Magnetic element, magnetic memory device, magnetoresistance effect head, and magnetic storage system

• US 6,365,286 B1
• Filed: 09/02/1999
• Issued: 04/02/2002
• Est. Priority Date: 09/11/1998
• Status: Expired due to Term

• Current Assignee: Toshiba Memory Corporation (Kioxia Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Saito, Yoshiaki, Inomata, Koichiro, Nakamura, Shinichi
• Primary Examiner(s): KILIMAN, LESZEK B
• Application Number:
  US09/388,604
• Time in Patent Office: 943 Days
• Field of Search: 428/692, 428/694.R, 428/694.T, 428/694.TM, 428/694.TS, 360/113, 365/173, 365/171
• US Class Current: 428/811.1
• 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 33/06 using galvano-magnetic devices
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/00 Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor G11B11/00 and G11B13/00 take precedence
• 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 5/66 the record carriers consisting of several layers
• CPC Class Codes: G11C 11/15 using multiple magnetic layers G11C11/155 takes precedence
• CPC Class Codes: H01F 10/3227 Exchange coupling via one or more magnetisable ultrathin or granular films
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/3268 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
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/1114 having tunnel junction effect
• CPC Class Codes: Y10T 428/1193 with interlaminar component [e.g., adhesion layer, etc.]

Abstract

A magnetic element which has a laminate film composed of ferromagnetic-dielectric mixed layer and dielectric layer laminated alternately, said ferromagnetic-dielectric mixed layer being a mixture of a ferromagnetic material having coercive force and a dielectric material, with the volume of the former being equal to or larger than that of the latter. The ferromagnetic-dielectric mixed layer 3 has the ferromagnetic layer 1 which is arranged close thereto with a dielectric layer interposed between them. Tunnel current flows between the ferromagnetic-dielectric mixed layer. The magnetic layer with a smaller coercive force has its spin switched so that the magnetoresistance effect is produced. The magnetic element having a ferromagnetic tunnel junction is designed such that the rate of change in magnetoresistance increases and the resistance of the element decreases and the rate of change in magnetoresistance varies less depending on voltage.

Claims

1. A magnetic element, comprising:

ferromagnetic-dielectric mixed layer having ferromagnetic material and dielectric material;

the ferromagnetic material in the ferromagnetic-dielectric mixed layer having volume not smaller than that of the dielectric material in the ferromagnetic-dielectric mixed layer,

first and second tunnel dielectric barriers respectively formed on the ferromagnetic-dielectric mixed layer,

first layer of ferromagnetic material formed so that the first dielectric barrier is interposed between the ferromagnetic-dielectric mixed layer and the first layer of ferromagnetic material; and

second layer of ferromagnetic material formed on the second dielectric barrier so that electric current flowing between the first and second layers of ferromagnetic material flows through each of the first and second dielectric tunnel barriers and the ferromagnetic-dielectric mixed layer.

2. The magnetic element as set forth in claim 1, wherein the dielectric material of the ferromagnetic-dielectric mixed layer is dispersed such that the ferromagnetic material serves as matrix to surround the dispersed ferromagnetic material.

3. The magnetic element as set forth in claim 1, further comprising antiferromagnetic layer;

the antiferromagnetic layer being exchange coupled with and providing coupling force to either one of first and second layers of ferromagnetic material.

4. The magnetic element as set forth in claim 1, further comprising layer of antiferromagnetic material;

the layer of antiferromagnetic material being exchange coupled with and providing coupling force to the ferromagnetic material in the ferromagnetic-dielectric layer.

5. The magnetic element as set force in claim 1, wherein the first and second tunnel dielectric barriers are formed by one dielectric layer, and the first and second layers of ferromagnetic material are formed on one surface of the dielectric layer.

6. The magnetic element as set forth in claim 1, wherein either one of the ferromagnetic material of the ferromagnetic-dielectric layer, and the first and second layers of ferromagnetic material comprises one material selected from the group consisting Co, CoPt, FePt, and alloy of transition metal and rare earth metal.

7. The magnetic element as set forth in claim 6, wherein other one of the ferromagnetic material of the ferromagnetic-dielectric layer, and the first and second layers of ferromagnetic material comprises one material selected from the group consisting Fe, Ni, Co, Fe alloy, Ni alloy, Co alloy, magnetite, oxide magnetic material, and Heusler alloy.

