Structure and Magnetic Properties of CoNi Thin Films Epitaxially Grown on MgO(100) and SrTiO $_{3}$ (100) Substrates

CoNi epitaxial thin films were prepared on MgO(100) and SrTiO₃(100) single-crystal substrates by ultra-high vacuum molecular beam epitaxy. Effects of substrate temperature on the structural and magnetic properties of epitaxial films were investigated. On MgO(100) substrate, CoNi epitaxial films consisting of hcp(112¿0) and fcc(100) crystals are obtained whereas on SrTiO₃(100) substrate, CoNi(100) single-crystal films with fcc structure are formed. CoNi film growth on both substrates seems to follow the Volmer-Weber mode. CoNi (100)_fcc single-crystal film with smaller strain is obtained on SrTiO₃ substrate rather than on MgO(100) substrate. The film strain decreases with increasing the substrate temperature. The magnetic hysteresis loops of CoNi epitaxial thin films reflect the magnetocrystalline anisotropies of hcp-CoNi and fcc-CoNi crystals.