Abstract
Electroless Co alloy films tor perpendicular magnetic recording medium were investigated as a function of thickness dependence on magnetic properties. The read/write characteristics, especially the dependence of overwrite on recording density showed a large difference between Co-Ni-Re-Mn-P and Co-Ni-Re-P films. Since those films displayed a different thickness dependence of perpendicular coercivity Hc(⊥) , the control of thickness dependence of Hc(⊥) was attempted for Co-Ni-Re-P alloy films. The thickness dependence of Hc(⊥) of Co-Ni-Re-P alloy films could be easily controlled by adjusting the sodium malonate concentration in the bath. When the film becomes very thin, such as 0.1 μm thick, the Hc(⊥) value and degree of c-axis orientation increased with an increase in sodium malonate concentration, however, when the film thickness increases up to 0.5 μm. those values become almost the same for different sodium malonate concentrations.
