Particle size dependence of magnetic behavior and giant magnetoresistance in granular Fe—Ag films

We have studied the magnetic, and magnetotransport properties of a metallic granular FexAg1−x alloys (x=0–0.45), fabricated by using an electron-beam coevaporation technique. Observations with a transmission electron microscope confirmed that these alloys consist of small Fe particles embedded in an Ag matrix. Based on the superparamagnetic theory, the average number N of iron atoms in a particle, ranging from 102 to 816 as x=0.05–0.21, and, therefore, the average granular size of iron particles, has been determined by simulating the magnetization curves above the blocking temperature. At 1.5 K, the average magnetic moment of iron particles has been found to be reduced as N