Effects of rare earth additions on GMR of melt-spun Cu–Co–Ni ribbons

The effects of Ni and rare earth (La, Ce, Nd, Dy, Tb) co-addition on GMR of the melt-spun Cu–Co alloys are investigated. The results indicate that Ni addition can increase the GMR of the melt-spun Cu–Co ribbons. The reasons are that Ni addition can restrain the liquid phase separation occurring at high temperature and increase the density of the fine magnetic Co-rich precipitates during the annealing process. Light rare earth, such as Ce and La, can further enhance GMR of the melt-spun Cu–Co–Ni ribbons. Among these elements, Ce is the most effective. However, heavy rare earth additions result in a GMR decline of the melt-spun Cu–Co–Ni ribbons. It is discovered that there exists an optimal addition quantity for Ce. Excessive Ce addition could result in a GMR decline as well. The reasons for the GMR improvement of Re addition are: role of purifying melt, promoting precipitates process and enhancing the magnetic susceptibility of the fine Co-rich precipitates.