Spin-valve type thin film magnetic element

• US 20020024781A1
• Filed: 06/20/2001
• Published: 02/28/2002
• Est. Priority Date: 03/24/2000
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Tanaka, Kenichi, Hasegawa, Naoya, Saito, Masamichi, Ide, Yosuke, Umetsu, Eiji, Ooshima, Masahiro
• Granted Patent: US 6,856,494 B2
• Time in Patent Office: Days
• US Class Current: 360/324.12
• 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 5/3932 Magnetic biasing films
• CPC Class Codes: H01F 10/3272 by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

The present invention provides a spin-valve type thin film magnetic element that is able to certainly align the magnetization direction of the free magnetic layer in one direction by improving the exchange coupling magnetic field generated between the bias layers and ferromagnetic layer, and is able to reduce the thickness of the bias layer to be smaller than the thickness of the bias layer of the conventional spin-valve type thin film magnetic element for obtaining the same magnitude of the exchange coupling magnetic layer as that in the conventional spin-valve type thin film magnetic element.

Claims

1. A spin-valve type thin film magnetic element comprising:

a laminate comprising an antiferromagnetic layer, a pinned magnetic layer in contact with an antiferromagnetic layer in which the magnetization direction of the pinned magnetic layer is fixed by an exchange anisotropic magnetic field with the antiferromagnetic layer, and a non-magnetic conductive layer formed between the pinned magnetic layer and a free magnetic layer;

bias layers for aligning the magnetization direction of the free magnetic layer in the direction substantially perpendicular to the magnetization direction of the pinned magnetic layer;

ferromagnetic layers formed in contact with the bias layers; and

conductive layers for applying a sensing current to the free magnetic layers,

wherein each of the ferromagnetic layers is divided into two sub-layers separated by a non-magnetic intermediate layer, the sub-layers being in a ferrimagnetic state in which the magnetization direction of one sub-layer is 180 degrees different from the magnetization direction of the other sub-layer.

2. A spin-valve type thin film magnetic element according to claim 1, wherein ferromagnetic layers are disposed on the free magnetic layer with a distance corresponding to a track width, the bias layers being provided on the ferromagnetic layers and the conductive layers being provided on the bias layers.

3. A spin-valve type thin film magnetic element according to claim 1, wherein the bias layers are provided at both sides in the track width direction of the laminate, the ferromagnetic layers being provided on the bias layers and the conductive layers being provided on the ferromagnetic layers.

4. A spin-valve type thin film magnetic element according to claim 1, wherein at least one of the pinned magnetic layer and free magnetic layer is divided into two sub-layers separated by the non-magnetic intermediate layer, the sub-layers being in a ferrimagnetic state in which the magnetization direction of one sub-layer is 180 degrees different from the magnetization direction of the other sub-layer.

5. A spin-valve type thin film magnetic element according to claim 1, wherein the ferromagnetic layer comprises at least one element selected from the group consisting of Ni, Fe and Co.

6. A spin-valve type thin film magnetic element according to claim 1, wherein the bias layers comprise an alloy containing at least one element selected from the group consisting of Pt, Pd, Rh, Fe, Ru, Ir, Os, Au, Ag, Cr, Ni, Ne, Ar, Xe and Kr, and Mn.

7. A spin-valve type thin film magnetic element according to claim 1, wherein the bias layers comprise at least one material selected from the group consisting of NiO, α

-Fe₂O₃ and CoO.

8. A spin-valve type thin film magnetic element according to claim 1, wherein the antiferromagnetic layer comprises an alloy containing at least one element selected from the group of Pt, Pd, Rh, Fe, Ru, Ir, Os, Au, Ag, Cr, Ni, Ne, Ar, Xe and Kr, and Mn.

9. A spin-valve type thin film magnetic element according to claim 1, wherein the bias layers comprise an antiferromagnetic material.

10. A spin-valve type thin film magnetic element according to claim 9, wherein the antiferromagnetic material has a lower heat treatment temperature than that of the antiferromagnetic layer.

11. A spin-valve type thin film magnetic element according to claim 1, wherein the free magnetic layer comprises a first free magnetic layer and a second free magnetic layer which are separated by a non-magnetic intermediate layer, the first free magnetic layer and the second free magnetic layer are in a ferrimagnetic state in which the magnetization direction of the first free magnetic layer is 180 degrees different from the magnetization direction of the second free magnetic layer, at least one of the first free magnetic layer and the second free magnetic layer comprise a CoFeNi alloy, and the non-magnetic intermediate layer comprises Ru.

12. A spin-valve type thin film magnetic element according to claim 11, wherein the first free magnetic layer is disposed between the non-magnetic conductive layer and the non-magnetic intermediate layer, and the first free magnetic layer comprises the CoFeNi alloy.

13. A spin-valve type thin film magnetic element according to claim 11, wherein both the first free magnetic layer and the second free magnetic layer comprise the CoFeNi alloy.

14. A spin-valve type thin film magnetic element according to claim 11, wherein the CoFeNi alloy comprises 9 to 17 atomic percent Fe, 0.5 to 10 atomic percent Ni, and the balance being Co.

15. A spin-valve type thin film magnetic element according to claim 1, wherein the free magnetic layer comprises a first free magnetic layer and a second free magnetic layer which are separated by a non-magnetic intermediate layer, the first free magnetic layer and the second free magnetic layer are in a ferrimagnetic state in which the magnetization direction of the first free magnetic layer is 180 degrees different from the magnetization direction of the second free magnetic layer, the first free magnetic layer is disposed between the non-magnetic conductive layer and the non-magnetic intermediate layer, the first free magnetic layer comprises a laminate of a CoFe alloy film and a CoFeNi alloy film, and the CoFe alloy film is formed at the non-magnetic conductive layer side.

16. A spin-valve type thin film magnetic element according to claim 15, wherein the second free magnetic layer comprises the CoFeNi alloy.

17. A spin-valve type thin film magnetic element according to claim 15, wherein the CoFeNi alloy film comprises 9 to 17 atomic percent Fe, 0.5 to 10 atomic percent Ni, and the balance being Co.

18. A spin-valve type thin film magnetic element according to claim 1, wherein the ferromagnetic layer comprises a first ferromagnetic layer and a second ferromagnetic layer which are separated by a non-magnetic intermediate layer, the first ferromagnetic layer and the second ferromagnetic layer are in a ferrimagnetic state in which the magnetization direction of the first ferromagnetic layer is 180 degrees different from the magnetization direction of the second ferromagnetic layer, at least one of the first ferromagnetic layer and the second ferromagnetic layer comprise a CoFeNi alloy, and the non-magnetic intermediate layer comprises Ru.

19. A spin-valve type thin film magnetic element according to claim 18, wherein both the first ferromagnetic layer and the second ferromagnetic layer comprise the CoFeNi alloy.