Microstructure and Magnetic Properties of Fe and Fe-alloy Thin Films Epitaxially Grown on MgO(100) Substrates

Abstract

Fe, Fe50Co50, and Fe80Ni20 (at. %) single-crystal films with the (100)bcc plane parallel to the substrate surface were prepared on MgO(100) single-crystals heated at 300 °C by ultra high vacuum molecular beam epitaxy. The film growth mechanism, the film structure, and the magnetic properties were investigated. In-situ reflection high energy electron diffraction and X-ray diffraction analyses indicate that the strains in the films are very small though there are fairly large mismatches of −3.7∼−4.3% at the film/substrate interface. Cross-sectional high-resolution transmission electron microscopy shows that misfit dislocations are introduced in the film at the interface. Dislocations are also observed in the film up to around 10∼20 nm distance from the interface. The presence of such dislocation relieves the strain caused by the lattice mismatch. The in-plane magnetization properties of these films reflect the magnetocrystalline anisotropies of respective bulk Fe, Fe50Co50, and Fe80Ni20 crystals.