Publication

Abstract : The quantum Hall effect is observed in a two-dimensional electron gas formed in millimeter-scale hydrogenated graphene, with a mobility less than 10 cm2/V⋅s and corresponding Ioffe-Regel disorder parameter (kFλ)−1≫1. In zero magnetic field and low temperatures, the hydrogenated graphene is insulating with a two-point resistance of order of 250h/e2. Application of a strong magnetic field generates a negative colossal magnetoresistance, with the two-point resistance saturating within 0.5% of h/2e2 at 45T. Our observations are consistent with the opening of an impurity-induced gap in the density of states of graphene. The interplay between electron localization by defect scattering and magnetic confinement in two-dimensional atomic crystals is discussed.