Magnetoresistance effect element

A magnetoresistance effect element comprising:

• an underlayer;
• a first ferromagnetic metal layer;
• a second ferromagnetic metal layer;
• and
• a tunnel barrier layer that is sandwiched between the first and second ferromagnetic metal layers,
• wherein the tunnel barrier layer has a spinel structure and comprises:
• at least one lattice-matched portion that is lattice-matched with both of the first ferromagnetic metal layer and the second ferromagnetic metal layer;
• and
• at least one lattice-mismatched portion that is not lattice-matched with at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer, and
• the underlayer is made of
• a nitride layer having a (001)-oriented NaCl structure and containing at least one element selected from the group consisting of Ti, Zr, Nb, V, Hf, Ta, Mo, W, B, Al and Ce;
• a layer having a (001)-oriented tetragonal or cubic structure and containing at least one element selected from the group consisting of Al, Cr, Fe, Co, Rh, Pd, Ag, Jr, Pt, Au, Mo, and W;
• or
• a layer having a stacked structure with a combination of a nitride layer having a (001)-oriented NaCl structure and containing at least one element selected from the group consisting of Ti, Zr, Nb, V, Hf, Ta, Mo, W, B, Al and Ce and a layer having a (001)-oriented tetragonal or cubic structure and containing at least one element selected from the group consisting of Al, Cr, Fe, Co, Rh, Pd, Ag, Ir, Pt, Au, Mo, and W.