PREFERENTIAL SITE DISTRIBUTION OF DILUTE PT AND TA IN COCR-BASED FILMS - AN EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE STUDY

Extended x-ray absorption fine structure (EXAFS) measurements of Co78C r22, Co86Cr12Ta2, and Co86Cr12Pt2 films were made to investigate the l ocal structure and chemistry around Ta and Pt atoms to determine their site distributions in these alloys. Comparisons between the measured data and data collected from experimental standards and calculated usi ng theoretical EXAFS simulation codes indicate that the Ta atoms are p referentially distributed to the Cr-enriched regions of the CoCr media , and the Pt atoms have an effect on the local environment of the Co a toms, Both Ta and Pt introduce a large amount of local structural diso rder to the local environments in which they reside. The presence of T a atoms in the Cr-enriched regions further reduces the magnetization o f these regions, which enhances the magnetic isolation of the Co regio ns from each other. This helps improve the noise characteristics of th e films. The portion of the Pt atoms residing in the Go-enriched regio ns increases the magnetic anisotropy of the films, thereby increasing their coercivity. (C) 1997 American Institute of Physics.