Abstract
The effect of thermal agitation of magnetization on the magnetic properties of granular (CoCrTa/Ti) perpendicular media was studied by using a pulse magnetometer. The values of the "intrinsic" remanence coercivity H_0, obtained by subtracting the thermal agitation of magnetization, gradually approaches magnetocrystalline anisotropy field of grains H_k as the CoCrTa thickness decreases. The H_0 shows values larger than 90% of H_k at thicknesses of less than 20nm. The activation volume gradually decreases as the thickness decreases, and is nearly the same as the mean grain volume at thickness of less than 30nm. This suggests that magnetization reversal within the grains is uniform at thicknesses of less than 30nm.
