Ir L3 Edge RIXS Study on REIr2Si2 Compounds

REIr2Si2 compounds (RE = Ho, Gd, Eu) crystallize in a ThCr2Si2-type structure and host complex magnetic orders depending on the rare-earth ion. ReIr2Si2 are generally good metals with the delocalized Ir 5d electrons, while the 4f RE electrons provide magnetism. However, when compared to isostructural RERu2Si2, the magnetic transition temperature is usually slower, suggesting that strong spin-orbit coupling between Ir 5d and the RE 4f might mediate magnetic exchange. and the localized 4f electrons. Yet, to date, direct evidence for 5d-4f hybridization in these compounds is lacking. Here, we show resonant inelastic x-ray experiments at the Ir L3, which when compared to DFT calculations in a joint density of states description, directly show 5d-4f hybridization in ReIr2Si2 compounds.