Multiorbital processes rule the Nd$_{1-x}$Sr$_x$NiO$_2$ normal state

Abstract

The predominant Ni-multiorbital nature of infinite-layer neodynium nickelate at stoichiometry and with doping is revealed. We investigate the correlated electronic structure of NdNiO$_2$ at lower temperatures and show that first-principles many-body theory may account for Kondo(-lattice) features. Yet those are not only based on localized Ni-$d_{x^2-y^2}$ and a Nd-dominated self-doping band, but heavily builds on the participation of Ni-$d_{z^2}$ in a Hund-assisted manner. In a tailored three-orbital study, the half-filled regime of the former inplane Ni orbital remains surprisingly robust even for substantial hole doping $\delta$. Reconstructions of the interacting Fermi surface designate the superconducting region within the experimental phase diagram. They furthermore provide clues to recent Hall measurements as well as to the astounding weakly-insulating behavior at larger experimental $\delta$. Finally, a strong asymmetry between electron and hole doping, with a revival of Ni single-orbital features in the former case, is predicted. Superconductivity in Nd$_{1-x}$Sr$_x$NiO$_2$ is unlike the one in cuprates of distinct multiorbital kind, building up on nearly localized Ni-$d_{x^2-y^2}$ and itinerant Ni-$d_{z^2}$.