Hund's metal physics: from SrNiO₂ to LaNiO₂

We study the normal state electronic structure of the recently discovered infinite-layer nickelate superconductor, Nd_1-xSr_xNiO₂, using DFT+DMFT calculations. Starting with the multi-orbital compound SrNiO₂, our calculations show that despite large charge carrier doping from SrNiO₂ to LaNiO₂, the Ni-3d total occupancy is barely changed due to the decreased hybridization with the occupied oxygen-2p states and increased hybridization with the unoccupied La-5d states. Thus, using SrNiO₂ as a reference, La_1-xSr_xNiO₂ is naturally and conclusively found to be a multi-orbital electronic system with characteristic Hund's metal behaviors, such as metallicity, the importance of high-spin configurations, tendency towards orbital differentiation, and the absence of magnetism in regimes which are ordered according to static mean-field theories. Our results are in good agreement with the existing spectroscopic studies and make an essential step towards understanding of the electronic structures of Nd_1-xSr_xNiO₂.