EP0145157A1
Expired / Lapsed
EP
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Thin film magnetic recording media
Assignee: HP Inc
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Filing: 1984-10-08
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Granted: —
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Expires: 2004-10-08
Abstract
Abstract A thin film magnetic recording disc is provided wherein a magnetic layer (8) is an alloy of cobalt and platinum disposed on a chromium layer (6). A barrier layer (10) of chromium is formed on the cobalt-platinum film and a wear layer (12) of an oxide of cobalt is provided on the barrier layer. The platinum content in the magnetic film is varied so as to provide a magnetic film with a desired coercivity which is significantly less dependent upon film thickness. This permits the cobalt-platinum film thickness to be adjusted to meet a wide range of recording system design parameters. The coercivity of the magnetic film may be deterined primarily by the amount of platinum in the alloy and the saturation magnetization-thickness product of the film is determined primarily by the film thickness.
Inventors
- 👤 James E. Opfer
- 👤 Bangalore R. Natarajan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 18:09
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/656; G11B5/73; G11B5/7368; G11B5/7369; G11B5/7373; G11B5/739; G11B5/73911; G11B5/73917; G11B5/73919; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12611; Y10T428/12771; Y10T428/12806; Y10T428/12826; Y10T428/12847; Y10T428/12854; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
37 words
A magnetic recording disc comprising a substrate (2) and characterized by a layer (6) of chromium disposed on said substrate, and a magnetic layer (8) of an alloy of cobalt and platinum disposed on said chromium layer.
Claim 2
Dependent Claim
37 words
A magnetic recording disc comprising a substrate (2) and characterized by a layer (6) of chromium disposed on said substrate, and a magnetic layer (8) of an alloy of cobalt and platinum disposed on said chromium layer.
Claim 3
Dependent Claim
19 words
A disc according to claim 1 characterized in that a barrier layer (10) is disposed on said magnetic layer.
Claim 4
Dependent Claim
30 words
A disc according to claim 2 characterized in that said barrier layer (10) is formed of a material selected from the group comprising chromium, titanium, tantalum and zirconium, preferably, chromium.
Claim 5
Dependent Claim
25 words
A disc according to any one of the preceding claims characterized in that said magnetic layer (8) contains up to about 20 atomic percent platinum.
Claim 6
Dependent Claim
29 words
A disc according to any one of the preceding claims characterized in that said magnetic layer (8) contains from about 1.5 to about 7, preferably 3, atomic percent platinum.
Claim 7
Dependent Claim
23 words
A disc according to any one of the preceding claims characterized in that a wear layer (12) is disposed on said barrier layer.
Claim 8
Dependent Claim
30 words
A disc according to claim 6 characterized in that said wear layer (12) is formed of an oxide selected frcm :he oxides of cobalt, titanium, silicon and aluminum, preferably, cobalt.
Claim 9
Dependent Claim
89 words
A magnetic recording disc comprising a substrate (2) of aluminium having a surface layer (4) thereon of an alloy of nickel and phosphorus; and characterized by a layer (6) of chromium disposed on said surface layer; a magnetic layer (8) of an alloy of cobalt and platinum disposed on said layer of chromium; a barrier layer (10) , disposed on said magnetic layer, said barrier layer being a material selected from chromium, titanium, tantalum and zirconium; and a wear layer (12) of cobalt oxide disposed on said barrier layer.
Claim 10
Dependent Claim
89 words
A magnetic recording disc comprising a substrate (2) of aluminium having a surface layer (4) thereon of an alloy of nickel and phosphorus; and characterized by a layer (6) of chromium disposed on said surface layer; a magnetic layer (8) of an alloy of cobalt and platinum disposed on said layer of chromium; a barrier layer (10) , disposed on said magnetic layer, said barrier layer being a material selected from chromium, titanium, tantalum and zirconium; and a wear layer (12) of cobalt oxide disposed on said barrier layer.
Claim 11
Dependent Claim
58 words
A disc according to claim 8 characterized in that said layer (6) of chromium on said surface layer (4) is at least about 1000 Angstroms thick, said magnetic layer (8) is at least about 125 Angstroms thick, said barrier layer (10) is at least 100 Angstroms thick, and said wear layer (12) is at least 250 Angstroms thick.
Claim 12
Dependent Claim
106 words
A magnetic recording disc comprising a substrate (2) of aluminium having a surface layer (4) thereon of an alloy of nickel and phosphorus; and characterized by a layer (6) of chromium about 2200 Angstroms thick disposed on said surface layer; a magnetic layer (8) of an alloy of cobalt and platinum about 410 Angstroms thick disposed on said chromium layer, the amount of platinum in said magnetic layer being about 3 atomic percent; a barrier layer (10) of chromium about 500 Angstroms thick disposed on said magnetic layer; and a wear layer (12) of cobalt' oxide about 420 Ang- troms thick disposed on said barrier layer.
Claim 13
Dependent Claim
106 words
A magnetic recording disc comprising a substrate (2) of aluminium having a surface layer (4) thereon of an alloy of nickel and phosphorus; and characterized by a layer (6) of chromium about 2200 Angstroms thick disposed on said surface layer; a magnetic layer (8) of an alloy of cobalt and platinum about 410 Angstroms thick disposed on said chromium layer, the amount of platinum in said magnetic layer being about 3 atomic percent; a barrier layer (10) of chromium about 500 Angstroms thick disposed on said magnetic layer; and a wear layer (12) of cobalt' oxide about 420 Ang- troms thick disposed on said barrier layer.
Claim 14
Dependent Claim
27 words
A disc according to claim 10 charracterized in that said substrate (2) is about 1.905 mm thick and said surface layer thereon is about 0.0076 mm thick.
Claim 15
Independent Claim
50 words
A method of making a film suitable for a magnetic recording disc characterized by forming a layer (8) of an alloy of cobalt and platinum, the thickness of the layer determining the magnetization-thickness product thereof, and the percentage of platinum in the alloy providing a predetermined coercivity of the film.
Claim 16
Independent Claim
50 words
A method of making a film suitable for a magnetic recording disc characterized by forming a layer (8) of an alloy of cobalt and platinum, the thickness of the layer determining the magnetization-thickness product thereof, and the percentage of platinum in the alloy providing a predetermined coercivity of the film.
Claim 17
Independent Claim
56 words
A method of making a film suitable for a magnetic recording disc characterized by depositing an alloy of cobalt and platinum to form a layer (8) to a predetermined thickness so as to establish a required magnetization-thickness product thereof, and controlling the percentage of platinum in the alloy to obtain a required coercivity of the film.
Claim 18
Independent Claim
56 words
A method of making a film suitable for a magnetic recording disc characterized by depositing an alloy of cobalt and platinum to form a layer (8) to a predetermined thickness so as to establish a required magnetization-thickness product thereof, and controlling the percentage of platinum in the alloy to obtain a required coercivity of the film.
Claim 19
Dependent Claim
34 words
A method according to claim 13 characterized in that the amount of platinum present in the alloy is from 1 to 20 atomic percent to provide a coercivity of not greater than 1600 Oersteds.
Claim 20
Independent Claim
30 words
A method according to either one of claims 13 and 14 characterized in that the layer (8) is formed upon a layer (6) of of chromium provided on a substrate.
Claim 21
Dependent Claim
31 words
A method according to claim 15 characterized in that the thickness of the layer (6) of chromium can be controlled as it is formed to adjust the value of the coercivity.
References Cited (Backward Citations)
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