Tunneling magnetic sensing element and method for producing same

• US 8,045,300 B2
• Filed: 02/25/2008
• Issued: 10/25/2011
• 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
• Primary Examiner(s): KLIMOWICZ, WILLIAM JOSEPH
• Application Number:
  US12/036,513
• Publication Number:
  US 20080225443A1
• Time in Patent Office: 1,338 Days
• Field of Search: 360324-3242
• 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,

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, and

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.

2. 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.

3. The tunneling magnetic sensing element according to claim 2, 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.

4. The tunneling magnetic sensing element according to claim 3, 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

.

5. The tunneling magnetic sensing element according to claim 3, wherein the first magnetic sublayer has an average thickness of about 10 Å

to about 20 Å

.

6. The tunneling magnetic sensing element according to claim 3, wherein the second magnetic sublayer has an average thickness of about 10 Å

or more.

7. 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.