Multi-layer epitaxial graphene (MEG) is investigated using far infrared (FIR) transmission experiments in the different limits of low magnetic fields and high temperatures. The cyclotron-resonance like absorption is observed at low temperature in magnetic fields below 50 mT, allowing thus to probe the nearest vicinity of the Dirac point and to estimate the conductivity in nearly undoped graphene. The carrier mobility is found to exceed 250,000 cm2/(V.s). In the limit of high temperatures, the well-defined Landau level (LL) quantization is observed up to room temperature at magnetic fields below 1 T, a phenomenon unique in solid state systems. A negligible increase in the width of the cyclotron resonance lines with increasing temperature indicates that no important scattering mechanism is thermally activated, supporting recent expectations of high room-temperature mobilities in graphene.
@article{arxiv.0808.3662,
title = {Approaching the Dirac point in high mobility multi-layer epitaxial graphene},
author = {Milan Orlita and Clement Faugeras and Paulina Plochocka and Petr Neugebauer and Gerard Martinez and Duncan K. Maude and Anne-Laure Barra and Mike Sprinkle and Claire Berger and Walter A. de Heer and Marek Potemski},
journal= {arXiv preprint arXiv:0808.3662},
year = {2009}
}