Correlation effects in Sr2RuO4 and Ca2RuO4:: Valence-band photoemission spectra and self-energy calculations -: art. no. 153106

We have studied the electronic structure of Sr2RuO4 and Ca2RuO4 using x-ray photoemission spectroscopy (XPS) and subsequent model calculations. While the t(2g) band of Sr2RuO4 has substantial spectral weight at the Fermi level, that of Ca2RuO4 has no spectral weight at E-F and shows a peak at -1.8 eV. In the valence-band XPS spectrum of Sr2RuO4, a satellite structure of the t(2g) band is observed. In order to explain the spectral features, we have carried out band-structure calculations using the unrestricted Hartree-Fock (HF) approximation and found good agreement with the experimental result for Ca2RuO4. In order to explain the satellite structure of Sr2RuO4, we have performed second-order perturbation calculations of the self-energy corrections around the unrestricted HF solution of Sr2RuO4.