Berry curvature, spin Hall effect, and nonlinear optical response in moiré transition metal dichalcogenide heterobilayers
Jin-Xin Hu, Ying-Ming Xie, K. T. Law
Abstract
Recently, topological flat bands and the spin Hall effect have been experimentally observed in AB-stacked ${\mathrm{MoTe}}_{2}/{\mathrm{WSe}}_{2}$ heterostructures. In this paper, we systematically study the Berry curvature effects in moir\'e transition metal dichalcogenide (TMD) heterobilayers. We point out that the moir\'e potential of the remote conduction bands would induce a sizable periodic pseudomagnetic field (PMF) on the valence band. This periodic PMF creates net Berry curvature flux in each valley of the moir\'e Brillouin zone. The combination of the effect of the Berry curvature and the spin-valley locking can induce the spin Hall effect being observed in the experiment. Interestingly, the valley-contrasting Berry curvature distribution generated by the PMF can be probed through shift currents, which are dc currents induced by linearly polarized light through nonlinear responses. Our work sheds light on the novel quantum phenomena induced by Berry curvature in moir\'e TMD heterobilayers.