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

Abstract

The spin dependence of L2,3 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 Co50Pt50 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 Co50Pt50 alloy. The experimental results are discussed on the basis of spin-polarized band-structure calculations.