CPP GMR free layer having ferromagnetic layers with parallel magnetization separated by non-magnetic layer

• US 6,927,952 B2
• Filed: 04/03/2002
• Issued: 08/09/2005
• Est. Priority Date: 11/12/2001
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Shimizu, Yutaka, Tanaka, Atsushi, Oshima, Hirotaka, Nagasaka, Keiichi, Seyama, Yoshihiko
• Primary Examiner(s): Renner, Craig A.
• Application Number:
  US10/114,767
• Publication Number:
  US 20030090844A1
• Time in Patent Office: 1,224 Days
• Field of Search: 360/324.12
• 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 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/00 Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor G11B11/00 and G11B13/00 take precedence
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A magnetoresistive device includes a laminated film, and a mechanism for applying sense current in a direction of lamination in the laminated film, wherein the laminated film includes a first ferromagnetic layer having a substantially fixed direction of magnetization, a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, the second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination, and a non-magnetic intermediate layer that separates the first and second ferromagnetic layer from each other.

Claims

1. A magnetoresistive device comprising:

a laminated film; and

a mechanism for applying sense current in a direction of lamination in said laminated film,

wherein said laminated film includes;

a first ferromagnetic layer having a substantially fixed direction of magnetization;

a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, said second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination; and

a non-magnetic intermediate layer that separates said first and second ferromagnetic layers from each other, and

wherein said two or more ferromagnetic metal layers in said second ferromagnetic layer have parallel directions of magnetization.

2. A magnetoresistive device according to claim 1, wherein the non-magnetic metal layer in said second ferromagnetic layer provides spin dependent scattering when laminated onto one of said two or more ferromagnetic metal layers in the second ferromagnetic layer.

3. A magnetoresistive device according to claim 1, wherein the non-magnetic metal layer in said second ferromagnetic layer is made of Cu.

4. A magnetoresistive device according to claim 1, wherein the non-magnetic metal layer in said second ferromagnetic layer is made of Ag.

5. A magnetoresistive device according to claim 1, wherein the non-magnetic metal layer in said second ferromagnetic layer is made of Au.

6. A magnetoresistive device according to claim 1, wherein said first ferromagnetic layer is a laminated layer that includes, in this order, a ferromagnetic metal layer, a non-magnetic metal layer, and another ferromagnetic metal layer,

wherein two ferromagnetic metal layers in said first ferromagnetic layer have antiparallel directions of magnetization via the non-magnetic metal layer in said first ferromagnetic layer.

7. A magnetoresistive device according to claim 6, wherein the ferromagnetic metal layer, the non-magnetic metal layer, and the other ferromagnetic metal layer in said first ferromagnetic layer are laminated layers made of a Co system, a Ru system, and a Co system.

8. A magnetoresistive device according to claim 1, wherein said first ferromagnetic layer, said non-magnetic intermediate layer, and said second ferromagnetic layer are laminated in this order on a substrate.

9. A magnetoresistive device according to claim 8, further comprising:

another non-magnetic intermediate layer laminated onto said second ferromagnetic layer, and

a third ferromagnetic layer that has a substantially fixed direction of magnetization and is mounted onto the other non-magnetic intermediate layer.

10. A magnetoresistive device according to claim 1, wherein said second ferromagnetic layer, said non-magnetic intermediate layer, and said first ferromagnetic layer are laminated in this order on a substrate.

11. A magnetoresistive device according to claim 1, wherein each of said two or more ferromagnetic metal layers in said second ferromagnetic layer has a thickness of 1 through 2 nm.

12. A magnetoresistive device according to claim 1, wherein said second ferromagnetic layer has a thickness of 3 through 10 nm.

13. A magnetoresistive device according to claim 1, wherein said second ferromagnetic layer has a thickness of 5 through 6 nm.

14. A magnetoresistive device according to claim 1, wherein said laminated film is a spin-valve film.

15. A magnetoresistive device according to claim 1, wherein at least one of said two or more ferromagnetic metal layers in said second ferromagnetic layer is made of CoFeB.

16. A magnetoresistive device comprising:

a laminated film; and

a mechanism for applying sense current in a direction of lamination in said laminated film,

wherein said laminated film includes;

a first ferromagnetic layer having a substantially fixed direction of magnetization;

a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, said second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination; and

a non-magnetic intermediate layer that separates said first and second ferromagnetic layers from each other,

wherein said first ferromagnetic layer has a lamination of a non-magnetic part and a ferromagnetic part in the direction of lamination in said laminated film,

wherein said two or more ferromagnetic metal layers in said second ferromagnetic layer have parallel directions of magnetization.

17. A read head comprising:

a magnetoresistive device that comprises a laminated film, and a mechanism for applying sense current in a direction of lamination in said laminated film, wherein said laminated film includes a first ferromagnetic layer having a substantially fixed direction of magnetization, a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, said second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination, and a non-magnetic intermediate layer that separates said first and second ferromagnetic layers from each other;

a mechanism for supplying sense current; and

a mechanism for reading a signal from changed electric resistance of said magnetoresistive device which changes according to a signal magnetic field,

wherein said two or more ferromagnetic metal layers in said second ferromagnetic layer have parallel directions of magnetization.

18. A read head comprising:

a magnetoresistive device that comprises a laminated film, and a mechanism for applying sense current in a direction of lamination in said laminated film, wherein said laminated film includes a first ferromagnetic layer having a substantially fixed direction of magnetization, a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, said second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination, and a non-magnetic intermediate layer that separates said first and second ferromagnetic layers from each other, wherein said first ferromagnetic layer has a lamination of a non-magnetic part and a ferromagnetic part in the direction of lamination in said laminated film;

a mechanism for supplying sense current; and

a mechanism for reading a signal from changed electric resistance of said magnetoresistive device which changes according to a signal magnetic field,

wherein said two or more ferromagnetic metal layers in said second ferromagnetic layer have parallel directions of magnetization.

19. A drive comprising:

a read part including a read head and a write part; and

a drive part for driving a magnetic record carrier to be recorded and reproduced by said read part,

wherein said read head includes;

a magnetoresistive device that comprises a laminated film, and a mechanism for applying sense current in a direction of lamination in said laminated film, wherein said laminated film includes a first ferromagnetic layer having a substantially fixed direction of magnetization, a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, said second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination, and a non-magnetic intermediate layer that separates said first and second ferromagnetic layers from each other;

a mechanism for supplying sense current; and

a mechanism for reading a signal from changed electric resistance of said magnetoresistive device which changes according to a signal magnetic field,

wherein said two or more ferromagnetic metal layers in said second ferromagnetic layer have parallel directions of magnetization.

21. A drive according to claim 19 or 20, wherein said drive is a hard disc drive and the magnetic record carrier has a surface recording density of 100 Gb/in² or higher.

20. A drive comprising:

a read part including a read head and a write part; and

a drive part for driving a magnetic record carrier to be recorded and reproduced by said read part,

wherein said read head includes;

a magnetoresistive device that comprises a laminated film, and a mechanism for applying sense current in a direction of lamination in said laminated film, wherein said laminated film includes a first ferromagnetic layer having a substantially fixed direction of magnetization, a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, said second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination, and a non-magnetic intermediate layer that separates said first and second ferromagnetic layers from each other, wherein said first ferromagnetic layer has a lamination of a non-magnetic part and a ferromagnetic part in the direction of lamination in said laminated film;

a mechanism for supplying sense current; and

a mechanism for reading a signal from changed electric resistance of said magnetoresistive device which changes according to a signal magnetic field,

wherein said two or more ferromagnetic metal layers in said second ferromagnetic layer have parallel directions of magnetization.