintronic devices, spin-controlled chemistry, and enantiomer separation. It focuses on organic molecules that exhibit poor electronic conductivity and inherent complexities, such as the debated role of SOC at the molecule-metal interface. In this work, we go beyond organic molecules and study chiral solids with excellent electrical conductivity, intrinsic SOC, and topological electronic structures. We demonstrate that electrons exhibit both spin and orbital polarization as they pass through chiral crystals. Both polarization increases with material thickness before saturating to the bulk values. The spin polarization is proportional to intrinsic SOC while the orbital polarization is insensitive to SOC. The large spin polarization comes with strong electrical magnetochiral anisotropy in the magneto-transport of these chiral crystals (e.g., RhSi). Our work reveals the interplay of chirality, electron spin, and orbital in chiral crystals, paving the way for developing chiral solids for chirality-induced phenomena.

Found 3 papers in prb
Date of feed: Thu, 25 Jan 2024 04:17:07 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)

Hidden magnetic instability in the substituted multiferroics $(\mathrm{Nd},\mathrm{Tb}){\mathrm{Fe}}_{3}{({\mathrm{BO}}_{3})}_{4}$
I. V. Golosovsky, A. A. Mukhin, V. Skumryev, E. Ressouche, V. Yu. Ivanov, and I. A. Gudim
Author(s): I. V. Golosovsky, A. A. Mukhin, V. Skumryev, E. Ressouche, V. Yu. Ivanov, and I. A. Gudim

In the substituted ${\mathrm{Nd}}_{1−x}{\mathrm{Tb}}_{x}{\mathrm{Fe}}_{3}{({\mathrm{BO}}_{3})}_{4}$ $(x=0.1 \text{and} x=0.2)$, possessing almost easy-axis magnetic structure at low temperatures, an unusual two-step transition in fields along the trigonal $c$ axis was observed by magnetization and s…

[Phys. Rev. B 109, 014421] Published Wed Jan 24, 2024

Ideal type-I Weyl phonons in ${\mathrm{BAsO}}_{4}$ with fewest Weyl points
Jian Liu, Xikui Ma, Lei Sun, Zeying Zhang, Yun Ni, Sheng Meng, and Mingwen Zhao
Author(s): Jian Liu, Xikui Ma, Lei Sun, Zeying Zhang, Yun Ni, Sheng Meng, and Mingwen Zhao

Weyl materials exhibit topologically nontrivial electronic or phonon energy-band crossings, offering promising conditions for fabricating novel topological devices and investigating exotic electrical and thermal transport properties. Here, we employ first-principles calculations to analyze the phono…

[Phys. Rev. B 109, 045203] Published Wed Jan 24, 2024

Hyperbolic topological flat bands
Hao Yuan, Weixuan Zhang, Qingsong Pei, and Xiangdong Zhang
Author(s): Hao Yuan, Weixuan Zhang, Qingsong Pei, and Xiangdong Zhang

Topological flat bands, which are regarded as the cornerstone of various topological states induced by the many-body interaction, have aroused great interest in the fields of physics and material science. To date, most of the established topological flat bands have been employed in Euclidean space. …

[Phys. Rev. B 109, L041109] Published Wed Jan 24, 2024

Found 1 papers in prl
Date of feed: Thu, 25 Jan 2024 04:17:04 GMT

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

Synthetic Non-Abelian Gauge Fields for Non-Hermitian Systems
Zehai Pang, Bengy Tsz Tsun Wong, Jinbing Hu, and Yi Yang
Author(s): Zehai Pang, Bengy Tsz Tsun Wong, Jinbing Hu, and Yi Yang

Non-Abelian gauge fields are versatile tools for synthesizing topological phenomena, but have so far been mostly studied in Hermitian systems, where gauge flux has to be defined from a closed loop in order for vector potentials, whether Abelian or non-Abelian, to become physically meaningful. We sho…

[Phys. Rev. Lett. 132, 043804] Published Wed Jan 24, 2024

Found 1 papers in pr_res
Date of feed: Thu, 25 Jan 2024 04:17:04 GMT

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

Ising model formulation for highly accurate topological color codes decoding
Yugo Takada, Yusaku Takeuchi, and Keisuke Fujii
Author(s): Yugo Takada, Yusaku Takeuchi, and Keisuke Fujii

Quantum error correction is an essential ingredient for reliable quantum computation for theoretically provable quantum speedup. Topological color codes, one of the quantum error correction codes, have an advantage against the surface codes in that all Clifford gates can be implemented transversally…

[Phys. Rev. Research 6, 013092] Published Wed Jan 24, 2024

Found 2 papers in acs-nano
Date of feed: Wed, 24 Jan 2024 14:04:26 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] Enabling Waveguide Optics in Rhombohedral-Stacked Transition Metal Dichalcogenides with Laser-Patterned Grating Couplers
Fabian Mooshammer, Xinyi Xu, Chiara Trovatello, Zhi Hao Peng, Birui Yang, Jacob Amontree, Shuai Zhang, James Hone, Cory R. Dean, P. James Schuck, and D. N. Basov

TOC Graphic

ACS Nano
DOI: 10.1021/acsnano.3c08522

[ASAP] Writing and Detecting Topological Charges in Exfoliated Fe5–xGeTe2
Alex Moon, Yue Li, Conor McKeever, Brian W. Casas, Moises Bravo, Wenkai Zheng, Juan Macy, Amanda K. Petford-Long, Gregory T. McCandless, Julia Y. Chan, Charudatta Phatak, Elton J. G. Santos, and Luis Balicas

TOC Graphic

ACS Nano
DOI: 10.1021/acsnano.3c09234

Found 1 papers in science-adv
Date of feed: Wed, 24 Jan 2024 18:58:28 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)

Hidden phonon highways promote photoinduced interlayer energy transfer in twisted transition metal dichalcogenide heterostructures
Amalya C. Johnson, Johnathan D. Georgaras, Xiaozhe Shen, Helen Yao, Ashley P. Saunders, Helen J. Zeng, Hyungjin Kim, Aditya Sood, Tony F. Heinz, Aaron M. Lindenberg, Duan Luo, Felipe H. da Jornada, Fang Liu
Science Advances, Volume 10, Issue 4, January 2024.

Found 2 papers in nat-comm

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

Alkali metal bilayer intercalation in graphene
< author missing >

Magnetoresistive-coupled transistor using the Weyl semimetal NbP
< author missing >