Patent EP0105705A2 successfully refreshed from Google Patents.
EP0105705A2
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Perpendicular magnetic recording medium
Assignee: Hitachi Ltd
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Filing: 1983-09-28
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Granted: —
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Expires: 2003-09-28
Abstract
Abstract in a perpendicular magnetic recording medium comprising a high permeability film (3) and a perpendicular magnetization film (4) which are laminated on a non-magnetic substrate (1), a perpendicular magnetic recording medium (5) is provided wherein a permanent magnet film (2) is further sandwiched between the non-magnetic substrate (1) and the high permeability film (3), thereby eliminating a spike noise.
Inventors
- 👤 Yasutaro Uesaka
- 👤 Sadao Hishiyama
- 👤 Masahiro Kitada
- 👤 Noboru Shimizu
- 👤 Hideo Tanabe
- 👤 Hideo Fujiwara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 09:21
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/66; G11B5/676; G11B5/68; G11B5/70; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
44 words
A perpendicular magnetic recording medium (5) comprising a non-magnetic substrate (1), a permanent magnet film (2) formed on said non-magnetic substrate, a high permeability film (3) formed on said permanent magnet film, and a perpendicular magnetization film (4) formed on said high permeability film.
Claim 2
Dependent Claim
44 words
A perpendicular magnetic recording medium (5) comprising a non-magnetic substrate (1), a permanent magnet film (2) formed on said non-magnetic substrate, a high permeability film (3) formed on said permanent magnet film, and a perpendicular magnetization film (4) formed on said high permeability film.
Claim 3
Dependent Claim
26 words
A perpendicular magnetic recording medium according to claim 1, wherein a non-magnetic insulating film is sandwiched between said permanent magnet film and said high permeability film.
Claim 4
Dependent Claim
38 words
A perpendicular magnetic recording medium according to claim 1 or claim 2, wherein said permanent magnet film is magnetized by applying magnetic fields in the same direction as the direction of track width in said perpendicular magnetization film.
Claim 5
Dependent Claim
36 words
A perpendicular magnetic recording medium according to any one of claims 1 to 3 wherein said permanent magnet film has a thickness of 0.02 µm or more and a coercive force of 100 Oe or more.
Claim 6
Dependent Claim
27 words
A perpendicular magnetic recording medium according to claim 4, wherein said permanent magnet film is a γ-Fe203 film containing Co, Co-Pt alloy film, or Al-Ni-Co alloy film.
Claim 7
Dependent Claim
31 words
A perpendicular magnetic recording medium according to claim 5, wherein said Co-Pt alloy film which contains Co whose content is within a range of 2 - 43 weight percent is used.
Claim 8
Dependent Claim
31 words
A perpendicular magnetic recording medium according to claim 4, wherein said Co-Pt alloy film which contains CO whose content is within a range of 15 - 25 weight percent is used.
Claim 9
Dependent Claim
67 words
A perpendicular magnetic recording medium according to any one of claims 1 to 7, wherein the thickness of said perpendicular magnetization film is within a range of 0.03 - 0.3 µm, and wherein after said perpendicular magnetization film has been produced, said recording medium is subjected to heat treatment in a vacuum, inert gas or reducing gas at a temperature in a range of 350 - 550°C.
Claim 10
Dependent Claim
62 words
A perpendicular magnetic recording medium according to claim 8 wherein the thickness of said perpendicular magnetization film is within a range of 0.1 - 0.2 µm, and wherein after said perpendicular magnetization film has been produced, said recording medium is subjected to heat treatment in a vacuum, inert gas or reducing gas at a temperature in a range of 400 - 500°C.
Claim 11
Dependent Claim
44 words
A perpendicular magnetic recording medium according to claim 8 or claim 9 wherein when said high permeability film is a magnetic alloy film which is preferentially amorphous, the crystallization temperature of said preferentially amorphous magnetic alloy film is higher than said heat treatment temperature.
Claim 12
Dependent Claim
27 words
A perpendicular magnetic recording medium according to any one of claims 1 to 10 wherein said permanent magnet film has a thickness of 0.1 µm or more.
References Cited (Backward Citations)
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