Recording characteristics of Co-γFe2O3 perpendicular magnetic recording media

The recording characteristics of Co-γFe2O3 perpendicular magnetic recording hard disk media were investigated. Sliding contact recording was performed to evaluate the intrinsic high-density recording performance of the media with using a metal-in-gap-type ring head. The half-voltage density D50 of 176 kFRPI and low-density reproduced voltage Ep of 143 nVp-p/[turn μm (m/s)] were obtained for the optimal medium whose Co-γFe2O3 layer thickness was 0.13 μm and perpendicular coercivity was 1800 Oe. The pass wear durability test was performed at 2 m/s, or at a disk rotation of 830 rpm. The reproduced voltage did not decrease with time, and scratches and damage were not observed on the tested track even after 18 000 000 passes. The Co-γFe2O3 medium is one of the candidates for ultrahigh-density recording media because of its specific advantages; superior high density recording performance and hardness tolerable for sliding contact use.