Experimental studies of longitudinal and perpendicular high density recording

Single layer and double layer Co-Cr disks of various coercivities were sputter-deposited on rigid substrates and magnetic parameters measured. Record and playback properties were studied using both ferrite and thin film heads under identical system environments. A well optimized Ni-Co plated longitudinal disk was used as a benchmark throughout this investigation for direct comparison. With the objective of using "off the shelf" ring heads to bring up the perpendicular recording technology on rigid substrates, it was found that the performance of both our preliminary single and double layer Co-Cr perpendicular disks were at least as good as the well optimized longitudinal disk. The double layer disks have an added advantage of lower write current. Signal processing via Hilbert transform using both rectangular and Hamming windows was also studied and applied to the output waveforms.