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

Abstract By incorporating high M s Fe 65 Co 35 alloy in the Tb/FeCo multilayer structure on 20 nm thick W underlayer, we obtained K u =4×10 6  erg/cm 3 , M s =350 emu/cm 3 , and H c =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.