X-ray-absorption spectroscopy and x-ray diffraction in discontinuous CoxFe1-x/Ag multilayers

This paper reports on the structural properties of CoxFe1-x/Ag discontinuou s multilayers with x = 0, 0.3, 0.7, and 1. The evolution of the structural properties has been investigated by x-ray diffraction and x-ray-absorption spectroscopy (XAS). Thermal treatments for 10 min at temperatures ranging b etween 200 and 800 degrees C, lead to breakup of the layers forming a heter ogeneous alloy with magnetic clusters embedded in a metallic Ag matrix. The as-deposited Co/Ag presents a high compressive stress, while a slight tens ile stress is observed in every other composition. After annealing there is a relaxation of the stress as well as a crystallo-graphic ordering of the magnetic clusters. It is found from XAS measurements that, for the alloys w ith x = 0.3 and 0.7, there is a better-ordered structure around Co than Fe absorbing atoms. We conclude that Co atoms are within the core of the magne tic clusters, while Fe atoms occupy preferentially the interfacial position s near Ag. Co atoms in Co/Ag multilayers have a fee structure.