Quantum Anomalous Hall Effect in Graphene Proximity Coupled to an Antiferromagnetic Insulator

TL;DR

This paper proposes a method to realize the quantum anomalous Hall effect in graphene by proximity coupling it to an antiferromagnetic insulator, demonstrated through ab initio calculations showing a tunable topological band gap.

Contribution

It introduces a novel approach to induce the quantum anomalous Hall effect in graphene via proximity to an antiferromagnetic insulator, with detailed computational analysis.

Findings

Proximity-induced exchange field of about 70 meV in graphene.

Topologically nontrivial band gap opened by Rashba spin-orbit coupling.

Band gap size tunable by adjusting graphene-substrate separation.

Abstract

We propose realizing the quantum anomalous Hall effect by proximity coupling graphene to an antiferromagnetic insulator that provides both broken time-reversal symmetry and spin-orbit coupling. We illustrate our idea by performing ab initio calculations for graphene adsorbed on the (111) surface of BiFeO3. In this case, we find that the proximity-induced exchange field in graphene is about 70 meV, and that a topologically nontrivial band gap is opened by Rashba spin-orbit coupling. The size of the gap depends on the separation between the graphene and the thin film substrate, which can be tuned experimentally by applying external pressure.