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

TL;DR

This paper investigates how moiré patterns in strained graphene/hBN trilayers influence nonlinear Hall-like currents, revealing that Berry dipoles wind and change orientation across the moiré lattice, with implications for 2D material electronics.

Contribution

It introduces a detailed ab initio and semiclassical analysis of Berry dipoles in strained graphene/hBN trilayers, highlighting their moiré-dependent winding behavior.

Findings

Berry dipoles change orientation across the moiré lattice

Moiré patterns influence nonlinear Hall-like currents

Local potential variations affect electronic properties

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.