Preparation of double-layered perpendicular media for fine magnetic structure

Two preparation methods for sputter deposition are examined in order to obtain a low noise double-layered layered perpendicular recording medium. Very thin intermediate layers between the recording layer and the soft magnetic backlayer was found to reduce the medium noise. Nitrogen addition to the NiFe system backlayer was also effective in reducing the noise. The medium noise reduction was attributed to the reduction in grain size and a magnetic domain size of the recording layer in both cases. An MFM image corresponding to a density beyond 50 Gbit/in/sup 2/ was observed for a medium with Co-Zr-Nb intermediate layer.