Observation of the quantum spin Hall effect up to 100 kelvin in a monolayer crystal.
basic_science · Level V
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- Record sourced from PubMed, PMID 29302010.
- Also identified by DOI 10.1126/science.aan6003.
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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<sub>2</sub>) at temperatures up to 100 kelvin. In the short-edge limit, the monolayer exhibits the hallmark transport conductance, ~<i>e</i><sup>2</sup>/<i>h</i> per edge, where <i>e</i> is the electron charge and <i>h</i> 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.