Ferromagnetic double tunnel junction element with asymmetric energy band

• US 6,995,962 B2
• Filed: 10/20/2004
• Issued: 02/07/2006
• Est. Priority Date: 03/12/2001
• Status: Expired due to Term

• Current Assignee: Kioxia Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kishi, Tatsuya, Takahashi, Shigeki, Saito, Yoshiaki, Amano, Minoru, Sagoi, Masayuki, Nakajima, Kentaro
• Primary Examiner(s): EVANS, JEFFERSON A
• Application Number:
  US10/968,336
• Publication Number:
  US 20050078418A1
• Time in Patent Office: 475 Days
• Field of Search: 360/324.2
• 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: 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 5/3954 the active elements transducing on a single track
• CPC Class Codes: G11C 11/15 using multiple magnetic layers G11C11/155 takes precedence
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H10B 61/10 comprising components having two electrodes, e.g. diodes or MIM elements
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

There is provided a magnetoresistance effect element including a first pinned ferromagnetic layer, a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer, surface regions of the first and second pinned ferromagnetic layer facing each other being different from each other in composition, a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers, a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer, and a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer.

Claims

1. A magnetoresistance effect element comprising:

a first pinned ferromagnetic layer;

a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer;

a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers;

a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer; and

a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer,

wherein the first and second tunnel barrier layers are different from each other in composition.

2. A magnetoresistance effect element according to claim 1, wherein the first and second tunnel barrier layers are different from each other in contained element.

3. A magnetoresistance effect element according to claim 1, further comprising:

an antiferromagnetic layer provided on at least one of outer surfaces of the first and second pinned ferromagnetic layers.

4. A magnetoresistance effect element according to claim 1, wherein at least one of the first and second pinned ferromagnetic layers and the free ferromagnetic layer includes ferromagnetic layers and a nonmagnetic metal layer intervening between the ferromagnetic layers.

5. A magnetic random access memory comprising:

word lines;

bit lines intersecting the word lines; and

memory cells each positioned in each of intersection regions of the word lines and the bit lines and each including a magnetoresistance effect element, the magnetoresistance effect element including;

a first pinned ferromagnetic layer,

a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer,

a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers,

a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer, and

a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer,

wherein the first and second tunnel barrier layers are different from each other in composition.

6. A magnetic random access memory according to claim 5, wherein each memory cell further comprises a switching element.

7. A magnetic random access memory according to claim 5, wherein the first and second tunnel barrier layers are different from each other in contained element.

8. A magnetic head comprising:

a support member; and

a magnetoresistance effect element supported by the support member, the magnetoresistance effect element including;

a first pinned ferromagnetic layer,

a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer,

a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers,

a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer, and

a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer,

wherein the first and second tunnel barrier layers are different from each other in composition.

9. A magnetic head according to claim 8, wherein the first and second tunnel barrier layers are different from each other in contained element.

10. A magnetoresistance effect element comprising:

a first pinned ferromagnetic layer;

a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer;

a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers;

a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer; and

a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer,

wherein the first and second tunnel barrier layers contain at least one material selected from the group consisting of Al₂O₃, SiO₂, MgO, AlN, AlON, GaO, Bi₂O₃, SrTiO₂ and AlLaO₃, and the material contained in the first tunnel barrier layer and the material contained in the second tunnel barrier layer are different from each other.

11. A magnetoresistance effect element according to claim 10, wherein at least one of the free ferromagnetic layer and the first and second pinned ferromagnetic layers includes a pair of ferromagnetic layers and a nonmagnetic metal layer intervening therebetween.

12. A magnetoresistance effect element according to claim 11, wherein the free ferromagnetic layer includes the pair of ferromagnetic layers and the nonmagnetic metal layer, and the ferromagnetic layers of the free ferromagnetic layer are ferromagnetically coupled with each other.

13. A magnetoresistance effect element according to claim 11, further comprising:

an antiferromagnetic layer provided on at least one of outer surfaces of the first and second pinned ferromagnetic layers.

14. A magnetic random access memory comprising:

word lines;

bit lines intersecting the word lines; and

memory cells each positioned in each of intersection regions of the word lines and the bit lines and each including the magnetoresistance effect element according to claim 10.

15. A magnetic random access memory according to claim 14, wherein each memory cell further comprises a switching element.

16. A magnetic head comprising:

the magnetoresistance effect element according to claim 10; and

a support member configured to support the magnetoresistance effect element.

17. A magnetic reproducer configured to reproduce data recorded on a magnetic recording medium, comprising:

the magnetic head according to claim 16; and

a moving device configured to move the magnetic head with respect to the magnetic recording medium.

18. A magnetoresistance effect element comprising:

a first ferromagnetic layer as a pinned ferromagnetic layer;

a first tunnel barrier layer formed on the first ferromagnetic layer such that the magnetoresistance effect element exhibits magnetoresistance effect;

a second ferromagnetic layer as a free ferromagnetic layer formed on the first tunnel barrier layer;

a second tunnel barrier layer formed on the second ferromagnetic layer such that the magnetoresistance effect element exhibits magnetoresistance effect; and

a third ferromagnetic layer as a pinned ferromagnetic layer formed on the second tunnel barrier layer,

wherein the second ferromagnetic layer includes a fourth ferromagnetic layer, a nonmagnetic metal layer formed on the fourth ferromagnetic layer, and a fifth ferromagnetic layer formed on the nonmagnetic metal layer, and a material contained in the first tunnel barrier layer and a material contained in the second tunnel barrier layer are different from each other.

19. A magnetoresistance effect element according to claim 18, wherein the fourth and fifth ferromagnetic layers are ferromagnetically coupled with each other.

20. A magnetoresistance effect element according to claim 18, further comprising:

an antiferromagnetic layer provided on at least one of outer surfaces of the first and third ferromagnetic layers.

21. A magnetic random access memory comprising:

word lines;

bit lines intersecting the word lines; and

memory cells each positioned in each of intersection regions of the word lines and the bit lines and each including the magnetoresistance effect element according to claim 18.

22. A magnetic random access memory according to claim 21, wherein each memory cell further comprises a switching element.

23. A magnetic head comprising:

the magnetoresistance effect element according to claim 18; and

a support member configured to support the magnetoresistance effect element.

24. A magnetic reproducer configured to reproduce data recorded on a magnetic recording medium, comprising:

the magnetic head according to claim 23; and

a moving device configured to move the magnetic head with respect to the magnetic recording medium.