The present invention relates to a magnetoresistive head and a manufacturing method thereof. It also relates to a magnetic disk drive using the magnetoresistive head.
A spin valve device utilizing a giant magnetoresistive effect (GMR) has been utilized as a reading device for a magnetic disk drive. A synthetic ferri-type spin valve film referred to as a bottom type generally comprises a constitution of substrate/underlayer/anti-ferromagnetic layer/first ferromagnetic layer/anti-ferromagnetic coupling layer/second ferromagnetic layer/Cu intermediate layer/free layer/protective layer. Materials often used for the layers described above can include MnPt or MnIr for the anti-ferromagnetic layer, CoFe for the first ferromagnetic layer, Ru for the anti-ferromagnetic coupling layer, CoFe for the second ferromagnetic layer and CoFe/NiFe for the free layer.
Patent Document 1 (JP-A No. 2002-289947) discloses that the exchange coupling magnetic field between the anti-ferromagnetic layer and the first ferromagnetic layer is increased in a bottom type coupling film by using an anti-ferromagnetic layer comprising MnZPt100-Z, 53≦Z≦57 at % and a first ferromagnetic layer comprising CoxFe100-X, 42≦X≦83 at %. The coupling film comprises a constitution of underlayer/anti-ferromagnetic layer/ferromagnetic layer, which is not constituted as a synthetic ferri-type spin valve film.
On the other hand, Patent Document 2 (JP-A No. 2001-189503) discloses that the magnetoresistance ratio increases and the soft magnetic property of the free layer is improved in a case of selecting the first ferromagnetic layer of the bottom type synthetic ferri-type spin valve film such that the closed packed face of fcc or hcp is oriented in the in-plane direction of the film. According to Patent Document 2, it is probable that in a case where the first ferromagnetic layer comprises CoFex, since it takes an fcc structure within a range of the Fe composition x of: 0≦x≦20 at %, high magnetoresistance ratio and improved soft magnetic property of the free layer can be obtained.
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