Interface resolved magnetism at metal-organic (Fe/Alq3) interfaces under x-ray standing wave condition

The isotope selective grazing-incidence nuclear resonance scattering (GI-NRS) technique, which is a time analog to Mossbauer spectroscopy, is made depth resolved to probe the magnetism of the diffused Fe (Fe-diffused) and bulk Fe (Fe-bulk) parts of the layer in an Fe/Alq(3) [ferromagnetic (FM)/organic semiconductor (OSC)] bilayer structure. On the basis of theoretical simulations, it is demonstrated that the antinode regions of x-ray standing waves (XSWs) generated through wave guide structures allow one to measure the Fe-diffused and Fe-bulk parts independently, providing evidence for a diffused layer with reduced electron density and hyperfine fields. Due to possible small isolated clusters of Fe in the diffused layer, Fe moments are found with random orientations, while in Fe-bulk moments, they are aligned in the film plane due to shape anisotropy. GI-NRS under XSW is suitable for FM/OSC structures to obtain interface resolved magnetic information, which is otherwise difficult with any other available lab based conventional methods.