Coulomb interaction and magnetic catalysis in the quantum Hall effect in graphene

The dynamics of symmetry breaking responsible for lifting the degeneracy of the Landau levels (LLs) in the integer quantum Hall (QH) effect in graphene is studied in a low-energy model with the Coulomb interaction. The gap equation for Dirac quasiparticles is analyzed for both the lowest and higher LLs, taking into account the LL mixing. It is shown that the characteristic feature of the long-range Coulomb interaction is the dependence of the gap parameters on the LL index n ('running' gaps). The renormalization (running) of the Fermi velocity as a function of n is also studied. The solutions of the gap equation reproduce correctly the experimentally observed integer QH plateaus in graphene in strong magnetic fields.