Long range Coulomb interaction in bilayer graphene

TL;DR

This paper investigates the significant role of long-range Coulomb interactions in bilayer graphene under magnetic fields, revealing their effects on band asymmetry, Landau level mixing, and ground state spin configurations.

Contribution

It provides new insights into how Coulomb interactions influence electronic properties and spin states in bilayer graphene, especially under different electrostatic bias conditions.

Findings

Coulomb interactions account for band asymmetry in optical magneto-absorption.

Interactions cause Landau level mixing in unbiased bilayer graphene.

Ground state spin changes occur due to interactions in biased bilayer at half-filled Landau levels.

Abstract

We report on our studies of interacting electrons in bilayer graphene in a magnetic field. We demonstrate that the long range Coulomb interactions between electrons in this material are highly important and account for the band asymmetry in recent optical magneto-absorption experiments. We show that in the unbiased bilayer (where both layers are at the same electrostatic potential), the interactions can cause mixing of Landau levels in moderate magnetic fields. For the biased bilayer (when the two layers are at different potentials), we demonstrate that the interactions are responsible for a change in the total spin of the ground state for half-filled Landau levels in the valence band.