Ultrathin epitaxial cobalt films formed under graphene

The intercalation of cobalt under a graphene monolayer grown on a Ni(111) single crystal film is studied. The experiments are conducted in ultrahigh vacuum. Samples are characterized in situ by low energy electron diffraction, high-energy-resolution photoelectron spectroscopy using synchrotron radiation, and magnetic linear dichroism in photoemission of Co 3$p$ electrons. New data are obtained on the evolution of the atomic and electronic structure and magnetic properties of the system with increasing thickness of the intercalated cobalt layer in the range up to 2 nm. It is shown that a pseudomorphic epitaxial film of Co(111) having magnetization perpendicular to the surface is formed under the grapheme layer during intercalation in an anomalously wide range of thicknesses.