Proximity-induced giant spin-orbit interaction in epitaxial graphene on topological insulator

TL;DR

This paper demonstrates that epitaxial graphene on topological insulator Sb2Te3 acquires a giant spin-orbit gap, inducing a quantum spin-Hall phase, which could enable new quantum electronic applications.

Contribution

It reveals that proximity to Sb2Te3 induces a giant spin-orbit interaction in graphene, leading to a quantum spin-Hall phase, a novel finding in heterostructure physics.

Findings

Graphene on Sb2Te3 exhibits a ~20 meV spin-orbit gap.

Proximity effect induces quantum spin-Hall phase in graphene.

Spin-orbit interaction in graphene is enhanced by three orders of magnitude.

Abstract

Heterostructures of Dirac materials such as graphene and topological insulators provide interesting platforms to explore exotic quantum states of electrons in solids. Here we study the electronic structure of graphene-Sb2Te3 heterostructure using density functional theory and tight-binding methods. We show that the epitaxial graphene on Sb2Te3 turns into quantum spin-Hall phase due to its proximity to the topological insulating Sb2Te3. It is found that the epitaxial graphene develops a giant spin-orbit gap of about ~20 meV, which is about three orders of magnitude larger than that of pristine graphene. We discuss the origin of such enhancement of the spin-orbit interaction and possible outcomes of the spin-Hall phase in graphene.