Electronic structure and magnetism in infinite-layer nickelates RNiO₂ (R= La-Lu)

Using first-principles calculations, we analyze the evolution of the electronic structure and magnetic properties of infinite-layer nickelates RNiO$_2$ (R= rare-earth) as R changes across the lanthanide series from La to Lu. By correlating these changes with in-plane and out-of-plane lattice parameter reductions, we conclude that the in-plane Ni-O distance is the relevant control parameter in infinite-layer nickelates. An antiferromagnetic ground state is obtained for all RNiO$_2$ (R=La-Lu). This antiferromagnetic state remains metallic across the lanthanide series and is defined by a multiorbital picture with low-energy relevance of a flat Ni-d$_{z^2}$ band pinned at the Fermi level, in contrast to cuprates. Other non-cuprate-like properties such as the involvement of R-$d$ bands at the Fermi level, a large charge transfer energy, and a suppressed superexchange are robust for all RNiO$_2$ materials.