SU(4) composite fermions in graphene: New fractional quantum Hall states

Csaba Toke, Jainendra K. Jain

Published 2007-01-01, updated 2007-06-06Version 2

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 new FQHE states that have no analog in GaAs. These result from an essential interplay between the two-fold spin and valley degeneracies at fractions of the form $\nu=n/(2pn\pm 1)$, for $n\geq 3$. 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.