US4782413A
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Magnetoresistive sensor with mixed phase antiferromagnetic film
Assignee: International Business Machines Corp
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Filing: 1987-04-28
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Granted: 1988-11-01
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Expires: 2007-04-28
Abstract
Abstract An improved thin film magnetoresistive (MR) sensor uses an iron-manganese (FeMn) alloy, with the alpha (body-centered-cubic) phase of FeMn present in the alloy, as an antiferromagnetic layer. The presence of alpha FeMn improves the longitudinal exchange bias in the ferromagnetic MR layer, especially when the amount of alpha FeMn exceeds the amount of gamma (face-centered-cubic) FeMn in the FeMn layer.
Inventors
- 👤 James K. Howard
- 👤 Ting C. Huang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 17:18
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
52 words
An improved magnetoresistive sensor of the type having an antiferromagnetic layer in direct contact with a magnetoresistive ferromagnetic layer for inducing a longitudinal bias in the ferromagnetic layer, wherein the improvement is an antiferromagnetic layer comprising an iron-manganese (FeMn) alloy having at least a portion of the FeMn in the alpha phase.
Claim 2
Dependent Claim
52 words
An improved magnetoresistive sensor of the type having an antiferromagnetic layer in direct contact with a magnetoresistive ferromagnetic layer for inducing a longitudinal bias in the ferromagnetic layer, wherein the improvement is an antiferromagnetic layer comprising an iron-manganese (FeMn) alloy having at least a portion of the FeMn in the alpha phase.
Claim 3
Dependent Claim
18 words
The improved sensor according to claim 1 wherein said ferromagnetic layer is an alloy comprising nickel and iron.
Claim 4
Dependent Claim
106 words
A magnetoresistive sensor for use as a read sensor when exposed to external magnetic fields and when connected to means for sensing changes in electrical resistance, the magnetoresistive sensor comprising: a thin magnetoresistive layer of ferromagnetic material; a thin layer of antiferromagnetic material in direct contact with the magnetoresistive layer for inducing a magnetic exchange bias in the magnetoresistive layer, the antiferromagnetic material being an alloy comprising iron (Fe) and manganese (Mn), wherein the Fe and Mn form the alpha phase in at least a portion of the antiferromagnetic layer; and means coupled to the magnetoresistive layer for producing a transverse bias in said magnetoresistive layer.
Claim 5
Dependent Claim
106 words
A magnetoresistive sensor for use as a read sensor when exposed to external magnetic fields and when connected to means for sensing changes in electrical resistance, the magnetoresistive sensor comprising: a thin magnetoresistive layer of ferromagnetic material; a thin layer of antiferromagnetic material in direct contact with the magnetoresistive layer for inducing a magnetic exchange bias in the magnetoresistive layer, the antiferromagnetic material being an alloy comprising iron (Fe) and manganese (Mn), wherein the Fe and Mn form the alpha phase in at least a portion of the antiferromagnetic layer; and means coupled to the magnetoresistive layer for producing a transverse bias in said magnetoresistive layer.
Claim 6
Dependent Claim
30 words
The sensor according to claim 3 wherein the FeMn layer also includes the gamma phase of FeMn and wherein the amount of alpha FeMn exceeds the amount of gamma FeMn.
Claim 7
Dependent Claim
17 words
The sensor according to claim 3 wherein said magnetoresistive layer is an alloy comprising nickel and iron.
References Cited (Backward Citations)
US4103315A
Cited
US4663685A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-11-01 | 1992-05-02 | 1992-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-01 | 1996-05-02 | 1996-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-01 | 2000-05-02 | 2000-11-01 | $7700.00 | Window Closed / Lapsed |