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US5627703A
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Dual magnetoresistive reproduce head utilizing multilayer magnetoresistive sensing elements
Assignee: Eastman Kodak Co
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Filing: 1995-07-17
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Granted: 1997-05-06
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Expires: 2015-07-17
Abstract
Abstract A spin-valve dual magnetoresistance reproduce head (SV-DMR), consists of two spin valve sensor elements configured such that the two individual spin valve elements are physically separated by a relatively high resistivity conductive gap spacer. As in a conventional dual magnetoresistive head (DMR) there is sense current flow through the SV-DMR, and signal generated magnetoresistance changes are detected as head output voltage variations. The SV-DMR eliminates the need for an exchange coupled pinning layer or the mismatch of spin valve layers to implement the perpendicular biasing arrangement disclosed in the prior art. The required perpendicular biasing is attained solely by the interaction between substantially equal thickness magnetic layers of the SV-DMR and the internal magnetic fields arising from the flow of the sense current in the device. The inherent high resolution of the prior art DMR is retained in the SV-DMR, and is effectively combined with the high output signal capability provided by the use of spin valve magnetoresistance elements.
Inventors
- 👤 Neil Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:47
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; B; B82; B82Y; B82Y10/00; G11B5/3906; G11B5/3945; G11B5/3948; G11B5/3951; G11B5/3954
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
299 words
A magnetoresistive reproduce head comprising: a) a substrate, b) a spin valve structure deposited on said substrate, said structure consisting of a first trilayer, a second trilayer and a central conductive non-magnetic non-antiferromagnetic spacer between said first and second trilayers, said first trilayer consisting of first and second ferromagnetic layers and a first conductive non-magnetic non-antiferromagnetic single layer, said first ferromagnetic layer deposited on said substrate, said first conductive non-magnetic non-antiferromagnetic single layer deposited on and in direct contact with said first ferromagnetic layer, and said second ferromagnetic layer deposited on and in direct contact with said first conductive non-magnetic non-antiferromagnetic single layer, said central conductive non-magnetic non-antiferromagnetic spacer deposited on and in direct contact with said second ferromagnetic layer, said second trilayer consisting of third and fourth ferromagnetic layers and a second conductive non-magnetic non-antiferromagnetic single layer, said third ferromagnetic layer deposited on and in direct contact with said central conductive non-magnetic non-antiferromagnetic spacer, said second conductive non-magnetic non-antiferromagnetic single layer deposited on and in direct contact with said third ferromagnetic layer, said fourth ferromagnetic layer deposited on and in direct contact with said second conductive non-magnetic non-antiferromagnetic single layer, c) means for producing a current flow through said magnetoresistive reproduce head to generate magnetic bias fields which magnetize said first ferromagnetic layer, said second ferromagnetic layer, said third ferromagnetic layer and said fourth ferromagnetic layer such that said first and said fourth ferromagnetic layers are magnetized substantially antiparallel to each other, said first and said second ferromagnetic layers are magnetized substantially perpendicular to each other, and said third and said fourth ferromagnetic layers are magnetized substantially perpendicular to each other, and d) means for differentially sensing the variations of resistivity of said first and second trilayers of said magnetoresistive head in response to an applied magnetic field.
