Hund's metal physics: From SrNiO2 to LaNiO2

We study the normal state electronic structure of the recently discovered infinite-layer nickelate superconductor, Nd1-xSrxNiO2, using density functional theory plus dynamical mean-field theory calculations. Starting with the multiorbital 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, La1-xSrxNiO2 is naturally and conclusively found to be a multiorbital 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 an understanding of the electronic structures of Nd1-xSrxNiO2.