Ferromagnetic tunnel magnetoresistive devices and magnetic head

• US 20020085319A1
• Filed: 08/31/2001
• Published: 07/04/2002
• Est. Priority Date: 12/26/2000
• Status: Active Grant

• Current Assignee: Hitachi Global Storage Technologies Japan Limited (Western Digital Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Hayakawa, Jun
• Granted Patent: US 6,826,023 B2
• Time in Patent Office: Days
• US Class Current: 360/324.2
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• 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: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
• CPC Class Codes: G11B 2005/0018 by current biasing control or regulation
• CPC Class Codes: G11B 5/39 using magneto-resistive devices or effects
• 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 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/3951 the active elements being arranged on several parallel planes
• 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 5/553 Details
• CPC Class Codes: G11B 5/59683 for magnetoresistive heads
• CPC Class Codes: H01F 10/00 Thin magnetic films, e.g. of one-domain structure magnetic record carriers G11B5/00; thin-film magnetic stores G11C
• CPC Class Codes: H01F 10/1936 Half-metallic, e.g. epitaxial CrO2 or NiMnSb films
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/3263 the exchange coupling being symmetric, e.g. for dual spin valve, e.g. NiO/Co/Cu/Co/Cu/Co/NiO
• 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
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

The present invention provides a ferromagnetic tunnel magnetoresistive film which is associated with a high output and whose magnetoresistive ratio is less dependent on a bias voltage.

In a three-terminal ferromagnetic tunnel magnetoresistive element, a decrease in an output is suppressed by a bias voltage V₁, applied to one of the tunnel junctions. By employing half-metallic ferromagnets 11 and 12 in the element, the output can be enhanced and the dependency on the applied bias voltage can be reduced.

Claims

1. A ferromagnetic tunnel magnetoresistive element, comprising:

a first ferromagnetic layer;

a first insulating barrier layer formed on the first ferromagnetic layer;

a second ferromagnetic layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the second ferromagnetic layer; and

a third ferromagnetic layer formed on the second insulating barrier layer,

wherein the element further comprises a terminal for applying a first bias voltage between the first ferromagnetic layer and the third ferromagnetic layer, and a terminal for applying a second bias voltage between the second ferromagnetic layer and the first or third ferromagnetic layer.

2. A ferromagnetic tunnel magnetoresistive element according to claim 1, further comprising a first antiferromagnetic layer under the first ferromagnetic layer for fixing the magnetization direction of the first ferromagnetic layer, and a second antiferromagnetic layer on the third ferromagnetic layer for fixing the magnetization direction of the third ferromagnetic layer.

3. A ferromagnetic tunnel magnetoresistive element according to either one of claims 1 and 2, wherein the second ferromagnetic layer is formed of a lamination of three ferromagnetic metal layers.

4. A ferromagnetic tunnel magnetoresistive element according to claim 1, wherein each of the first and second ferromagnetic layers is formed of a lamination of two ferromagnetic metal layers.

5. A ferromagnetic tunnel magnetoresistive element according to any one of claims 1 to 4, wherein at least one of the first, second and third ferromagnetic layers makes contact with a non-magnetic metal layer.

6. A magnetic head provided with a magnetoresistive element comprising:

a first ferromagnetic layer;

a first insulating barrier layer formed on the first ferromagnetic layer;

a second ferromagnetic layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the second ferromagnetic layer; and

a third ferromagnetic layer formed on the second insulating barrier layer,

wherein the element further comprises a terminal for applying a first bias voltage between the first ferromagnetic layer and the third ferromagnetic layer, and a terminal for applying a second bias voltage between the second ferromagnetic layer and the first or third ferromagnetic layer.

7. A magnetic head according to claim 6, wherein the element further comprises a first antiferromagnetic layer under the first ferromagnetic layer for fixing the magnetization direction of the first ferromagnetic layer, and a second antiferromagnetic layer on the third ferromagnetic layer for fixing the magnetization direction of the third ferromagnetic layer.

8. A magnetic head according to either one of claims 6 and 7, wherein the second ferromagnetic layer is formed of a lamination of three ferromagnetic metal layers.

9. A magnetic head according to claim 6, wherein each of the first and second ferromagnetic layers is formed of a lamination of two ferromagnetic metal layers.

10. A magnetic head according to any one of claims 6 to 9, wherein at least one of the first, second and third ferromagnetic layers makes contact with a non-magnetic metal layer.

