Superconductivity in a minimal two-band model for infinite-layer nickelates*

While the recent discovery of superconductivity in infinite-layer nickelates has drawn considerable attention, a common ingredient of the fundamental building blocks to describe their ground states has been lacking. A series of experimental and theoretical studies have suggested that an effective two-band Hubbard model with Ni 3dx2-y2 and rare-earth (R) 5d character may describe the low-energy physics. We study the ground-state properties of this two-band model on four-leg cylinders using the density-matrix renormalization group (DMRG). At half-filling, the ground state of the system is consistent with a Luttinger liquid, characterized by quasi-long-range charge and spin correlations in the R layer but short-range correlations in the Ni layer. This appears compatible with the experimental observations where electrons in the R layer are responsible for the electron pocket. When the R layer becomes nearly empty and insulating at 12.5% hole doping concentration, our results show that the ground state of the system is consistent with a Luther-Emery liquid, where we find power-law superconducting and charge density correlations in the Ni layer, but exponentially decaying spin correlations. The consistency of our results with experimental observations may help to reveal the microscopic mechanism for pairing in these nickelates and other unconventional superconductors.