Patent US966264A successfully refreshed from Google Patents.
Patent US4775576A successfully refreshed from Google Patents.
US4775576A
Expired / Lapsed
US
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Perpendicular anisotropic magnetic recording
Assignee: Bull SAS
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Filing: 1986-07-14
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Granted: 1988-10-04
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Expires: 2006-07-14
Abstract
Abstract A substrate for perpendicular anisotropic magnetic recording comprises a nonmagnetic substrate (SUBSI) on which a thin metal magnetic medium (CMI) having a negative magnetostrictive effect is deposited. The direction of easy magnetization of the medium is perpendicular to the surface. In order to minimize the magnetostrictive effect in the metal magnetic medium, the medium comprises a stack of alternate thin magnetic and nonmagnetic layers (CI 1 -CI n , ISO 1 -ISO n-1 ), the nonmagnetic layers (ISO 1 -ISO n-1 ) being sufficiently flexible so as to dampen the effect of the strains in the magnetic layers and enable strong magnetic coupling between them. The thickness of the nonmagnetic layers is between 150 and 250 angstroms, while the thickness of the magnetic layers is between 700 and 2000 angstroms. The stack may include as many as 10 or more magnetic layers of a chrome/cobalt alloy. The nonmagnetic layers may be SiO, SiO 2 and mixtures thereof. The invention is applicable to magnetic recording disks.
Inventors
- 👤 Jean-Claude Bouchand
- 👤 Jacques Desserre
- 👤 Dominque Jeanniot
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:56
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/66; G11B5/676; G11B5/678; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
139 words
A recording medium for perpendicular anisotropic magnetic recording comprising a nonmagnetic substrate (SUBS I), a metal magnetic medium (CMI) thereon characterized by a negative magnetostrictive effect and a direction of easy magnetization perpendicular to the surface, said metal magnetic medium comprising a stack of alternate thin magnetic and nonmagnetic layers (CI 1 -CI n , ISO 1 -ISO n-1 ), for minimizing the magnetostrictive effect in the metal magnetic medium, the nonmagnetic layers (ISO 1 -ISO n-1 ) being sufficiently flexible so as to dampen the effect of the strains in the magnetic layers and enabling strong magnetic coupling between them, and wherein the thickness of the nonmagnetic layers is on the order of 200 angstroms; and wherein the nonmagnetic layers are selected from the group consisting of silicon monoxide (SiO), silicon dioxide (SiO 2 ) and mixtures thereof.
Claim 2
Dependent Claim
139 words
A recording medium for perpendicular anisotropic magnetic recording comprising a nonmagnetic substrate (SUBS I), a metal magnetic medium (CMI) thereon characterized by a negative magnetostrictive effect and a direction of easy magnetization perpendicular to the surface, said metal magnetic medium comprising a stack of alternate thin magnetic and nonmagnetic layers (CI 1 -CI n , ISO 1 -ISO n-1 ), for minimizing the magnetostrictive effect in the metal magnetic medium, the nonmagnetic layers (ISO 1 -ISO n-1 ) being sufficiently flexible so as to dampen the effect of the strains in the magnetic layers and enabling strong magnetic coupling between them, and wherein the thickness of the nonmagnetic layers is on the order of 200 angstroms; and wherein the nonmagnetic layers are selected from the group consisting of silicon monoxide (SiO), silicon dioxide (SiO 2 ) and mixtures thereof.
Claim 3
Dependent Claim
19 words
A recording medium according to claim 1, wherein the magnetic layers are embodied of a chrome and cobalt alloy.
Claim 4
Dependent Claim
19 words
A recording medium according to claim 1, wherein the number of magnetic layers, n, is between 1 and 15.
Claim 5
Dependent Claim
21 words
A recording medium according to claim 1, wherein the thickness of the magnetic layers is included between 700 and 2000 angstroms.
Claim 6
Dependent Claim
141 words
A recording medium for perpendicular anisotropic magnetic recording comprising a nonmagnetic substrate (SUBS I), a metal magnetic medium (CMI) thereon characterized by a negative magnetostrictive effect and a direction of easy magnetization perpendicular to the surface, said metal magnetic medium comprising a stack of alternate thin magnetic and nonmagnetic layers (CI 1 -CI n , ISO 1 -ISO n-1 ), for minimizing the magnetostrictive effect in the metal magnetic medium, the nonmagnetic layers (ISO 1 -ISO n-1 ) being sufficiently flexible so as to dampen the effect of the strains in the magnetic layers and enabling strong magnetic coupling between them, and wherein the thickness of the nonmagnetic layers is in a range between 150 and 200 angstroms; and wherein the nonmagnetic layers are selected from the group consisting of silicon monoxide (SiO), silicon dioxide (SiO 2 ) and mixtures thereof.
Claim 7
Dependent Claim
141 words
A recording medium for perpendicular anisotropic magnetic recording comprising a nonmagnetic substrate (SUBS I), a metal magnetic medium (CMI) thereon characterized by a negative magnetostrictive effect and a direction of easy magnetization perpendicular to the surface, said metal magnetic medium comprising a stack of alternate thin magnetic and nonmagnetic layers (CI 1 -CI n , ISO 1 -ISO n-1 ), for minimizing the magnetostrictive effect in the metal magnetic medium, the nonmagnetic layers (ISO 1 -ISO n-1 ) being sufficiently flexible so as to dampen the effect of the strains in the magnetic layers and enabling strong magnetic coupling between them, and wherein the thickness of the nonmagnetic layers is in a range between 150 and 200 angstroms; and wherein the nonmagnetic layers are selected from the group consisting of silicon monoxide (SiO), silicon dioxide (SiO 2 ) and mixtures thereof.
Claim 8
Dependent Claim
21 words
A recording medium according to claim 5, wherein the thickness of the magnetic layers is included between 700 and 2000 angstroms.
Claim 9
Dependent Claim
19 words
A recording medium according to claim 6, wherein the magnetic layers are embodied of a chrome and cobalt alloy.
Claim 10
Dependent Claim
19 words
A recording medium according to claim 5 wherein the magnetic layers are embodied of a chrome and cobalt alloy.
Claim 11
Dependent Claim
19 words
A recording medium according to claim 5 wherein the number of magnetic layers, n, is between 1 and 15.
Claim 12
Dependent Claim
19 words
A recording medium according to claim 9, wherein the magnetic layers are embodied of a chrome and cobalt alloy.
Claim 13
Dependent Claim
20 words
A recording medium according to claim 9, wherein the thickness of the magnetic layers is between 700 and 2000 angstroms.
Claim 14
Dependent Claim
19 words
A recording medium according to claim 11, wherein the magnetic layers are embodied of a chrome and cobalt alloy.
References Cited (Backward Citations)
US3350180A
Cited
US3375091A
Cited
US3460968A
Cited
US3479156A
Cited
US3516076A
Cited
US3549428A
Cited
US3829372A
Cited
US4268369A
Cited
US4307156A
Cited
US4385098A
Cited
US4396575A
Cited
US4555444A
Cited
US4667032A
Cited
US4540600A
Cited
US4578322A
Cited
JPS6083218A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-04 | 1992-04-04 | 1992-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-04 | 1996-04-04 | 1996-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-04 | 2000-04-04 | 2000-10-04 | $7700.00 | Window Closed / Lapsed |