CONTROL OF THICKNESS DEPENDENCE OF PERPENDICULAR COERCIVITY ON ELECTROLESS Co-Ni-Re-P ALLOY THIN FILMS.

Electroless plated Co alloy films for use as perpendicular magnetic recording media were investigated with respect to the thickness-dependence of their magnetic properties. The read/write characteristics, especially the dependence of the overwrite on the recording density, were found to be very different for Co-Ni-Re-Mn-P films and Co-Ni-Re-P films. The films displayed different thickness dependences of perpendicular coercivity H//c// PERPEND . The thickness dependence of the H//c// PERPEND of Co-Ni-Re-P alloy films was seen to be easily controlled by adjusting the sodium malonate concentration in the plating bath. When films are very thin, the H//c// PERPEND value and degree of c-axis orientation increased with increasing sodium malonate concentration. When the film thickness was increased, these properties were nearly the same for different sodium malonate concentrations.