US5422571A
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Magnetoresistive spin valve sensor having a nonmagnetic back layer
Assignee: HGST Netherlands BV
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Filing: 1993-02-08
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Granted: 1995-06-06
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Expires: 2013-02-08
Abstract
Abstract A magnetoresistive read sensor based on the spin valve effect in which a component of the read element resistance varies as the cosine of the angle between the magnetization directions in two adjacent magnetic layers is described. The sensor read element includes two adjacent ferromagnetic layers separated by a nonmagnetic metallic layer. A layer of nonmagnetic electrically conductive material is deposited adjacent to and in contact with one of the ferromagnetic layers, referred to as a filter layers to form a back or conduction layer which provides a low resistance path for conduction electrons transmitted through the adjacent filter layer. The thickness of the filter layer is selected such that it effectively blocks conduction electrons having spins antiparallel to the direction of magnetization in the filter layer while allowing conduction electrons with parallel spins to be transmitted through the layer into the adjacent back layer. The magnetization of the filter layer is free to rotate in response to an applied magnetic field thereby effectively varying the electrically resistance to conduction electrons in the back/filter layer. The thickness of the back layer is selected to optimize the sensor parameters being measured and is in a range of about 4.0 A to 1000 A.
Inventors
- 👤 Bruce A. Gurney
- 👤 David E. Heim
- 👤 Haralambos Lefakis
- 👤 Omar U. Need, III
- 👤 Virgil S. Speriosu
- 👤 Dennis R. Wilhoit
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:25
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; B; B82; B82Y; B82Y25/00; B82Y10/00; G01; G01R; G01R33/00; G01R33/02; G01R33/06; G01R33/09; G01R33/093; G11B5/3903; G11B2005/3996; H; H10; H10W; H10W72/00; H10W72/851; H10W72/853; H10W72/865; H10W90/00; H10W90/701; H10W90/731; H10W90/736; H10W90/751; H10W90/756
Claims Analysis
Total Claims: 51
Claim 1
Independent Claim
100 words
A magnetoresistive sensor comprising: a first and a second layer of ferromagnetic material separated by a spacer layer of nonmagnetic material, the magnetization direction of said first layer of ferromagnetic material being substantially perpendicular to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field; a back layer of nonmagnetic electrically conductive material adjacent to and in contact with said first ferromagnetic layer, said back layer being coextensive with said first ferromagnetic layer covering substantially the entire first ferromagnetic layer; and means for maintaining the magnetization in said second ferromagnetic layer in a desired direction.
Claim 2
Dependent Claim
100 words
A magnetoresistive sensor comprising: a first and a second layer of ferromagnetic material separated by a spacer layer of nonmagnetic material, the magnetization direction of said first layer of ferromagnetic material being substantially perpendicular to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field; a back layer of nonmagnetic electrically conductive material adjacent to and in contact with said first ferromagnetic layer, said back layer being coextensive with said first ferromagnetic layer covering substantially the entire first ferromagnetic layer; and means for maintaining the magnetization in said second ferromagnetic layer in a desired direction.
Claim 3
Dependent Claim
54 words
A magnetoresistive sensor as in claim 1 wherein said means comprises an exchange bias layer of antiferromagnetic material adjacent to and in contact with said second ferromagnetic layer, said antiferromagnetic layer for providing a bias field in said second ferromagnetic layer for maintaining the magnetization in said second ferromagnetic layer in a desired direction.
Claim 4
Dependent Claim
25 words
A magnetoresistive sensor as in claim 2 wherein said antiferromagnetic layer is comprised of a material selected from the group consisting of iron-manganese and nickel-manganese.
Claim 5
Dependent Claim
18 words
A magnetoresistive sensor as in claim 3 wherein said antiferromagnetic layer is comprised of an alloy of iron-manganese.
Claim 6
Dependent Claim
26 words
A magnetoresistive sensor as in claim 2 wherein the thickness of said antiferromagnetic layer being within the range of about 50 angstroms to about 150 angstroms.
Claim 7
Dependent Claim
20 words
A magnetoresistive sensor as in claim 1 wherein the minimum thickness of said nonmagnetic back layer being about 4 angstroms.
Claim 8
Dependent Claim
32 words
A magnetoresistive sensor as in claim 6 wherein the maximum thickness of said nonmagnetic back layer being about three mean free path lengths for conduction electrons in said nonmagnetic back layer material.
