Quasi-particle Spectra of Sr₂RuO₄

Abstract

Recent theoretical and experimental results for the electronic structure and correlation effects in Sr₂RuO₄ are discussed. Multi-band quasi-particle calculations based on perturbation theory and dynamical mean field methods show that the creation of a photoemission hole state in Sr₂RuO₄ is associated with a highly anisotropic self-energy resulting from the coexistence of Ru-derived narrow and wide t _2g subbands. The narrow, nearly one-dimensional d _xz,yz bands are more strongly distorted by Coulomb correlations than the wide, approximately two-dimensional d _xy band. Thus, charge is partially transferred from d _xz,yz to d _xy. This correlation-induced inter-subband charge transfer gives rise to a substantial redshift of the d _xy van Hove singularity towards the Fermi level by about 50 meV and to a slight deformation of the shape of the Fermi surface. The theoretical results are in good agreement with recent angle-resolved photoemission spectra.