National Synchrotron Light Source Seminar

For the past three years, photoelectron and optical spectroscopies have provided most of the momentum behind the tremendous research effort on the electronic structure of the new superconducting iron pnictides. In contrast, resonant inelastic x-ray scattering (RIXS) has yet to make a solid contribution to the research on this new class of superconductors. This is because the iron pnictides are metals, and hence have a very low Raman scattering cross-section.
In this talk, I will present RIXS data recently obtained at both Fe-K and Fe-L edges on single-crystals of PrFeAsOx (x=0.7,1), which belong to the so-called 1111 family. Owing to a combination of high energy resolution and high incident flux, we were able to observe features corresponding to two types of charge excitations: dd interband transitions between 0.2 and 2.0 eV energy loss, and As4p-Fe3d charge transfer around 4 eV. A weak momentum dependence across the Fe-As plane is observed for the dd interband transitions. The knowledge of these excitations enables us to readily assess the strength of the electron correlation effects, believed to play a central role in the peculiar physics of the iron-based superconductors. Finally, I will discuss which other iron pnictide compounds are likely to be well suited to RIXS.