POLARIZATION-DEPENDENT XAFS STUDIES ON THE ROLE OF TA IN THE COMPOSITIONAL SEGREGATION OF CO-CR-TA MAGNETIC RECORDING MEDIA

Extended x-ray absorption fine structure (EXAFS) measurements of Ta in Co-Cr-Ta films were performed using normal and glancing incident radi ation in order to investigate, respectively, the in-plane and out-of-p lane local structure and chemistry about the Ta atom sites. The Fourie r transformed EXAFS data illustrates the presence of an anisotropy bet ween the in-plane and out-of-plane structures around the Ta atoms, ind icating that the Ta atoms are incorporated in a closed-packed structur e with the c-axis aligned in the plane of the film. Analysis of the lo cal environments around Ta indicates that the Ta atoms are either rand omly distributed throughout the film or have preferentially segregated to the Cr-rich regions. Results indicate that an increase in disposit ion temperature results in Ta having a broader distribution of first-n eighbor distances as well as a slight decrease in the number of surrou nding atoms. This is consistent with a local structure model which has vacancies preferentially segregating to the Ta atoms thereby decreasi ng the diffusion of Cr within the grains.