| 摘要 |
PURPOSE:To improve the recording, reproduction and erasure of a medium by forming a magnetic layer into two-layered structure consisting of a reproduction layer having prescribed characteristics and record holding layer. CONSTITUTION:The 1st magnetic layer which records and holds information, the 2nd magnetic layer 13 which reads out the information recorded by the layer 2, a reflecting layer 14 and a protective layer 15 are laminated on a transparent substrate 11. The coercive force Hc1 of the layer 12 and the coercive force Hc2 of the layer 13 are set at the relation Hc1>Hc2. These layers are so formed as to satisfy the relations HE>¦-HW¦, HE>¦+ or -HR¦, Hc1>¦+ or -HR¦ when the external magnetic field at the erasure from this medium is designated as HE, the external magnetic field at the time of recording thereto as -HW and the external magnetic field at the time of reproduction therefrom as + or -HR. The layer 12 can be formed of a perpendicularly magnetized film by a BaAl3 InFe8O19 target or the like and the layer 13 can be formed by RF sputtering using a CoCrFeO4 target or the like.
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