Surface alloying upon Co intercalation between graphene and Ir(1Â 1Â 1)

Using X-ray reflectivity, grazing incidence X-ray diffraction, scanning tunneling microscopy, and X-ray photoelectron spectroscopy, we investigate the morphology of Co ultra-thin films grown at room temperature on Ir(1 1 1) and graphene/Ir(1 1 1) surfaces, a system of interest in view of novel nanomagnetism and spintronics systems. When Co/graphene/Ir(1 1 1) heterostructures are annealed at 570 K, Co intercalates below the graphene layer. Subsequent annealing to 770 K leads to Co and Ir intermixing and formation of a surface alloy extending over a thickness of about 2-3 monolayers.