EP0611033A2
Expired / Lapsed
EP
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A magnetoresistive spin valve sensor and magnetic storage system incorporating such a sensor
Assignee: International Business Machines Corp
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Filing: 1994-01-11
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Granted: —
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Expires: 2014-01-11
Abstract
Abstract A magnetoresistive read sensor based on the spin valve effect is described, 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 (35,39). The sensor read element includes two adjacent ferromagnetic layers (35,39) separated by a nonmagnetic metallic layer (37). A layer (33) of nonmagnetic electrically conductive material is deposited adjacent to and in contact with at least one of the ferromagnetic layers (35) (referred to as a filter layer) to form a back or conduction layer (33) which provides a low resistance path for conduction electrons transmitted through the adjacent filter layer (35). The thickness of the filter layer (35) is selected such that it effectively blocks conduction electrons having spins antiparallel to the direction of magnetization in the filter layer (35) while allowing conduction electrons with parallel spins to be transmitted through the layer into the adjacent back layer (33). The magnetization of the filter layer (35) 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 (33) is selected to optimize the sensor parameters being measured and is in a range of about 4.0A to 1000A.
Inventors
- 👤 Bruce Alvin Gurney
- 👤 David Eugene Heim
- 👤 Haralambos Lefakis
- 👤 Omar U. Need Iii
- 👤 Virgil Simon Speriosu
- 👤 Dennis Richard Wilhoit
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 00:21
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: 24
Claim 1
Independent Claim
81 words
A magnetoresistive sensor comprising: a first (35) and a second (39) layer of ferromagnetic material separated by a spacer layer (37) 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; the sensor being characterised in that: a back layer (33) of nonmagnetic electrically conductive material is provided adjacent to and in contact with said first ferromagnetic layer (35).
Claim 2
Dependent Claim
28 words
A magnetoresistive sensor as claimed in Claim 1, further comprising a biasing means (41) for maintaining the magnetization in said second ferromagnetic layer (39) in a desired direction.
Claim 3
Dependent Claim
56 words
A magnetoresistive sensor as claimed in Claim 2 wherein said biasing means comprises an exchange bias layer (41) of antiferromagnetic material adjacent to and in contact with said second ferromagnetic layer (39), said antiferromagnetic layer providing a bias field in said second ferromagnetic layer maintaining the magnetization in said second ferromagnetic layer in a desired direction.
Claim 4
Dependent Claim
26 words
A magnetoresistive sensor as claimed in Claim 3 wherein said antiferromagnetic layer is comprised of a material selected from the group consisting of iron-manganese and nickel-manganese.
Claim 5
Dependent Claim
26 words
A magnetoresistive sensor as claimed in Claim 3 wherein said antiferromagnetic layer has a thickness within the range of about 50 angstroms to about 150 angstroms.
Claim 6
Dependent Claim
100 words
A magnetoresistive sensor comprising a first (87) and a second (91) layer of ferromagnetic material separated by a spacer layer (89) of nonmagnetic material, the sensor being characterised by: a first back layer (85) of nonmagnetic electrically conductive material adjacent to and in contact with said first ferromagnetic layer (87), said first ferromagnetic layer disposed between said first back layer and said spacer layer; and a second back layer (93) of nonmagnetic electrically conductive material adjacent to and in contact with said second ferromagnetic layer (91), said second ferromagnetic layer disposed between said second back layer and said spacer layer.
Claim 7
Dependent Claim
23 words
A magnetoresistive sensor as claimed in any preceding claim wherein each nonmagnetic back layer (33) has a minimum thickness of about 4 angstroms.
Claim 8
Dependent Claim
34 words
A magnetoresistive sensor as claimed in Claim 7, wherein each nonmagnetic back layer (33) has a maximum thickness of about three mean free path lengths for conduction electrons in said nonmagnetic back layer material.
Claim 9
Dependent Claim
28 words
A magnetoresistive sensor as claimed in Claim 7 wherein each nonmagnetic back layer (33) has a thickness within the range of about 4 angstroms to about 1000 angstroms.
Claim 10
Dependent Claim
27 words
A magnetoresistive sensor as claimed in Claim 7 wherein each nonmagnetic back layer has a thickness within the range of about 4 angstroms to about 60 angstroms.
Claim 11
Dependent Claim
30 words
A magnetoresistive sensor as claimed in any preceding claim wherein said first and second ferromagnetic layers have a thickness within the range of about 5 angstroms to about 150 angstroms.
Claim 12
Dependent Claim
33 words
A magnetoresistive sensor as claimed in any preceding claim wherein each ferromagnetic layer (35;87,91) having an associated back layer has a thickness within the range of about 5 angstroms to about 30 angstroms.
Claim 13
Dependent Claim
33 words
A magnetoresistive sensor as claimed in any preceding claim wherein said nonmagnetic spacer layer (37;89) has a thickness less than the mean free path length of conduction electrons in said nonmagnetic spacer material.
Claim 14
Dependent Claim
28 words
A magnetoresistive sensor as in claimed in Claim 13 wherein said nonmagnetic spacer layer has a thickness within the range of about 10 angstroms to about 40 angstroms.
Claim 15
Dependent Claim
35 words
A magnetoresistive sensor as claimed in any preceding claim 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
20 words
A magnetoresistive sensor as claimed in Claim 15 wherein said nonmagnetic spacer layer comprises a thin film layer of copper.
Claim 17
Dependent Claim
29 words
A magnetoresistive sensor as claimed in any preceding claim wherein each nonmagnetic back layer is comprised of a material selected from the group consisting of silver, gold and copper.
Claim 18
Dependent Claim
20 words
A magnetoresistive sensor as claimed in Claim 17 wherein each nonmagnetic back layer comprises a thin film layer of copper.
Claim 19
Dependent Claim
24 words
A magnetoresistive sensor as claimed in any preceding claim wherein at least one of said first and second ferromagnetic layers comprise a multilayered structure.
Claim 20
Dependent Claim
37 words
A magnetoresistive sensor as claimed in Claim 19 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
41 words
A magnetoresistive sensor as claimed in Claim 19 or 20 wherein one or both of said ferromagnetic layers 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 22
Dependent Claim
29 words
A magnetoresistive sensor as claimed in Claim 21 wherein said thin layer of cobalt has a thickness selected from a range of about 0.5 angstroms to about 20 angstroms.
Claim 23
Dependent Claim
23 words
A magnetoresistive sensor as claimed in any preceding claim wherein each nonmagnetic back layer and said nonmagnetic spacer layer comprise the same material.
Claim 24
Dependent Claim
120 words
A magnetic storage system comprising: a magnetic storage medium (12) having a plurality of tracks for recording of data; a magnetic transducer (21) maintained in a closely spaced position relative to said magnetic storage medium (12) during relative motion between said magnetic transducer and said magnetic storage medium, said magnetic transducer including a magnetoresistive sensor (30) as claimed in any preceding claim; actuator means (27) coupled to said magnetic transducer for moving said magnetic transducer to selected tracks on said magnetic storage medium; and detection means (107) coupled to said magnetoresistive sensor for detecting resistance changes in said magnetoresistive sensor responsive to magnetic fields representative of data bits recorded in said magnetic storage medium (12) intercepted by said magnetoresistive sensor.
References Cited (Backward Citations)
No citation records indexed.
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