Preparation and Characterization of NiFe Epitaxial Thin Films Grown on MgO(100) and SrTiO $_{3}$ (100) Single-Crystal Substrates

NiFe epitaxial thin films were prepared on MgO(100) and SrTiO₃(100) single-crystal substrates by UHV-molecular beam epitaxy. The effects of substrate material and substrate temperature on the structure and the magnetic properties were investigated. In the early stage of NiFe film growth on MgO(100) substrate, formation of NiFe(112macr0) epitaxial film with hcp structure is observed by in-situ RHEED. The metastable hcp-NiFe phase is presumably favored to relax the strain caused by a lattice mismatch at the NiFe/MgO(100) interface. With increasing the film thickness, fcc-NiFe(100) phase appears and the RHEED intensity from the fcc-phase increases. On the contrary, a high-quality fcc-NiFe(100) single-crystal film epitaxially grows on an SrTiO₃ (100) substrate. The magnetic properties of the NiFe epitaxial thin films grown on both the MgO(100) and the SrTiO ₃(100) substrates are influenced by the magnetocrystalline anisotropy of fcc-NiFe crystal and the shape anisotropy caused by the surface undulations.