Chiral states around a mass-inverted quantum dot in graphene

TL;DR

This paper investigates topologically protected chiral states around a mass-inverted quantum dot in graphene, revealing robust metallic channels that could enable new topological state engineering in graphene-based systems.

Contribution

It introduces a model of a mass-inverted quantum dot in graphene and demonstrates the existence and robustness of chiral topological states at the heterojunction.

Findings

Emergent metallic channels across the mass gap when mass signs are opposite.

Eigenstates are doubly degenerate and propagate in opposite directions.

Chiral states are robust unless atomic vacancies are near the domain wall.

Abstract

Topologically protected chiral states at a mass-inverted quantum dot in graphene are studied by analyzing both tight-binding and kernal polynomial method calculations. The mass-inverted quantum dot is introduced by considering a heterojunction between two different mass domains, which is similar to the domain wall in bilayer graphene. The numerical results show emergent metallic channels across the mass gap when the signs of the mass terms are opposite. The eigenstates of the metallic channels are revealed to be doubly degenerate---each state propagates along opposite directions, maintaining the time-reversal symmetry of graphene. The robustness of the metallic channels is further examined, concluding with the fact that chiral states are secured unless atomic vacancies form near the domain wall. Such chiral states circulating along the topological defects may pave a novel route to engineering topological states based on graphene.