NANOSCALE STRUCTURAL EVOLUTION AND ASSOCIATED CHANGES IN MAGNETORESISTANCE IN THE GRANULAR FEXAG100-X THIN-FILMS

The microstructure of sputter-deposited granular FexAg100-x thin films (0<X<60) has been investigated by using a high resolution transmissio n electron microscope. For x less-than-or-equal-to 14 at. % Fe, two ki nds of morphological regions exist, i.e., the crystallized and the hig hly disordered. As the x changes within 20-36 at. % Fe, small clusters with sizes around 1 nm are formed in the films. Further increase of x leads to the crystal grain fining and crystal frustration. The observ ed microstructural evolution in the films with the increase of Fe cont ent can be correlated with the evolution of giant magnetoresistance at 4.2 K in the Fe-Ag films: a linear relationship of the magnetoresista nce ratio, DELTArho/rho, with H for x less-than-or-equal-to 20 at. %, the saturation trend and the decrease of DELTArho/rho for x greater-th an-or-equal-to 36 at. % Fe.