Correlated random hopping disorder in graphene at high magnetic fields:   Landau level broadening and localization properties
  We study the density of states and localization properties of the lowest Landau levels of graphene at high magnetic fields. We focus on the effects caused by correlated long-range hopping disorder, which, in exfoliated graphene, is induced by static ripples. We find that the broadening of the lowest Landau level shrinks exponentially with increasing disorder correlation length. At the same time, the broadening grows linearly with magnetic field and with disorder amplitudes. The lowest Landau level peak shows a robust splitting, whose origin we identify as the breaking of the sublattice (valley) degeneracy. 
A. L. C. Pereira, C. H. Lewenkopf, E. R. Mucciolo
cond-mat.mes-hall cond-mat.mtrl-sci