Magnetoresistance in Ni-Fe/Cu Multilayers

Ni80Fe20/Cu multilayer films were prepared on glass substrate by magnetron sputtering. The dependence of the magnetoresistance on the thickness of the Cu layer, the thickness of the Ni-Fe layer, the thickness of the buffer layers for Fe, Ni80Fe20 and Cu, and the number of bilayers, was investigated. The MR ratio peaked at dCu= 10Ã…, where the MR ratio was about 20% at room temperature. When the thickness of the Ni80Fe20 layer was varied, the MR ratio had a broad peak from dNi-Fe=15 to 30Ã…. The interlayer exchange interaction was evaluated as 3×10^¿2 erg/cm², irrespective of the thickness of the buffer layer. The MR ratio increased with the number of bilayers N, and reached saturation when the total film thickness was about 800 to 1000Ã….