Graphene-metal interface: Two-terminal resistance of low-mobility graphene in high magnetic fields

The two-terminal magnetotransport of a single graphene layer was investigated up to a field of 55 T. The dependence of the electron transmission probability at the organo-metallic interface between the graphene and the metal electrodes was studied as a function of filling factor and electron density. A resistance-plateau spanning several tens of tesla width was observed. We argue that this plateau originates from an augmented sublattice spin-splitting due to the high surface-impurity concentration of the graphene layer. At electron densities close to the Dirac point, fingerprints of a thermally activated energy gap were observed.