Structural and magnetic studies of thin Fe57 films formed by ion beam assisted deposition

•Thin films of Fe57with 120nm thickness has deposited on glass by ion beam assisted technique.•Element-phase composition and magnetic properties of both as-deposited and subsequently annealed in vacuum films has been investigated.•As-deposited iron films are in astressful state with nanocrystalline structure containing nanosized inclusions of α-phase iron.•Strong contribution of out-of-plane anisotropy in magnetic behaviour of Fe57 films is observed due to microstresses in the films.•Iron films becomestress-free after thermal annealing and reveal in-plane anisotropy only. Thin Fe57 films with the thickness of 120nm have been prepared on glass substrates by using the ion-beam-assisted deposition technique. X-ray diffraction, electron microdiffraction and Mössbauer spectroscopy studies have shown that as-deposited films are in a stressful nanostructured state containing the nanoscaled inclusions of α-phase iron with the size of ∼10nm. Room temperature in-plane and out-of-plane magnetization measurements confirmed the presence of the magnetic α-phase in the iron film and indicated the strong effect of residual stresses on magnetic properties of the film as well. Subsequent thermal annealing of iron films in vacuum at the temperature of 450°C stimulates the growth of α-phase Fe crystallites with the size of up to 20nm. However, electron microdiffraction and Mössbauer spectroscopic data have shown the partial oxidation and carbonization of the iron film during annealing. The stress disappeared after annealing of the film. The magnetic behaviour of the annealed samples was characterized by the magnetic hysteresis loop with the coercive field of ∼10mT and the saturation magnetization decreased slightly in comparison with the α-phase Fe magnetization due to small oxidation of the film.