11. A ferromagnetic tunnel magnetoresistive element, comprising:

a first half-metallic ferromagnetic layer;

a first insulating barrier layer formed on the first half-metallic ferromagnetic layer;

a ferromagnetic metal layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the ferromagnetic metal layer; and

a second half-metallic ferromagnetic layer formed on the second insulating barrier layer,

wherein the element further comprises a terminal for applying a first bias voltage between the first half-metallic ferromagnetic layer and the second half-metallic ferromagnetic layer, and a terminal for applying a second bias voltage between the ferromagnetic metal layer and the first or second half-metallic ferromagnetic layer.

12. A ferromagnetic tunnel magnetoresistive element according to claim 11, further comprising a first antiferromagnetic layer under the first half-metallic ferromagnetic layer for fixing the magnetization direction of the first half-metallic ferromagnetic layer, and a second antiferromagnetic layer on the second half-metallic ferromagnetic layer for fixing the magnetization direction of the second half-metallic ferromagnetic layer.

13. A ferromagnetic tunnel magnetoresistive element according to either one of claims 11 and 12, wherein the ferromagnetic metal layer is formed of a lamination of three ferromagnetic metal layers.

15. A ferromagnetic tunnel magnetoresistive element according to claim 14, wherein each of the first and second ferromagnetic metal layers has a lamination of two ferromagnetic metal layers.

16. A ferromagnetic tunnel magnetoresistive element according to claim 14, further comprising a first antiferromagnetic layer under the first ferromagnetic metal layer for fixing the magnetization direction of the first ferromagnetic metal layer, and a second antiferromagnetic layer on the second ferromagnetic metal layer for fixing the magnetization direction of the second ferromagnetic metal layer.

17. A ferromagnetic tunnel magnetoresistive element according to any one of claims 11 to 16, wherein the half-metallic ferromagnetic layer is an oxide or a compound comprising Fe, Co or Mn.

19. A ferromagnetic tunnel magnetoresistive element according to claim 18, wherein the first ferromagnetic metal layer is formed of a lamination of three ferromagnetic metal layers.

21. A ferromagnetic tunnel magnetoresistive element according to any one of claims 11 to 20, wherein each of the first and second insulating barrier layers is made of an oxide or a compound comprising at least one of Al, Mg, Ti, Ta, Hf, Nb, Mo, Cr, Ga and As.

14. A ferromagnetic tunnel magnetoresistive element, comprising:

a first ferromagnetic metal layer;

a first insulating barrier layer formed on the first ferromagnetic metal layer;

a half-metallic ferromagnetic layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the half-metallic ferromagnetic layer; and

a second ferromagnetic metal layer formed on the second insulating barrier layer,

wherein the element further comprises a terminal for applying a first bias voltage between the first ferromagnetic metal layer and the second ferromagnetic metal layer, and a terminal for applying a second bias voltage between the half-metallic ferromagnetic layer and the first or second ferromagnetic metal layer.

18. A ferromagnetic tunnel magnetoresistive element, comprising:

a first antiferromagnetic layer;

a half-metallic ferromagnetic layer formed on the first antiferromagnetic layer;

a first insulating barrier layer formed on the first half-metallic ferromagnetic layer;

a first ferromagnetic metal layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the first ferromagnetic metal layer;

a second ferromagnetic metal layer formed on the second insulating barrier layer; and

a second antiferromagnetic layer formed on the second ferromagnetic metal layer,

wherein the element further comprises a terminal for applying a first bias voltage between the half-metallic ferromagnetic layer and the second ferromagnetic metal layer, and a terminal for applying a second bias voltage between the first ferromagnetic metal layer and the half-metallic ferromagnetic layer or the second ferromagnetic metal layer.

20. A ferromagnetic tunnel magnetoresistive element, comprising:

a first antiferromagnetic layer;

a first ferromagnetic metal layer formed on the first antiferromagnetic layer;

a first insulating barrier layer formed on the first ferromagnetic metal layer;

a second ferromagnetic metal layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the second ferromagnetic metal layer;

a third ferromagnetic metal layer formed on the second insulating barrier layer; and

a second antiferromagnetic layer formed on the third ferromagnetic metal layer,

wherein the element further comprises a terminal for applying a first bias voltage between the first ferromagnetic metal layer and the third ferromagnetic metal layer, and a terminal for applying a second bias voltage between the second ferromagnetic metal layer and the first or third ferromagnetic metal layer.

