Thermometry for Dirac fermions in graphene

Abstract

We use both the zero-magnetic-field resistivity and the phase coherence time determined by weak localization as independent thermometers for Dirac fermions (DF) in multilayer graphene. In the high current (I) region, there exists a simple power law T DF ∝ I ~0.5, where T DF is the effective Dirac fermion temperature for epitaxial graphene on SiC. In contrast, T DF ∝ I ~1 in exfoliated multilayer graphene. We discuss possible reasons for the different power laws observed in these multilayer graphene systems. Our experimental results on DF-phonon scattering may find applications in graphene-based nanoelectronics.