Observation of the quantum spin Hall effect up to 100 kelvin in a monolayer crystal

By Sanfeng Wu, V. Fatemi, Q. Gibson, Kenji Watanabe, Takashi Taniguchi, R. Cava, P. Jarillo-Herrero. Science, 2017

811 citations recorded by the source corpus.

Heating up the quantum spin Hall effect Taking practical advantage of the topologically protected conducting edge states of topological insulators (TIs) has proven difficult. Semiconductor systems that have been identified as two-dimensional TIs must be cooled down to near liquid helium temperatures to bring out their topological character. Wu et al. fabricated a heterostructure consisting of a monolayer of WTe2 placed between two layers of hexagonal boron nitride and found that its topological properties persisted up to a relatively high temperature of 100 K. Engineering this so-called quantum spin Hall effect in a van der Waals heterostructure makes it possible to apply many established experimental tools and functionalities. Science, this issue p. 76 Transport measurements show that the monolayer of WTe2 has helical edge modes at elevated temperatures. 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 (WTe2) at temperatures up to 100 kelvin. In the short-edge limit, the monolayer exhibits the hallmark transport conductance, ~e2/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.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/f4cc2e846a6bc2461c9fbf7c88d19946eb310c49

Citations in the corpus

• Angle-resolved photoemission studies of quantum materials (2020, neutral): “…dimensions, interactions of types and strengths that are uncommon in 3D become possible, giving rise to a wealth of new material properties ranging from interfacial electron gasses to the high temperature quantum spin Hall effect (Ohtomo and Hwang, 2004; Shkolnikov et al., 2002; Wu et al., 2018).”