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US4654276A
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Magnetic recording medium with an underlayer and a cobalt-based magnetic layer
Assignee: HGST Netherlands BV
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Filing: 1986-04-29
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Granted: 1987-03-31
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Expires: 2006-04-29
Abstract
Abstract An improved cobalt-platinum (CoPt) thin film metal alloy media for horizontal magnetic recording has a coercivity substantially greater than prior CoPt thin film metal alloy media. A tungsten underlayer between the substrate and the CoPt magnetic layer improves the coercivity above that of media wiht conventional underlayers, such as chromium. The coercivity of the CoPt layer can be increased even further if the CoPt film is deposited in such a manner as to form an intermetallic compound of Co 3 W in the interface region between the tungsten underlayer and the CoPt magnetic layer. The tungsten underlayer also improves the magnetic properties of the media when the magnetic layer is an alloy of cobalt-platinum-chromium (CoPtCr).
Inventors
- 👤 Richard H. Ahlert
- 👤 James K. Howard
- 👤 Grace S. Lim
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:49
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/656; G11B5/73; G11B5/7368; G11B5/739; G11B5/73911; G11B5/73913; G11B5/73917; G11B5/73919; Y; Y10; Y10S; Y10S428/00; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12597; Y10T428/12625; Y10T428/12674; Y10T428/12736; Y10T428/12743; Y10T428/1275; Y10T428/12771; Y10T428/12861; Y10T428/12875; Y10T428/12937; Y10T428/12944
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
47 words
A magnetic recording medium for horizontal recording comprising: a substrate; a nonmagnetic layer formed on the substrate from an element selected from the group consisting of tungsten, molybdenum, niobium and vanadium; and a magnetic layer of an alloy comprising cobalt and platinum formed on the nonmagnetic layer.
Claim 2
Dependent Claim
47 words
A magnetic recording medium for horizontal recording comprising: a substrate; a nonmagnetic layer formed on the substrate from an element selected from the group consisting of tungsten, molybdenum, niobium and vanadium; and a magnetic layer of an alloy comprising cobalt and platinum formed on the nonmagnetic layer.
Claim 3
Dependent Claim
31 words
The magnetic recording medium according to claim 1 further comprising an intermetallic compound of cobalt and the element of the nonmagnetic layer at the interface of the nonmagnetic and magnetic layers.
Claim 4
Dependent Claim
17 words
The magnetic recording medium according to claim 1 wherein the alloy of the magnetic layer includes chromium.
Claim 5
Dependent Claim
30 words
The magnetic recording medium according to claim 2 wherein the element in the nonmagnetic layer is tungsten and wherein the intermetallic compound formed at the interface is Co 3 W.
Claim 6
Dependent Claim
13 words
The magnetic recording medium according to claim 1 wherein the substrate is silicon.
Claim 7
Dependent Claim
24 words
The magnetic recording medium according to claim 1 wherein the substrate further comprises an aluminum alloy disk having a nickel-phosphorus surface film formed thereon.
Claim 8
Dependent Claim
18 words
The magnetic recording medium according to claim 1 further comprising a protective overcoat formed over the magnetic layer.
Claim 9
Dependent Claim
54 words
A magnetic recording medium for horizontal recording comprising: a substrate; a layer of tungsten formed on the substrate; and a magnetic layer of an alloy comprising cobalt, platinum and chromium formed on the tungsten layer, wherein an intermetallic compound of cobalt and tungsten is formed at the interface of the tungsten and magnetic layers.
Claim 10
Dependent Claim
54 words
A magnetic recording medium for horizontal recording comprising: a substrate; a layer of tungsten formed on the substrate; and a magnetic layer of an alloy comprising cobalt, platinum and chromium formed on the tungsten layer, wherein an intermetallic compound of cobalt and tungsten is formed at the interface of the tungsten and magnetic layers.
Claim 11
Dependent Claim
93 words
A process for the fabrication of a magnetic recording medium comprising: providing a substrate; sputter depositing onto the substrate an element from the group consisting of tungsten, molybdenum, niobium and vanadium so as to form a nonmagnetic underlayer; and sputter depositing an alloy comprising cobalt and platinum onto the nonmagnetic underlayer so as to form a magnetic layer while maintaining the temperature of the substrate within a range sufficient to form an intermetallic compound interface between the magnetic layer and the underlayer, the intermetallic compound comprising cobalt and the element in the underlayer.
Claim 12
Dependent Claim
93 words
A process for the fabrication of a magnetic recording medium comprising: providing a substrate; sputter depositing onto the substrate an element from the group consisting of tungsten, molybdenum, niobium and vanadium so as to form a nonmagnetic underlayer; and sputter depositing an alloy comprising cobalt and platinum onto the nonmagnetic underlayer so as to form a magnetic layer while maintaining the temperature of the substrate within a range sufficient to form an intermetallic compound interface between the magnetic layer and the underlayer, the intermetallic compound comprising cobalt and the element in the underlayer.
Claim 13
Dependent Claim
23 words
The process according to claim 9 wherein the step of sputter depositing an alloy comprises depositing an alloy comprising cobalt, platinum and chromium.
Claim 14
Dependent Claim
23 words
The process according to claim 9 wherein the step of sputtering depositing the element of the underlayer comprises the step of depositing tungsten.
Claim 15
Dependent Claim
18 words
The process according to claim 9 comprising the step of forming a protective overcoat over the magnetic layer.
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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) | 1990-03-30 | 1990-09-29 | 1991-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-30 | 1994-09-29 | 1995-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-30 | 1998-09-29 | 1999-03-31 | $7700.00 | Window Closed / Lapsed |