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US4438508A
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Magneto-optical memory element
Assignee: US Philips Corp
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Filing: 1981-05-27
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Granted: 1984-03-20
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Expires: 2001-05-27
Abstract
Abstract A magneto-optical memory element consisting of a substrate, provided with an amorphous layer of an alloy of a rare-earth metal and a transition metal. The layer has a uniaxial magnetic anisotropy. Such memory elements are suitable for storing digital information in the form of magnetized areas, the magnetization direction of which can be read by means of the Kerr effect or Faraday effect. By adding bismuth and/or tin to the alloy the Kerr rotation and Faraday rotation can each be increased considerably, so that simpler reading of the stored information is possible.
Inventors
- 👤 Marlies Urner-Willie
- 👤 Peter Hansen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:28
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/06; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/12; H01F10/13; H01F10/133; H01F10/135; G11B11/10589; G11B11/10593; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31678; Y10T428/31681
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
48 words
A magneto-optical memory element comprising: a nonmagnetizable substrate; and an amorphous layer provided on the substrate, said layer comprising an alloy of a rare-earth metal and a transition metal, said alloy having a uniaxial magnetic anisotropy; Characterized in that the alloy comprises at least one atomic percent tin.
Claim 2
Dependent Claim
48 words
A magneto-optical memory element comprising: a nonmagnetizable substrate; and an amorphous layer provided on the substrate, said layer comprising an alloy of a rare-earth metal and a transition metal, said alloy having a uniaxial magnetic anisotropy; Characterized in that the alloy comprises at least one atomic percent tin.
Claim 3
Dependent Claim
43 words
A magneto-optical memory element as claimed in claim 1, characterized in that the alloy has a composition defined by the formula (R.sub.1-x M.sub.x).sub.1-y Sn.sub.y wherein R is at least one rare-earth metal, M is at least one transition metal, and 0.6≦x≦0.9 and 0.01≦y≦0.25.
Claim 4
Dependent Claim
20 words
A magneto-optical memory element, as claimed in claim 2, characterized in that R is a gadolinium and M is iron.
Claim 5
Dependent Claim
15 words
A magneto-optical memory element, as claimed in claim 3, characterized in that 0.73≦x≦0.74 and y≦0.13.
Claim 6
Dependent Claim
44 words
A magneto-optical memory element comprising: a nonmagnetizable substrate; and an amorphous layer provided on the substrate, said layer comprising an alloy of a rare-earth metal and a transition metal, said alloy having a uniaxial magnetic anisotropy; characterized in that the alloy further comprises tin.
Claim 7
Dependent Claim
44 words
A magneto-optical memory element comprising: a nonmagnetizable substrate; and an amorphous layer provided on the substrate, said layer comprising an alloy of a rare-earth metal and a transition metal, said alloy having a uniaxial magnetic anisotropy; characterized in that the alloy further comprises tin.
Claim 8
Dependent Claim
63 words
A magneto-optical memory device comprising: a memory plate; and means for optically reading and writing information on the memory plate, said information being in the form of memory cells which are magnetized in one of two opposite directions normal to the memory plate; characterized in that the memory plate is a memory element as claimed in claim 1, 2, 3, 4, or 5.
Claim 9
Dependent Claim
38 words
A magneto-optical memory element, as claimed in claim 1, 2, 3, 4, or 5, characterized in that the substrate comprises a photoconductor layer sandwiched between two transparent flat electrodes, and the amorphous layer is provided on one electrode.
Claim 10
Dependent Claim
21 words
A magneto-optical memory element, as claimed in claim 1, 2, 3, or 4, characterized in that the alloy further comprises bismuth.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-20 | 1987-09-19 | 1988-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-20 | 1991-09-19 | 1992-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-20 | 1995-09-19 | 1996-03-20 | $7700.00 | Window Closed / Lapsed |