Perpendicular magnetic recording media based on Co-Pd multilayer with granular seed layer

We have investigated Co-Pd multilayer deposited on a Pd-SiN granular seed layer and a FeTaC soft magnetic underlayer (SUL) for perpendicular magnetic recording. The Pd-SiN granular seed layer of 3 nm was found to be very effective to get good magnetic properties with coercivity of 3.9 kOe, a negative nucleation field of -2.1 kOe, and a M-H loop slope parameter 4pi (dM/dH)(H=Hc) of 1.3. The average column diameter of 13.7 nm with a dispersion of 21.7% was evaluated from the transmission electron microscopy image of well-separated columns with a clear boundary. This Co-Pd medium gave better playback performances by a merged ring giant magnetoresistive head compared to the medium with a Pd seed layer. The effect of Ar plasma etching on the SUL was also investigated to improve playback performance.