| 摘要 |
PURPOSE:To improve a reproduction S/N ratio by making the 1st recording layer made of a magnetic body which has an easy magnetization axis perpendicular to a film surface successively from the incidence side of luminous flux thinner than a spacer layer and the 2nd recording layer made of a magnetic body which has an easy magnetization axis perpendicular to the film surface. CONSTITUTION:A protection film or reflection preventive film 12 is formed on a substrate 11a, the 1st recording layer 13, spacer layer 14, and the 2nd recording layer 15 are formed, and further the substrate 11a is stuck on an external substrate 11b across a protection film 16 and a cutting layer 17. The 1st recording layer 13 is formed of the magnetic body which has the easy magnetization axis perpendicular to the film surface, e.g. GdTbFeHo quarternary amorphous alloy having a large angle of Kerr rotation. The 2nd recording layer 15 is also formed of the magnetic body having the easy magnetization axis perpendicular to the film surface. The 1st recording layer 13 is thinner than the 2nd recording layer 15. The Kerr effect and Faraday effect of the 1st recording layer 13 and further the Kerr effect of the 2nd recording layer 15 are superposed to increase the angle of the apparent Kerr rotation, so that information is reproduced at a higher S/N ratio than before. |
