Thermo-Electric Power of Dirac Fermions in Graphene

On the basis of self-consistent Born approximation for Dirac fermions under charged impurity scatterings in graphene, the theory for calculating the thermo-electric power is developed by using the heat current-current correlation function. The advantage of the present approach is its ability to effectively treat the low doping case where the coherence process involving carriers in both upper and lower bands becomes important. We show that the low temperature behavior of the thermo-electric power as function of the carrier concentration and the temperature observed by the experiments can be successfully explained by our calculation.