Giant magnetoresistance in melt-spun granular Cu/sub 100-x/Co/sub x/ alloys with correlated magnetic moments

A study of giant magnetoresistance (GMR) has been performed on melt-spun ribbons of Cu/sub 100-x/Co/sub x/ (5/spl les/x/spl les/20) subjected to DC Joule heating in order to optimise the GMR response. The GMR results, plotted as functions of the reduced magnetisation, exhibit significant deviations from the parabolic behavior predicted in the case of no correlation among magnetic moments. A simple theory of the GMR in Cu-Co granular systems, taking explicitly into account the correlation existing among the magnetic particles, is highlighted. The effect of both Co content and degree of magnetic correlation on the maximum GMR values attained for each composition is briefly discussed.