MICROSTRUCTURAL STUDY OF ELECTROLESS PLATED CONIP TERNARY ALLOY-FILMS FOR PERPENDICULAR MAGNETIC RECORDING MEDIA

The microstructure of electroless CoNiP films with various Hc(perpendicular-to) values for use as perpendicular magnetic recording media was investigated. It was observed that the Hc(perpendicular-to) values of the films varied according to their microstructure. The film which showed the highest Hc(perpendicular-to) value contained large columnar grains with high crystallinity, whereas such a clear columnar structure was not observed in the films with lower Hc(perpendicular-to) values. The shape anisotropy due to the columnar structure effectively contributes to the magnetic properties of the films as well as magnetocrystalline anisotropy associated with preferred crystallographic orientation. The contribution of the shape anisotropy which is due to each particle forming the columns is also expected. The initial deposition region consisted of randomly oriented, granular fee crystallites with Ni-rich composition, while the upper region had a columnar structure consisting of <002> perpendicularly oriented hcp crystallites for high coercivity films, and mixed crystallites of <002> oriented hcp and randomly oriented fcc for the lower coercivity films. The results of compositional analysis of ultra small regions suggested that the formation of low Ms and low Hc regions at the initial deposition stage was due to a preferential deposition of Ni.