Stacked structure, magnetoresistive effect element, magnetic head, sensor, high frequency filter, and oscillator

A magnetoresistive effect element comprising:

• a first ferromagnetic layer;
• a second ferromagnetic layer;
• and
• a nonmagnetic spacer layer that is disposed between the first ferromagnetic layer and the second ferromagnetic layer,
• wherein the nonmagnetic spacer layer includes:
• a nonmagnetic metal layer, and
• at least one of a first intermediate layer provided under the nonmagnetic metal layer and a second intermediate layer provided over the nonmagnetic metal layer, and
• wherein the first intermediate layer and the second intermediate layer include an NiAlX alloy that is expressed by General Formula (1):
• Niγ1Alγ2Xγ3 (1)
• wherein
• X indicates one element selected from the group consisting of Si, Sc, Ti, Cr, Mn, Fe, Co, Cu, Zr, Nb, and Ta, and
• 0<γ<0.5 in a case of γ=γ3/(γ1+γ2+γ3).