SU(4) composite fermions in graphene: Fractional quantum Hall states without analog in GaAs

Theoretical studies of the fractional quantum Hall effect (FQHE) in graphene have so far focused on the plausibility and stability of the previously known FQHE states for the interaction matrix elements appropriate for graphene. We consider FQHE for SU(4) symmetry, as appropriate for the situation when all four spin and valley Landau bands are degenerate, and predict FQHE states that have no analog in GaAs. These result from an essential interplay between the twofold spin and valley degeneracies at fractions of the form ν=n∕(2pn±1), for n⩾3. Conditions are outlined for the observation of these states and quantum phase transitions between them; the structure of these states and their excitations is also described.