Characterization of Oxide Materials for Exchange Decoupling in Perpendicular Thin Film Media

We report on continued measurements using an experimental model system to quantify intergranular exchange coupling in CoCrPt-oxide perpendicular magnetic recording media. A thin film multi-layered structure comprising a high coercivity CoPt unicrystal layer separated from a low coercivity CoPt layer by a thin oxide interlayer is used to model the vertically aligned grains separated by oxide boundaries in CoCrPt-oxide media. Exchange coupling is measured by field shifts of the minor loop from the low coercivity layer. Results on coupling energy as a function of interlayer thickness are presented for several different oxides. Additional measurements are presented to understand the possible role of the added alloying elements, Cr and Mn, to the magnetic grains in terms of intergranular exchange coupling.