Anomalous Thermoelectric Transport of Dirac Particles in Graphene

We report a thermoelectric study of graphene in both zero and applied magnetic fields. As a direct consequence of the linear dispersion of massless particles, we find that the Seebeck coefficient Sxx diverges with 1/sqrt[|n_{2D}|], where n_{2D} is the carrier density. We observe a very large Nernst signal S_{xy} ( approximately 50 microV/K at 8 T) at the Dirac point, and an oscillatory dependence of both Sxx and S_{xy} on n_{2D} at low temperatures. Our results underscore the anomalous thermoelectric transport in graphene, which may be used as a highly sensitive probe for impurity bands near the Dirac point.