Size-dependent reversal of grains in perpendicular magnetic recording media measured by small-angle polarized neutron scattering

Polarized small-angle neutron scattering has been used to measure the magnetic structure of a CoCrPt–SiOx thin-film data storage layer, contained within a writable perpendicular recording media, at granular (<10 nm) length scales. The magnetic contribution to the scattering is measured as the magnetization is reversed by an external field, providing unique spatial information on the switching process. A simple model of noninteracting nanomagnetic grains provides a good description of the data and an analysis of the grain-size dependent reversal provides strong evidence for an increase in magnetic anisotropy with grain diameter.