Magnetoresistive read transducer having improved bias profile

• US 5,285,339 A
• Filed: 02/28/1992
• Issued: 02/08/1994
• Est. Priority Date: 02/28/1992
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ju, Kochan, Chen, Mao-Min, Krounbi, Mohamad T., Wang, Po-Kang, Tsang, Ching H.
• Primary Examiner(s): HEINZ, ALLEN J
• Application Number:
  US07/843,702
• Time in Patent Office: 711 Days
• Field of Search: 360/113
• US Class Current: 360/327.1
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures

Abstract

An MR read transducer having passive end regions separated by a central active region comprises an MR layer made from a material having a low uniaxial magnetic anisotropy. A soft magnetic bias layer is adjacent to but spaced from the MR layer in the central region only, and the soft magnetic bias layer is made from a material having a high uniaxial magnetic anisotropy. A longitudinal bias is produced directly in each of the end regions only, and the means for producing the longitudinal bias comprise a layer made from a material having a high uniaxial magnetic anisotropy. Control of the uniaxial anisotropy can be achieved by choosing materials of appropriate magnetostriction or intrinsic uniaxial anisotropy.

Claims

1. A magnetoresistive read transducer having passive end regions separated by a central active region comprising:

a magnetoresistive layer made from a material having a low uniaxial magnetic anisotropy corresponding to a high permeability, said magnetoresistive layer having a sensing edge;

a soft magnetic bias layer in said central active region, adjacent to but spaced from said magnetoresistive layer, said soft magnetic bias layer made from a material having a high uniaxial magnetic anisotropy along a direction transverse to said sensing edge; and

means for producing a longitudinal bias directly in each of said end regions only, said means for producing a longitudinal bias comprising a layer made from a material having a high uniaxial magnetic anisotropy along a longitudinal direction of said magnetoresistive layer.

2. The magnetoresistive read transducer of claim 1 wherein said magnetoresistive layer extends over said central region only.

3. A magnetoresistive read transducer having passive end regions separated by a central active region comprising:

a magnetoresistive layer made from a material having a low magnetostriction coefficient;

a soft magnetic bias layer in said central active region, adjacent to but spaced from said magnetoresistive layer, said soft magnetic bias layer made from a material having a high positive magnetostriction coefficient; and

means for producing a longitudinal bias directly in each of said end regions only, said means for producing a longitudinal bias comprising a layer made from a material having a high negative magnetostriction coefficient.

4. The magnetoresistive read transducer of claim 3 wherein said magnetoresistive layer extends over said central region only.

5. The magnetoresistive read transducer of claim 3 wherein said soft magnetic bias layer comprises a ternary alloy NiFeX where X is taken from the group consisting of Rh, Ti, Cr, Ir and Nb.

6. The magnetoresistive read transducer of claim 3 wherein said magnetoresistive layer has a magnetostriction coefficient of 1×

10^-6 or less and said soft magnetic bias layer has a magnetostriction coefficient of 5×

10^-6 or greater.

7. The magnetoresistive read transducer of claim 3 wherein said means for producing a longitudinal bias has a magnetostriction coefficient of -15×

10^-6 or greater.

8. The magnetoresistive read transducer of claim 3 wherein said means for producing a longitudinal bias comprises an antiferromagnetic material in contact with a ferromagnetic material to produce an exchange bias field of a level sufficient to maintain said end regions of said transducer in a single domain state.

9. The magnetoresistive read transducer of claim 3 wherein said means for producing a longitudinal bias comprises a hard magnetic layer.

10. The magnetoresistive read transducer of claim 3 wherein said means for producing a longitudinal bias comprises a layer of ferromagnetic material.

11. The magnetoresistive read transducer of claim 10 wherein said layer of ferromagnetic material is subjected to a thermal oxidation treatment.

12. A magnetoresistive read transducer having passive end regions separated by a central active region comprising:

a magnetoresistive layer made from a material having a low magnetostriction coefficient, said magnetoresistive layer having a sensing edge extending over said central active region;

a soft magnetic bias layer in said central active region, adjacent to but spaced from said magnetoresistive layer, said soft magnetic bias layer made from a material having a high magnetic anisotropy in a direction normal to said sensing edge; and

means for producing a longitudinal bias directly in each of said end regions only of a level sufficient to maintain said end regions in a single domain state.

13. The magnetoresistive read transducer of claim 12 wherein said soft magnetic bias layer comprises a ternary alloy NiFeX where X is taken from the group consisting of Rh, Ti, Cr, Ir and Nb.

14. The magnetoresistive read transducer of claim 12 wherein said soft magnetic bias layer comprises a cobalt based material.

15. The magnetoresistive read transducer of claim 12 wherein said means for producing a longitudinal bias comprises an antiferromagnetic material in contact with a ferromagnetic material to produce an exchange bias field of a level sufficient to maintain said end regions of said transducer in a single domain state.

16. The magnetoresistive read transducer of claim 12 wherein said means for producing a longitudinal bias comprises a hard magnetic layer.

17. The magnetoresistive read transducer of claim 12 wherein said means for producing a longitudinal bias comprises a layer of ferromagnetic material.

18. The magnetoresistive read transducer of claim 17 wherein said layer of ferromagnetic material is subjected to a thermal oxidation treatment.

19. A magnetoresistive read transducer having passive end regions separated by a central active region comprising:

a magnetoresistive layer made from a material having a low magnetostriction coefficient, said magnetoresistive layer having a sensing edge extending over said central active region and said end regions; and

a soft magnetic bias layer in said central active region, adjacent to but spaced from said magnetoresistive layer, said soft magnetic bias layer made from a material having a high magnetic anisotropy in a direction normal to said sensing edge.