Patent ID: 7248448

Claim:
A magnetoresistance effect element, comprising: a nonmagnetic spacer layer; first and second ferromagnetic layers 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 magnetization of the first ferromagnetic layer freely rotating in a magnetic field signal; a magnetoresistance effect-improving layer comprising a metal-alloy film and disposed in contact with the first ferromagnetic layer so that the first ferromagnetic layer is disposed between the nonmagnetic spacer layer and the magnetoresistance effect-improving layer, the metal-alloy film disposed in contact with the first ferromagnetic layer and not forming a solid solution with a metal element of the first ferromagnetic layer, the metal-alloy film comprising first and second elements that form a solid solution with each other; and a nonmagnetic underlayer or a nonmagnetic protecting layer disposed in contact with the magnetoresistance effect-improving layer so that the magnetoresistance effect-improving layer is disposed between the first ferromagnetic layer and the nonmagnetic underlayer or the nonmagnetic protecting layer; wherein the metal element of the first ferromagnetic layer is nickel, said first ferromagnetic layer being a Ni-alloy, wherein said first element of said metal alloy film is Ru and said metal alloy film has Ru as a main component.