Inversion Symmetry Breaking Induced Valley Hall Effect in Multilayer WSe2.

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 (WSe2) 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 WSe2. This observation of the VHE illustrates that the K (K') valley DOF can be generated in multilayer WSe2, which makes it an alternative candidate for valleytronics.