Microstructural properties and local order around iron in granular metal-insulator Fe/Si3N4 systems prepared by magnetron sputtering

[Fe/Si3N4] multilayers have been prepared by magnetron sputtering with a layer thickness of 3 nm for silicon nitride and the iron layer ranging from 1 to 10 nm. A variety of techniques for determining the microstructure, such as x-ray reflectivity, transmission electron microscopy and Rutherford backscattering spectrometry techniques, have been performed to unveil the microstructure of such samples. Also, an analysis of the local environment around iron, by means of extended x-ray absorption fine structure and x-ray absorption near-edge structure spectroscopies performed at the Fe K-edge, confirms the presence of two phases forming the iron layers, the metallic Fe and the FeN phase. Special emphasis has been placed on the x-ray absorption analysis for multilayers with smaller Fe layer thicknesses, which present features of granular systems.