Topological charge pumping in twisted bilayer graphene

TL;DR

This paper demonstrates that sliding layers in twisted bilayer graphene can induce topological charge pumping and chiral currents, linking mechanical motion to electrical effects with potential applications in nanotechnology.

Contribution

It introduces the concept of topological charge pumping in twisted bilayer graphene via layer sliding, revealing a novel mechanical-electrical coupling in moire superlattices.

Findings

Sliding motion induces electric currents in twisted bilayer graphene.

A transverse chiral charge pump is possible in twisted homobilayers.

The effect is confirmed through adiabatic current calculations.

Abstract

We show that a sliding motion between the two layers of a \moire superlattice induces an electric current and realizes a two-dimensional version of the topological Thouless pump when the Fermi energy lies in one of the minigaps. Interestingly, a chiral charge pump, namely, a transverse current induced by the sliding motion, is possible in twisted homobilayers. This result is confirmed by a concrete calculation of the adiabatic current in twisted bilayer graphene. Our work reveals an interesting link between mechanical motion and electricity unique to \moire superlattices, and may find applications in nanogenerators and nanomotors.