| 摘要 |
PROBLEM TO BE SOLVED: To provide a multilayer film perpendicular magnetic recording medium which achieves improvement in SNR, stability in magnetization and ease of writing through a magnetic head. SOLUTION: The perpendicular magnetic recording medium has a structure in which a lower vertical magnetic layer 4 with multilayer films in which soft magnetic layer (CoZrNb)2, a first underlayer (a Ta layer)31, a second underlayer (the layer with Ni being a principal component)32, a third underlayer (an Ru layer)33, Co-SiO<SB>2</SB>and Pd-SiO<SB>2</SB>are alternatively laminated; an upper perpendicular magnetic layer 5 with the multilayer film in which Co and Pd-SiO<SB>2</SB>or Co and Pd (or Co and Pt) are alternatively laminated; and a C protection layer 6 are laminated on a non-magnetism substrate 1. The upper perpendicular magnetic layer has a larger perpendicular magnetic anisotropy, a larger coercive force, and a larger reversed magnetic-domain formation magnetic field compared with the lower layer perpendicular magnetic layer. The perpendicular magnetic-anisotropy constant is 2×10<SP>6</SP>erg/cc or less for the lower perpendicular magnetic layer and 2×10<SP>6</SP>erg/cc or more and 7×10<SP>6</SP>erg/cc or less for the upper perpendicular magnetic layer. COPYRIGHT: (C)2005,JPO&NCIPI
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