Correlation between activation volume and intergranular magnetic interaction in longitudinal media

We have investigated the correlation between the activation grain diameter derived from activation volume and the intergranular magnetic interaction, in CoCrPt-based thin film media fabricated by an ultra clean sputtering process. We found that the activation grain diameter depends on the physical grain diameter and intergranular exchange interaction, but is independent of intergranular magnetostatic interaction (4/spl pi/M/sub s//H/sub k//sup grain/). The activation grain diameter normalized by the physical grain diameter, which corresponds with the normalized coercivity (H/sub c//H/sub k//sup grain/) and microstructure, indicate the character of the intergranular exchange interaction in the media with various compositions. It is also clarified that the media noise can be characterized by the activation grain diameter together with the intergranular magnetostatic interaction.