Valley Edelstein effect in monolayer transition-metal dichalcogenides

We predict the emergence of the valley Edelstein effect (VEE), which is an electric-field-induced spin-polarization effect, in gated monolayer transition-metal dichalcogenides (MTMDs). We found an unconventional valley-dependent response in which the spin polarization is parallel to the applied electric field with opposite spin polarization generated by opposite valleys. This is in sharp contrast to the conventional Edelstein effect in which the induced spin polarization is perpendicular to the applied electric field. We identify the origin of VEE as combined effects of conventional Edelstein effect and valley-dependent Berry curvatures induced by coexisting Rashba and Ising spin-orbit couplings in gated MTMDs. Experimental schemes to detect the VEE are also considered.