Inversion Symmetry Breaking Induced Valley Hall Effect in Multilayer WSe<sub>2</sub>.

Guan, Hongming; Tang, Ning; Huang, Hao; Zhang, Xiaoyue; Su, Meng; Liu, Xingchen; Liao, Lei; Ge, Weikun et al. · ACS Nano · 2019

basic_science · Level V

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Abstract

Two-dimensional transition metal dichalcogenides possess the K (K') valley degree of freedom (DOF). Based on that, the research on valleytronics draws considerable attention. In this report, by breaking the spatial-inversion symmetry by an out-of-plane electric field, the valley Hall effect (VHE) is observed in multilayer tungsten diselenide (WSe<sub>2</sub>) at room temperature. The non-zero Berry curvature emerges, leading to the carriers at K (K') valley being deflected to the opposite sides of the channel, giving rise to a spatial polarization of carriers at K (K') valleys in multilayer WSe<sub>2</sub>. This observation of the VHE illustrates that the K (K') valley DOF can be generated in multilayer WSe<sub>2</sub>, which makes it an alternative candidate for valleytronics.