Low density ferromagnetism in biased bilayer graphene

TL;DR

This paper investigates the phase diagram of biased bilayer graphene, revealing a first-order ferromagnetic transition with unequal magnetization in the two layers and contrasting electronic densities.

Contribution

It provides the first detailed analysis of ferromagnetism in biased bilayer graphene, highlighting a first-order transition and layer-dependent magnetic properties.

Findings

Ferromagnetic transition is first order.

Unequal magnetization in the two graphene layers.

Electronic densities are hole-like in one layer and electron-like in the other.

Abstract

We compute the phase diagram of a biased graphene bilayer. The existence of a ferromagnetic phase is discussed with respect both to carrier density and temperature. We find that the ferromagnetic transition is first order, lowering the value of $U$ relatively to the usual Stoner criterion. We show that in the ferromagnetic phase the two planes have unequal magnetization and that the electronic density is hole like in one plane and electron like in the other.