Compositions, magnetic properties and GMR performances of melt-spun Cu-Co-Ni ribbons

The effect of composition on the giant magnetoresistance (GMR) of melt-spun Cu-Co-Ni ribbons is investigated in this paper. The relations between GMR ratios and microstructure of the ribbons are analyzed by magnetic measurements and microstructure characterization. The results indicate that when Co and Ni are at a suitable percentage, melt-spun Cu-Co-Ni ribbons give a larger GMR ratio (8.6%, H = 1.355 T) than that of Cu-Co ribbons without Ni addition. But it is noticed that if the Co and Ni percentage is not within the suitable range, the GMR ratios are smaller than that of Cu-Co ribbons. The reason is that the Ni addition restrains the liquid-phase separation of Cu-Co alloys during melt-spinning process which results in a higher supersaturation of Co(Ni) in the Cu matrix and thereafter increases the densities of fine magnetic Co-rich precipitations during annealing process. (C) 2003 Elsevier B.V. All rights reserved.