Many body electronic structure of infinite layer and trilayer nickelates

Motivated by recent experiments on infinite layer (RNiO₂) and trilayer (R₄Ni₃O₈) nickelate analogs of cuprate superconductors, we use a combination of density functional and dynamical mean field (DFT+DMFT) methods to perform a comparative study many body electronic structure of these materials, with a focus on CaCuO₂, NdNiO₂, and Pr₄Ni₃O₈. We find that the correlated Ni-3d shells of both families of nickelates have similar many-body configurations. Additionally, when compared at the same nominal carrier concentration, the materials exhibit similar many-body electronic structures, self energies, and correlation strengths. Compared to cuprates, the nickelates are closer to the Mott-Hubbard regime due to their larger charge transfer energies. Moreover, doping involves the charge reservoir provided by the rare earth 5d electrons, as opposed to cuprates where it is realized via the oxygen 2p electrons. Like cuprates, the correlations in the nickelates are dominated by a d_x²-y² and O-p_σ hybrid. Differences between the two families of nickelates can be attributed to the lack of c-axis dispersion in the trilayer nickelates, leading to differences in Fermiology that may be the primary driver of differences in material properties.