Measurement of the anisotropy field dispersion in perpendicular media using complex transverse AC susceptibility

In this paper, easy-axis and hard-axis hysteresis loops to measure magnetic anisotropy. In the isothermal remanent magnetisation and DC demagnetization measurement, the thermal relaxation effect was corrected in order to extract H/spl kappa/ dispersion. However the grain volumes were assumed to be monodispersed for simplification, hence the extracted H/spl kappa/ dispersions are convoluted with volume dispersions. In the hard-axis hysteresis loop measurements, Papusoi et.al fitted the hard-axis curves to extract the H/spl kappa/ dispersion by taking into account the angular dispersion, which needs to be determined from separate measurements. We note that this method is also affected by the presence of high order anisotropy constants.