Co/Pd multilayer media with Pd inorganic granular seed layer for perpendicular recording

We have investigated the Co/Pd multilayer media with a Pd-SiN granular seed layer as perpendicular recording media. The Pd-SiN granular seed layer and the Co(0.2 nm)/Pd(0.8 nm) multilayer were formed by dc and rf sputtering at room temperature on a FeTaC soft magnetic underlayer. The Pd-SiN granular seed layer of 3 nm was very effective to get good magnetic properties with coercivity of 3.9 kOe, a nucleation field of -2.1 kOe, and a M-H slope parameter 4pi(dM/dH)(H=H c) of 1.4. In addition, it was found that growth of multilayer grains is sensitive to surface conditions of the soft magnetic underlayer. The average column diameter of 13.7 nm with a dispersion of 21.7% was evaluated from the plan-view transmission electron microscope image of well-separated Co/Pd columns with a boundary, which was grown on the Pd-SiN seed layer and the soft magnetic underlayer with Ar plasma etching. Atomic force microscope measurements showed that mean roughness (R-a) of the FeTaC surface decreased from 0.46 to 0.39 nm by the plasma etching. This surface treatment on the soft magnetic underlayer gave better signal to noise ratio by 1.6 dB in playback performance by using of a spin stand with a merged-type ring writer and giant magnetoresistance reader. (C) 2002 American Institute of Physics.