The peculiar case of graphene growth on Co(100)

Chemical vapor deposition (CVD) stands as one of the most effective methods for obtaining large-area, high-quality graphene sheets. While extensive research has focused on hexagonally symmetric substrates, there is a striking scarcity in the literature addressing graphene growth on quadratic surfaces of ferromagnetic transition metals. In this study, we devised a growth pathway of monolayer graphene on a thin Co(100) film and unraveled the electronic and magnetic properties using a combination of surface-sensitive spectro-microscopy techniques. X-ray photoemission (XPS) and angle-resolved photoemission spectroscopy (ARPES) reveal the formation of a free-standing graphene layer decoupled from the cobalt support due to the presence of a metal-carbide interlayer. Notably, high-temperature annealing transforms this decoupled graphene into a strongly interacting system, with the recrystallized cobalt assuming a hexagonal symmetry. Finally, oxygen intercalation at the Gr/C/Co(100) interface leads to the removal of the carbidic layer, forms an oxygen interlayer, which induces p-doping in the graphene layer and decouples it from the substrate.