Compare of the electronic structures of F- and Ir-doped SmFeAsO

The electronic structures of Fe-based superconductor SmFeAsO1−xFx and SmFe1−yIryAsO are compared through X-ray photoemission spectroscopy in this study. With fluorine or iridium doping, the electronic structure and chemical environment of the SmFeAsO system were changed. The fluorine was doped at an oxygen site which introduced electrons to a reservoir Sm-O layer. The iridium was doped at an Fe site which introduced electrons to a conduction Fe-As layer directly. In a parent material SmFeAsO, the magnetic ordering corresponding to Fe3d in the low-spin state is suppressed by both fluorine and iridium doping through suppressing the magnetism of 3d itinerant electrons. Compared to fluorine doping, iridium doping affected superconductivity more significantly due to an iridium-induced disorder in FeAs layers.