Quantum spin Hall effect
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Large anomalous Hall effect driven by a nonvanishing Berry curvature in the noncolinear antiferromagnet Mn <sub>3</sub> Ge Open
A large anomalous Hall effect is observed in the triangular antiferromagnet Mn 3 Ge arising from an intrinsic electronic Berry phase.
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The Quantum Anomalous Hall Effect: Theory and Experiment Open
The quantum anomalous Hall effect is defined as a quantized Hall effect realized in a system without an external magnetic field. The quantum anomalous Hall effect is a novel manifestation of topological structure in many-electron systems a…
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Quantum metric nonlinear Hall effect in a topological antiferromagnetic heterostructure Open
Quantum geometry in condensed-matter physics has two components: the real part quantum metric and the imaginary part Berry curvature. Whereas the effects of Berry curvature have been observed through phenomena such as the quantum Hall effe…
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Higher-order quantum spin Hall effect in a photonic crystal Open
The quantum spin Hall effect lays the foundation for the topologically protected manipulation of waves, but is restricted to one-dimensional-lower boundaries of systems and hence limits the diversity and integration of topological photonic…
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Strong Intrinsic Spin Hall Effect in the TaAs Family of Weyl Semimetals Open
Since their discovery, topological insulators have been expected to be ideal\nspintronic materials owing to the spin currents carried by surface states with\nspin--momentum locking. However, the bulk doping problem remains an obstacle\ntha…
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Quantum Hall effect in a bulk antiferromagnet EuMnBi <sub>2</sub> with magnetically confined two-dimensional Dirac fermions Open
Quantum transport of quasi–two-dimensional Dirac fermions is largely controlled by magnetic order in a layered magnet.
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3D Quantum Hall Effect of Fermi Arcs in Topological Semimetals Open
The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surfac…
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Quantum Spin Hall Effect and Spin Bott Index in a Quasicrystal Lattice Open
Despite the rapid progress in the field of the quantum spin Hall (QSH) effect, most of the QSH systems studied up to now are based on crystalline materials. Here we propose that the QSH effect can be realized in quasicrystal lattices (QLs)…
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Imaging quantum spin Hall edges in monolayer WTe <sub>2</sub> Open
Real-space imaging reveals rich microscopic details of the quantum spin Hall edge conduction in monolayer WTe 2 .
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On the Quantum Spin Hall Gap of Monolayer 1T′‐WTe<sub>2</sub> Open
Positive quantum spin Hall gap in mono-layer 1T'-WTe2 is consistently supported by density-functional theory calculations, ultrafast pump-probe, and electrical transport measurements. It is argued that monolayer 1T'-WTe2 , which was predic…
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Lectures on the Quantum Hall Effect Open
The purpose of these lectures is to describe the basic theoretical structures underlying the rich and beautiful physics of the quantum Hall effect. The focus is on the interplay between microscopic wavefunctions, long-distance effective Ch…
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Even-denominator fractional quantum Hall states in bilayer graphene Open
Exotic states pop up in bilayer graphene Particles with exotic quantum statistics are expected to be able to support an especially appealing flavor of quantum computing (QC) called topological QC. A particular fractional quantum Hall state…
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Spontaneous fractional Chern insulators in transition metal dichalcogenide moiré superlattices Open
The Moiré superlattice realized in two-dimensional heterostructures offers an exciting platform to access strongly correlated electronic states. In this work, we study transition metal dichalcogenides (TMD) Moiré superlattices with time-re…
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Intrinsic spin currents in ferromagnets Open
First principles calculations show that electric fields applied to\nferromagnets generate spin currents flowing perpendicularly to the electric\nfield. Reduced symmetry in these ferromagnets enables a wide variety of such\nspin currents. H…
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Symmetry and quantum kinetics of the nonlinear Hall effect Open
We argue that the static non-linear Hall conductivity can always be\nrepresented as a vector in two-dimensions and as a pseudo-tensor in\nthree-dimensions independent of its microscopic origin. In a single band model\nwith a constant relax…
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Visualizing broken symmetry and topological defects in a quantum Hall ferromagnet Open
The interaction between electrons in graphene under high magnetic fields drives the formation of a rich set of quantum Hall ferromagnetic (QHFM) phases with broken spin or valley symmetry. Visualizing atomic-scale electronic wave functions…
