1988 年 29 巻 2 号 p. 89-98
Iron-nitride films were prepared by reactive sputtering with a two-facing targets type dc sputtering apparatus, and their magnetic properties as well as their film texture and crystal structure were investigated with reference to preparation conditions including sputtering conditions. The microstructure of films was observed by transmission electron microscopy supplemented with electron diffraction analysis. The magnetization curves were measured by a vibrating sample magnetometer (VSM), and Ms and Hc were evaluated in two directions parallel and perpendicular to the film plane. The magnetic domain structures were also studied by Lorentz electron microscopy. Various types of Fe–N compounds, ε-Fe2–3N, γ′-Fe4N and α-Fe, were formed by controlling the sputtering conditions, and the phase stability of each phase was confirmed: A single phase γ′-Fe4N film was prepared in two different ways; a direct deposition onto heated substrates and a successive heating of deposited films. Structural changes with annealing temperature are discussed with reference to the changes in magnetic properties. The change in magnetic coercivity with annealing temperature was found to be related to several parameters such as internal stress in film, grain size and precipitation process.
