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 discontinuous 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 between 200 and 800 degrees C, lead to breakup of the layers forming a heterogeneous alloy with magnetic clusters embedded in a metallic Ag matrix. The as-deposited Co/Ag presents a high compressive stress, while a slight tensile 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 with 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 magnetic clusters, while Fe atoms occupy preferentially the interfacial positions near Ag. Co atoms in Co/Ag multilayers have a fee structure.