8. A magnetic memory device, comprising;

memory cell, having

ferromagnetic-dielectric mixed layer having ferromagnetic material and dielectric material;

the ferromagnetic material in the ferromagnetic-dielectric mixed layer having volume not smaller than that of the dielectric material in the ferromagnetic-dielectric mixed layer,

first and second tunnel dielectric barriers respectively formed on the ferromagnetic-dielectric mixed layer,

first layer of ferromagnetic material formed so that the first dielectric barrier is interposed between the ferromagnetic-dielectric mixed layer and the first layer of ferromagnetic material; and

second layer of ferromagnetic material formed on the second dielectric barrier so that electric current flowing between the first and second layers of ferromagnetic material flows through each of the first and second dielectric tunnel barriers and the ferromagnetic-dielectric mixed layer.

9. A magnetoresistance effect head, comprising;

ferromagnetic-dielectric mixed layer having ferromagnetic material and dielectric material;

the ferromagnetic material in the ferromagnetic-dielectric mixed layer having volume not smaller than that of the dielectric material in the ferromagnetic-dielectric mixed layer,

first and second tunnel dielectric barriers respectively formed on the ferromagnetic-dielectric mixed layer,

first layer of ferromagnetic material formed so that the first dielectric barrier is interposed between the ferromagnetic-dielectric mixed layer and the first layer of ferromagnetic material; and

second layer of ferromagnetic material formed on the second dielectric barrier so that electric current flowing between the first and second layers of ferromagnetic material flows through each of the first and second dielectric tunnel barriers and the ferromagnetic-dielectric mixed layer.

10. A magnetic storage system, comprising:

magnetic media;

magnetoresistance effect head for reproducing magnetic information of the magnetic media having

ferromagnetic-dielectric mixed layer having ferromagnetic material and dielectric material;

the ferromagnetic material in the ferromagnetic-dielectric mixed layer having volume not smaller than that of the dielectric material in the ferromagnetic-dielectric mixed layer,

first and second tunnel dielectric barriers respectively formed on the ferromagnetic-dielectric mixed layer,

first layer of ferromagnetic material formed so that the first dielectric barrier is interposed between the ferromagnetic-dielectric mixed layer and the first layer of ferromagnetic material; and

second layer of ferromagnetic material formed on the second dielectric barrier so that electric current flowing between the first and the second layers of ferromagnetic material flows through each of the first and second dielectric tunnel barriers and the ferromagnetic-dielectric mixed layer.

11. A magnetic element, comprising:

ferromagnetic-dielectric mixed layer having ferromagnetic material and dielectric material;

tunnel dielectric barrier formed on the ferromagnetic-dielectric mixed layer;

layer of ferromagnetic material formed on the tunnel dielectric barrier so that the tunnel dielectric barrier is interposed between the ferromagnetic-dielectric mixed layer and the layer of ferromagnetic material;

electrode formed in direct contact with the ferromagnetic material of the ferromagnetic-dielectric mixed layer so that electric current flowing between the layer of ferromagnetic material and the electrode flows through the dielectric tunnel barrier and the ferromagnetic-dielectric mixed layer.

12. The magnetic element as set forth in claim 11, wherein the magnetic element has plurality of the layer of ferromagnetic material formed on one surface of the first dielectric barrier.

13. The magnetic element as set forth in claim 12, further comprising layer of antiferromagnetic material;

the layer of antiferromagnetic material being exchange coupled with and providing coupling force to the layer of ferromagnetic material.

14. The magnetic device as set forth in claim 11, further comprising layer of antiferromagnetic material;

the layer of antiferromagnetic material being exchange coupled with and providing coupling force to the ferromagnetic material of the ferromagnetic-dielectric mixed layer.

15. The magnetic device as set forth in claim 11, wherein the ferromagnetic material of the ferromagnetic-dielectric mixed layer comprising material selected from the group consisting FeNi, amorphous alloy, Fe, Co, Ni, Fe alloy, Co alloy, Ni alloy, half metal, and alloy of transition metal and rare earth metal.

16. The magnetic element as set forth in claim 11, wherein the dielectric material of the ferromagnetic-dielectric mixed layer comprises material selected from the group consisting Al₂O₃, SiO₂, MgO, MgF₂, Ni₂O₃, AlN, and CaF₂.

