Effects of Spacing on Recording Characteristics of a Perpendicular Double-Layer Disk

We studied the effect of head-disk spacing on the relationship between the signal output and magnetic properties of a Co-Cr magnetic film on double-layer disks. Using the magnetic circuit model, we found that, for low coercivity, output saturated as spacing decreased. Output saturation depended on the saturation magnetization rather than the coercivity, however. We considered disks with different magnetic properties and various spacings, and confirmed our findings by experiment. We studied how to improve the recording density by using a single-pole head with a narrow main pole width (less than 2 μm) and a narrower spacing (0.07 μm). We obtained a C/N value of 40 dB at an areal density corresponding to 1.0 Gbit/in2.