A study on the crystal growth of electroless plated Co-Ni-Re-P alloy films for perpendicular magnetic recording

The structure of electroless Co-Ni-Re-P alloy films for perpendicular magnetic recording media was investigated in order to clarify the correlation between magnetic properties and structure. The electron diffraction measurements made it clear that the thickness dependence of perpendicular coercivity is produced by the variation of the degree of c-axis orientation normal to the substrate at the very thin deposition stage. The high resolution transmission electron microscopy measurements indicated that the films consist of two different regions of highly crystallized and slightly crystallized parts. From the dark field image observation, the crystallized parts of columnar structure were confirmed to be fine and slender. The results derived the segregated structure model that the ferromagnetic Co-rich phase inside a columnar particle is surrounded by a non-magnetic Ni-P alloy phase.