Perpendicular magnetic recording is promising for the achievement of higher recording density. Magnetic and crystal orientational properties of double layer rigid disks for perpendicular magnetic recording were studied. Coercive force distribution of the Mo-Cu-permalloy underlayer was investigated as a function of sputtering gas pressure. At optimum Ar gas pressure, good uniformity of coercive force distribution was obtained. Even in double layer medium, crystal orientation of the Co-Cr layer was influenced by the characteristics and thickness of the substrate surface treatment layer. Higher recording density was obtained with lower flying height and a thinner Co-Cr layer. The D50 recording density of 70kFRPI was achieved for a 0.15 μm thick Co-Cr layer and a 0.3 μm thick single pole type head at 0.1 μm flying height.
