The Role of Hydrogen Heat Treatment during Ordering Processes in FePd- and FePt-Based Nanosize Films

The review presents experimental results obtained during the study of the solid-state reaction of A1→L10 ordering within the nanosize FePd and FePt films of equiatomic composition and doped with Ag, Au during annealing in both a vacuum and hydrogen. The behaviour of hydrogen within the film and its influence on the phase composition, structure, and the hydrogen-induced change in magnetic states and properties are considered. Ordering processes in films based on equiatomic FePd and FePt alloys are accelerated during annealing in hydrogen environment compared to annealing in vacuum. Introduction of hydrogen atoms leads to the change in electronic structure, the magnetic properties, and states of the film based on FePd. Reversible changes in the magnetic states of the FePd film are shown: ferromagnetic↔paramagnetic by changing the temperature and time of annealing the film in a hydrogen environment. The dynamics of structural changes in FePd films during the ordering processes is investigated by means of the Raman spectroscopy.