Claim 2
Dependent Claim
299 words
A magnetoresistive reproduce head comprising: a) a substrate, b) a spin valve structure deposited on said substrate, said structure consisting of a first trilayer, a second trilayer and a central conductive non-magnetic non-antiferromagnetic spacer between said first and second trilayers, said first trilayer consisting of first and second ferromagnetic layers and a first conductive non-magnetic non-antiferromagnetic single layer, said first ferromagnetic layer deposited on said substrate, said first conductive non-magnetic non-antiferromagnetic single layer deposited on and in direct contact with said first ferromagnetic layer, and said second ferromagnetic layer deposited on and in direct contact with said first conductive non-magnetic non-antiferromagnetic single layer, said central conductive non-magnetic non-antiferromagnetic spacer deposited on and in direct contact with said second ferromagnetic layer, said second trilayer consisting of third and fourth ferromagnetic layers and a second conductive non-magnetic non-antiferromagnetic single layer, said third ferromagnetic layer deposited on and in direct contact with said central conductive non-magnetic non-antiferromagnetic spacer, said second conductive non-magnetic non-antiferromagnetic single layer deposited on and in direct contact with said third ferromagnetic layer, said fourth ferromagnetic layer deposited on and in direct contact with said second conductive non-magnetic non-antiferromagnetic single layer, c) means for producing a current flow through said magnetoresistive reproduce head to generate magnetic bias fields which magnetize said first ferromagnetic layer, said second ferromagnetic layer, said third ferromagnetic layer and said fourth ferromagnetic layer such that said first and said fourth ferromagnetic layers are magnetized substantially antiparallel to each other, said first and said second ferromagnetic layers are magnetized substantially perpendicular to each other, and said third and said fourth ferromagnetic layers are magnetized substantially perpendicular to each other, and d) means for differentially sensing the variations of resistivity of said first and second trilayers of said magnetoresistive head in response to an applied magnetic field.
Claim 3
Dependent Claim
39 words
The magnetoresistive reproduce head of claim 1, wherein said first and said fourth ferromagnetic layers are substantially identical in magnetic and electrical properties, and said second and said third ferromagnetic layers are substantially identical in magnetic and electrical properties.
Claim 4
Dependent Claim
27 words
The magnetoresistive reproduce head of claim 1, wherein said ferromagnetic layers are layers fabricated from at least one of the group consisting of Co, Fe, and Ni.
Claim 5
Dependent Claim
33 words
The magnetoresistive reproduce head of claim 3, wherein said first and said second conductive non-magnetic non-antiferromagnetic single layers are fabricated from at least one of the group consisting of Au, Ag, and Cu.
Claim 6
Dependent Claim
24 words
The magnetoresistive reproduce head of claim 1, wherein said first, said second, said third, and said fourth ferromagnetic layers are each of equal thickness.
Claim 7
Dependent Claim
35 words
The magnetoresistive reproduce head of claim 1, wherein said first and said second conductive non-magnetic non-antiferromagnetic single layers are each of a thickness less than the thickness of each individual layer of said ferromagnetic layers.
Claim 8
Dependent Claim
25 words
The magnetoresistive reproduce head of claim 1, wherein said conductive non-magnetic non-antiferromagnetic spacer has a resistivity higher than that of said first and second trilayers.
Claim 9
Dependent Claim
325 words
A magnetoresistive head assembly for detecting magnetically recorded signals having a characteristic recorded minimum bit length, said head assembly comprising: a) a substrate, b) a spin valve structure deposited on said substrate, said structure consisting of a first trilayer, a second trilayer and a central conductive non-magnetic non-antiferromagnetic spacer between said first and second trilayers, said first trilayer consisting of first and second ferromagnetic layers and a first conductive non-magnetic non-antiferromagnetic single layer, said first ferromagnetic layer deposited on said substrate, said first conductive non-magnetic non-antiferromagnetic single layer deposited on and in direct contact with said first ferromagnetic layer, and said second ferromagnetic layer deposited on and in direct contact with said first conductive non-magnetic non-antiferromagnetic single layer, said central conductive non-magnetic non-antiferromagnetic spacer deposited on and in direct contact with said second ferromagnetic layer and having a thickness substantially equal to said characteristic recorded bit length, said second trilayer consisting of third and fourth ferromagnetic layers and a second conductive non-magnetic non-antiferromagnetic single layer, said third ferromagnetic layer deposited on and in direct contact with said central conductive non-magnetic non-antiferromagnetic spacer, said second conductive non-magnetic non-antiferromagnetic single layer deposited on and in direct contact within said third ferromagnetic layer, said fourth ferromagnetic layer deposited on and in direct contact with said second conductive non-magnetic non-antiferromagnetic single layer, (c) means for producing a current flow through said magnetoresistive head assembly to generate magnetic bias fields which magnetize said first ferromagnetic layer, said second ferromagnetic layer, said third ferromagnetic layer and said fourth ferromagnetic layer such that said first and said fourth ferromagnetic layers are magnetized substantially antiparallel to each other, said first and said second ferromagnetic layers are magnetized substantially perpendicular to each other, and said third and said fourth ferromagnetic layers are magnetized substantially perpendicular to each other, and d) means for differentially sensing the variations of said first and second trilayers of said magnetoresistive head assembly in response to said magnetically recorded signals.