Claim 9
Dependent Claim
27 words
A magnetoresistive sensor as in claim 6 wherein the thickness of said nonmagnetic back layer being within the range of about 4 angstroms to about 1000 angstroms.
Claim 10
Dependent Claim
27 words
A magnetoresistive sensor as in claim 6 wherein the thickness of said nonmagnetic back layer being within the range of about 4 angstroms to about 60 angstroms.
Claim 11
Dependent Claim
31 words
A magnetoresistive sensor as in claim 1 wherein the thickness of said first and said second ferromagnetic layers each being within the range of about 5 angstroms to about 150 angstroms.
Claim 12
Dependent Claim
27 words
A magnetoresistive sensor as in claim 10 wherein the thickness of said first ferromagnetic layer being within the range of about 5 angstroms to about 30 angstroms.
Claim 13
Dependent Claim
30 words
A magnetoresistive sensor as in claim 1 wherein said nonmagnetic spacer layer has a thickness less than the mean free path length of conduction electrons in said nonmagnetic spacer material.
Claim 14
Dependent Claim
27 words
A magnetoresistive sensor as in claim 12 wherein the thickness of said nonmagnetic spacer layer being within the range of about 10 angstroms to about 40 angstroms.
Claim 15
Dependent Claim
33 words
A magnetoresistive sensor as in claim 1 wherein said nonmagnetic spacer layer is comprised of a material selected from the group consisting of silver, gold, copper and alloys of silver, copper and gold.
Claim 16
Dependent Claim
19 words
A magnetoresistive sensor as in claim 14 wherein said nonmagnetic spacer layer comprises a thin film layer of copper.
Claim 17
Dependent Claim
28 words
A magnetoresistive sensor as in claim 1 where in said nonmagnetic back layer is comprised of a material selected from the group consisting of silver, gold and copper.
Claim 18
Dependent Claim
19 words
A magnetoresistive sensor as in claim 16 wherein said nonmagnetic back layer comprises a thin film layer of copper.
Claim 19
Dependent Claim
22 words
A magnetoresistive sensor as in claim 1 wherein at least one of said first and second ferromagnetic layers comprise a multilayered structure.
Claim 20
Dependent Claim
36 words
A magnetoresistive sensor as in claim 18 wherein said multilayered structure comprises at least one layer of a first ferromagnetic material and at least one layer of a second ferromagnetic material, said layers being alternatively laminated.
Claim 21
Dependent Claim
35 words
A magnetoresistive sensor as in claim 18 wherein said first ferromagnetic layer comprises a thin layer of cobalt and a thin layer of nickel-iron, said thin layer of cobalt formed adjacent said nonmagnetic spacer layer.
Claim 22
Dependent Claim
38 words
A magnetoresistive sensor as in claim 18 wherein said first and second ferromagnetic layers each comprise a thin layer of cobalt and a thin layer of nickel-iron, said thin layer of cobalt formed adjacent said nonmagnetic spacer layer.
Claim 23
Dependent Claim
28 words
A magnetoresistive sensor as in claim 21 wherein the thickness of said thin layer of cobalt being within the range of about 0.5 angstroms to about 20 angstroms.
Claim 24
Dependent Claim
23 words
A magnetoresistive sensor as in claim 1 wherein both said nonmagnetic back layer and said nonmagnetic spacer layer comprise the same nonmagnetic material.
Claim 25
Dependent Claim
22 words
A magnetoresistive sensor as in claim 1 wherein both said nonmagnetic back layer and said nonmagnetic spacer layer comprise different nonmagnetic materials.
Claim 26
Dependent Claim
209 words
A magnetic storage system comprising: a magnetic storage medium having a plurality of tracks for recording of data; a magnetic transducer maintained in a closely spaced position relative to said magnetic storage medium during relative motion between said magnetic transducer and said magnetic storage medium, said magnetic transducer including a magnetoresistive sensor comprising: a first and a second layer of ferromagnetic material separated by a spacer layer of nonmagnetic material, the magnetization direction of said first layer of ferromagnetic material being substantially perpendicular to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field; a back layer of nonmagnetic electrically conductive material adjacent to and in contact with said first ferromagnetic layer, said back layer being coextensive with said first ferromagnetic layer covering substantially the entire first ferromagnetic layer; and bias means for maintaining the magnetization in said second ferromagnetic layer in a desired direction; actuator means coupled to said magnetic transducer for moving said magnetic transducer to selected tracks on said magnetic storage medium; and detection means coupled to said magnetoresistive sensor for detecting resistance changes in said magnetoresistive sensor in response to magnetic fields intercepted by said magnetoresistive sensor, said magnetic fields representative of data bits recorded in said magnetic storage medium.
