  A minimum in resistivity as a function of temperature for an as-quenched
Au80Co20 ribbon prepared by melt-spinning using a wheel surface speed of 20 m
s^{-1} is found at 25 K. No resistivity minimum is found for an as-quenched
ribbon using a wheel surface speed of 60 m s^{-1}, however, upon heat treatment
of this ribbon a resistivity minimum is recovered. The temperature of the
minimum decreases with increasing total time of heat treatment. These
observations are interpretted as evidence for the microstructural control of
the Kondo effect typically found in dilute magnetic alloys in a giant
magnetoresistance granular material.
