Patent ID: 7008702

Claim:
A magnetoresistance effect head, comprising: a magnetoresistance effect element including, a nonmagnetic spacer layer, first and second ferromagnetic layer separated by the nonmagnetic spacer layer, the first ferromagnetic layer having a magnetization direction at an angle relative to a magnetization direction of the second ferromagnetic layer at zero applied magnetic field, the second ferromagnetic layer comprising first and second ferromagnetic films antiferromagnetically coupled to one another and an antiferromagnetically coupling film located between and in contact with the first and second ferromagnetic films for coupling the first and second ferromagnetic films together antiferromagnetically so that their magnetizations are aligned antiparallel with one another and remain antiparallel in the presence of an applied magnetic field, the magnetization of the first ferromagnetic layer freely rotating in a magnetic field signal, and a nonmagnetic high-conductivity layer disposed in contact with the first ferromagnetic layer so that the first ferromagnetic layer is disposed between the nonmagnetic conductivity layer and the nonmagnetic spacer layer, wherein: the first ferromagnetic layer has a film thickness between 0.5 nanometers and 4.5 nanometers, and the nonmagnetic spacer layer, the first ferromagnetic layer, and the second ferromagnetic layer have a film thickness so that a bias point B.P. is in the range of 30–50% when a product of a magnetic saturation M s and a thickness t of the first ferromagnetic layer is between 2 and 3 nm·T, in which, B.P. =50×( Hshift/Hs )+50, and Hshift=−Hin+Hpin±Hcu, Hshift is the sum of magnetic fields applied to the first ferromagnetic layer, Hs is an inclination of a transfer curve, Hin is a coupling magnetic field of the first and second ferromagnetic layers via the nonmagnetic spacer layer, Hpin is a stray magnetic field from the second ferromagnetic layer to the first ferromagnetic layer, and Hcu is a magnetic field to be applied to the first ferromagnetic layer.