Magneto-resistive element and thin film magnetic head comprising the same

• US 6,353,316 B1
• Filed: 06/17/1999
• Issued: 03/05/2002
• Est. Priority Date: 06/18/1998
• Status: Expired due to Fees

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Amano, Hajime
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Andersen, Henry S.
• Application Number:
  US09/334,932
• Time in Patent Office: 992 Days
• Field of Search: 360/113, 360/327.3, 360/313, 360/317, 324/252, 338/32.R
• US Class Current: 324/252
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3932 Magnetic biasing films
• CPC Class Codes: G11B 5/3967 Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read G11B5/3906 takes precedence
• CPC Class Codes: G11B 5/398 Specially shaped layers
• CPC Class Codes: H01F 10/3268 the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn

Abstract

A magnetoresistive film through which a sense current for detecting a resistance change due to a magnetic field to be detected flows in a longitudinal direction, and a lateral bias film which is magnetized in a fixed direction by a constant magnitude such that a lateral bias is applied to said magnetoresistive film in a lateral direction intersecting said longitudinal direction are arranged to be opposed to each other via a magnetic isolation film. By conducting said sense current by means of a pair of lead conductive films coupled electrically to both edges of said magnetoresistive film, a magnetization recorded on a magnetic record medium can be detected. Since the lateral bias is applied to the magnetoresistive film such that the lateral bias is not affected by the sense current and external magnetic fields, the magnetization of the magnetic record medium can be stably detected without being influenced by the sense current and external magnetic fields. Said lateral bias film is preferably provided to extend beyond both edges of the magnetoresistive film viewed in the longitudinal direction.

Claims

1. A magnetoresistive element, comprising:

a magnetoresistive film through which a sense current for detecting a change in resistance due to a magnetization to be detected flows in a longitudinal direction;

a pair of lead conductive films coupled with both ends of the magnetoresistive film viewed in the longitudinal direction in an electrically conductive manner and conducting the sense current in the longitudinal direction;

a lateral bias film magnetized in a fixed direction by a constant magnitude to apply a lateral bias in a lateral direction which crosses with said longitudinal direction, said lateral bias being not influenced by said sense current and external magnetic field;

a magnetic isolation film arranged between the magnetoresistive film and the lateral bias film and being made of an electrically insulating non-magnetic material; and

a substrate supporting said magnetoresistive film, lead conductive films, lateral bias film and magnetic isolation film.

2. A magnetoresistive element according to claim 1, wherein said longitudinal direction and said lateral direction are perpendicularly crossed with each other.

3. A magnetoresistive element according to claim 1, wherein said lateral bias film comprises an antiferromagnetic film and a magnetic film which is exchange-coupled with said antiferromagnetic film.

4. A magnetoresistive element according to claim 3, wherein said antiferromagnetic film is made of a material selected from the group consisting of PtMn, NiMn, NiO, CoO, α

-Fe₂O₃ and compounds containing α

-Fe₂O₃.

5. A magnetoresistive element according to claim 3, wherein said magnetic film is made of a material selected from the group consisting of Co, compounds containing Co and at least one metal;

NiFe, alloys containing NiFe and at least one metal;

Fe, alloys containing Fe and at least one metal; and

compounds containing Fe, at least one metal and at least one of N, C and B.

6. A magnetoresistive element according to claim 1, wherein said lateral bias film includes a hard magnetic film.

7. A magnetoresistive element according to claim 6, wherein said hard magnetic film is made of a material selected from the group consisting of Co, Ni, Fe and alloys containing at least one of these metals.

8. A magnetoresistive element according to claim 1, wherein said lateral bias film is arranged closer to said substrate than said magnetoresistive film.

9. A magnetoresistive element according to claim 1, wherein said lateral bias film is arranged more remote from said substrate than said magnetoresistive film.

10. A magnetoresistive element according to claim 1, wherein said lateral bias film and magnetoresistive film have plane configurations such that corresponding edges of said lateral bias film and magnetoresistive film are aligned with each other.

11. A magnetoresistive element according to claim 1, wherein said lateral bias film and magnetoresistive film have plane configurations such that both edges of said lateral bias film are protruded outwardly from corresponding edges of said magnetoresistive film.

12. A combination type thin film magnetic head comprising a reading thin film head constructed by the magnetoresistive element as claimed in claim 1 and an inductive type writing thin film magnetic head, said thin film heads being stacked one on the other on a substrate.

