Magnetic Properties and Microstructure of Electroless-Plated CoNiP Perpendicular Magnetic Recording Media

The correlation between the magnetic properties and micro-structure of electroless-plated CoNiP perpendicular magnetic recording media was investigated. By adjusting the plating bath factors, the perpendicular coercivity, Hc¿, of the film can be controlled to up to 1500 Oe without changing the saturation magnetization Ms and the shapes of the M-H loops. Reflection high-energy electron diffraction (RHEED) analysis showed that these films consist of mixtures of ≪002≫ perpendicularly oriented hep structure regions, and fcc regions without an obvious crystal orientation. The increase in the proportion of the ≪002≫ oriented hep region in such films results in higher Hc values; film with the maximum Hc of 1500 Oe consisted almost entirely of ≪002≫ oriented hep crystal region. Transmission electron microscope observations revealed that the grain size increases to about 0.03 ¿m with an increase in Hc¿, up to 1500 Oe. It was also clarified that in the initial growth stage, these films show a low Hc, and consist of fine crystallites with low crystal orientation.