Coulomb drag in grapheme
In this talk I present a theory of the Coulomb drag effect between two closely positioned graphene monolayers. The interest to the Coulomb drag is motivated by recent experiments with by-layer graphene systems, which use either boron-nitride or aluminium oxide as a spacer. These experiments reveal a strongly non-monotonous dependence of drag resistivity on the electron concentration in graphene. I give a qualitative explanation of the experimental data and discuss the limits of applicability of the Fermi-liquid theory of the Coulomb drag. I also show how to extend the theory to the regime of non-degenerate Fermi liquid which is realized in clean graphene samples doped to a close vicinity of the Dirac point. A further increase in the drag resistivity is predicted in this case.