Magnetic sensing device including a sense enhancing layer

• US 20070139827A1
• Filed: 12/16/2005
• Published: 06/21/2007
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Xue, Song, Gao, Zheng, Karr, Brian, Granstrom, Eric, Li, Yi, Tran, Khuong
• Granted Patent: US 7,800,868 B2
• Time in Patent Office: Days
• US Class Current: 360/324.200
• 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 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G11B 5/3906 Details related to the use of magnetic thin film layers or to their effects
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• 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: 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: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: Y10T 428/1114 having tunnel junction effect
• CPC Class Codes: Y10T 428/1121 Multilayer

Abstract

A magnetic sensor includes a sensor stack having a first magnetic portion, a second magnetic portion, and a barrier layer between the first magnetic portion and the second magnetic portion. At least one of the first magnetic portion and the second magnetic portion includes a multilayer structure having a first magnetic layer having a positive magnetostriction adjacent to the barrier layer, a second magnetic layer, and an intermediate layer between the first magnetic layer and the second magnetic layer. The magnetic sensor has an MR ratio of at least about 80% when the magnetic sensor has a resistance-area (RA) product of about 1.0 Ω·μm².

Claims

1. A magnetic sensor comprising:

a sensor stack including a first magnetic portion, a second magnetic portion, and a barrier layer between the first magnetic portion and the second magnetic portion,

wherein at least one of the first magnetic portion and the second magnetic portion comprises a multilayer structure including a first magnetic layer having a positive magnetostriction adjacent to the barrier layer, a second magnetic layer, and an intermediate layer between the first magnetic layer and the second magnetic layer, and

wherein the magnetic sensor exhibits a magnetoresistive ratio of at least about 80% when the magnetic sensor has a resistance-area (RA) product of about 1.0 Ω

·

μ

m².

2. The magnetic sensor of claim 1, wherein the intermediate layer comprises a material selected from the group consisting of Ta, Ru, Zr, Hf, Nb, Mo, W, Pt, Rh, Ir, Al, Cu, Cr, Ti, CoZrNb, CoZrTa, FeTa, FeTaN, NiFeZr, CoFeTa, CoNb, and alloys thereof.

3. The magnetic sensor of claim 1, wherein the intermediate layer comprises a non-magnetic material and has a thickness in a range of about 0.5 Å

to about 10 Å

.

4. The magnetic sensor of claim 1, wherein the barrier layer comprises a material selected from the group consisting of MgO and Mg.

5. The magnetic sensor of claim 1, wherein the first magnetic layer comprises a material selected from the group consisting of CoFeB, CoFeNiB, CoFe, and alloys thereof.

6. The magnetic sensor of claim 1, wherein the at least one of the first magnetic portion and the second magnetic portion is a free layer and the second magnetic layer comprises a material having a negative magnetostriction.

7. The magnetic sensor of claim 6, wherein the second magnetic layer comprises a material selected from the group consisting of Ni and Ni based alloys.

8. The magnetic sensor of claim 1, wherein the second magnetic layer comprises a material selected from the group consisting of a crystalline ferromagnetic material and an amorphous ferromagnetic material.

9. A sensor stack comprising:

a barrier layer comprising MgO; and

a first multilayer magnetic structure including a first ferromagnetic layer adjacent to the barrier layer, a second ferromagnetic layer, and an intermediate layer between the first and second ferromagnetic layers, the intermediate layer comprising a material selected from the group consisting of Ta, Ru, Zr, Hf, Nb, Mo, W, Pt, Rh, Ir, Al, Cu, Cr, Ti, CoZrNb, CoZrTa, FeTa, FeTaN, NiFeZr, CoFeTa, CoNb, and alloys thereof.

10. The sensor stack of claim 9, the intermediate layer has a thickness in a range of about 0.5 Å

to about 10 Å

.

11. The sensor stack of claim 9, wherein the first ferromagnetic layer comprises a material selected from the group consisting of CoFeB, CoFeNiB, CoFe, and alloys thereof.

12. The sensor stack of claim 11, wherein the second ferromagnetic layer comprises a material selected from the group consisting of Ni and Ni based alloys.

13. The magnetic sensor of claim 9, wherein the first multilayer structure is a free layer and the second ferromagnetic layer comprises a material having a negative magnetostriction.

14. The sensor stack of claim 9, wherein the second ferromagnetic layer comprises a material selected from the group consisting of a crystalline ferromagnetic material and an amorphous ferromagnetic material.

15. The sensor stack of claim 9, wherein the first multilayer magnetic structure is a free layer and a coupling between the first ferromagnetic layer and the second ferromagnetic layer is selected from the group consisting of ferromagnetic coupling and antiferromagnetic coupling.

16. The sensor stack of claim 9, wherein the first multilayer magnetic structure is a free layer and the second ferromagnetic layer comprises a material having a negative magnetostriction.

17. The sensor stack of claim 9, and further comprising:

a second multilayer magnetic structure including a third ferromagnetic layer having a positive magnetostriction adjacent to the barrier layer, a fourth ferromagnetic layer, and an intermediate layer between the third and fourth ferromagnetic layers, the intermediate layer comprising a material selected from the group consisting of Ta, Ru, Zr, Hf, Nb, Mo, W, Pt, Rh, Ir, Al, Cu, Cr, Ti, CoZrNb, CoZrTa, FeTa, FeTaN, NiFeZr, CoFeTa, CoNb, and alloys thereof.

18. A magnetoresistive (MR) sensor having improved sensitivity comprising:

a first magnetic structure;

a MgO barrier layer adjacent to the first magnetic structure; and

a second magnetic structure adjacent to the MgO barrier layer on a side opposite the first magnetic structure, the second magnetic structure including a positive magnetostriction layer adjacent to the barrier layer, a negative magnetostriction layer, and a sense enhancing layer between the positive magnetostriction layer and the negative magnetostriction layer,

wherein the MR sensor is characterized by an MR ratio of (a) at least about 30% with a resistance-area (RA) product of about 0.5 Ω

·

μ

m², (b) at least about 50% with an RA product of about 0.8 Ω

·

μ

m², (c) at least about 80% with an RA product of about 1.0 Ω

·

μ

m², and (d) at least about 100% with an RA product of about 1.4 Ω

·

μ

m².

19. The magnetic sensor of claim 18, wherein the sense enhancing layer comprises a material selected from the group consisting of Ta, Ru, Zr, Hf, Nb, Mo, W, Pt, Rh, Ir, Al, Cu, Cr, Ti, CoZrNb, CoZrTa, FeTa, FeTaN, NiFeZr, CoFeTa, CoNb, and alloys thereof.

20. The magnetic sensor of claim 18, wherein the sense enhancing layer comprises a non-magnetic material and has a thickness in a range of about 0.5 Å

to about 10 Å

.

21. The sensor stack of claim 18, wherein the positive magnetostriction layer comprises a material selected from the group consisting of CoFeB, CoFeNiB, CoFe, and alloys thereof.