| 摘要 |
PROBLEM TO BE SOLVED: To improve reproducing output in a short wavelength recording region by controlling plural parameters representing the surface profile of a support where a metal thin film type magnetic film is formed to specified ranges. SOLUTION: As for the parameters which represent the surface profile of a support where a magnetic film is formed, a distortion value Rsk and a kurtosis value Rku are defined by formula I and formula II, respectively. In each definition, Rq is the RMS roughness coefft. defined by formula III, f(x) is a roughness curve, L is the measuring length. The average of the distortion value Rsk is specified to -1.0 to 0 and the average of kurtosis value Rku is specified to 2 to 3. After the support is subjected to surface treatment such as ion bombard and then a magnetic film and a protective film are formed, the obtd. medium is evaluated by measuring the distortion value Rsk kurtosis value Rku on five points in a sample region in about 10×50 mm size with using a laser interference microscope or the like and calculating the average of each value.
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