Observation of the quantum spin Hall effect up to 100 kelvin in a monolayer crystal
Sanfeng Wu,Valla Fatemi,Quinn Gibson,Kenji Watanabe,Takashi Taniguchi,Robert J. Cava,Pablo Jarillo-Herrero +6 more
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TLDR
The QSHE is established in monolayer tungsten ditelluride (WTe2) at temperatures much higher than in semiconductor heterostructures and allow for exploring topological phases in atomically thin crystals.Abstract:
A variety of monolayer crystals have been proposed to be two-dimensional topological insulators exhibiting the quantum spin Hall effect (QSHE), possibly even at high temperatures. Here we report the observation of the QSHE in monolayer tungsten ditelluride (WTe 2 ) at temperatures up to 100 kelvin. In the short-edge limit, the monolayer exhibits the hallmark transport conductance, ~ e 2 / h per edge, where e is the electron charge and h is Planck’s constant. Moreover, a magnetic field suppresses the conductance, and the observed Zeeman-type gap indicates the existence of a Kramers degenerate point and the importance of time-reversal symmetry for protection from elastic backscattering. Our results establish the QSHE at temperatures much higher than in semiconductor heterostructures and allow for exploring topological phases in atomically thin crystals.read more
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Topological Axion States in the Magnetic Insulator MnBi 2 Te 4 with the Quantized Magnetoelectric Effect
TL;DR: It is predicted that the tetradymite-type compound MnBi_{2}Te_{4} and its related materials host topologically nontrivial magnetic states that might lead to a minimal ideal Weyl semimetal.
Journal ArticleDOI
Ferroelectric switching of a two-dimensional metal
Zaiyao Fei,Wenjin Zhao,Tauno Palomaki,Bosong Sun,Moira Miller,Zhiying Zhao,Zhiying Zhao,Jiaqiang Yan,Xiaodong Xu,David Cobden +9 more
TL;DR: In this paper, the topological semimetal WTe2 provides an embodiment of this principle, showing that two- or three-layer Wte2 exhibits spontaneous out-of-plane electric polarization that can be switched using gate electrodes.
Journal ArticleDOI
Observation of the nonlinear Hall effect under time-reversal-symmetric conditions
Qiong Ma,Su-Yang Xu,Huitao Shen,David MacNeill,Valla Fatemi,Tay-Rong Chang,Andrés M. Mier Valdivia,Sanfeng Wu,Z. Z. Du,Z. Z. Du,Chuang-Han Hsu,Shiang Fang,Quinn Gibson,Kenji Watanabe,Takashi Taniguchi,Robert J. Cava,Efthimios Kaxiras,Hai-Zhou Lu,Hsin Lin,Liang Fu,Nuh Gedik,Pablo Jarillo-Herrero +21 more
TL;DR: The nonlinear Hall effect is observed in bilayer WTe2 in the absence of a magnetic field, providing a direct measure of the dipole moment of the Berry curvature, which arises from layer-polarized Dirac fermions in bilayers WTe 2 under time-reversal-symmetric conditions.
Journal ArticleDOI
Nonlinear anomalous Hall effect in few-layer WTe 2
TL;DR: A nonlinear anomalous Hall effect, allowed for certain point group symmetries, is observed in metallic WTe2, and can be understood as an AHE induced by the bias current, which generates an out-of-plane magnetization.
Journal ArticleDOI
van der Waals heterostructures combining graphene and hexagonal boron nitride
TL;DR: A detailed overview of the physics and device properties of van der Waals heterostructures consisting of graphene and hexagonal boron nitride can be found in this article, including the integer and fractional quantum Hall effects, novel plasmonic states and emergent moire superlattices.
References
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Colloquium: Topological insulators
M. Z. Hasan,Charles L. Kane +1 more
TL;DR: In this paper, the theoretical foundation for topological insulators and superconductors is reviewed and recent experiments are described in which the signatures of topologically insulators have been observed.
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Topological insulators and superconductors
Xiao-Liang Qi,Shou-Cheng Zhang +1 more
TL;DR: Topological superconductors are new states of quantum matter which cannot be adiabatically connected to conventional insulators and semiconductors and are characterized by a full insulating gap in the bulk and gapless edge or surface states which are protected by time reversal symmetry.
Journal ArticleDOI
Quantum spin Hall effect in graphene
Charles L. Kane,Eugene J. Mele +1 more
TL;DR: Graphene is converted from an ideal two-dimensional semimetallic state to a quantum spin Hall insulator and the spin and charge conductances in these edge states are calculated and the effects of temperature, chemical potential, Rashba coupling, disorder, and symmetry breaking fields are discussed.
Journal ArticleDOI
Quantum Spin Hall Insulator State in HgTe Quantum Wells
Markus König,Steffen Wiedmann,Steffen Wiedmann,Christoph Brüne,Christoph Brüne,Andreas Roth,Andreas Roth,Hartmut Buhmann,Hartmut Buhmann,Laurens W. Molenkamp,Laurens W. Molenkamp,Xiao-Liang Qi,Xiao-Liang Qi,Shou-Cheng Zhang,Shou-Cheng Zhang +14 more
TL;DR: The quantum phase transition at the critical thickness, d = 6.3 nanometers, was independently determined from the magnetic field–induced insulator-to-metal transition, providing experimental evidence of the quantum spin Hall effect.
Quantum Spin Hall Insulator State in HgTe Quantum Wells
Markus König,Steffen Wiedmann,Steffen Wiedmann,Christoph Brüne,Christoph Brüne,Andreas Roth,Andreas Roth,Hartmut Buhmann,Hartmut Buhmann,Laurens W. Molenkamp,Laurens W. Molenkamp,Xiao-Liang Qi,Xiao-Liang Qi,Shou-Cheng Zhang,Shou-Cheng Zhang +14 more
TL;DR: In this article, the quantum spin Hall effect was observed in HgTe/(Hg,Cd)Te quantum wells with well width d 6.3 nanometers and the residual conductance was independent of sample width, indicating that it is caused by edge states.