Topological electric field-defined quantum dots in bilayer graphene: An atomistic approach

TL;DR

This paper investigates topological bound states in electric field-defined quantum dots in bilayer graphene using an atomistic tight-binding approach, revealing effects related to atomic structure and valley properties.

Contribution

It introduces an atomistic method to analyze topological quantum dots in bilayer graphene, capturing atomic-scale effects beyond continuum models.

Findings

Discrete bound states localized at the dot boundary

Effects of atomic structure on valley mixing and asymmetry

Identification of new phenomena related to electric field and atomic details

Abstract

We study topological bound states in quantum dots defined by an electric field in bilayer graphene. An external field is perpendicular to the bilayer and changes sign in a finite region that defines the quantum dot. The electric field opens a gap in the bilayer graphene, and the reversed field creates a domain wall with one-dimensional chiral gapless bands localized therein. The finite size of dots leads to the quantization of these bands and the appearance of discrete bound states localized at the dot boundary. We consider rectangular dots oriented along the armchair and zigzag directions. We go beyond a simple continuum one-valley model and use an atomistic tight-binding approach. This allows us to identify new effects related to the atomic structure of graphene, strengths of the electric field, valley mixing, and valley asymmetry.