MAGNETORESISTANCE IN BULK CU-CO BASED ALLOYS

An enhanced magnetoresistance of up to 11% at room temperature has bee n found in granular Cu1-xCox (0.1 less-than-or-equal-to x less-than-or -equal-to 0.5) alloys, which were prepared by melt-spinning and a subs equent annealing treatment. The rapid solidification extends the solub ility of Co in Cu, i.e. the as-quenched state consists of a supersatur ated Cu matrix with some quenched-in Co-precipitates. During a subsequ ent heat treatment, the size and the density of the precipitates can b e varied. Since the precipitates behave superparamagnetically at room temperature, the average particle sizes and the amount of precipitated Co can be estimated from magnetization curves.