Recording Characteristics of Co-.GAMMA.Fe2O3 Perpendicular Magnetic Recording Media.

The pass-wear durability and recording characteristics of Co-γFe2O3 perpendicular magnetic recording thin-film disks were measured by using a MIG-type ring head with a gap length of about 0.2μm in contact sliding use. Co-γFe2O3 perpendicular magnetic anisotropy films were pre- pared by annealing CoO/Fe3O4 multilayers deposited onto an NiO underlayer in air at 280-350°C The Co-γFe2O3 perpendicular hard disk had no protective overcoat layers. The head wear was drastically improved by introducing a liquid lubricant. Reproduction demagnetization did not occur, and no damage or scratches were found after more than eighteen million passes. A D50 of 180 kFRPI and a low-density reproduced voltage of 143 nVp-p/{turu-pm- (m/s)) were obtained for a Co-γFe2O3 disk with an optimized film thickness and perpendicular coercivity. It is con- eluded that the Co-γFe2O3 perpendicular disks are suitable for ultra-high density recording media used in contact re- cording without an overcoat layer.