Melt-spun Cu-Co ribbons are annealed by linearly varying current Joule heat
ing. During the annealing, the electrical resistance is measured in order t
o follow the structural transformations within the samples. The resistance
versus current curves show a characteristic behavior for all samples studie
d. This fact is used to specify optimum conditions to obtain the best nanos
tructure which displays the maximum giant magnetoresistance ratio. (C) 1998
American Institute of Physics. [S0021-8979(98)04521-6].