US4476454A
Expired / Lapsed
US
⏱️ 0.0 years remaining
New magnetoresistive materials
Assignee: International Business Machines Corp
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Filing: 1983-06-30
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Granted: 1984-10-09
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Expires: 2003-06-30
Abstract
Abstract Devices and circuits are described employing magnetoresistive materials exhibiting a negative DELTA rho effect ( DELTA rho = rho PARALLEL - rho ORTHOGONAL ). In these materials, the electrical resistivity rho of the material in a direction perpendicular to the direction of current through the material is greater than the electrical resistivity rho PARALLEL of the material in a direction parallel to the direction of the electrical current through the material. These are ferromagnetic materials exhibiting magnetoresistance in the presence of an electrical current through the material and a magnetic field applied to the material to magnetize it to saturation at room temperature. These devices and circuits have advantages over conventional devices and circuits employing magnetoresistive materials of the conventional type, in which DELTA rho is a positive quantity.
Inventors
- 👤 Joseph A. Aboaf
- 👤 Erik Klokholm
- 👤 Thomas R. McGuire
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 09:16
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; H; H10; H10N; H10N50/00; H10N50/80; H10N50/85
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
96 words
A device responsive to a magnetic field including in combination: at least one magnetoresistive element exhibiting a negative anisotropic magnetoresistance Δρ=ρ∥-ρ⊥ at room temperature, said magnetoresistive element being comprised of a material chosen from the group consisting of Ni, Fe, and Co together with Ir, and ferromagnetic alloys and compounds of Ni, Fe, or Co together with Ir, the amount of Ir present being an amount sufficient to cause negative anisotropic magnetoresistance, and a source of current through said element, wherein the magnetoresistance of said element changes when said element is intercepted by said magnetic field.
Claim 2
Independent Claim
96 words
A device responsive to a magnetic field including in combination: at least one magnetoresistive element exhibiting a negative anisotropic magnetoresistance Δρ=ρ∥-ρ⊥ at room temperature, said magnetoresistive element being comprised of a material chosen from the group consisting of Ni, Fe, and Co together with Ir, and ferromagnetic alloys and compounds of Ni, Fe, or Co together with Ir, the amount of Ir present being an amount sufficient to cause negative anisotropic magnetoresistance, and a source of current through said element, wherein the magnetoresistance of said element changes when said element is intercepted by said magnetic field.
Claim 3
Dependent Claim
23 words
The device of claim 1, where the amount of Iridium in said magnetoresistive element is between about 1.5 and about 15 atomic percent.
Claim 4
Dependent Claim
18 words
The device of claim 1, further including a magnetoresistive element exhibiting a positive anisotropic magnetoresistance at room temperature.
Claim 5
Dependent Claim
30 words
The device of claim 3, in which the same magnetic field will cause opposite effects in each of said magnetoresistive elements in response to external factors such as temperature differences.
Claim 6
Dependent Claim
24 words
The device of claim 3, wherein said magnetic field produces changes in said magnetoresistive elements which are cumulative to provide an enhanced output signal.
Claim 7
Dependent Claim
15 words
The device of claim 3, wherein said magnetoresistive elements are connected in a bridge circuit.
Claim 8
Independent Claim
15 words
The device of FIG. 3, wherein said magnetoresistive elements are connected to a differential amplifier.
Claim 9
Independent Claim
15 words
The device of FIG. 3, wherein said magnetoresistive elements are connected to a differential amplifier.
Claim 10
Dependent Claim
19 words
The device of claim 1, where said magnetic field is a transition between magnetic domains in a recording medium.
Claim 11
Independent Claim
129 words
A device including a magnetoresistive element responsive to a magnetic field, said device including at least one magnetoresistive element having current flow therethrough, the room temperature resistivity of said element when the magnetization M of said element is perpendicular to the direction of current therethrough being greater than the room temperature resistivity of said element when its magnetization M is parallel to the direction of current flow therethrough, said magnetoresistive element having negative anisotropic magnetoresistance and being comprised of a material selected from the group consisting of Ni, Fe, and Co together with Ir, the amount of Ir present being an amount sufficient to cause negative anisotropic magnetoresistance, means for establishing a current flow through said element, and means for providing said magnetic field acting upon said magnetoresistive element.
Claim 12
Independent Claim
129 words
A device including a magnetoresistive element responsive to a magnetic field, said device including at least one magnetoresistive element having current flow therethrough, the room temperature resistivity of said element when the magnetization M of said element is perpendicular to the direction of current therethrough being greater than the room temperature resistivity of said element when its magnetization M is parallel to the direction of current flow therethrough, said magnetoresistive element having negative anisotropic magnetoresistance and being comprised of a material selected from the group consisting of Ni, Fe, and Co together with Ir, the amount of Ir present being an amount sufficient to cause negative anisotropic magnetoresistance, means for establishing a current flow through said element, and means for providing said magnetic field acting upon said magnetoresistive element.
Claim 13
Dependent Claim
36 words
The device of claim 9, where said magnetoresistive element is biased to have its magnetization at an angle with the direction of current through said element, said angle being greater than 0° and less than 90°.
Claim 14
Dependent Claim
21 words
The device of claim 9, wherein said magnetoresistive element is biased to have a substantially linear response to said magnetic field.
Claim 15
Dependent Claim
23 words
The device of claim 9, further including at least one additional magnetoresistive element, wherein said additional magnetoresistive element exhibits a positive Δρ effect.
Claim 16
Dependent Claim
14 words
The device of claim 12, wherein said magnetoresistive elements are arranged electrically in parallel.
Claim 17
Dependent Claim
15 words
The device of claim 12, where said magnetoresistive elements are located close to one another.
Claim 18
Dependent Claim
14 words
The device of claim 12, where said magnetoresistive elements are connected to an amplifier.
Claim 19
Dependent Claim
12 words
The device of claim 15, where said magnetoresistive elements bias one another.
Claim 20
Dependent Claim
15 words
The device of claim 12, where said magnetic field is produced by a recording medium.
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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) | 1987-10-09 | 1988-04-09 | 1988-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-09 | 1992-04-09 | 1992-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-09 | 1996-04-09 | 1996-10-09 | $7700.00 | Window Closed / Lapsed |