Low energy two-dimensional plasmon in epitaxial graphene on Ni (111)

Single layer graphene has been obtained on Ni (111) by dissociation of ethylene. Angle-resolved electron-energy-loss spectra show a low energy plasmon dispersing up to about 2 eV, resulting from fluctuation of a charge density located around the Fermi energy, due to hybridization between Ni and graphene states. The dispersion is typical of a two-dimensional charge layer, and the calculated Fermi velocity is a factor of ~ 0.5 lower than in isolated graphene.