PURPOSE: To stabilize CSS durability by treating the surface of a protective layer by irradiation with actinic rays before a lubricant layer is formed.
CONSTITUTION: An underlayer 2 is formed on a nonmagnetic base 1 consisting of a nonmagnetic substrate 1a and a nonmagnetic metallic layer 1b formed on the substrate 1a, and a magnetic layer 3, a protective layer 4 and a lubricant layer 5 are successively formed on the underlayer 2. The substrate 1a is, e.g. made of Al, glass or carbon and the layer 1b is, e.g. made of Ni-P, Cr or Ti and has 5-20μm thickness. The surface of the base 1 is preferably textured with an abrasive tape or the like so as to regulate the surface roughness Ra to 30-80 and Rp to 100-300. The increase of the thickness of a fixed layer in the lubricant layer 5 with the lapse of time is inhibited and CSS durability is stabilized.
KUBO HIROKI