Improvement in the magnetic properties of Tb/FeCo films for perpendicular magnetic recording media

Abstract By incorporating high Ms Fe65Co35 alloy in the Tb/FeCo multilayer structure on 20 nm thick W underlayer, we obtained Ku=4×106 erg/cm3, Ms=350 emu/cm3, and Hc=7.5 kOe. The W underlayer was deposited under 13.5mTorr Ar gas pressure to induce micro-roughness at the surface with lateral feature size of a few nm to 20 nm. Both X-ray diffraction and transmission electron microscopy methods confirmed that the Tb/FeCo multilayer was amorphous. We observed density fluctuation in the amorphous Tb/FeCo layer, which is the most probable candidate of domain wall pinning sites created in the amorphous magnetic film.