17. A magnetic memory device, comprising

magnetic memory cell having

ferromagnetic-dielectric mixed layer of ferromagnetic material and dielectric material;

tunnel dielectric barrier formed on the ferromagnetic-dielectric mixed layer;

layer of ferromagnetic material formed so that the tunnel dielectric barrier is interposed between the ferromagnetic-dielectric mixed layer and layer of ferromagnetic material;

electrode formed in direct contact with the ferromagnetic material of the ferromagnetic-dielectric mixed layer and formed so that electric current flowing between the layer of ferromagnetic material and the electrode flows through the dielectric tunnel barrier and the ferromagnetic-dielectric mixed layer.

18. A magnetoresistance effect head, comprising:

ferromagnetic-dielectric mixed layer having ferromagnetic material and dielectric material;

tunnel dielectric barrier formed on the ferromagnetic-dielectric mixed layer;

layer of ferromagnetic material formed so that the tunnel dielectric barrier is interposed between the ferromagnetic-dielectric mixed layer and layer of ferromagnetic material;

electrode formed in direct contact with the ferromagnetic material of the ferromagnetic-dielectric mixed layer and formed so that electric current flowing between the layer of ferromagnetic material and the electrode flows through the dielectric tunnel barrier and the ferromagnetic-dielectric mixed layer.

19. A magnetic storage system, comprising:

magnetic media;

magnetoresistance effect head for reproducing magnetic information of the magnetic media having

ferromagnetic-dielectric mixed layer having ferromagnetic material and dielectric material;

tunnel dielectric barrier formed on the ferromagnetic-dielectric mixed layer;

layer of ferromagnetic material formed so that the tunnel dielectric barrier is interposed between the ferromagnetic-dielectric mixed layer and layer of ferromagnetic material;

electrode formed in direct contact with the ferromagnetic material of the ferromagnetic-dielectric mixed layer and formed so that electric current flowing between the layer of ferromagnetic material and the electrode flows through the dielectric tunnel barrier and the ferromagnetic-dielectric mixed layer.

20. A magnetic element, comprising:

a ferromagnetic-dielectric layer comprising two or more zones of ferromagnetic material interrupted by at least one zone of dielectric material in which the volume of ferromagnetic material is not less than the volume of dielectric material;

first and second tunnel dielectric barriers respectively formed on the ferromagnetic-dielectric layer;

first layer of ferromagnetic material formed so that the first dielectric barrier is interposed between the ferromagnetic-dielectric layer and the first layer of ferromagnetic material; and

second layer of ferromagnetic material formed on the second dielectric barrier so that the electric current flowing between the first and second layers of ferromagnetic material flows through each of the first and second dielectric tunnel barriers and the ferromagnetic-dielectric layer.

21. The magnetic element as set forth in claim 20, wherein the dielectric material of the ferromagnetic-dielectric layer is dispersed in the layer such that the ferromagnetic material serves as a matrix surrounding the dispersed ferromagnetic material.

22. The magnetic element as set forth in claim 20, which further comprises an antiferromagnetic layer, the antiferromagnetic layer being exchange coupled with and providing coupling force to either one of the first and second layers of ferromagnetic material.

23. The magnetic element as set forth in claim 20, which further comprises an antiferromagnetic layer, the antiferromagnetic layer being exchange coupled with and providing coupling force to the ferromagnetic material in the ferromagnetic-dielectric layer.

24. The magnetic element as set forth in claim 20, wherein the first and second tunnel dielectric barriers are formed by one dielectric layer, and the first and second layers of ferromagnetic material are formed on one surface of the dielectric layer.

25. The magnetic element as set forth in claim 20, wherein either one of the ferromagnetic material of the ferromagnetic-dielectric layer or the first and second layers of ferromagnetic material comprises one material selected from the group consisting of Co, CoPt, FePt and an alloy of a transition metal and a rare earth metal.

26. The magnetic element as set forth in claim 25, wherein the other one of the ferromagnetic material of the ferromagnetic-dielectric layer, and the first and second layers of ferromagnetic material comprises one material selected from the group consisting of Fe, Ni, Co, Fe alloy, Ni alloy, Co alloy, magnetite, a magnetic oxide material and Heusler alloy.

27. A magnetic memory device, comprising:

a memory cell, having;

a ferromagnetic-dielectric layer comprising two or more zones of ferromagnetic material interrupted by at least one zone of dielectric material in which the volume of ferromagnetic material is not less than the volume of dielectric material;

first and second tunnel dielectric barriers respectively formed on ferromagnetic-dielectric mixed layer;

a first layer of ferromagnetic material formed so that the first dielectric barrier is interposed between the ferromagnetic-dielectric layer and the first layer of ferromagnetic material; and

a second layer of ferromagnetic material formed on the second dielectric barrier so that the electric current flowing between the first and second layers of ferromagnetic material flows through each of the first and second dielectric tunnel barriers and the ferromagnetic-dielectric layer.

