US5001586A
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Very low noise magnetoresistive sensor for high density media applications
Assignee: International Business Machines Corp
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Filing: 1989-08-01
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Granted: 1991-03-19
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Expires: 2009-08-01
Abstract
Abstract A soft film biased magnetoresistive sensor (10) is fabricated to have reduced Barkhausen noise. The magnetic ratio of the film layers (14 and 18) is controlled to be in the range of 1.7 to 1.95 and the optimum bias point is controlled to be in the range of 35 and 41 degrees.
Inventors
- 👤 Joseph A. Aboaf
- 👤 Vincent N. Kahwaty
- 👤 James L. Nix
- 👤 Frank B. Shelledy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:05
CPC Classifications
B; B82; B82Y; B82Y25/00; G; G01; G01R; G01R33/00; G01R33/02; G01R33/06; G01R33/09; G01R33/093; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; G11B5/399; H; H10; H10N; H10N50/00; H10N50/10
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
149 words
In a soft film biased magnetoresistive sensor with reduced Barkhausen noise, comprising a magnetoresistive film having a first saturated magnetic flux density for said magnetoresistive film and first film thickness for said magnetoresistive film, and a magnetically soft film positioned in close proximity to said magnetoresistive film and spaced therefrom by a non-magnetic shunt layer, said magnetically soft film having a second saturated magnetic flux density for said magnetically soft film and a second film thickness for said magnetically soft film, the improvement wherein a magnetic ratio of a first product of said first saturated magnetic flux density and said first film thickness to a second product of said second saturated magnetic flux density and said second film thickness is substantially in the range of about 1.7 to 1.95, said magnetic ratio corresponding to a nominal bias point substantially in a range of about 35 to 41 degrees, respectively.
Claim 2
Dependent Claim
149 words
In a soft film biased magnetoresistive sensor with reduced Barkhausen noise, comprising a magnetoresistive film having a first saturated magnetic flux density for said magnetoresistive film and first film thickness for said magnetoresistive film, and a magnetically soft film positioned in close proximity to said magnetoresistive film and spaced therefrom by a non-magnetic shunt layer, said magnetically soft film having a second saturated magnetic flux density for said magnetically soft film and a second film thickness for said magnetically soft film, the improvement wherein a magnetic ratio of a first product of said first saturated magnetic flux density and said first film thickness to a second product of said second saturated magnetic flux density and said second film thickness is substantially in the range of about 1.7 to 1.95, said magnetic ratio corresponding to a nominal bias point substantially in a range of about 35 to 41 degrees, respectively.
Claim 3
Dependent Claim
30 words
A soft film biased magnetoresistive sensor as recited in claim 1 wherein said magnetic ratio is substantially 1.83, said magnetic ratio corresponding to a nominal bias point of substantially 38.
Claim 4
Dependent Claim
32 words
A soft film biased magnetoresistive sensor as recited in claim 1 wherein said magnetoresistive film is comprised of a nickel-iron alloy and said magnetically soft film is comprised of a nickel-iron-rhodium alloy.
Claim 5
Dependent Claim
20 words
A soft film biased magnetoresistive sensor as recited in claim 3 wherein said non-magnetic shunt layer is comprised of tantalum.
Claim 6
Dependent Claim
38 words
A soft film biased magnetoresistive sensor as recited in claim 3 wherein the magnetostriction of said nickel-iron alloy is less than substantially 0.2*10 -6 and the magnetostriction of said nickel-iron-rhodium alloy is less than substantially 1.7*10 -6 .
Claim 7
Dependent Claim
25 words
A soft film biased magnetoresistive sensor as recited in claim 1 wherein said magnetically soft film has a magnetostriction less than substantially 1.7*10 -6 .
Claim 8
Dependent Claim
20 words
A soft film biased magnetoresistive sensor as recited in claim 1 wherein said magnetoresistive sensor is a center-tapped magnetoresistive sensor.
Claim 9
Dependent Claim
122 words
In a soft film biased magnetoresistive sensor with reduced Barkhausen noise, comprising a magnetoresistive film having a first saturated magnetic flux density for said magnetoresistive film and a first film thickness for said magnetoresistive film, and a magnetically soft film positioned in close proximity to said magnetoresistive film, said magnetically soft film having a second saturated magnetic flux density for said magnetically soft film and a second film thickness for said magnetically soft film, the improvement wherein a magnetic ratio of a first produce of said first saturated magnetic flux density and said first film thickness to a second product of said second saturated magnetic flux density and said second film thickness is substantially in the range of about 1.7 to 1.95.
Claim 10
Dependent Claim
122 words
In a soft film biased magnetoresistive sensor with reduced Barkhausen noise, comprising a magnetoresistive film having a first saturated magnetic flux density for said magnetoresistive film and a first film thickness for said magnetoresistive film, and a magnetically soft film positioned in close proximity to said magnetoresistive film, said magnetically soft film having a second saturated magnetic flux density for said magnetically soft film and a second film thickness for said magnetically soft film, the improvement wherein a magnetic ratio of a first produce of said first saturated magnetic flux density and said first film thickness to a second product of said second saturated magnetic flux density and said second film thickness is substantially in the range of about 1.7 to 1.95.
