Perpendicular Hard Disk Media for Contact SPT Head Recording System

A Co-Cr/Ni-Fe double layer hard disk medium for a new contact SPT head system was investigated in regard to its design. The medium was prepared with an RF sputtering system, sequentially depositing a Cr or a Ti underlayer, a soft-magnetic backlayer, a Co-Cr recording layer and a SiO2 protective layer. The Cr underlayer with thickness of 0.025 μm realized the most excellent crystallinity of the backlayer. The largest signal-to-noise ratio of 35 dB was obtained with thickness of 0.5 to 1.0 μm for the Cu-Mo-Permalloy backlayer, and with about 2.0 μm thickness for the Nb-Permalloy one, respectively. Addition of Ta to a Co-Cr system was also examined to narrow the anisotropy field distribution. It was found that a high output at high recording densities could be obtained for the narrowed anisotropy field distribution.