Novel Composite Perpendicular Recording Medium with Co₇₈Cr₂₂ over Cr-Rich Co₇₂Cr₂₈ for Merged MR Heads

We propose a new type of composite perpendicular medium consisting of a 50-nm-thick Co₇₈Cr₂₂ upper layer and a 50-nm-thick Cr-rich Co₇₂Cr2s lower layer for magnetic recording systems using MR heads. The lower Cr-rich layer, with strong magnetic interaction in the perpendicular direction and good crystalline orientation, contributes to the high resolution and high signal-to-noise ratio (S/N). The upper layer, with large saturation magnetization (Ms) and large anisotropy field (Hiu. ), plays a major role in increasing the signal amplitude. Magnetic recording characterization using this medium and a merged MR head yielded a Dso of 140 kFCI, an S/N of 33. 4 dB, and a signal amplitude of 411 (xVpp at 100 kFCI with a 62-hm magnetic spacing.