Thermal evolution and aging of Co-sputtered iron-tin thin films

The composition, structure, magnetic properties and stability of iron-tin thin films produced by co-evaporation with dc magnetron sputtering are studied. Rutherford backscattering, Auger electron spectroscopy, X-ray diffraction and conversion electron Moessbauer spectroscopy indicate the formation of a homogeneous solid solution of tin in iron with a concentration well above the limit of equilibrium solid solubility. Measurements with a vibrating-sample magnetometer show that the films present saturation magnetization and remanence similar to those of pure iron, but a much smaller coercivity. Thermal treatment or aging lead to second-phase precipitation, which is accompanied by a growth of coercivity and remanence. (orig.)