| 摘要 |
PROBLEM TO BE SOLVED: To obtain a sufficient coercive force and reduce the distribution of the coercive force in a surface by successively providing a specific amount of Ge and Cr primary coats and a Co alloy magnetic layer on a non-magnetic smoothing substrate where an arithmetic average roughness of a surface is equal to or less than a specific value and no mechanical matching of a concentric texture is performed. SOLUTION: The Ra of a substrate surface should be 1nm or less. An NiP electroless plating layer with a thickness of 20μm is formed on an Al-Mg substrate and is polished by an aluminum abrasive particle with a grain diameter of 0.45μm, thus obtaining the NiP plating substrate with a thickness of 10μm and a surface roughness of 0.5nm. In a vacuum chamber with 4.5×10<-3> Torr vacuum degree where a small amount of highly pure argon gas is introduced, the temperature of the substrate is heated to 250 deg.C and 5-20nm Ge primary coat, 10-100nm Cr primary coat, 20nm alloy magnetic layer of Co-13Cr-4Ta, and 10nm amorphous carbon protection layer are formed by sputtering successively. The Ge content of the Ge primary coat and the Cr content of the Cr primary coat are set to values that are at least 90at.% and at least 80at.%, respectively.
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