MAGNETIC DISK

PURPOSE:To increase the number of times of contact start stop (CSS) by coating a CrO2 magnetic medium layer on a non-magnetic hardened layer consisting of an Ni-Cu-P alloy contg. 1-95wt% copper. CONSTITUTION:The hardened layer 2 on a non-magnetic substrate 1 is subjected to a heat treatment at >=350 deg.C to form a non-magnetized Ni-Cu-P alloy layer, by which the magnetization of the hardened layer is obviated even if a thin CrO2 film to be formed by heating is used. The decrease in the reproduced output is obviated and since the layer has substantial hardness, the number of times of CSS increases and a magnetic disk having high reliability is obtd. The Ni-Cu-P plating film which is not magnetized even if the film is subjected to the heat treatment of, for example, 350 deg.C contains 1-95wt% Cu.