| 摘要 |
PURPOSE:To improve the corrosion resistance of the titled carrier and to evade the deterioration in recording sensitivity by forming a magnetic film on a substrate, and further laminating a derivative film and a niobium film. CONSTITUTION:A magnetic thin film of a rare earth transition metal is laminated directly or through a transparent dielectric layer on an optically transparent substrate, and a protective layer of a niobium thin film is further laminated thereon through a dielectric film. The dielectric film plays the role of evading the deterioration of recording sensitivity when the niobium film is formed directly on the magnetic film, and is composed of an oxide film and a nitride film having low heat conductivity. The thickness of the dielectric film is preferably regulated to 1,000-5,000Angstrom , the heat insulating effect is insufficient at <1,000Angstrom , and the recording sensitivity invariably deteriorates. At >5,000Angstrom , cracks are easily generated, and the corrosion resistance is conversely deteriorated. Meanwhile, the thickness of the niobium film is preferably adjusted to 3,000-10,000Angstrom . At <3,000Angstrom , the corrosion resistance decreases, and the function as the protective layer is not satisfied. At >10,000Angstrom , the protective layer is liable to strip off.
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