Winding Berry dipole on uniaxially strained graphene/hBN/hBN moir\'e trilayers

Abstract

Nonlinear Hall-like currents can be generated by a time-periodic alternating bias on two-dimensional (2D) materials lacking inversion symmetry. To hint that the moir\'e between graphene and its supporting substrate contributes to the homogeneity of nonlinear currents, the change in the local potential $\Delta V(r)$ around horizontally strained graphene due to a homobilayer of hexagonal boron nitride (hBN) was obtained from ab initio calculations, and corrections to on-site energies and hopping matrix elements on graphene's tight-binding electronic dispersion of $\pi-$electrons were calculated. Relying on a semiclassical approximation, Berry dipoles $D$ are seen to change orientation and wind throughout the moir\'e lattice.