Electronic structure of the Au-intercalated graphene/Ni(111) surface

We report the electronic structure of the Au-intercalated graphene/Ni(111) surface using angle-resolved photoemission spectroscopy and low energy electron diffraction. The graphene/Ni(111) shows no Dirac cone near the Fermi level and a relatively broad C is core level spectrum probably due to the broken sublattice symmetry in the graphene on the Ni(111) substrate. When Au atoms are intercalated between them, the characteristic Dirac cone is completely recovered near the Fermi level and the C 1s spectrum becomes sharper with the appearance of a 10 x 10 superstructure. The fully Au-intercalated graphene/Ni(111) surface shows a p-type character with a hole pocket of similar to 0.034 angstrom(-1) diameter at the Fermi level. When the surface is doped with Na and K, a clear energy gap of similar to 0.4 eV is visible irrespective of alkali metal.