Influence of the SMCo5 hard magnetic phase on the magnetoresistive properties of Cu-Fe ribbons

The SmCo5 hard magnetic phase was added to magnetoresistive granular Cu-Fe alloys in order to investigate the influence of the presence of a hard magnetic phase on the magnetoresistive properties of a granular alloy that contains a soft magnetic phase. Cu-80(Sm0.17Co0.83)(x)Fe20-x ribbons, with x = 20, 15, 10, 5, obtained by melt spinning, were investigated. The ribbons are composed of magnetic Fe, SmCo5, and Co precipitates embedded in a Cu matrix. In the as-quenched state, the magnetic interactions between magnetic precipitates lead to the formation of magnetic coherent regions and the magnetoresistance effect is only observed at high field (>1T). After annealing, the strength of interactions decreases and a magnetoresistance effect is observed at low field (<1T). The largest magnetoresistance effect (16%) is observed at 5K for the Cu-80(Sm0.17Co0.83)(10)Fe-10 alloy annealed at 450degreesC.