Distinguishing Spontaneous Quantum Hall States in Graphene Bilayers

TL;DR

This paper investigates how different broken symmetry states in bilayer graphene respond to external magnetic and electric fields, aiming to identify their unique experimental signatures.

Contribution

It analyzes the effects of Zeeman and interlayer electric fields on the layer antiferromagnet and other states in bilayer graphene, proposing ways to distinguish them experimentally.

Findings

Zeeman fields influence spin polarization in bilayer states.

Interlayer electric fields affect layer pseudospin configurations.

Response and edge state signatures can identify the ground state.

Abstract

Chirally stacked N-layer graphene with N>=2 is susceptible to a variety of distinct broken symmetry states in which each spin-valley flavor spontaneously transfers charge between layers. In mean-field theory the neutral bilayer ground state is a layer antiferromagnet (LAF) state that has opposite spin-polarizations in opposite layers. In this Letter we analyze how the LAF and other competing states are influenced by Zeeman fields that couple to spin and by interlayer electric fields that couple to layer pseudospin, and comment on the possibility of using response and edge state signatures to identify the character of the bilayer ground state experimentally.