Structural evolution and magnetoresistance properties of heat treated Cu(80)Co(15)Fe(5) ribbons

Heat treated Cu(80)C(15)Fe(5) melt-spun ribbons are analyzed for their structural and magnetoresistance (MR) properties. Magnetoresistance values are found to be a maximum for the sample annealed at 500 deg C. Structural characterization using X-ray diffraction and absorption measurements and transmission electron microscopy show this sample to have two precipitate phases within a Cu-rich fcc matrix, i.e., a Co-rich fcc phase and a CoFe bcc phase. Heat treatments at higher temperatures bring about a decrease in MR. Dark field transmission electron microscope (TEM) images illustrate the clustering of the precipitate particles concurrent with the decrease in MR, suggesting that a clustering mechanism may contribute to the MR effect in these materials