22. A magnetic head provided with a magnetoresistive element comprising:

a first half-metallic ferromagnetic layer;

a first insulating barrier layer formed on the first half-metallic ferromagnetic layer;

a ferromagnetic metal layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the ferromagnetic metal layer; and

a second half-metallic ferromagnetic layer formed on the second insulating barrier layer,

wherein the element further comprises a terminal for applying a first bias voltage between the first and second half-metallic ferromagnetic layers, and a terminal for applying a second bias voltage between the ferromagnetic metal layer and the first or second half-metallic ferromagnetic layer.

23. A magnetic head according to claim 22, wherein the element further comprises a first antiferromagnetic layer under the first half-metallic ferromagnetic layer for fixing the magnetization direction of the first half-metallic ferromagnetic layer, and a second antiferromagnetic layer on the second half-metallic ferromagnetic layer for fixing the magnetization direction of the second half-metallic ferromagnetic layer.

24. A magnetic head according to either one of claims 22 and 23, wherein the ferromagnetic metal layer is formed of a lamination of three ferromagnetic metal layers.

26. A magnetic head according to claim 25, wherein each of the first and second ferromagnetic metal layers is formed of a lamination of two ferromagnetic metal layers.

27. A magnetic head according to claim 25, wherein the element further comprises a first antiferromagnetic layer under the first ferromagnetic metal layer for fixing the magnetization direction of the first ferromagnetic metal layer, and a second antiferromagnetic layer on the second ferromagnetic metal layer for fixing the magnetization direction of the second ferromagnetic metal layer.

28. A magnetic head according to any one of claims 22 to 27, wherein the half-metallic ferromagnetic layer is an oxide or a compound comprising Fe, Co or Mn.

30. A magnetic head according to claim 29, wherein the first ferromagnetic metal layer is formed of a lamination of three ferromagnetic metal layers.

32. A magnetic head according to any one of claims 22 to 31, wherein each of the first and second insulating barrier layers is made of an oxide or a compound comprising at least one of Al, Mg, Ti, Ta, Hf, Nb, Mo, Cr, Ga and As.

25. A magnetic head provided with a magnetoresistive element comprising:

a first ferromagnetic metal layer;

a first insulating barrier layer formed on the first ferromagnetic metal layer;

a half-metallic ferromagnetic layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the half-metallic ferromagnetic layer; and

a second ferromagnetic layer formed on the second insulating barrier layer,

wherein the element further comprises a terminal for applying a first bias voltage between the first ferromagnetic metal layer and the second ferromagnetic metal layer, and a terminal for applying a second bias voltage between the half-metallic ferromagnetic layer and the first or second ferromagnetic metal layer.

29. A magnetic head provided with a magnetoresistive element comprising:

a first antiferromagnetic layer;

a half-metallic ferromagnetic layer formed on the first antiferromagnetic layer;

a first insulating barrier layer formed on the first half-metallic ferromagnetic layer;

a first ferromagnetic metal layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the first ferromagnetic metal layer;

a second ferromagnetic metal layer formed on the second insulating barrier layer; and

a second antiferromagnetic layer formed on the second ferromagnetic metal layer,

wherein the element further comprises a terminal for applying a first bias voltage between the half-metallic ferromagnetic layer and the second ferromagnetic metal layer, and a terminal for applying a second bias voltage between the first ferromagnetic metal layer and the half-metallic ferromagnetic layer or the second ferromagnetic metal layer.

31. A magnetic head provided with a magnetoresistive element comprising:

a first antiferromagnetic layer;

a first ferromagnetic metal layer formed on the first antiferromagnetic layer;

a first insulating barrier layer formed on the first ferromagnetic metal layer;

a second ferromagnetic metal layer formed on the first insulating barrier layer;

a second insulating barrier layer formed on the second ferromagnetic metal layer;

a third ferromagnetic metal layer formed on the second insulating barrier layer; and

a second antiferromagnetic layer formed on the third ferromagnetic metal layer,

wherein the element further comprises a terminal for applying a first bias voltage between the first ferromagnetic metal layer and the third ferromagnetic metal layer, and a terminal for applying a second bias voltage between the second ferromagnetic metal layer and the first or third ferromagnetic metal layer.