Theory of Resonant Inverse Photoemission Spectroscopy in Ce Compounds: Selection Rule and Hybridization Strength

Abstract

We analyze the recently measured resonant inverse photoemission spectroscopy (IPES) at the Ce 3 d threshold in CeNi 2 and CeRh 3 , which corresponds to a superposition of 4 f n →3 d 9 4 f n +2 →4 f n +1 processes with n = 0 and 1, and predict an expected resonant IPES in CeO 2 on the basis of the Anderson impurity model including the full multiplet effect. By discussing a difference in selection rule of the final state between off- and on-resonances, the observed difference in spectrum is interpreted. The analysis shows that the magnitude of 4 f -ligand hopping integral connecting the 4 f 2 and 4 f 3 configurations with a 3 d core hole is to be reduced to ∼ 1/3 for CeNi 2 and ∼ 1/2 for CeRh 3 of that connecting the 4 f 0 and 4 f 1 configurations without the core hole, which dominantly determines the 4 f ground state. A tentative calculation assuming the reduction of ∼ 0.8 is performed for CeO 2 . The calculation is also extended to IPES at the 4 d core thrshold for CeNi 2 .