Artificially lattice-mismatched graphene/metal interface: Graphene/Ni/Ir(111)

We report on the structural and electronic properties of an artificial graphene/Ni(111) system obtained by the intercalation of a monatomic layer of Ni in graphene/Ir(111). Upon intercalation, Ni grows epitaxially on Ir(111), resulting in a lattice-mismatched graphene/Ni system. By performing scanning tunneling microscopy measurements and density functional theory calculations, we show that the intercalated Ni layer leads to a pronounced buckling of the graphene film. At the same time, an enhanced interaction is measured by angle- resolved photoemission spectroscopy, showing a clear transition from a nearly undisturbed to a strongly hybridized graphene π -band. A comparison of the intercalation-like graphene system with flat graphene on bulk Ni(111), and mildly corrugated graphene on Ir(111), allows us to disentangle the two key properties which lead to the observed increased interaction, namely lattice matching and electronic interaction. Although the latter determines the strength of the hybridization, we find an important influence of the local carbon configuration resulting from the lattice mismatch.