Preparation of Co(0001)hcp and (111)fcc Films on Single-Crystal Oxide Substrates

Co thin film were prepared on oxide single-crystal substrates of Al2O3(0001)D51, MgO(111)B1, and SrTiO3(111)E21 by ultra high vacuum molecular beam epitaxy. Effects of substrate material and substrate temperate on the film growth and the crystallographic properties were investigated. Co epitaxial thin films of hcp(0001) and/or fcc(111) orientations are obtained on all the substrate. With increasing the substrate temperature, the volume ratio of hcp to fcc increases for the Co films grown on Al2O3 and MgO substrates, whereas the ratio decrease for the Co film grown on SrTiO3 substrate. The in-plane lattice strain is larger than the out-of-plane strain due to accommodation of lattice mismatch between the film and the substrate