Rashba and intrinsic spin-orbit interactions in biased bilayer graphene

TL;DR

This paper explores how intrinsic and Rashba spin-orbit interactions influence the energy spectrum of biased and unbiased bilayer graphene, revealing conditions for Dirac cone formation and band splitting effects.

Contribution

It provides new insights into the effects of spin-orbit interactions on bilayer graphene's electronic structure, including Dirac cone emergence and K point splitting.

Findings

Dirac cone can form from a parabolic band under certain conditions.

A 'Mexican hat'-like dispersion can be created in unbiased bilayer.

Intralayer Rashba interaction splits K points into four.

Abstract

We investigate the effect that the intrinsic spin-orbit and the inter- and intra-layer Rashba interactions have on the energy spectrum of either an unbiased or a biased graphene bilayer. We find that under certain conditions, a Dirac cone is formed out of a parabolic band and that it is possible to create a "Mexican hat"-like energy dispersion in an unbiased bilayer. In addition, in the presence of only an intralayer Rashba interaction, the K (K') point splits into four distinct ones, contrarily to the case in single-layer graphene, where the splitting also takes place, but the low-energy dispersion at these points remains identical.