| We describe electrical and thermal transport in ideal single-layer graphene close to zero applied bias (Dirac point). There is a crossover from collisionless transport at frequencies larger than kB T/h-bar (T is the temperature) to collision-dominated transport at lower frequencies. We compute the frequency conductivity solving a quantum Boltzmann equation. Due to a peculiarity of the relativistic dispersion in two dimensions the non-equilibrium distribution functions and the quantum critical conductivity can be computed exactly to leading order in 1/log(α) where α characterizes the strength of Coulomb interactions. We also discuss the collision-dominated regime at finite bias and in magnetic fields, making contact with a purely hydrodynamic description of the relativistic plasma of electrons and holes. We predict a collective cyclotron mode of this plasma that should be readily observable at room temperature. |
|