EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE STUDY ON LOCAL-STRUCTURE AROUND FE ATOMS IN FE AG GRANULAR-MATERIALS/

The short-range structure of Fe/Ag granular materials has been studied by means of extended X-ray absorption fine structure (EXAFS). The loc al structure around Fe atoms is a distorted bcc structure for the as-d eposited state of Fe/Ag granular films produced by the ionized cluster beam (ICB) deposition technique. Fe atoms are rather randomly distrib uted in the Fe/Ag alloy films produced by cosputtering. With increasin g annealing temperature and time, the local structure around Fe atoms becomes a strain-free bcc structure in the ICB-deposited films, while Fe clusters are formed in the sputter-deposited films. The formation o f small Fe clusters and rough interfaces between the Fe cluster and th e Ag matrix is responsible for giant magnetoresistance (GMR) in Fe/Ag granular materials.