Tunable Fermi surface topology and Lifshitz transition in bilayer graphene

TL;DR

This paper reviews how external parameters like electric fields and strain can tune the Fermi surface topology in bilayer graphene, enabling experimental observation of Lifshitz transitions through quantum Hall measurements.

Contribution

It provides a theoretical overview of band structure modifications in bilayer graphene and proposes experimental methods to detect Lifshitz transitions via high displacement fields and quantum Hall effects.

Findings

External perturbations can induce Lifshitz transitions in bilayer graphene.

High displacement fields enable experimental probing of Fermi surface topology changes.

Quantum Hall measurements can detect Lifshitz transition signatures.

Abstract

Bilayer graphene is a highly tunable material: not only can one tune the Fermi energy using standard gates, as in single-layer graphene, but the band structure can also be modified by external perturbations such as transverse electric fields or strain. We review the theoretical basics of the band structure of bilayer graphene and study the evolution of the band structure under the influence of these two external parameters. We highlight their key role concerning the ease to experimentally probe the presence of a Lifshitz transition, which consists in a change of Fermi contour topology as a function of energy close to the edges of the conduction and valence bands. Using a device geometry that allows the application of exceptionally high displacement fields, we then illustrate in detail the way to probe the topology changes experimentally using quantum Hall effect measurements in a gapped bilayer graphene system.