Cyclotron resonance in bilayer graphene

E. A. Henriksen, Z. Jiang, L. -C. Tung, M. E. Schwartz, M. Takita, Y. -J. Wang, P. Kim, H. L. Stormer

Published 2008-01-11, updated 2008-02-23Version 2

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.