Claim 10
Dependent Claim
325 words
A magnetoresistive head assembly for detecting magnetically recorded signals having a characteristic recorded minimum bit length, said head assembly comprising: a) a substrate, b) a spin valve structure deposited on said substrate, said structure consisting of a first trilayer, a second trilayer and a central conductive non-magnetic non-antiferromagnetic spacer between said first and second trilayers, said first trilayer consisting of first and second ferromagnetic layers and a first conductive non-magnetic non-antiferromagnetic single layer, said first ferromagnetic layer deposited on said substrate, said first conductive non-magnetic non-antiferromagnetic single layer deposited on and in direct contact with said first ferromagnetic layer, and said second ferromagnetic layer deposited on and in direct contact with said first conductive non-magnetic non-antiferromagnetic single layer, said central conductive non-magnetic non-antiferromagnetic spacer deposited on and in direct contact with said second ferromagnetic layer and having a thickness substantially equal to said characteristic recorded bit length, said second trilayer consisting of third and fourth ferromagnetic layers and a second conductive non-magnetic non-antiferromagnetic single layer, said third ferromagnetic layer deposited on and in direct contact with said central conductive non-magnetic non-antiferromagnetic spacer, said second conductive non-magnetic non-antiferromagnetic single layer deposited on and in direct contact within said third ferromagnetic layer, said fourth ferromagnetic layer deposited on and in direct contact with said second conductive non-magnetic non-antiferromagnetic single layer, (c) means for producing a current flow through said magnetoresistive head assembly to generate magnetic bias fields which magnetize said first ferromagnetic layer, said second ferromagnetic layer, said third ferromagnetic layer and said fourth ferromagnetic layer such that said first and said fourth ferromagnetic layers are magnetized substantially antiparallel to each other, said first and said second ferromagnetic layers are magnetized substantially perpendicular to each other, and said third and said fourth ferromagnetic layers are magnetized substantially perpendicular to each other, and d) means for differentially sensing the variations of said first and second trilayers of said magnetoresistive head assembly in response to said magnetically recorded signals.
Claim 11
Dependent Claim
39 words
The magnetoresistive head assembly of claim 8, wherein said first and said fourth ferromagnetic layers are substantially identical in magnetic and electrical properties, and said second and said third ferromagnetic layers are substantially identical in magnetic and electrical properties.
Claim 12
Dependent Claim
28 words
The magnetoresistive head assembly of claim 8, wherein said ferromagnetic layers are layers fabricated from the at least one of the group consisting of Co, Fe, and Ni.
Claim 13
Dependent Claim
33 words
The magnetoresistive head assembly of claim 10, wherein said first and said second conductive non-magnetic non-antiferromagnetic single layers are fabricated from at least one of the group consisting of Au, Ag, and Cu.
Claim 14
Dependent Claim
24 words
The magnetoresistive head assembly of claim 8, wherein said first, said second, said third, and said fourth ferromagnetic layers are each of equal thickness.
Claim 15
Dependent Claim
35 words
The magnetoresistive head assembly of claim 8, wherein said first and said second conductive non-magnetic non-antiferromagnetic single layers are each of a thickness less than the thickness of each individual layer of said ferromagnetic lagers.
Claim 16
Dependent Claim
25 words
The magnetoresistive head assembly of claim 8, wherein said conductive non-magnetic non-antiferromagnetic spacer has a resistivity higher than that of said first and second trilayers.
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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) | 2000-05-05 | 2000-11-04 | 2001-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-05-05 | 2004-11-04 | 2005-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-05-05 | 2008-11-04 | 2009-05-06 | $7700.00 | Window Closed / Lapsed |