Magnetic Properties and Microstrueture 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 hcp structure regions, and fee regions without an obvious crystal orientation. The increase in the proportion of the <002> oriented hcp region in such films results in higher Hc values; film with the maximum Hc of 1500 Oe consisted almost entirely of <002> oriented hcp crystal region. Transmission electron microscope observations revealed that the grain size increases to about 0.03 μm 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.