Claim 27
Dependent Claim
209 words
A magnetic storage system comprising: a magnetic storage medium having a plurality of tracks for recording of data; a magnetic transducer maintained in a closely spaced position relative to said magnetic storage medium during relative motion between said magnetic transducer and said magnetic storage medium, said magnetic transducer including a magnetoresistive sensor comprising: a first and a second layer of ferromagnetic material separated by a spacer layer of nonmagnetic material, the magnetization direction of said first layer of ferromagnetic material being substantially perpendicular to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field; a back layer of nonmagnetic electrically conductive material adjacent to and in contact with said first ferromagnetic layer, said back layer being coextensive with said first ferromagnetic layer covering substantially the entire first ferromagnetic layer; and bias means for maintaining the magnetization in said second ferromagnetic layer in a desired direction; actuator means coupled to said magnetic transducer for moving said magnetic transducer to selected tracks on said magnetic storage medium; and detection means coupled to said magnetoresistive sensor for detecting resistance changes in said magnetoresistive sensor in response to magnetic fields intercepted by said magnetoresistive sensor, said magnetic fields representative of data bits recorded in said magnetic storage medium.
Claim 28
Dependent Claim
56 words
A magnetic storage system as in claim 25 wherein said bias means comprises an exchange bias layer of antiferromagnetic material adjacent to and in contact with said second ferromagnetic layer, said antiferromagnetic layer for providing a bias field in said second ferromagnetic layer for maintaining the magnetization in said second ferromagnetic layer in a desired direction.
Claim 29
Dependent Claim
26 words
A magnetic storage system as in claim 26 wherein said antiferromagnetic layer is comprised of a material selected from the group consisting of iron-manganese and nickel-manganese.
Claim 30
Dependent Claim
40 words
A magnetic storage system as in claim 26 wherein said magnetoresistive sensor further comprises: a capping layer deposited over said antiferromagnetic layer; and electrical lead means deposited over said capping layer for coupling said magnetoresistive sensor to said detection means.
Claim 31
Dependent Claim
24 words
A magnetic storage system as in claim 28 wherein said capping layer comprises a material selected from the group consisting of tantalum and zirconium.
Claim 32
Dependent Claim
34 words
A magnetic storage system as in claim 26 wherein said nonmagnetic spacer layer is comprised of a material selected from the group consisting of silver, gold, copper and alloys of silver, copper and gold.
Claim 33
Dependent Claim
20 words
A magnetic storage system as in claim 30 wherein said nonmagnetic spacer layer comprises a thin film layer of copper.
Claim 34
Dependent Claim
29 words
A magnetic storage system as in claim 25 where in said nonmagnetic back layer is comprised of a material selected from the group consisting of silver, gold and copper.
Claim 35
Dependent Claim
20 words
A magnetic storage system as in claim 32 wherein said nonmagnetic back layer comprises a thin film layer of copper.
Claim 36
Dependent Claim
168 words
A magnetoresistive sensor comprising: a first and a second layer of ferromagnetic material separated by a spacer layer of a nonmagnetic conductive material, the direction of magnetization in said first and second layers of ferromagnetic material responsive to a magnetic field generated by a sense current in said magnetoresistive sensor being oriented at equal and opposite angles with respect to the sensor magnetic easy axis; a first back layer of nonmagnetic electrically conductive material adjacent to and in contact with said first ferromagnetic layer, said first ferromagnetic layer disposed between said first back layer and said spacer layer, said first back layer being coextensive with said first ferromagnetic layer covering substantially the entire first ferromagnetic layer; and a second back layer of nonmagnetic electrically conductive material adjacent to and in contact with said second ferromagnetic layer, said second ferromagnetic layer disposed between said second back layer and said spacer layer, said second back layer being coextensive with said second ferromagnetic layer covering substantially the entire second ferromagnetic layer.
