[CoAl/Pd] _n multilayers as perpendicular recording media

Co/Pd multilayer medium is a potential candidate to realize the high density magnetic recording, however, the long-range exchange coupling and weak domain wall pinning energies result in low SNR recording. We investigated [Co _1-xAl _x/Pd] _n multilayer media and found this kind of media may be used as a stable perpendicular media for high density recording purposes. The samples were sputter-deposited onto the glass substrates with varying Al compositions, bilayer numbers, and [Co _1-xAl _x] _n magnetic sublayer thickness. Compared with [Co/Pd] _n multilayer films, the high perpendicular anisotropy and high squareness properties were basically reserved, while smaller and more uniform grains were observed. Much smaller domain size was observed for the sample with Al doping by magnetic force microscopy imaging. A magnetization reversal mechanism study showed that Al atoms might emerge into the grain boundaries, thus compressing the grains and weakening the intergranular exchange coupling. A new type of multilayer CGC media was proposed based on the study.