TUNNELING MAGNETIC SENSING ELEMENT AND METHOD FOR PRODUCING SAME

• US 20080225443A1
• Filed: 02/25/2008
• Published: 09/18/2008
• Est. Priority Date: 03/14/2007
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Nishimura, Kazumasa, Kobayashi, Hidekazu, Hasegawa, Naoya, Saito, Masamichi, Nakabayashi, Ryo, Ide, Yosuke, Nishiyama, Yoshihiro
• Granted Patent: US 8,045,300 B2
• Time in Patent Office: Days
• US Class Current: 360/324.2
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• 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: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/3295 Spin-exchange coupled multilayers wherein the magnetic pinned or free layers are laminated without anti-parallel coupling within the pinned and free layers
• CPC Class Codes: H01F 41/302 for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices spin-exchange-coupled multilayers H01F10/32

Abstract

A free magnetic layer has a laminated structure in which a first magnetic sublayer composed of Co—Fe or Fe and a second magnetic sublayer composed of Co—Fe—B or Fe—B are formed, in that order, on an insulating barrier layer composed of Mg—O. This effectively improves the rate of change in resistance (ΔR/R) compared with the related art.

Claims

1. A tunneling magnetic sensing element comprising:

a pinned magnetic layer;

an insulating barrier layer; and

a free magnetic layer, the insulating layer being disposed between the pinned magnetic layer and the free magnetic layer;

wherein the insulating barrier layer is composed of Mg—

O, and

wherein the free magnetic layer has a first magnetic region and a second magnetic region, the first magnetic region is in contact with the insulating barrier layer, located between the second magnetic region and the insulating barrier layer, and composed of Co—

Fe or Fe, and the second magnetic region is remote from the insulating barrier layer, in contact with the first magnetic region, and composed of Co—

Fe—

B or Fe—

B.

2. The tunneling magnetic sensing element according to claim 1, wherein the second magnetic region has a compositionally modulated portion where the B concentration decreases gradually as the distance from the interface between the free magnetic layer and the insulating barrier layer decreases.

5. The tunneling magnetic sensing element according to claim 1, wherein the free magnetic layer has a laminated structure with a first magnetic sublayer and a second magnetic sublayer, the first magnetic sublayer is in contact with the insulating barrier layer, located between the second magnetic sublayer and the insulating barrier layer, and composed of Co—

Fe or Fe, and the second magnetic sublayer is remote from the insulating barrier layer, in contact with the first magnetic sublayer, and composed of Co—

Fe—

B or Fe—

B, and

wherein the free magnetic layer has at least a portion formed by elemental diffusion at the interface between the first magnetic sublayer and the second magnetic sublayer.

7. The tunneling magnetic sensing element according to claim 5, wherein the total average thickness obtained by the sum of the average thickness of the first magnetic sublayer and the average thickness of the second magnetic sublayer is in the range of about 15 Å

to about 80 Å

, the first magnetic sublayer has an average thickness of about 5 Å

to about 30 Å

, and the second magnetic sublayer has an average thickness of about 5 Å

or more.

8. The tunneling magnetic sensing element according to claim 7, wherein the total average thickness obtained by the sum of the average thickness of the first magnetic sublayer and the average thickness of the second magnetic sublayer is in the range of about 20 Å

to about 60 Å

.

9. The tunneling magnetic sensing element according to claim 7, wherein the first magnetic sublayer has an average thickness of about 10 Å

to about 20 Å

.

10. The tunneling magnetic sensing element according to claim 7, wherein the second magnetic sublayer has an average thickness of about 10 Å

or more.

11. The tunneling magnetic sensing element according to claim 1, wherein the preferred orientation of equivalent crystal planes each typically expressed as the {100} plane is achieved at the interface between the free magnetic layer and the insulating barrier layer in the plane parallel to the layer surfaces.

12. The tunneling magnetic sensing element according to claim 1, wherein the preferred orientation of equivalent crystal planes each typically expressed as the {100} plane is achieved at the interface between the pinned magnetic layer and the insulating barrier layer in the plane parallel to the layer surfaces.

