| 摘要 |
The invention relates to a magnetic recording medium comprises a nonmagnetic substrate on which at least a soft magnetic under layer, an orientation adjusting layer that controls the orientation of a layer just thereon, a vertical magnetic layer with an axis of easy magnetization being mainly oriented vertically to the nonmagnetic substrate and a protective layer are disposed, the vertical magnetic layer is constituted of three or more layers including a lower layer, an intermediate layer and an upper layer from the substrate side, wherein the lower, intermediate and upper magnetic layers are constituted of magnetic particles which are columnar crystals extending continuously from the lower layer to the upper layer, the magnetic recording medium further comprises a nonmagnetic layer between the lower and intermediate magnetic layers or between the intermediate and upper magnetic layers, wherein the upper layer has a magnetic anisotropic constant (Ku) ranging from 0.8×106 to 4×106 (erg/cc), the intermediate layer has a magnetic anisotropic constant (Ku) ranging from 2×106 to 7×106 (erg/cc) and the lower layer has a magnetic anisotropic constant (Ku) ranging from 1×106 to 4×106 (erg/cc), and the lower, intermediate and upper magnetic layers are bound by ferro-coupling.
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