Determination of intrinsic switching field distributions in perpendicular recording media (invited)

Abstract

We describe a method for the experimental characterization of intrinsic switching field distributions in perpendicular media. The method is based upon a comparison between the major loop and a set of recoil loops, which start at a certain distance ΔM away from saturation. In particular, we measure the applied field difference ΔH between the recoil loops and the major loop at identical M values, for which the average demagnetizing fields are the same. By analyzing complete ΔH(M,ΔM) data sets taken from multiple recoil loops, we gain a detailed measure of the intrinsic switching field distribution D(HS). We have also studied the reliability and precision of this method by means of micromagnetic modeling and find it to be robust and overall very precise in reproducing the input parameters. In particular, the method is sufficiently insensitive to intergranular exchange coupling as long as it is only moderate in strength. Using polar-Kerr effect measurements of recording disk samples, we demonstrate the capabilities of our approach and its suitability for being a practical characterization tool for perpendicular recording media.