Novel composite perpendicular recording medium with Co/sub 78/Cr/sub 22/ over Cr-rich Co/sub 72/Cr/sub 28/ for merged MR heads

We propose a new type of composite perpendicular medium consisting of a 50-nm-thick Co/sub 78/Cr/sub 22/ upper layer and a 50-nm-thick Cr-rich Co/sub 72/Cr/sub 28/ 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 (M/sub s/) and large anisotropy field (H/sub kl/), plays a major role in increasing the signal amplitude. Magnetic recording characterization using this medium and a merged MR head yielded a D/sub 50/ of 140 kFCI, an S/N of 33.4 dB, and a signal amplitude of 411 /spl mu/V/sub pp/ at 100 kFCI with a 62-nm magnetic spacing.