13. The tunneling magnetic sensing element according to claim 1, wherein the tunneling magnetic sensing element comprises:

the pinned magnetic layer;

the insulating barrier layer; and

the free magnetic layer, in that order from the bottom, and

wherein the pinned magnetic layer has a portion that is in contact with the insulating barrier layer, and at least the portion is composed of Co—

Fe—

B or Fe—

B.

3. A tunneling magnetic sensing element comprising:

a pinned magnetic layer;

an insulating barrier layer; and

a free magnetic layer, the insulating layer being disposed between the pinned magnetic layer and the free magnetic layer;

wherein the insulating barrier layer is composed of Mg—

O,

the free magnetic layer has a magnetic region composed of Co—

Fe—

B or Fe—

B, the magnetic region is in contact with the insulating barrier layer, and

the B concentration at a portion of the magnetic region adjacent to the interface between the free magnetic layer and the insulating barrier layer is lower than that at a portion of the magnetic region remote from the interface.

4. The tunneling magnetic sensing element according to claim 3, wherein the magnetic region has a compositionally modulated portion where the B concentration decreases gradually as the distance from the interface between the free magnetic layer and the insulating barrier layer decreases.

6. A tunneling magnetic sensing element comprising:

a pinned magnetic layer;

an insulating barrier layer; and

a free magnetic layer, the insulating layer being disposed between the pinned magnetic layer and the free magnetic layer;

wherein the insulating barrier layer is composed of Mg—

O, and

wherein the free magnetic layer includes a first magnetic sublayer and a second magnetic sublayer, the first magnetic sublayer is in contact with the insulating barrier layer, located between the second magnetic sublayer and the insulating barrier layer, and composed of Co—

Fe or Fe, and the second magnetic sublayer is remote from the insulating barrier layer, in contact with the first magnetic sublayer, and composed of Co—

Fe—

B or Fe—

B.

14. A method for producing a tunneling magnetic sensing element including a laminated portion having a pinned magnetic layer, an insulating barrier layer, and a free magnetic layer, formed in that order from the bottom, the method comprising:

(a) forming the insulating barrier layer composed of Mg—

O on the pinned magnetic layer;

(b) forming the free magnetic layer on the insulating barrier layer in such a manner that the free magnetic layer includes a laminated portion having a first magnetic sublayer and a second magnetic sublayer, formed in that order from the bottom, the first magnetic sublayer being in contact with the insulating barrier layer and composed of Co—

Fe or Fe, and the second magnetic sublayer being in contact with the first magnetic sublayer and composed of Co—

Fe—

B or Fe—

B; and

(c) performing heat treatment.

15. The method according to claim 14, wherein in (a), at least a portion of the pinned magnetic layer in contact with the insulating barrier layer is composed of Co—

Fe—

B or Fe—

B.

17. The method according to claim 14, wherein the total average thickness obtained by the sum of the average thickness of the first magnetic sublayer and the average thickness of the second magnetic sublayer is in the range of about 15 Å

to about 80 Å

, the first magnetic sublayer has an average thickness of about 5 Å

to about 30 Å

, and the second magnetic sublayer has an average thickness of about 5 Å

or more.

18. The method according to claim 17, wherein the total average thickness obtained by the sum of the average thickness of the first magnetic sublayer and the average thickness of the second magnetic sublayer is in the range of about 20 Å

to about 60 Å

.

19. The method according to claim 17, wherein the first magnetic sublayer has an average thickness of about 10 Å

to about 20 Å

.

20. The method according to claim 17, wherein the second magnetic sublayer has an average thickness of about 10 Å

or more.

16. A method for producing a tunneling magnetic sensing element including a laminated portion having a free magnetic layer, an insulating barrier layer, and a pinned magnetic layer, formed in that order from the bottom, the method comprising:

forming the free magnetic layer including a laminated portion having a second magnetic sublayer and a first magnetic sublayer, formed in that order from the bottom, the second magnetic sublayer being composed of Co—

Fe—

B or Fe—

B, and the first magnetic sublayer being in contact with the second magnetic sublayer and composed of Co—

Fe or Fe;

forming the insulating barrier layer composed of Mg—

O on the first magnetic sublayer and forming the pinned magnetic layer on the insulating barrier layer; and

performing heat treatment.