Patterning Quasi-Periodic Co 2D-Clusters underneath Graphene on SiC(0001)

Abstract

The behavior of Co nanoparticles (NPs) grown on graphene/SiC(0001) after oxygen exposure and heating in ultrahigh vacuum is investigated. The results of photoelectron spectroscopy (XPS) show that, as grown, the metal is on the surface of the graphene/SiC and suffers oxidation forming a single phase CoO when exposed to O2, even at low doses. After heating in ultrahigh vacuum (UHV), there is a deoxidation of cobalt and intercalation between the graphene (G) and the buffer layer (BL), as indicated by scanning tunneling microscopy (STM) and XPS. Cobalt forms almost regular small 2D clusters between G and BL. Moreover, graphene acts as a barrier to oxidation, preserving the metallic and the magnetic character of the material even when exposed to O2. This paper shows a method for patterning chemically protected Co NPs on graphene/SiC(0001) which could be used in nanomagnetism based devices.