We have investigated the change in crystallographic and magnetic properties of sendust thin films before/after annealing. Films were deposited by both rf diode and rf magnetron sputtering. rf diode-sputtered films did not possess soft magnetic properties in the as-deposited state. Films were subsequently annealed in both a conventional oven and a rapid thermal annealing (RTA) system. The coercivity of the films decreased from over 10 Oe to a minimum value of 0.6 Oe after annealing and a systematic shift in the (110) x-ray diffraction (XRD) peak position towards that of bulk sendust was observed. No additional XRD peaks were observed after annealing. The optimum annealing conditions to minimize coercivity was found to be 1-2 h at 550 degrees C. By comparison, films processed by RTA resulted in minimum coercivity of 0.9 Oe obtained after annealing for 2 min at 550 degrees C. XRD for films annealed by both RTA and oven annealing showed a similar decrease in the d spacing of the (110) plane, indicating a release of tensile strain in the films that had been introduced during deposition. rf magnetron-deposited samples possessed coercivities as low as 1.4 Oe as deposited and showed in-plane anisotropy. XRD again showed a (110) texture, however, the peak intensity of magnetron-sputtered samples was a factor of 20 less than the diode-sputtered films of the same thickness. The position of the (110) peak, however, was close to that of rf diode deposited films after annealing indicating that the magnetron-sputtered films were relatively stress-free.
Dodd, PM., Atkinson, R., Papakonstantinou, P., Araghi, MS., & Gamble, HS. (1997). Correlation between crystalline structure and soft magnetic properties in sputtered sendust films. Journal of Applied Physics, 81, 4104-4106. https://doi.org/10.1063/1.365094