Thermal stability and magnetic anisotropy dispersion in high-density hard-disk media

Abstract

Abstract A method to correct the anisotropy field distribution for granular recording media, measured by switching methods (isothermal remanent magnetization (IRM) and direct-current demagnetisation (DCD) processes were used as an example) for the effects of thermal relaxation, that supposes an a priori knowledge of the grain size distribution, is presented. For a hard-disk medium, it is shown that the anisotropy field distribution is much narrower (about one order of magnitude) with respect to the grain size distribution. The anisotropy field value estimated from the dependence of the remanence coercivity on the field application time is found in agreement (to within less than 10 %) with the most probable value of the anisotropy field distribution.