Magnetic sensing element including laminated film composed of half-metal and NiFe alloy as free layer

• US 20060250727A1
• Filed: 05/01/2006
• Published: 11/09/2006
• Est. Priority Date: 09/03/2004
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Ishizone, Masahiko, Hasegawa, Naoya, Saito, Masamichi, Ide, Yosuke
• Granted Patent: US 7,466,525 B2
• Time in Patent Office: Days
• US Class Current: 360/324.120
• 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: H10N 50/85 Magnetic active materials

Abstract

A magnetic sensing element exhibiting a large ΔRA is provided, in which a free magnetic layer has a small coercive force Hc and a small magnetostriction constant λs. The free magnetic layer includes a Co₂MnZ alloy layer (where Z may represent at least one element selected from the group consisting of Al, Sn, In, Sb, Ga, Si, Ge, Pb, and Zn) and a (Ni_aFe_100-a)_bX_100-b alloy layer (where X may represent at least one element selected from the group consisting of Cu, Au, Ag, Zn, Mn, Al, Cd, Zr, and Hf, a may represent a composition ratio satisfying 80<a≦100, and b may represent a composition ratio satisfying 60<b≦100). Consequently, the magnetostriction constant λs and the coercive force Hc of the free magnetic layer may be decreased and the soft magnetic properties of the free magnetic layer may be improved.

Claims

1. A magnetic sensing element comprising a multilayer film including a pinned magnetic layer, a free magnetic layer, and a non-magnetic material layer disposed therebetween,

wherein the free magnetic layer comprises a Co₂MnZ alloy layer (where Z represents at least one element selected from the group consisting of Al, Sn, In, Sb, Ga, Si, Ge, Pb, and Zn) and a (Ni_aFe_100-a)_bX_100-b alloy layer (where X represents at least one element selected from the group consisting of Cu, Au, Ag, Zn, Mn, Al, Cd, Zr, and Hf, and a represents a composition ratio satisfying 80<

a≦

100 in terms of atomic percent and b represents a composition ratio satisfying 60<

b≦

100 in terms of atomic percent).

2. The magnetic sensing element according to claim 1, wherein b represents a composition ratio satisfying 90<

b≦

100 in terms of atomic percent.

3. The magnetic sensing element according to claim 1, wherein a represents a composition ratio satisfying 81.5<

a≦

100 in terms of atomic percent.

4. The magnetic sensing element according to claim 3, wherein a represents a composition ratio satisfying 81.5<

a≦

100 in terms of atomic percent and b represents a composition ratio satisfying 90<

b≦

100 in terms of atomic percent.

5. The magnetic sensing element according to claim 1, wherein the (Ni_aFe_100-a)_bX_100-b alloy layer has a film thickness of about 10 angstroms or more and about 60 angstroms or less.

6. The magnetic sensing element according to claim 5, wherein the (Ni_aFe_100-a)_bX_100-b alloy layer has a film thickness of about 40 angstroms or more and about 60 angstroms or less.

7. The magnetic sensing element according to claim 1, wherein the Co₂MnZ alloy layer has a film thickness of about 40 angstroms or more and about 80 angstroms or less.

8. The magnetic sensing element according to claim 1, wherein the Co₂MnZ alloy layer has a superlattice structure.

9. The magnetic sensing element according to claim 1, wherein the Co₂MnZ alloy layer is in contact with the non-magnetic material layer.

10. The magnetic sensing element according to claim 1, wherein the Co₂MnZ alloy layer is disposed on the (Ni_aFe_100-a)_bX_100-b alloy layer.

11. The magnetic sensing element according to claim 1, wherein the (Ni_aFe_100-a)_bX_100-b alloy layer is disposed on the Co₂MnZ alloy layer.

12. The magnetic sensing element according to claim 1, wherein the free magnetic layer further comprises a third layer.

13. The magnetic sensing element according to claim 1, wherein the pinned magnetic layer comprises a Co₂YZ alloy layer (where Y represents at least one element selected from the group consisting of Mn, Fe, and Cr, and Z represents at least one element selected from the group consisting of Al, Ga, Si, Ge, Sn, In, Sb, Pb, and Zn).

14. The magnetic sensing element according to claim 1, wherein a product Δ

RA of a resistance variation and an element area is 5 mΩ

μ

m² or more.

15. The magnetic sensing element according to claim 1, wherein the pinned magnetic layer is disposed above the free magnetic layer.

16. The magnetic sensing element according to claim 1, wherein the pinned magnetic layer is disposed below the free magnetic layer.

17. The magnetic sensing element according to claim 1, wherein the non-magnetic material layer and the pinned magnetic layer are disposed under the free magnetic layer, and an upper non-magnetic material layer and an upper pinned magnetic layer are disposed above the free magnetic layer.

18. The magnetic sensing element according to claim 17,

wherein the free magnetic layer comprises an upper free magnetic layer and a lower free magnetic layer laminated directly or with another magnetic material layer or a non-magnetic material layer therebetween, and

wherein either a multilayer film lower portion, including the lower free magnetic layer as well as the non-magnetic material layer and the pinned magnetic layer disposed under the lower free magnetic layer, or a multilayer film upper portion, including the upper free magnetic layer as well as the upper non-magnetic material layer and the upper pinned magnetic layer disposed above the upper free magnetic layer, whichever is located on the upstream side of the conduction electron flow, is assumed to be a multilayer film upstream portion, and the other portion, which is located on the downstream side of the conduction electron flow, is assumed to be a multilayer film downstream portion;

and

a product Δ

RA of a resistance variation and an element area of the multilayer film upstream portion is smaller than the product Δ

RA of the multilayer film downstream portion.

19. The magnetic sensing element according to claim 1, wherein a current flows in a direction perpendicular to a film surface of each layer of the multilayer film.