Laminated magnetorestrictive element of an exchange coupling film, an antiferromagnetic film and a ferromagnetic film and a magnetic disk drive using same

• US 6,313,973 B1
• Filed: 06/30/1999
• Issued: 11/06/2001
• Est. Priority Date: 06/30/1998
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Saito, Kazuhiro, Fukuzawa, Hideaki, Koui, Katsuhiko, Saito, Akiko, Iwasaki, Hitoshi, Fuke, Hiromi
• Primary Examiner(s): Heinz, A. J.
• Application Number:
  US09/343,270
• Time in Patent Office: 860 Days
• Field of Search: 360/324--32
• US Class Current: 360/324.1
• 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 5/012 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: G11B 5/3967 Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read G11B5/3906 takes precedence
• CPC Class Codes: H01F 10/3263 the exchange coupling being symmetric, e.g. for dual spin valve, e.g. NiO/Co/Cu/Co/Cu/Co/NiO
• CPC Class Codes: H01F 10/3268 the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn
• 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

Abstract

A magnetoresistive element comprises an exchange coupling film having a under layer, an antiferromagnetic film and a ferromagnetic film, which are laminated in that order, the under layer including a metal having a face centered cubic crystal structure or hexagonal closest packing crystal structure which have a longer nearest neighbor atomic distance than that of the antiferromagnetic film. With this construction, it is possible to improve the exchange coupling field and to satisfy a stable output over a long period of time. A magnetoresistive element having a dual spin valve structure has a magnetization adjusting layer, which is antiferromagnetically connected to a pinned layer via an anti-parallel connection layer, to adjust the value of the product of the saturation magnetization of each of the magnetization adjusting layer and the pinned layer by the thickness thereof. Moreover, a magnetoresistance head use a giant magnetoresistance effect, and has at least one pair of pinned layer and free layer arranged via a non-magnetic spacer layer. The pinned layer has a pair of ferromagnetic layers which have different compositions and different coercive forces and which are antiferromagnetically connected to each other via a connection layer, so that the effective exchange coupling field of the pinned layer is 200 Oe or more.

Claims

1. A magnetorestrictive element, comprising an exchanging coupling film comprising:

an under layer of a single film, a laminate film, or an alloy film, said under layer containing one metal selected from the group consisting of Tc, Zn, Cd, Tl and Pb, said metal having a face centered cubic crystal structure or hexagonal closest-packing crystal structure;

an antiferromagnetic film; and

a ferromagnetic film.

2. A magnetorestrictive element as set forth in claim 1, wherein said under layer has a first layer contacting said antiferromagnetic film and a second layer contacting said first layer, said first layer contains said metal and said second layer contains at least one metal selected from the group consisting of Ti, Ta, Hf, Zr, Nb and V.

3. A magnetorestrictive element as set forth in claim 1 or 2, wherein at least part of said antiferromagnetic film has a face centered cubic crystal structure.

4. A magnetoresistive element as set forth in claim 3, wherein said antiferromagnetic film includes R_xMn₁₀₀₋

x (R is at least one element selected from the group consisting of Ir, Rh, Pt, Ru, Au, Ag, Co, Pd, Ge, Re, Ni and Cu, 5≦

x≦

40).

5. A magnetoresistive element as set forth in claim 3, wherein said antiferromagnetic film includes (R_xMn₁₀₀₋

x)<sub>100−

y</sub>Fe_y (R is at least one element selected from the group consisting of Ir, Rh, Pt, Ru, Au, Ag, Co, Pd, Ge, Re, Ni and Cu, 5≦

x≦

40, 0<

y<

30).

6. A magnetorestrictive element as set forth in claim 1 or 2, wherein at least part of said antiferromagnetic film has a face centered tetragonal crystal structure.

7. A magnetorestrictive element as set forth in claim 1 or 2, wherein at least part of said antiferromagnetic film has a body-centered cubic crystal structure.

8. A magnetoresistive element as set forth in claim 7, wherein said antiferromagnetic film includes R_xMn₁₀₀₋

x, (R is at least one element selected from the group consisting of Pt, Ni, Pd and Cr, 40≦

x≦

60).

