Spin-dependent x-ray absorption in Co/Pt multilayers and Co50Pt50 alloy

The spin dependence of $L_{2,3}$ absorption in 5d atoms oriented in a ferromagnetic matrix contains information on the spin density of the empty d‐projected states of the absorbing atom. Spin‐dependent absorption spectroscopy using circularly polarized synchrotron radiation was applied to study the polarization of the Pt atoms in the binary alloy $Co_{50}Pt_{50}$ and Pt/Co layered structures, which are promising candidates for magneto‐optical recording. The spin‐dependent absorption signals for vapor‐deposited 250(4 Å Co+18 Å Pt) and 250(6 Å Co+18 Å Pt) multilayers indicate a ferromagnetic coupling on Pt and Co atoms with a significant Pt polarization. This is reduced on average by about 60% with respect to the Pt polarization in the $Co_{50}Pt_{50}$ alloy. The experimental results are discussed on the basis of spin‐polarized band‐structure calculations