US4615944A
Expired / Lapsed
US
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Amorphous magneto optical recording medium
Assignee: 3M Co
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Filing: 1984-04-12
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Granted: 1986-10-07
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Expires: 2004-04-12
Abstract
Abstract A magneto optical thin film recording medium is disclosed having very high carrier-to-noise ratios and high rotation angles. A transmission electron microscope photomicrograph (at 200,000×) of one such medium is shown in FIG. 1. These are multi-phase amorphous materials having magnetic anisotropy perpendicular to the plane of the thin film. They are produced in a triode vacuum sputtering process at vacuums in the range of 4×10 -3 to 6×10 -4 Torr. By adjusting process parameters such as substrate temperature, anode bias and deposition rate, the properties of the thin film can be altered.
Inventors
- 👤 Richard N. Gardner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:44
CPC Classifications
A; A46; A46B; A46B15/00; G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10589; G11B5/00; G11B5/62; G11B5/72; G11B5/84; G11B5/851; H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/12; H01F10/13; H01F10/133; H01F10/135; H01F10/26; H01F10/265; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12542; Y10T428/12736; Y10T428/12771; Y10T428/12861; Y10T428/26
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
48 words
A magneto-optical recording medium comprising a substrate and magnetizable amorphous film having a magnetic anisotropy perpendicular to the film surface, and said film being characterized by having a multiplicity of magnetic domains substantially all of which have a domain size of less than 500 angstroms in largest dimension.
Claim 2
Dependent Claim
48 words
A magneto-optical recording medium comprising a substrate and magnetizable amorphous film having a magnetic anisotropy perpendicular to the film surface, and said film being characterized by having a multiplicity of magnetic domains substantially all of which have a domain size of less than 500 angstroms in largest dimension.
Claim 3
Dependent Claim
19 words
The magneto-optical recording medium of claim 1 wherein the magnetizable amorphous film has been directly deposited on the substrate.
Claim 4
Dependent Claim
22 words
The magneto-optical recording medium of claim 2 which further comprises a transparent passivating layer coated on top of the magnetizable amorphous film.
Claim 5
Dependent Claim
23 words
The recording medium of claim 1 which comprises an alloy of at least one rare earth element and at least one transition metal.
Claim 6
Dependent Claim
13 words
The recording medium of claim 4 wherein said alloy comprises a gadolinium-terbium-iron alloy.
Claim 7
Dependent Claim
20 words
The recording medium of claim 4 wherein said alloy is selected from the group consisting of terbium-iron and terbium-iron-cobalt alloys.
Claim 8
Dependent Claim
21 words
The recording medium of claim 1 which further comprises a reflecting layer on which the magnetizable amorphous film has been deposited.
Claim 9
Dependent Claim
28 words
The recording medium of claim 7 in which the reflecting layer has been deposited on the substrate prior to depositing the magnetizable amorphous film on the reflecting layer.
Claim 10
Dependent Claim
38 words
The recording medium of claim 8 which further comprises a priming layer made of a material selected from the group consisting of the oxides of chromium, titanium, tantalum and aluminum located between the reflecting layer and the substrate.
Claim 11
Dependent Claim
94 words
A magneto optical recording medium comprising a substrate and a passivated magnetizable amorphous film having a magnetic anisotropy perpendicular to the film surface, said film being characterized by a magneto-optic rotation angle, for polarized light reflected from the recording medium, of at least 0.24° measured with a helium neon laser at a wavelength of 6328 angstroms and at least 0.4° measured with a laser diode at a wavelength of about 7800 to 8500 angstroms, and having a multiplicity of magnetic domains characterized by a domain size of less than 500 angstroms in largest dimension.
Claim 12
Dependent Claim
94 words
A magneto optical recording medium comprising a substrate and a passivated magnetizable amorphous film having a magnetic anisotropy perpendicular to the film surface, said film being characterized by a magneto-optic rotation angle, for polarized light reflected from the recording medium, of at least 0.24° measured with a helium neon laser at a wavelength of 6328 angstroms and at least 0.4° measured with a laser diode at a wavelength of about 7800 to 8500 angstroms, and having a multiplicity of magnetic domains characterized by a domain size of less than 500 angstroms in largest dimension.
Claim 13
Dependent Claim
23 words
The recording medium of claim 10 which comprises an alloy of at least one rare earth element and at least one transition metal.
Claim 14
Dependent Claim
13 words
The recording medium of claim 11 wherein said alloy is a gadolinium-terbium-iron alloy.
Claim 15
Dependent Claim
19 words
The recording medium of claim 11 wherein said alloy is selected from the group consisting of terbium-iron and terbium-iron-cobalt.
Claim 16
Dependent Claim
19 words
The magneto-optical recording medium of claim 10 wherein the magnetizable amorphous film has been directly deposited on the substrate.
Claim 17
Dependent Claim
22 words
The magneto-optical recording medium of claim 14 which further comprises a transparent passivating layer coated on top of the magnetizable amorphous film.
Claim 18
Dependent Claim
21 words
The recording medium of claim 10 which further comprises a reflecting layer on which the magnetizable amorphous film has been deposited.
Claim 19
Dependent Claim
28 words
The recording medium of claim 16 in which the reflecting layer has been deposited on the substrate prior to depositing the magnetizable amorphous film on the reflecting layer.
Claim 20
Dependent Claim
34 words
The recording medium of claim 17 which further comprises a priming layer made of a material selected from the oxides of chromium, titanium, tantalum and aluminum located between the substrate and the reflecting layer.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1989-10-06 | 1990-04-07 | 1990-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-06 | 1994-04-07 | 1994-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-06 | 1998-04-07 | 1998-10-07 | $7700.00 | Window Closed / Lapsed |