First-principles study of electronic structures of infinite-layer nickelates

Recently, experimentalists obtained the angle-resolved photo-emission spectroscopic (ARPES) results of superconducting La_0.8Sr_0.2NiO₂. Here we perform first-principles calculations to compare the electronic structure of La_0.8Sr_0.2NiO₂ to experiment by using density functional theory plus dynamical mean field theory (DFT+DMFT) calculations. We find that there is a large Ni-d_x²-y²-derived Fermi sheet that evolves from hole-like to electronic-like along k_z and a three-dimensional (3D) electron pocket centered at the Brillouin zone corner. The theoretical Fermi topology is in good agreement with the measured momentum-resolved electronic structure. By fitting the theoretical spectrum function to the ARPES data, the band renormalization of Ni-d_x²-y²-derived band is observed with the mass enhancements factor of around 2-3, while the band renormalization of the 3D electron band is negligible.