Epitaxial Growth of Co Thin Films on SrTiO<sub>3</sub> Single-Crystal Substrates

Abstract

Co thin films were prepared on SrTiO3(100), SrTiO3(110), and SrTiO3(111) single-crystal substrates by ultra-high vacuum molecular beam epitaxy. The film structure and the magnetic properties were investigated. Co epitaxial thin films are obtained on these SrTiO3 substrates at elevated temperatures with different film orientations. The nucleation of Co thin film on SrTiO3 substrate varies depending on the substrate orientation and the substrate temperature. Co(100)fcc single-crystal films are obtained on SrTiO3(100) substrates. On SrTiO3(110) substrates, Co epitaxial thin films with Co(110)fcc, Co(111)fcc and/or Co(0001)hcp, and Co(100)fcc planes parallel to the substrate surface are formed. Thin films consisting of Co(111)fcc and Co(0001)hcp crystals epitaxially grow on SrTiO3(111) substrates. 0.4-0.5% reductions in lattice spacing normal to the substrate surface are observed for Co thin films prepared at a substrate temperature of 300°C. The film strain decreases with increasing the substrate temperature. The in-plane magnetization properties of Co thin films are influenced by the magnetocrystalline anisotropy and the shape anisotropy caused by the roughness of Co islands which form the Co thin films.