Charge redistribution and interlayer coupling in twisted bilayer graphene under electric fields

TL;DR

This study reveals that twisted bilayer graphene exhibits layer coupling and charge redistribution under electric fields across all angles, with inhomogeneous charge patterns linked to moiré structures at small angles.

Contribution

It demonstrates that rotated bilayer graphene remains coupled for all angles, challenging the notion that large angles decouple the layers.

Findings

Layer coupling persists at all twist angles.

Charge transfer depends on external voltage.

Inhomogeneous charge distribution relates to moiré patterns.

Abstract

We investigate the electronic density redistribution of rotated bilayer graphene under a perpendicular electric field, showing that the layers are actually coupled even for large angles. This layer-layer coupling is evidenced by the charge transfer on these structures as a function of the external voltage. We find an inhomogeneous excess charge distribution that is related to the moir\'e patterns for small angles, but that persists for larger angles where the carriers' velocity is equal to that of single layer graphene. Our results show that rotated bilayer systems are coupled for all rotation angles.