Claim 37
Dependent Claim
168 words
A magnetoresistive sensor comprising: a first and a second layer of ferromagnetic material separated by a spacer layer of a nonmagnetic conductive material, the direction of magnetization in said first and second layers of ferromagnetic material responsive to a magnetic field generated by a sense current in said magnetoresistive sensor being oriented at equal and opposite angles with respect to the sensor magnetic easy axis; a first back layer of nonmagnetic electrically conductive material adjacent to and in contact with said first ferromagnetic layer, said first ferromagnetic layer disposed between said first back layer and said spacer layer, said first back layer being coextensive with said first ferromagnetic layer covering substantially the entire first ferromagnetic layer; and a second back layer of nonmagnetic electrically conductive material adjacent to and in contact with said second ferromagnetic layer, said second ferromagnetic layer disposed between said second back layer and said spacer layer, said second back layer being coextensive with said second ferromagnetic layer covering substantially the entire second ferromagnetic layer.
Claim 38
Dependent Claim
25 words
A magnetoresistive sensor as in claim 34 wherein the minimum thickness of said first and said second nonmagnetic back layers each being about 4 angstroms.
Claim 39
Dependent Claim
38 words
A magnetoresistive sensor as in claim 35 wherein the maximum thickness of said first and said second nonmagnetic back layers each being about three mean free path lengths for conduction electrons in said nonmagnetic back layer material, respectively.
Claim 40
Dependent Claim
32 words
A magnetoresistive sensor as in claim 35 wherein the thickness of said first and said second nonmagnetic back layers each being within the range of about 4 angstroms to about 1000 angstroms.
Claim 41
Dependent Claim
32 words
A magnetoresistive sensor as in claim 35 wherein the thickness of said first and said second nonmagnetic back layers each being within the range of about 4 angstroms to about 60 angstroms.
Claim 42
Dependent Claim
31 words
A magnetoresistive sensor as in claim 34 wherein the thickness of said first and said second ferromagnetic layers each being within the range of about 5 angstroms to about 30 angstroms.
Claim 43
Dependent Claim
30 words
A magnetoresistive sensor as in claim 34 wherein said nonmagnetic spacer layer has a thickness less than the mean free path length of conduction electrons in said nonmagnetic spacer material.
Claim 44
Dependent Claim
27 words
A magnetoresistive sensor as in claim 40 wherein the thickness of said nonmagnetic spacer layer being within the range of about 10 angstroms to about 40 angstroms.
Claim 45
Dependent Claim
33 words
A magnetoresistive sensor as in claim 34 wherein said nonmagnetic spacer layer is comprised of a material selected from the group consisting of silver, gold, copper and alloys of silver, copper and gold.
Claim 46
Dependent Claim
31 words
A magnetoresistive sensor as in claim 34 where in said first and second nonmagnetic back layers are comprised of a material selected from the group consisting of silver, gold and copper.
Claim 47
Dependent Claim
23 words
A magnetoresistive sensor as in claim 43 wherein said first and second nonmagnetic back layers each comprise a thin film layer of copper.
Claim 48
Dependent Claim
90 words
A magnetoresistive sensor comprising: a first and a second layer of ferromagnetic material separated by a spacer layer of nonmagnetic material, the direction of magnetization of said first layer of ferromagnetic material being substantially perpendicular to the direction of magnetization of said second layer of ferromagnetic material at zero applied magnetic field; and a back layer of nonmagnetic electrically conductive material adjacent to and in contact with said first layer of ferromagnetic material, said back layer being coextensive with said first ferromagnetic layer covering substantially the entire first ferromagnetic layer.
Claim 49
Dependent Claim
90 words
A magnetoresistive sensor comprising: a first and a second layer of ferromagnetic material separated by a spacer layer of nonmagnetic material, the direction of magnetization of said first layer of ferromagnetic material being substantially perpendicular to the direction of magnetization of said second layer of ferromagnetic material at zero applied magnetic field; and a back layer of nonmagnetic electrically conductive material adjacent to and in contact with said first layer of ferromagnetic material, said back layer being coextensive with said first ferromagnetic layer covering substantially the entire first ferromagnetic layer.
Claim 50
Dependent Claim
19 words
A magnetoresistive sensor as in claim 45, the minimum thickness of said nonmagnetic back layer being about 4 angstroms.
Claim 51
Dependent Claim
27 words
A magnetoresistive sensor as in claim 45, wherein said nonmagnetic back layer is comprised of a material selected from the group consisting of silver, gold and copper.
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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) | 1998-06-05 | 1998-12-05 | 1999-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-06-05 | 2002-12-05 | 2003-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-06-05 | 2006-12-05 | 2007-06-06 | $7700.00 | Window Closed / Lapsed |