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Quantum Anomalous Hall Effects in Graphene from Proximity-Induced Uniform and Staggered Spin-Orbit and Exchange Coupling Open
We investigate an effective model of proximity modified graphene (or symmetrylike materials) with broken time-reversal symmetry. We predict the appearance of quantum anomalous Hall phases by computing bulk band gap and Chern numbers for be…
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Scattering-free edge states between heterogeneous photonic topological insulators Open
We propose a set of three simple photonic platforms capable of emulating\nquantum topologically insulating phases corresponding to Hall, spin-Hall, and\nvalley-Hall effects. It is shown that an interface between any two of these\nheterogen…
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Quantized photonic spin Hall effect in graphene Open
We examine the photonic spin Hall effect (SHE) in a graphene-substrate system\nwith the presence of external magnetic field. In the quantum Hall regime, we\ndemonstrate that the in-plane and transverse spin-dependent splittings in\nphotoni…
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Prediction of a Large-Gap and Switchable Kane-Mele Quantum Spin Hall Insulator Open
Fundamental research and technological applications of topological insulators are hindered by the rarity of materials exhibiting a robust topologically nontrivial phase, especially in two dimensions. Here, by means of extensive first-princ…
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Topological Phase Transitions in the Photonic Spin Hall Effect Open
The recent synthesis of two-dimensional staggered materials opens up burgeoning opportunities to study optical spin-orbit interactions in semiconducting Dirac-like systems. We unveil topological phase transitions in the photonic spin Hall …
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Approximately Quantized Thermal Hall Effect of Chiral Liquids Coupled to Phonons Open
The recent observation of a half-integer quantized thermal Hall effect in\n$\\alpha$-RuCl$_3$ is interpreted as a unique signature of a chiral spin liquid\nwith a Majorana edge mode. A similar quantized thermal Hall effect is expected\nin …
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Quantum Spin Hall States and Topological Phase Transition in Germanene Open
We present the first experimental evidence of a topological phase transition in a monoelemental quantum spin Hall insulator. Particularly, we show that low-buckled epitaxial germanene is a quantum spin Hall insulator with a large bulk gap …
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Theory of spin Bott index for quantum spin Hall states in nonperiodic systems Open
This is a joint publication with the Letter by H. Huang and F. Liu [Phys. Rev. Lett. 121, 126401 (2018)]. In this work, we propose the spin Bott index to identify the quantum spin Hall (QSH) state in both crystalline and non-periodic syste…
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Theory of spin Hall magnetoresistance (SMR) and related phenomena Open
We review the so-called spin Hall magnetoresistance (SMR) in bilayers of a magnetic insulator and a metal, in which spin currents are generated in the normal metal by the spin Hall effect. The associated angular momentum transfer to the fe…
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Fractional Quantum Hall Effects Open
Certain fractional quantum Hall wavefunctions -- particularly including the\nLaughlin, Moore-Read, and Read-Rezayi wavefunctions -- have special structure\nthat makes them amenable to analysis using an exeptionally wide range of\ntechnique…
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Fibonacci anyons and charge density order in the 12/5 and 13/5 quantum Hall plateaus Open
The $\nu=12/5$ fractional quantum Hall plateau observed in $\mathrm{GaAs}$ semiconductor wells is a suspect in the search for non-Abelian Fibonacci anyons. Using the infinite density matrix renormalization group, we find clear evidence tha…
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Elastic quantum spin Hall effect in kagome lattices Open
A Quantum Spin-Hall Insulator (QSHI) is implemented into a simple mass-spring\nKagome lattice. The transition from the trivial state to the topological one is\ndescribed by an invariant Chern number function of a contrast parameter. The\nb…
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Challenges in identifying chiral spin textures via the topological Hall effect Open
Chiral spin textures such as skyrmions are of interest to the field of spintronics for their potential use in future computing devices. Hall effect measurements are a simple and powerful method to probe the electronic and magnetic properti…
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Quantum Hall effect and semiconductor-to-semimetal transition in biased black phosphorus Open
We study the quantum Hall effect of 2D electron gas in black phosphorus in\nthe presence of perpendicular electric and magnetic fields. In the absence of a\nbias voltage, the external magnetic field leads to a quantization of the energy\ns…