Spinel ferrite Co-/spl gamma/Fe/sub 2/O/sub 3/ perpendicular media on exchange-coupled underlayers

Spinel ferrite Co-/spl gamma/Fe/sub 2/O/sub 3/ films have the advantages of high coercivity, high stability without a protective layer, and low noise performance for magnetic recording layers. Also, exchange-coupled Co-Zr-Nb/Co-Sm underlayers show superior characteristics. The Co-Sm hard magnetic layer pins the domains of the Co-Zr-Nb soft magnetic layer effectively and decreases the noise coming from the latter. By combining the Co-/spl gamma/Fe/sub 2/O/sub 3/ recording layer and exchange-coupled Co-Zr-Nb/Co-Sm underlayers, the triple-layered perpendicular media show promise for ultrahigh-density perpendicular recording.