Patent US4367257A successfully refreshed from Google Patents.
US4367257A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thin magnetic recording medium
Assignee: Fujifilm Holdings Corp
•
Filing: 1981-04-16
•
Granted: 1983-01-04
•
Expires: 2001-04-16
Abstract
Abstract A magnetic recording medium having a thin magnetic amorphous rare earth metal-transition metal alloy film is disclosed, the amorphous alloy film having an axis of easy magnetization in a direction substantially vertical to the film surface and containing a crystalline phase in the amorphous phase. The magnetic recording medium exhibits high coercive force over a wide compositional range.
Inventors
- 👤 Yoshihiro Arai
- 👤 Makoto Nagao
- 👤 Akira Nahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:40
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/658; H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/12; H01F10/13; H01F10/133; H01F10/135; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
87 words
A magnetic recording medium having a thin magnetic amorphous rare earth metal-transition metal alloy film that has an axis of easy magnetization in a direction substantially vertical to the film surface and which contains a crystalline phase in the amorphous phase wherein said rare earth metal is selected from the group consisting of Gd, Tb and Dy and said transition metal is selected from the group consisting of Fe, Co and Ni and said crystalline phase is composed of an elemental rare earth metal and/or oxide thereof.
Claim 2
Dependent Claim
87 words
A magnetic recording medium having a thin magnetic amorphous rare earth metal-transition metal alloy film that has an axis of easy magnetization in a direction substantially vertical to the film surface and which contains a crystalline phase in the amorphous phase wherein said rare earth metal is selected from the group consisting of Gd, Tb and Dy and said transition metal is selected from the group consisting of Fe, Co and Ni and said crystalline phase is composed of an elemental rare earth metal and/or oxide thereof.
Claim 3
Dependent Claim
30 words
A magnetic recording medium of claim 1, wherein said crystalline phase is composed of elemental Gd, elemental Tb, elemental Dy, Tb 4 O 7 or Gd 2 O 3 .
Claim 4
Dependent Claim
42 words
A magnetic recording medium of claim 1, wherein said amorphous alloy film is an amorphous Tb-Fe alloy film containing more than 30 atomic% Tb and containing in the amorphous phase of the film a crystalline phase of elemental Tb and/or Tb oxide.
Claim 5
Dependent Claim
23 words
A magnetic recording medium of claim 1, wherein said amorphous alloy film has a thickness of from about 300 A to about 2μ.
Claim 6
Dependent Claim
21 words
A magnetic recording medium of claim 1, wherein said amorphous alloy film has a coercive force of more than 700 Oe.
Claim 7
Dependent Claim
43 words
A magnetic recording medium of claim 1, wherein said amorphous alloy film is capable of forming a reverse magnetic domain having a diameter of, at the minimum, 0.3 to 0.4μ having a magnetic polarity opposite to the magnetic polarity of the film surface.
References Cited (Backward Citations)
US3342591A
Cited
JPS5438135A
Cited
US4210946A
Cited
JPS54121719A
Cited
US4293621A
Cited
US4277809A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-01-03 | 1986-07-05 | 1987-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-03 | 1990-07-05 | 1991-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-03 | 1994-07-05 | 1995-01-04 | $7700.00 | Window Closed / Lapsed |