13. A magnetoresistive element, comprising:

a magnetoresistive film through which a sense current for detecting a change in resistance due to a magnetization to be detected flows in a longitudinal direction;

a pair of lead conductive films coupled with both ends of the magnetoresistive film viewed in the longitudinal direction in an electrically conductive manner and conducting the sense current in the longitudinal direction;

a lateral bias film magnetized in a fixed direction by a constant magnitude to apply a lateral bias in a lateral direction which crosses with said longitudinal direction, said lateral bias being not influenced by said sense current and external magnetic field;

a magnetic isolation film arranged between the magnetoresistive film and the lateral bias film and being made of an electrically insulating non-magnetic material;

a pair of longitudinal bias films provided at respective end portions of said magnetoresistive film for applying a longitudinal bias to the magnetoresistive film in a longitudinal direction crossing with the lateral direction; and

a substrate supporting said magnetoresistive film, lead conductive films, lateral and longitudinal bias films and magnetic isolation film such that said lateral bias film is isolated from said lead conductive films and longitudinal film magnetically and electrically.

14. A magnetoresistive element according to claim 13, wherein said magnetic isolation film is made of an electrically insulating non-magnetic material selected from the group consisting of Al₂O₃, AlN, SiO₂, SiN, BN and AlON.

15. A magnetoresistive element, comprising:

a substrate made of an electrically insulating material and having a surface;

a lateral bias film provided on said surface of the substrate;

a magnetic isolation film made of an electrically insulating non-magnetic material and arranged to completely cover said lateral bias film such that the magnetic isolation film extends over the surface of the substrate;

a magnetoresistive film provided on the magnetic isolation film, through said magnetoresistive film a sense current flowing in a longitudinal direction for detecting a change in resistance due to a magnetization to be detected; and

a pair of lead conductive films provided on said magnetic isolation film such that the lead conductive films are coupled with both ends of the magnetoresistive film viewed in the longitudinal direction in an electrically conductive manner and conducting the sense current in the longitudinal direction;

wherein said lateral bias film is magnetized in a fixed direction by a constant magnitude to apply a lateral bias to the magnetoresistive film in the lateral direction which crosses with said longitudinal direction, said lateral bias being not influenced by said sense current and external magnetic field.

16. A magnetoresistive element according to claim 15, wherein said magnetoresistive film is provided on said magnetic isolation film such that longitudinal edges of the magnetoresistive film viewed in the longitudinal direction are retarded inwardly with respect to corresponding longitudinal edges of the lateral bias film by a given distance, and said lead conductive films are provided to extend on the magnetic isolation film inwardly over the lateral edges of the lateral bias film.

17. A magnetoresistive element according to claim 15, further comprising a pair of longitudinal bias films provided between said magnetic isolation film and said lead conductive films at respective end portions of said magnetoresistive film for applying a longitudinal bias to the magnetoresistive film in the longitudinal direction.

18. A magnetoresistive element according to claim 17, wherein said magnetoresistive film is provided on said magnetic isolation film such that longitudinal edges of the magnetoresistive film viewed in the longitudinal direction are retarded inwardly with respect to corresponding longitudinal edges of the lateral bias film by a given distance, and longitudinal bias films and lead conductive films are provided to extend on the magnetic isolation film inwardly over the lateral edges of the lateral bias film.

19. A magnetoresistive element, comprising:

a magnetoresistive film through which a sense current for detecting a change in resistance due to a magnetization to be detected flows in a longitudinal direction;

a pair of lead conductive films coupled with both ends of the magnetoresistive film viewed in the longitudinal direction in an electrically conductive manner and conducting the sense current in the longitudinal direction;

a lateral bias film magnetized in a fixed direction by a constant magnitude to apply a lateral bias in a lateral direction which crosses with said longitudinal direction, said lateral bias being not influenced by said sense current and external magnetic field;

a magnetic isolation film arranged between the magnetoresistive film and the lateral bias film; and

a substrate supporting said magnetoresistive film, lead conductive films, lateral bias films and magnetic isolation film such that longitudinal edges of the magnetoresistive film viewed in the longitudinal direction are retarded inwardly with respect to corresponding longitudinal edges of the lateral bias film by a given distance Δ

d1 which is determined by a track width defined by a longitudinal length Δ

d2 of the magnetoresistive film between the lead conductive films.

20. A magnetoresistive element according to claim 19, wherein said distance Δ

d1 is not less than 0.2 μ

m when Δ

d2 is not less than 1.0 μ

m, and said distance Δ

d1 is not less than 0.10 μ

m when Δ

d2 is smaller than 1.0 μ

m.

21. A magnetoresistive element according to claim 19, wherein said magnetic isolation film is made of an electrically insulating non-magnetic material, and said lateral bias film is isolated from the lead conductive films magnetically and electrically.

22. A magnetoresistive element according to claim 21, wherein said magnetic isolation film is made of an electrically insulating non-magnetic material selected from the group consisting of Al₂O₃, AlN, SiO₂, SiN, BN and AlON.

23. A magnetoresistive element according to claim 19, further comprising a pair of longitudinal bias films provided between said magnetic isolation film and said lead conductive films at respective end portions of said magnetoresistive film for applying a longitudinal bias to the magnetoresistive film in the longitudinal direction.