Ordered Fe-Pt Composite Media with Fe-Si Back-Layers for High-Density Perpendicular Recording.

Abstract

An ordered Fe-Pt(001) perpendicular composite medium was designed with a high Bs soft-magnetic Fe-Si back-layer. When an MgO layer was introduced between the Fe-Si back-layer and the Fe-Pt layer, a square-shaped Kerr loop was obtained for the Fe-Pt recording layer, as a result of the exchange-decoupling between the two layers. Introduction of the MgO layer led to a slight improvement of the crystallinity and orientation. The medium showed a high signal output and a recording resolution D50 of 220 kFRPI for an MR reproducing head with a Gs of 0.2 μm. A high SNR, 38.9 dBp-p/rms, was achieved for a track width of 1.2 μm at a recording density of 40 kFRPI. Furthermore, an MFM image of a 500-kFRPI recorded pattern was obtained, even though a strong exchange interaction in the lateral direction of the film was implied. It is safe to conclude that the Fe-Pt composite medium will be useful for future ultra-high-density recording.