Structure, microstructure, and giant magnetoresistance in nanogranular FeAgNi thin films

Structural, microstructural, and magnetoresistive properties of metallic Fe(x)Ag(y)Ni(z) granular thin films were studied. These films with several compositions were prepared by dc magnetron sputtering. X-ray diffraction (XRD) measurements carried out on the samples show only Ag(111) peaks. The d-spacings determined from the Ag(111) peaks are smaller than the standard value for bulk Ag indicating a partial intermixing of Fe and Ni atoms in Ag. The diffraction pattern obtained using Transmission electron microscope (TEM) shows a number of Ag rings. Both XRD and TEM studies did not reveal any diffraction peaks due to Fe or Ni. The average particle size determined from the TEM micrograph is 5.5 nm whereas that determined from the XRD patterns is always higher. The magnetoresistance ratio for all the samples lies in the range 3 to 4.3%, except for a sample.