Giant magneto-crystalline anisotropy of fct Fe3Pt ordered alloy thin films fabricated onto MgO substrates

The magnetic anisotropy of Fe₃Pt thin films in conjunction with structure is investigated. The thin films with thickness of about 50 nm are fabricated by electron beam evaporation onto MgO(100) and MgO(111) substrates held at the substrate deposition temperatures ranging from ambient to 550°C. X-ray diffraction and transmission electron microscopy analyses reveal that the alloy thin films are epitaxially grown onto MgO(100) and MgO(111) substrates with <001> and <111> orientation, respectively. The in-plane magnetic anisotropy constants, K₁ for the <001> oriented films and K₂ for the <111> oriented ones, are found to be large when the films become ordered and lattice constant ratios are increased. K₁ and K₂ on the other hand decrease for increasing temperature but vanish as the temperature approaches the Curie temperature.