The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 05, 1998
Filed:
Sep. 20, 1994
Keiji Shono, Kawasaki, JP;
Yasunobu Hashimoto, Kawasaki, JP;
Sumio Kuroda, Kawasaki, JP;
Ken Tamanoi, Kawasaki, JP;
Fujitsu, Ltd., Kawasaki, JP;
Abstract
A magneto-optic disk has a readout layer formed of a bismuth-substituted garnet having a chemical composition represented by Bi.sub.x R.sub.3-x M.sub.y Fe.sub.5-y O.sub.12 and a recording layer formed of a nonbismuth-substituted garnet having a chemical composition represented by R.sub.3 M, Fe.sub.5-z O.sub.12 (where 0.ltoreq.x.ltoreq.3, 0.ltoreq.y<2, 0.ltoreq.z<2, R represents yttrium or a rare earth element, and M represents element which can be substituted for iron (Fe). The readout layer has a smaller coercive force and a higher Curie temperature in comparison with the recording layer, and exhibits a characteristic of a large angle of Faraday rotation 200 times that of the recording layer with respect to a short-wavelength laser beam of about 500 nm. Therefore, the MSR technique utilizing masking of the recording layer with the readout layer can be applied to this magneto-optic disk to achieve a high recording density about 16 times that in the case of a magneto-optic disk having an amorphous alloy thin film formed of a rare earth element and a transition metal and effective with respect to a laser beam of a comparatively long wavelength about 800 nm.