Quantum Hall activation gaps in bilayer graphene

TL;DR

This study measures quantum Hall activation gaps in bilayer graphene at high magnetic fields, revealing energy levels follow a relativistic dispersion and that Landau level broadening has both field-independent and field-dependent components.

Contribution

It provides the first detailed measurement of activation gaps in bilayer graphene at high magnetic fields and analyzes the Landau level broadening mechanisms.

Findings

Activation gaps at ν=±4 and ν=±8 are measured up to 30 T.

Energy levels follow a 4-band relativistic hyperbolic dispersion.

Landau level width has both field-independent and linearly field-dependent components.

Abstract

We have measured the quantum Hall activation gaps in bilayer graphene at filling factors $\nu=\pm4$ and $\nu=\pm8$ in high magnetic fields up to 30 T. We find that energy levels can be described by a 4-band relativistic hyperbolic dispersion. The Landau level width is found to contain a field independent background due to an intrinsic level broadening and a component which increases linearly with magnetic field.