Fe and N diffusion in nitrogen-rich FeN measured using neutron reflectometry

Grazing incidence neutron reflectometry provides an opportunity to measure the depth profile of a thin film sample with a resolution <1 nm, in a non-destructive way. In this way the diffusion across the interfaces can also be measured. In addition, neutrons have contrast among the isotopes, making it feasible to measure the self-diffusion. In the present work, the isotope multilayers of [FeN/⁵⁷FeN]₁₀ and [FeN/Fe¹⁵N]₁₀ were prepared using magnetron sputtering and self-diffusion of Fe and N was investigated. It was found that N diffusion is slower compared to Fe and does not follow the atomic size dependence.