▎ 摘　　要

By taking into account the charge and spin orderings and the exchange interactions between all the Landau levels, we investigate the integer quantum Hall effect of electrons in graphene using the mean-field theory. We find that the fourfold degeneracy of the Landau levels cannot be completely lifted by the Coulomb interactions. In particular, at fillings v = 4n + 2 with n = 0,1,..., there is no splitting between the fourfold degenerated Landau levels. We show that with doping the degenerated lowest empty level can be sequentially filled one by one; the filled level is lower than the empty ones because of the Coulomb-exchange interactions. This result explains the step Delta v. = 1 in the quantized Hall conductivity. We present a highly efficient method for dealing with a huge number of the Coulomb couplings between all the Landau levels of the Dirac fermions.