Valley-Polarized Quantum Anomalous Hall Phase in Bilayer Graphene with Layer-Dependent Proximity Effects

TL;DR

This paper predicts a controllable valley-polarized quantum anomalous Hall phase in bilayer graphene achieved through layer-specific proximity effects, offering potential for low-power electronics and valleytronics.

Contribution

It introduces a novel method to realize and control a valley-polarized quantum anomalous Hall effect in bilayer graphene via layer-dependent spin-orbit and magnetic proximity effects.

Findings

Valley-polarized edge states are robust and controllable.

The topological phase can be switched by gate voltage and exchange sign.

Quantum transport confirms the resilience of the edge states.

Abstract

Realizations of some topological phases in two-dimensional systems rely on the challenge of jointly incorporating spin-orbit and magnetic exchange interactions. Here, we predict the formation and control of a fully valley-polarized quantum anomalous Hall effect in bilayer graphene, by separately imprinting spin-orbit and magnetic proximity effects in different layers. This results in varying spin splittings for the conduction and valence bands, which gives rise to a topological gap at a single Dirac cone. The topological phase can be controlled by a gate voltage and switched between valleys by reversing the sign of the exchange interaction. By performing quantum transport calculations in disordered systems, the chirality and resilience of the valley-polarized edge state are demonstrated. Our findings provide a promising route to engineer a topological phase that could enable low-power electronic devices and valleytronic applications.