Recording performance of granular-type FePt-MgO perpendicular media

Double-layered perpendicular magnetic recording media, composed of granular-type FePt-MgO films on Fe-Ta-C soft magnetic underlayer, are fabricated on to 2.5-in glass discs with the stack structure of [MgO x-nm/FePt y-nm]_n/MgO 4-nm/SiO₂ 4-nm/Fe-Ta-C 200-nm/Glass disk. After annealing, granular films of FePt-MgO with high perpendicular magnetic anisotropy of the order of 10⁶ erg/cc and with the texture <001> along the film normal can be successfully fabricated. The perpendicular coercivity, magnetic activation volume, and the exchange coupling between the FePt grains are found to be strongly dependent on the initial multilayer structures and the optimum annealing conditions. The recording performance of the double-layered disks is evaluated by a spin-stand. The obtained results reveal a close correlation between the recording performance and magnetic properties.