AA-stacked bilayer graphene in an applied electric field: Tunable antiferromagnetism and coexisting exciton order parameter

TL;DR

This paper investigates how an applied electric field influences the electronic and magnetic properties of AA-stacked bilayer graphene, revealing tunable antiferromagnetism and exciton order that affect transport behavior.

Contribution

It demonstrates the coexistence and controllability of antiferromagnetic and exciton orders in bilayer graphene under an electric field, a novel insight into tunable 2D material properties.

Findings

Electric field suppresses antiferromagnetic order.

Electric field stabilizes exciton order parameter.

Coexistence of antiferromagnetism and exciton order with sizable energy gaps.

Abstract

We study the electronic properties of AA-stacked bilayer graphene in a transverse electric field. The strong on-site Coulomb repulsion stabilizes the antiferromagnetic order in such a system. The antiferromagnetic order is suppressed by the transverse bias voltage, at least partially. The inter-plane Coulomb repulsion and non-zero voltage stabilize an exciton order parameter. The exciton order parameter coexists with the antiferromagnetism and can be as large as several tens of meV for realistic values of the bias voltage and interaction constants. The application of a transverse bias voltage can be used to control the transport properties of the bilayer.