Effect of parameters of media on perpendicular magnetic recording properties

Effect of medium parameters on the recording properties such as write sensitivity, overwrite, recording resolution, medium noise, S/N and NLTS were experimentally investigated for Co-Cr-Pt-Nb double-layered perpendicular magnetic recording media. S/N improvement with an increase in the hysteresis loop slope parameter, α, was obtained as well as increase in the recording resolution. The increased loop slope also improved the modulation overwrite of the media where a low-frequency signal was overwritten with a high-frequency signal. The NLTS value for media with increased loop slope was found to be dominated by phase distortion which could be minimized by phase precompensation. Decrease in the intermediate layer thickness was effective to increase the S/N as well as the recording resolution, but the modulation overwrite value decreased in spite of the expected increase in the head field gradient. Permeability of the soft magnetic backlayer exhibited little effect on the recording properties.