Experimental and theoretical analysis of rotational hysteresis loss in CoCrTa perpendicular recording media

We measured the value of rotational hysteresis loss W/sub r/ for various CoCrTa perpendicular media, and discussed the dependence of W/sub r/ and the hysteresis integral R/sub h/ on the perpendicular anisotropy and the strength of intergranular exchange coupling. Simulated results using a model based on the Landau-Lifshitz-Gilbert equation were compared with the experimental results. The experimental and theoretical studies revealed that improvement of the c-axis alignment significantly reduces W/sub r/, resulting in a small R/sub h/ value of /spl sim/0.2. Increase of intergranular exchange coupling shifts the applied field at which W/sub r/ reaches a maximum, H/sub p/, to a lower field and produces a large R/sub h/. Decrease of K/sub u/ also shifts H/sub p/ to a lower field but is accompanied by a reduction of R/sub h/. These results imply that the values of R/sub h/ and H/sub p/ are strongly related to the structural and magnetic properties, and analysis of rotational hysteresis loss appears to be a useful technique to characterize perpendicular media.