Effect of electron-electron interactions on the conductivity of clean graphene.
Minimal conductivity of a single undoped graphene layer is known to be of the order of the conductance quantum, independent of the electron velocity. We show that this universality does not survive electron-electron interaction, which results in nontrivial frequency dependence. We begin with analyzing the perturbation theory in the interaction parameter g for the electron self-energy and observe the failure of the random-phase approximation. The optical conductivity is then derived from the quantum kinetic equation, and the exact result is obtained in the limit when g<<1<< g|lnomega|.
Department of Physics, University of Utah, Salt Lake City, Utah 84112, USA.
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Mishchenko