The role of Ta and Pt in segregation within Co-Cr-Ta and Co-Cr-Pt thin film magnetic recording media

Polarization dependent extended x-ray absorption fine structure (PD-EXAFS) and magnetic circular dichroism (MCD) measurements of CoCrTa and CoCrPt films, sputter deposited at varying substrate temperatures, were performed to investigate the average local structure and chemistry about the Ta, Pt, and Co atoms and the average magnetic moment of the Co and Cr atoms within these films. Results from the MCD measurements indicate the average net magnetic moment of the Cr atoms is opposite in direction and five percent in amplitude relative to the Co moments. Inspection of the Fourier transforms of the XAFS data from these samples shows an increase in structural disorder around the Ta and Pt atoms with increasing substrate deposition temperature. A further comparison between the Ta and Pt edge EXAFS results show that the temperature-dependent increase in structural disorder is greater around the Ta atoms in the CoCrTa system than it is around the Pt atoms in the CoCrPt system.