| 摘要 |
PROBLEM TO BE SOLVED: To improve the resolution and reduce the noise by setting the product of an activation volume and a spontaneous magnetization at a remanence coercive force point of a magnetic layer to a specified value or less, the product of a uniaxial anisotropic constant and a magnetization inversion volume divided by the product of the Boltzmann's constant and an absolute temp. to a specified or less and the dispersion thereof to a specified value or more. SOLUTION: The product v.Isb of an activation volume v and spontaneous magnetization Isb at a remanence coercive force point of a magnetic layer is set to 0.8×10-15emu or less, the product of a uniaxial anisotropic constant K and a magnetization inversion volume V divided by the product of the Boltzmann's constant k and an absolute temp. T, KV/kT is set to 80-120, and the dispersion thereof, S(KV/kT) is set to 0.7 or more. It is composed of a nonmagnetic substrate 1 of Al-Mg alloy, etc., covered with an amorphous Ni-P film, an adhesive reinforcing layer 2 required for less adhesion of a glassmade nonmagnetic substrate, etc., to a magnetic film, a Cr alloy orientation control layer 3, a magnetic film 4 contg. C as a main component such as Co-Cr-Ta, and a protection layer 5.
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