Epitaxial Growth of Cobalt Oxide Phases on Ru(0001) for Spintronic Device Applications
Co3O4(111) and CoO(111) films are grown by molecular beam epitaxy on Ru(0001) structures at 500 K. Co3O4(111) films, with distinct photoemission, LEED and electron energy loss spectra are grown in O2 pressures of 10-4 Torr, but only at average film thicknesses > 20 angstroms. CoO films are grown at 7.5 x 10(-7) Torr O2. Co3O4(111) films exhibit surface roughness values of < 1 nm, and dielectric breakdown strengths > 1 MV/cm, with evidence of reversible switching. Both films can support the growth of graphene/graphene oxide heterostructures by MBE, and are therefore suitable device-worthy substrates for graphene growth on magnetic insulators.