US4612068A
Expired / Lapsed
US
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Magneto-optical recording medium
Assignee: KDDI Corp
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Filing: 1984-03-20
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Granted: 1986-09-16
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Expires: 2004-03-20
Abstract
Abstract Amorphous thin film with easy magnetization axis perpendicular to film surface for magneto-optical recording with low recording power and high S/N in reading signal is set forth. The medium is an alloy of heavy rare earth element and iron with substitution of some heavy rare earth elements by light rare earth element, and the preferable chemical formula of the thin film is (R z A 1-z ) x Fe 1-x , or [(R z A 1-z ) y B 1-y ] x Fe 1-x where R is a light rare earth element, A and B are heavy rare earth elements, and the atom ratios satisfy 0.15≦x≦0.35, 0.00<y<1.00, 0.00<z<1.00. Recording is effected by using Curie point, or magnetic compensation temperature, and reading of information is effected by using the Kerr effect.
Inventors
- 👤 Shinsuke Tanaka
- 👤 Nobutake Imamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:55
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10589; G11B11/10591; H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/12; H01F10/13; H01F10/133; H01F10/135; H01F10/136
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
48 words
A magneto-optical recording medium using an amorphous thin film having an easy magnetization axis perpendicular to the film surface, wherein the chemical formula of said medium is: (Sm.sub.z A.sub.1-z).sub.x Fe.sub.1-x where A is a heavy rare earth element, and wherein the following atom ratio is satisfied: 0.15≦x≦0.35, 0.06<z<0.31.
Claim 2
Dependent Claim
48 words
A magneto-optical recording medium using an amorphous thin film having an easy magnetization axis perpendicular to the film surface, wherein the chemical formula of said medium is: (Sm.sub.z A.sub.1-z).sub.x Fe.sub.1-x where A is a heavy rare earth element, and wherein the following atom ratio is satisfied: 0.15≦x≦0.35, 0.06<z<0.31.
Claim 3
Dependent Claim
52 words
A magneto-optical recording medium comprising an amorphous thin film having an easy magnetization axis perpendicular to the film surface, wherein the chemical formula of said medium is: [(Sm.sub.z A.sub.1-z).sub.y B.sub.1-y ].sub.x Fe.sub.1-x where A and B are heavy rare earth elements, and wherein the following atom ratio is satisfied: 0.15≦x≦0.35, 0.57≦y, 0.10<z<0.26.
Claim 4
Dependent Claim
52 words
A magneto-optical recording medium comprising an amorphous thin film having an easy magnetization axis perpendicular to the film surface, wherein the chemical formula of said medium is: [(Sm.sub.z A.sub.1-z).sub.y B.sub.1-y ].sub.x Fe.sub.1-x where A and B are heavy rare earth elements, and wherein the following atom ratio is satisfied: 0.15≦x≦0.35, 0.57≦y, 0.10<z<0.26.
Claim 5
Dependent Claim
26 words
A magneto-optical recording medium according to claim 1, wherein said heavy rare earth element is selected from the group consisting of Gd, Tb, Dy and Ho.
Claim 6
Dependent Claim
26 words
A magneto-optical recording medium according to claim 2, wherein said heavy rare earth element is selected from the group consisting of Gd, Tb, Dy and Ho.
Claim 7
Dependent Claim
10 words
A magneto-optical recording medium according to claim 2, wherein y≦0.60.
References Cited (Backward Citations)
US4126494A
Cited
US4308474A
Cited
GB2071696A
Cited
US4390600A
Cited
JPS5848650A
Cited
US4374665A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-09-15 | 1990-03-17 | 1990-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-09-15 | 1994-03-17 | 1994-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-09-15 | 1998-03-17 | 1998-09-16 | $7700.00 | Window Closed / Lapsed |