Hallmark of strong electronic correlations in LaNiO ₃: Photoemission kink and broadening of fully occupied bands

Recent angular-resolved photoemission experiments on LaNiO ₃ reported a renormalization of the Fermi velocity of e _g quasiparticles, a kink in their dispersion at -0.2 eV and a large broadening and weakened dispersion of the occupied t _2g states. We show here that all these features result from electronic correlations and are quantitatively reproduced by calculations combining density-functional theory and dynamical mean-field theory. The importance and general relevance of correlation effects in filled bands coupled by interorbital interactions to a partially filled band are pointed out.