Low noise Co-Cr-Nb perpendicular recording media with high squareness

Co-Cr based perpendicular recording media with high perpendicular squareness, SQ(perpendicular to), were developed by sputter-deposition, and their noise properties as well as recording performances were studied. It was found that the medium noise strongly correlated to M(3)(.)delta(3/2)(1-SQ(perpendicular to))(1/2), where M-s and delta are saturation magnetization and the thickness of the medium, respectively. Thus a 50 nm thick Co-Cr-Nb medium with a high SQ(perpendicular to) of 0.74 exhibited the lowest noise among investigated films. A high S/N of 38 dB for a track width of 2.7 mu m with a D-50 of 155 kFRPI was obtained for the Co-Cr-Nb medium by using an MR head. This medium could be used for a recording density of 5 Gbit/in(2).