9. A magnetoresistive element as set forth in claim 7, wherein said antiferromagnetic film includes (R_xMn₁₀₀₋

x)<sub>100−

y</sub>Fe_y (R is at least one element selected from the group consisting of Pt, Ni, Pd and Cr, 40≦

x≦

60, 0<

y<

30).

10. A magnetorestrictive element as set forth in claim 1 or 3, wherein at least part of said antiferromagnetic film has a body-centered cubic crystal structure and wherein said antiferromagnetic film comprises at least one metal selected from the group consisting of Ta, Hf, Nb, Si, Al, W, Zr, Ga, Be, In, V, Mo, Os, Cd, Zn, N, Cr and Ni.

11. A magnetorestrictive element as set forth in claim 1 or 2, wherein said antiferromagnetic film is arranged so that the axis <

111>

is perpendicular to the plane of the film.

12. A magnetorestrictive element as set forth in claim 1 or 2, wherein said antiferromagnetic film has a full width at half maximum of a rocking curve obtained by XRD, which is 15°

or less.

13. A magnetorestrictive element as set forth in claim 1 or 2, wherein the matching between atoms in the interface between said under layer and said antiferromagnetic film is −

6% or more and 15% or less.

14. A magnetorestrictive element as set forth in claim 13, wherein said antiferromagnetic film of an exchange coupling film has a laminated structure of first ferromagnetic film/non-magnetic film/second ferromagnetic film.

15. A magnetorestrictive element as set forth in claim 1 or 2, wherein said ferromagnetic film is formed of Co or a Co alloy.

16. A magnetorestrictive element as set forth in claim 1 or 2, wherein a first pinned layer of a ferromagnetic film is arranged on the top of said antiferromagnetic film, and a free layer of a ferromagnetic film is arranged on the top of said first pinned layer.

17. A magnetoresistive element as set forth in claim 16, wherein a second pinned layer of said ferromagnetic film is further arranged on the upper side of said free layer.

18. A magnetoresistance effect film as set forth in claim 17, wherein at least part of said antiferromagnetic film has a face centered cubic crystal structure.

19. A magnetoresistance effect film as set forth in claim 17, wherein at least part of said antiferromagnetic film has a face centered tetragonal crystal structure.

20. A magnetoresistance effect film as set forth in claim 17, wherein at least part of said antiferromagnetic film has a body-centered cubic crystal structure.

21. A magnetoresistive element as set forth in claim 17, wherein said antiferromagnetic film is formed of an alloy target having an oxygen content of 0.5 wt % or less.

22. A magnetorestrictive element as set forth in claim 1, wherein said antiferromagnetic film is formed of an alloy target having an oxygen comtent of 0.05w % or less.

23. A magnetic head comprising:

an under magnetic shield layer;

an under read magnetic gap formed on said under magnetic shield layer;

a magnetorestrictive element formed on said under read magnetic gap;

an upper read magnetic gap formed on said magnetorestrictive element; and

an upper magnetic shield layer formed on said upper read magnetic gap,

wherein said magnetorestrictive element comprises an exchanging coupling film comprising an under layer, a laminate film, or an alloy film, said under layer containing one metal selected from the group consisting of Tc, Zn, Cd, Tl and Pb, said metal having a face centered cubic crystal structure or a hexagonal closest packing crystal structure, an antiferromagnetic film, and a ferromagnetic film.

24. A magnetic disk drive which comprises a read magnetic head and a magnetic disk and which reads information recorded in said magnetic disk, by said read magnetic head, wherein said read magnetic head comprises an under magnetic shield layer;

an under read magnetic gap formed on said under magnetic shield layer, a magnetorestrictive element formed on said under read magnetic gap;

an upper read magnetic gap formed on said magnetorestrictive element; and

an upper magnetic shield layer formed on said upper read magnetic gap, and

wherein said magnetorestrictive element comprises an exchanging coupling film comprising an under layer, a laminate film, or an alloy film, said under layer containing one metal selected from the group consisting of Tc, Zn, Cd, Tl and Pb, said metal having a face centered cubic crystal structure or a hexagonal closest packing crystal structure, an antiferromagnetic film, and a ferromagnetic film.