  We report on our studies of interacting electrons in bilayer graphene in a
magnetic field. We demonstrate that the long range Coulomb interactions between
electrons in this material are highly important. We show that in the unbiased
bilayer (where both layers are at the same electrostatic potential), the
interactions can cause mixing of Landau levels in moderate magnetic fields. For
the biased bilayer (when the two layers are at different potentials), we
demonstrate that the interactions are responsible for a change in the total
spin of the ground state for half-filled Landau levels in the valence band.
