Soft magnetic properties of ion beam reactively sputtered Fe–N thin films on Ge(100)

Abstract

Several iron nitride thin films with nitrogen concentration less than 15 at.% were synthesized on Ge(100) wafers by a reactive ion beam sputtering method in an ammonia atmosphere. The composition and microstructure of these films were monitored by Rutherford backscattering spectroscopy analyses and X-ray diffraction experiments. The soft magnetic properties of these films were measured by a vibrating sample magnetometer. The changes in microstructure and magnetic properties during an annealing process at 180 °C under a flowing nitrogen atmosphere were investigated. It was found that both the saturation magnetization σ s and the coercivity H c of these Fe–N films are higher than that of pure iron film. However, no direct relationship between the higher σ s values and the α′+ α″ phase could be found in the as-synthesized and annealed iron nitride films.