Cyclotron resonance in bilayer graphene

TL;DR

This paper reports the first experimental observation of cyclotron resonance in bilayer graphene, revealing unique magnetic field-dependent transition behaviors indicative of a change from parabolic to linear energy dispersion.

Contribution

It provides the first measurements of cyclotron resonance in bilayer graphene and compares results with theoretical models, highlighting discrepancies and the need for refined theories.

Findings

Observation of four distinct intraband transitions in bilayer graphene

Transition energies show linear B dependence at low levels and  B at higher levels

Experimental data generally agrees with tight binding calculations but reveals inconsistencies

Abstract

We present the first measurements of cyclotron resonance of electrons and holes in bilayer graphene. In magnetic fields up to B = 18 T we observe four distinct intraband transitions in both the conduction and valence bands. The transition energies are roughly linear in B between the lowest Landau levels, whereas they follow \sqrt{B} for the higher transitions. This highly unusual behavior represents a change from a parabolic to a linear energy dispersion. The density of states derived from our data generally agrees with the existing lowest order tight binding calculation for bilayer graphene. However in comparing data to theory, a single set of fitting parameters fails to describe the experimental results.