The structural and magnetotransport properties of (Fe(y)Col(1-y))(100-
x)Ag-x films were studied as a function of composition. Giant magnetor
esistance (GMR) values were measured in these granular films, with the
best GMR obtained for the composition (Fe0.33Co0.67)(27)Ag-73, with v
alues of 29% at 30 K and 11.7% at 300 K. XRD and TEM results have show
n a fee crystal structure with a relatively homogeneous microstructure
. Magnetic data for the samples with the best GMR indicate a superpara
magnetic behavior. The narrow peak in thermomagnetic data and low bloc
king temperature suggest a small and uniform size distribution of magn
etic granules. A summary of the electrical transport properties is pre
sented, in relation to the structural, microstructural, and magnetic p
roperties.