Claim 11
Dependent Claim
18 words
A soft film biased magnetoresistive sensor as recited in claim 8 wherein said magnetic ratio is substantially 1.83.
Claim 12
Dependent Claim
32 words
A soft film biased magnetoresistive sensor as recited in claim 8 wherein said magnetoresistive film is comprised of a nickel-iron alloy and said magnetically soft film is comprised of a nickel-iron-rhodium alloy.
Claim 13
Dependent Claim
38 words
A soft film biased magnetoresistive sensor as recited in claim 10 wherein the magnetostriction of said nickel-iron alloy is less than substantially 0.2*10 -6 and the magnetostriction of said nickel-iron-rhodium alloy is less than substantially 1.7*10 -6 .
Claim 14
Dependent Claim
27 words
A soft film biased magnetoresistive sensor as defined in claim 8 further including a non-magnetic shunt layer placed between said magnetoresistive film and said magnetically soft film.
Claim 15
Dependent Claim
20 words
A soft film biased magnetoresistive sensor as recited in claim 12 wherein said non-magnetic shunt layer is comprised of tantalum.
Claim 16
Dependent Claim
25 words
A soft film biased magnetoresistive sensor as recited in claim 8 wherein said magnetically soft film has a magnetostriction less than substantially 1.7*10 -6 .
Claim 17
Dependent Claim
20 words
A soft film biased magnetoresistive sensor as recited in claim 8 wherein said magnetoresistive sensor is a center-tapped magnetoresistive sensor.
Claim 18
Dependent Claim
27 words
A soft film biased magnetoresistive sensor as defined in claim 8 wherein said magnetically soft film provides a nominal bias point of between 35 and 41 degrees.
Claim 19
Dependent Claim
19 words
A soft film biased magnetoresistive sensor as defined in claim 16 wherein said nominal bias point is 38 degrees.
Claim 20
Dependent Claim
25 words
A soft film biased magnetoresistive sensor as defined in claim 17 wherein said nominal bias point is 38 degrees and has a ±4 degree variation.
Claim 21
Dependent Claim
89 words
A soft film biased magnetoresistive sensor with reduced Barkhausen noise comprising a magnetoresistive film having a first saturated magnetic flux density for said magnetoresistive film and a first film thickness for said magnetoresistive film, and a magnetically soft film positioned in close proximity to said magnetoresistive film, said magnetically soft film having a second saturated magnetic flux density for said magnetically soft film and a second film thickness for said magnetically soft film and providing a nominal bias point substantially in the range of about 35 to 41 degrees.
Claim 22
Dependent Claim
89 words
A soft film biased magnetoresistive sensor with reduced Barkhausen noise comprising a magnetoresistive film having a first saturated magnetic flux density for said magnetoresistive film and a first film thickness for said magnetoresistive film, and a magnetically soft film positioned in close proximity to said magnetoresistive film, said magnetically soft film having a second saturated magnetic flux density for said magnetically soft film and a second film thickness for said magnetically soft film and providing a nominal bias point substantially in the range of about 35 to 41 degrees.
Claim 23
Dependent Claim
19 words
A soft film biased magnetoresistive sensor as recited in claim 19 wherein said nominal bias point is approximately 38.
Claim 24
Dependent Claim
32 words
A soft film biased magnetoresistive sensor as recited in claim 19 wherein said magnetoresistive film is comprised of a nickel-iron alloy and said magnetically soft film is comprised of a nickel-iron-rhodium alloy.
Claim 25
Dependent Claim
39 words
A soft film biased magnetoresistive sensor as recited in claim 21 wherein the magnetostriction of said nickel-iron alloy is less than substantially 0.2*10 -6 and the magnetostriction of said nickel-iron-rhodium alloy is less than substantially pb 1.7*10 -6 .
Claim 26
Dependent Claim
27 words
A soft film biased magnetoresistive sensor as defined in claim 19 further including a non-magnetic shunt layer placed between said magnetoresistive film and said magnetically soft film.
Claim 27
Dependent Claim
20 words
A soft film biased magnetoresistive sensor as recited in claim 23 wherein said non-magnetic shunt layer is comprised of tantalum.
Claim 28
Dependent Claim
25 words
A soft film biased magnetoresistive sensor as recited in claim 19 wherein said magnetically soft film has a magnetostriction less than substantially 1.7*10 -6 .
Claim 29
Dependent Claim
20 words
A soft film biased magnetoresistive sensor as recited in claim 19 wherein said magnetoresistive sensor is a center-tapped magnetoresistive sensor.
Claim 30
Dependent Claim
57 words
A soft film biased magnetoresistive sensor as described in claim 19 wherein a magnetic ratio of a first product of said first saturated magnetic flux density and said first film thickness to a second product of said second saturated magnetic flux density and said second film thickness is substantially in the range of about 1.7 to 1.95.
Claim 31
Dependent Claim
18 words
A soft film biased magnetoresistive sensor as recited in claim 27 wherein said magnetic ratio is substantially 1.83.
References Cited (Backward Citations)
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| 3.5 Years (Year 4) | 1994-03-18 | 1994-09-17 | 1995-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-18 | 1998-09-17 | 1999-03-19 | $3760.00 | Window Closed / Lapsed |
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