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Patent US4666789A successfully refreshed from Google Patents.
US4666789A
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US
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Magneto-optic recording medium
Assignee: Compagnie Internationale pour l'Informatique CII-Honeywell Bull SA
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Filing: 1985-02-26
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Granted: 1987-05-19
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Expires: 2005-02-26
Abstract
Abstract A multilayer magnetic recording medium including at least one magnetic layer (CMOI) formed of an alloy including one of the group of heavy rare earths and a metal of the group of the first series of transition metals surrounded by at least two dielectric layers. According to the invention, the magnetic medium is characterized in that it includes means for preventing the diminution of the number of atoms of rare earth participating in the magnetism of the magnetic layer disposed on both sides of the magnetic layer. Applicable to magnetooptic disks.
Inventors
- 👤 Catherine Gueugnon
- 👤 Pierre Bernstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:50
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10589; G11B11/10591; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12771; Y10T428/12861; Y10T428/12944; Y10T428/12951
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
121 words
A multilayered magnetic recording medium comprising a magnetic layer formed of an alloy of a metal of the heavy rare earth group and a metal of the group of the first series of transition metals, first and second dielectric oxide layers disposed on opposite sides of the magnetic layer, and blocking means disposed on opposite sides of the magnetic layer between the magnetic layer and said dielectric oxide layers for blocking both the migration of rare earth atoms from the magnetic layer to the dielectric oxide layers and the migration of oxygen atoms from the dielectric oxide layers to the magnetic layer, said blocking means comprising first and second blocking layers formed of a metal of the group of rare earths.
Claim 2
Dependent Claim
121 words
A multilayered magnetic recording medium comprising a magnetic layer formed of an alloy of a metal of the heavy rare earth group and a metal of the group of the first series of transition metals, first and second dielectric oxide layers disposed on opposite sides of the magnetic layer, and blocking means disposed on opposite sides of the magnetic layer between the magnetic layer and said dielectric oxide layers for blocking both the migration of rare earth atoms from the magnetic layer to the dielectric oxide layers and the migration of oxygen atoms from the dielectric oxide layers to the magnetic layer, said blocking means comprising first and second blocking layers formed of a metal of the group of rare earths.
Claim 3
Dependent Claim
26 words
A multilayered magnetic recording medium according to claim 1, wherein said blocking layers each have a thickness of the order of a few tens of angstroms.
Claim 4
Dependent Claim
54 words
A multilayered magnetic recording medium according to claim 1, wherein said alloy is formed of a metal of the heavy rare earth group selected from the group consisting of terbium, gadolinium, and dysprosium, and said metal of the first series of transition metals is selected from the group consisting of iron, cobalt, and nickel.
Claim 5
Dependent Claim
32 words
A multilayered magnetic recording medium according to claim 1, further comprising a reflective layer disposed upon a substrate, and wherein one of said dielectric oxide layers is disposed upon said reflective layer.
Claim 6
Dependent Claim
26 words
A multilayered magnetic recording medium according to claim 1 wherein said dielectric oxide layers are selected from the group consisting of silicon oxide and aluminum oxide.
References Cited (Backward Citations)
US4525028A
Cited
US4569881A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-18 | 1990-11-17 | 1991-05-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-18 | 1994-11-17 | 1995-05-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-18 | 1998-11-17 | 1999-05-19 | $7700.00 | Window Closed / Lapsed |