28. A megnetoresistance effect head, comprising;

a ferromagnetic-dielectric layer comprising two or more zones of ferromagnetic material interrupted by at least one zone of dielectric material in which the volume of ferromagnetic material is not less than the volume of dielectric material;

first and second tunnel dielectric barriers respectively formed on the ferromagnetic-dielectric mixed layer;

a first layer of ferromagnetic material formed so that the first dielectric barrier is interposed between the ferromagnetic-dielectric layer and the first layer of ferromagnetic material; and

a second layer of ferromagnetic material formed on the second dielectric barrier so that the electric current flowing between the first and second layers of ferromagnetic material flows through each of the first and second dielectric tunnel barriers and the ferromagnetic-dielectric layer.

29. A magnetic storage system, comprising:

magnetic media, and

magnetoresistance effect head for reproducing magnetic information on the magnetic media having;

a ferromagnetic-dielectric layer comprising two or more zones of ferromagnetic material interrupted by at least one zone of dielectric material in which the volume of ferromagnetic material is not less than the volume of dielectric material;

first and second tunnel dielectric barriers respectively formed on the ferromagnetic-dielectric mixed layer;

a first layer of ferromagnetic material formed so that the first dielectric barrier is interposed between the ferromagnetic-dielectric layer and the first layer of ferromagnetic material; and

a second layer of ferromagnetic material formed on the second dielectric barrier so that the electric current flowing between the first and second layers of ferromagnetic material flows through each of the first and second dielectric tunnel barriers and the ferromagnetic-dielectric layer.

30. A magnetic element, comprising:

a ferromagnetic-dielectric layer comprising ferromagnetic material and dielectric material;

a tunnel dielectric barrier formed on the ferromagnetic-dielectric layer;

a layer of ferromagnetic material formed on the tunnel dielectric barrier so that the tunnel dielectric barrier is interposed between the ferromagnetic-dielectric layer and the layer of ferromagnetic material; and

an electrode formed in direct contact with the ferromagnetic material of the ferromagnetic-dielectric layer so that electric current flowing between the layer of ferromagnetic material and the electrode flows through the dielectric tunnel barrier and the ferromagnetic-dielectric layer.

31. A magnetic memory device, comprising:

a magnetic memory cell, having;

a ferromagnetic-dielectric layer comprising ferromagnetic material and dielectric material;

a tunnel dielectric barrier formed on the ferromagnetic-dielectric layer;

a layer of ferromagnetic material formed so that the tunnel dielectric barrier is interposed between the ferromagnetic-dielectric layer and the layer of ferromagnetic material; and

an electrode formed in direct contact with the ferromagnetic material of the ferromagnetic-dielectric layer so that electric current flowing between the layer of ferromagnetic material and the electrode flows through the dielectric tunnel barrier and the ferromagnetic-dielectric layer.

32. A magnetoresistance effect head, comprising:

a ferromagnetic-dielectric layer comprising ferromagnetic material and dielectric material;

a tunnel dielectric barrier formed on the ferromagnetic-dielectric layer;

a layer of ferromagnetic material formed so that the tunnel dielectric barrier is interposed between the ferromagnetic-dielectric layer and the layer of ferromagnetic material; and

an electrode formed in direct contact with the ferromagnetic material of the ferromagnetic-dielectric layer so that electric current flowing between the layer of ferromagnetic material and the electrode flows through the dielectric tunnel barrier and the ferromagnetic-dielectric layer.

33. A magnetic storage system, comprising:

magnetic media, and

a magnetoresistance effect head for reproducing magnetic information on the magnetic media having;

a ferromagnetic-dielectric layer comprising ferromagnetic material and dielectric material;

a tunnel dielectric barrier formed on the ferromagnetic-dielectric layer;

a layer of ferromagnetic material formed so that the tunnel dielectric barrier is interposed between the ferromagnetic-dielectric layer and the layer of ferromagnetic material; and

an electrode formed in direct contact with the ferromagnetic material of the ferromagnetic-dielectric layer so that electric current flowing between the layer of ferromagnetic material and the electrode flows through the dielectric tunnel barrier and the ferromagnetic-dielectric layer.