Correlation between activation volume and intergranular magnetic interaction in longitudinal media

We have investigated the correlation between activation grain diameter deri ved from activation volume and intergranular magnetic interaction, in CoCrP t-based thin film media fabricated by ultra clean sputtering process. As th e results, we found that activation grain diameter depends on the physical grain diameter and intergranular exchange interaction, but is independent o f intergranular magnetostatic interaction (4 piM(s) /H-k(gram)). The activa tion grain diameter normalized by physical grain diameter, which correspond s with normalized coercivity (H-c/H-k(gram)) and microstructure, well indic ate the character of intergranular exchange interaction in the media with v arious compositions. It is also clarified that the media noise can be chara cterized by activation grain diameter together with intergranular magnetost atic interaction.