Landau Level Spectroscopy of Ultrathin Graphite Layers

Abstract

Far infrared transmission experiments are performed on ultrathin epitaxial graphite samples in a magnetic field. The observed cyclotron resonancelike and electron-positron-like transitions are in excellent agreement with the expectations of a single-particle model of Dirac fermions in graphene, with an effective velocity of $\stackrel{\texttildelow{}}{c}=1.03\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }\mathrm{m}/\mathrm{s}$.