Swift heavy ion induced mixing in Fe/Ni multilayer

Investigation of the effect of 120 MeV Au ion irradiation on a Fe/Ni multilayer has been made through X-ray diffraction, X-ray reflectivity, magneto-optic Kerr effect and four probe resistivity measurements. Interface mixing, resulting in FeNi3 and FeNi alloy phase formation, has been observed as a result of the irradiation. The saturation magnetization of the film has been observed to increase after irradiation because of the high magnetic moment of the mixed phase. A drop in resistivity after irradiation to nearly half of its pristine value observed throughout the measured temperature range of 4.2–300 K is an evidence of a considerable smoothening of the interfaces due to interface mixing. It has also been argued that the mixing takes place due to an interdiffusion during the transient melt phase predicted by the thermal spike model of swift heavy ion–matter interaction.