Anneal-induced transformations in the transport and magnetic properties of CoCu granulars

The electrical and magnetic properties of granular Co 5Cu 95, Co 10Cu 90 and Co 15Cu 85 ribbons treated with different annealing procedures were measured from helium to room temperatures. The isochronous anneals had fixed heating rate and the transformations were followed by “in situ” resistivity measurements. We found that the transformation occurs at nearly the same region of temperature for the three compositions. Besides, our results for magnetoresistance on Co 10Cu 90 could be understood in the light of the re-dissolution of Co into the Cu matrix, as suggested in previous works (Miranda et al., J. Magn. Magn. Mater. 185 (1998) 331; da Silva et al., IEEE Trans. Mag., to appear).