Photoemission Quasiparticle Spectra of ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$

Multiband quasiparticle calculations based on perturbation theory and dynamical mean-field methods show that the creation of a photoemission hole state in ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ is associated with a highly anisotropic self-energy. Since the narrow Ru-derived $d_{xz,yz}$ bands are more strongly distorted by Coulomb correlations than the wide $d_{\mathrm{xy}}$ band, charge is partially transferred from $d_{xz,yz}$ to $d_{\mathrm{xy}}$, thereby shifting the $d_{\mathrm{xy}}$ Van Hove singularity close to the Fermi level.