| 摘要 |
PROBLEM TO BE SOLVED: To improve durability and prevent deterioration of a magnetic disk when the magnetic disk is set to a high recording density. SOLUTION: A magnetic disk 4 is provided with a substrate layer having a surface recording density of 158.7 Mbit/cm<SP>2</SP>or more and practically made of a nonmagnetic substance disposed on a nonmagnetic support, and a magnetic layer formed by dispersing ferromagnetic hexagonal ferrite fine powders in a binder and layered on the substrate layer. Further, a frictional force between a magnetic disk 4 and a magnetic head for recording/reproducing information on/from the magnetic disk 4 is 10 mN or less when the rotational speed of the magnetic disk is 3,600 rpm, and rotational torque between the magnetic disk 4 and the liner 6 is 15 mN-cm or less when the rotational speed of the magnetic disk 4 is 3,600 rpm. COPYRIGHT: (C)2005,JPO&NCIPI
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