Giant magnetoresistance studies in (Fe,Co)-Ag films

Giant magnetoresistance (GMR) values were measured in thin films of Fe and Co in Ag. The best GMR results were observed in Ag-rich specimens, with maxima of 25% (30 K) and 14% (20 K) observed in Co20Ag80 and Fe25Ag75, respectively. Magnetic data indicate a spin glasslike behavior in the as-deposited Ag-rich films. The as-made samples have a nanostructure, with a face centered cubic structure. Annealing of the samples over the temperature range of 200 °C to 700 °C led to grain growth and subsequent phase separation of the constituent metals. A summary of the magnetic and electrical transport properties is presented, in relation to the crystal structure and microstructure of the TM-Ag films (TM=Fe,Co).