Henkel Plots in a Thermally Demagnetized Scalar Preisach Model

The implications of thermal demagnetization with respect to the observation of interaction effects in Henkel plots are discussed within the framework of a scalar moving Preisach model. The Preisach distribution is assumed to be a product of a Gaussian coercive field distribution and a Gaussian interaction field distribution. Numerical calculations of the magnetizing and demagnetizing remanences show that, by contrast with other demagnetizing procedures, thermal demagnetization yields Henkel plots whose direction of curvature is uniquely related to the sign of the mean interaction field. In particular, a distribution of interaction fields which is symmetric about the origin yields the same linear Wohlfarth relation as a completely noninteracting system, while demagnetizing (magnetizing)-like mean fields always curve the Henkel plot below (above) the Wohlfarth line. The simple linearity of the Henkel plot in the absence of mean field effects was exploited to evaluate the effectiveness of a recent proposal for experimentally suppressing shape demagnetizing effects in perpendicular recording media.