Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Physical dimension specified
Patent
1998-07-17
2000-12-26
Kiliman, Leszek
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Physical dimension specified
428336, 428692, 428694R, 428694T, 428694TM, 428900, 427128, 427129, 427130, 360113, 2041922, 148314, G11B 566
Patent
active
061656070
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a sputtering target, an anti-ferromagnetic material film formed using thereof and a magneto-resistance effect element formed using the same.
BACKGROUND ART
Until now, as a reproducing magnetic head for high density magnetic recording, a magnetic head (MR head) using a magneto-resistance effect element (hereinafter referred to as MR element) is under study. At present time, for a magneto-resistance effect film (MR film), Ni.sub.80 Fe.sub.20 (atomic %) alloy (permalloy) or the like, which shows anisotropic magneto-resistance effect (AMR), is generally used. Since the AMR film possesses such a small magneto-resistance change rate as about 3% (MR change rate), as an alternative material for the magneto-resistance effect film material, an artificial lattice film and a spin valve film such as (Co/Cu)n and the like, which display giant magneto-resistance effect (GMR), are attracting attention.
In an MR element using an AMR film, since the AMR film possesses magnetic domains, Barkhausen noise resulting from the existence of the magnetic domains becomes a drawback when putting to practical use. Therefore, various means for making an AMR film into a single domain are being studied. As one method among them, there is a method in which the magnetic domains in an AMR film is controlled in one particular direction by utilizing exchange coupling between an AMR film, which is a ferromagnetic material, and an anti-ferromagnetic material film. As an anti-ferromagnetic material in this case, .gamma.-FeMn alloy is so far well known (see the specification of U.S. Pat. No. 4,103,315, the specification of U.S. Pat. No. 5,014,147, and the specification of U.S. Pat. No. 5,315,468, for example).
Besides, a spin valve film comprises a sandwich film possessing a laminate structure formed of a ferromagnetic layer/a non-magnetic layer/a ferromagnetic layer, and, by pinning magnetization of one ferromagnetic layer, a GMR is obtained. For pinning magnetization of another ferromagnetic layer of the spin valve film, a technology utilizing exchange coupling between an anti-ferromagnetic film and a ferromagnetic film is generally used. For a constituent material of the anti-ferromagnetic material film in this case, .gamma.-FeMn alloy is generally in use.
However, .gamma.-FeMn alloy is poor in corrosion resistivity. In particular, it is easily corroded by water. Thus, since an MR element utilizing an anti-ferromagnetic material film consisting of .gamma.-FeMn alloy is easily corroded by, particularly, water in the air during processing step into an element shape or a head shape, thus, as a result of this corrosion, the exchange coupling force with an MR film tends to gradually deteriorate in time.
For an exchange coupling film formed between an anti-ferromagnetic material film and a ferromagnetic material film, from reliability view-point, an exchange coupling force is required to be 200 Oe and more at, for example, 393 K. To realize an exchange coupling force of 200 Oe and more at 393 K, in addition to an exchange coupling force at room temperature, temperature dependency of the exchange coupling force is required to be good. Concerning the temperature dependency of the exchange coupling force, a blocking temperature at which temperature the exchange coupling force between a ferromagnetic material film and an anti-ferromagnetic material film is lost is desirable to be high as much as possible. However, .gamma.-FeMn alloy is as low as 443 K in the blocking temperature, and also the temperature dependency of the exchange coupling force thereof is very poor.
Besides, in U.S. Pat. No. 5315468 for example, .theta.-Mn alloy, such as NiMn alloy, possessing a crystal structure of face-centered tetragonal crystal system is described as an anti-ferromagnetic material film. When an anti-ferromagnetic material film consisting of the .theta.-Mn alloy is used, it is shown that the exchange coupling force between the anti-ferromagnetic material film and the ferromagnetic material film does not deteriorate.
Furt
REFERENCES:
patent: 4103315 (1978-07-01), Hempstead et al.
patent: 4836865 (1989-06-01), Sakakima et al.
patent: 5014147 (1991-05-01), Parkin et al.
patent: 5049209 (1991-09-01), Sakakima et al.
patent: 5315468 (1994-05-01), Lin et al.
Fujioka Naomi
Fuke Hiromi
Ishigami Takashi
Iwasaki Hitoshi
Katsui Nobuo
Kabushiki Kaisha Toshiba
Kiliman Leszek
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