Spinel ferrite Co/-λFe/sub 2/O/sub 3/ perpendicular media on exchange-coupled underlayers

In ultra-high density perpendicular magnetic recording, double-layered media consisting of a recording layer on a soft magnetic layer are required. For the recording layer, spinel ferrite Co-γFe/sub 2/O/sub 3/ films have been investigated. The films have advantages of high coercivity, high stability without protective layer, and low noise performance. For the soft magnetic layer, exchange-coupled CoZrNb/CoSm underlayers have been studied. The CoSm hard magnetic layer pins the domains of amorphous CoZrNb soft magnetic layer effectively, and decreases the noise coming from the soft magnetic layer. Also, signal stability under stray fields and high frequency responses have been observed in the media consisting of a CoCrTa recording layer on the CoZrNb/CoSm underlayers. In this study, the preparation and properties of Co-γFe/sub 2/O/sub 3/ media, combined with exchange-coupled CoZrNb/CoSm underlayers, are described.