XPS and XAS investigations of multilayer nanostructures based on the amorphous CoFeB alloy

Abstract

We analyzed two amorphous multilayer nanostructures (MLNS) [(CoFeB)60C40/SiO2]200and [(CoFeB)34(SiO2)66/C]46with the same element composition, but with the inverse location of the non-metallic phases C and SiO2in the metal-composite layers or interlayers. Based on the analysis of XPS and X-ray absorption spectra, it was found that in the metal-composite layers the chemical bonds prevailing at the interphase boundaries between the CoFeB metal clusters and the elements of the surrounding matrix, forming predominantly carbide or oxide phases depending on the C or SiO2 matrix composition.Quantitative fitting of the Fourier transforms for the Fourier transformed EXAFS signal from two MLNSs shows, that in [(CoFeB)60C40/SiO2]200with carbon in metal-composite the Fe and Co atoms of metal clusters have coordination numbers comparable to each other (6.73 and 7.68).In another MLNS [(CoFeB)34(SiO2)66/C]46, in which carbon forms interlayers, and its place in metal-composite layers is taken by SiO2, the number of atoms in the nearest environment of Co (6.71) close to the previous one, and the number of atoms in the environment of iron atoms (3.37) most two times less and, rather, is typical for compounds of iron with oxygen from the composite matrix in this MLNS. This lead to noticeable violations of the planarity of the interface and the anisotropy of electromagnetic properties in this MLNS.