Origin of the vortex displacement field in twisted bilayer graphene

TL;DR

This paper presents a model explaining vortex displacement fields in twisted bilayer graphene using dislocation ensembles, clarifying the structural features observed experimentally.

Contribution

It introduces a dislocation-based model that accounts for vortex-like displacements and layer rotation in twisted bilayer graphene.

Findings

Three dislocation ensembles suffice to describe layer rotation and vortex displacements.

The model explains observed vortex patterns and alternating stacking in twisted bilayer graphene.

Provides a unified framework for understanding atomic displacement patterns.

Abstract

Model description of patterns of atomic displacements in twisted bilayer systems has been proposed. The model is based on the consideration of several dislocation ensembles, employing a language that is widely used for grain boundaries and film/substrate systems. We show that three ensembles of parallel screw dislocations are sufficient both to describe the rotation of the layers as a whole, and for the vortex-like displacements resulting from elastic relaxation. The results give a clear explanation of the observed features of the structural state such as vortices, accompanied by alternating stacking.