| 摘要 |
PROBLEM TO BE SOLVED: To decrease the polishing allowance of a hard dense layer even when a thin hard dense layer such as a NiP plating film is formed on an aluminum alloy disk surface, to obtain high recording density of a magnetic disk and to prevent sticking of a magnetic head to a magnetic disk surface in a halting state of a magnetic disk device. SOLUTION: This magnetic disk substrate comprises an aluminum alloy disk 1 the surface of which is concentrically roughened, and a hard dense layer 2 formed on the surface of the aluminum alloy disk 1. The surface roughness of the aluminum alloy disk 1 is controlled to <10ÅRa measured in the perpendicular direction to the tangential lines of the concentric circles. The surface roughness of the CSS zone in the surface of the hard dense layer 2 is >=10ÅRa. Then a recording medium 3 is formed on the obtd. substrate.
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