The effect of heat-treatment on the magnetic and structural properties of electroless-plated CoNiReP films with various compositions were studied to determine their microstructure in the as-deposited conditions, as well as to estimate their thermal stability. Due to the difference in compositions, magnetic properties of the films were found to behave differently with heat-treatment. The films with high crystallinity showed larger changes in magnetic properties. The Co32Ni55Re6P7 film with the largest perpendicular magnetic anisotropy kept its positive anisotropy energy with treatment up to 500°C. The 002-oriented hcp structure of this film was also maintained with treatment up to 500°C. However, heat-treatment at 600°C altered the crystal structure of the films from the 002oriented hexagonal close-packed structure to face-centered cubic without preferred crystal orientation, causing a sharp change in the magnetic properties of the films. Since the formation of Ni3P compound and fcc regions was detected in the film with treatment higher than 500°C, it was assumed that in the as-deposited films the 002-oriented hcp crystallites with high crystallinity segregate in the amorphous NiP phase.
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