Motivated by the report of superconductivity in bilayer La3Ni2O7 at high pressure, we examine the interacting electrons in this system. First-principles many-body theory is utilized to study the normal-state electronic properties. Below 100\,K, a multi-orbital non-Fermi liquid state resulting from loss of Ni-ligand coherence within a flat-band dominated low-energy landscape is uncovered. The incoherent low-temperature Fermi surface displays strong mixing between Ni-dz2 and Ni-dx2−y2 orbital character. In a model-Hamiltonian picture, spin fluctuations originating mostly from the Ni-dz2 orbital give rise to strong tendencies towards a superconducting instability with B1g or B2g order parameter. The dramatic enhancement of Tc in pressurized La3Ni2O7 is due to stronger Ni-dz2 correlations compared to those in the infinite-layer nickelates.
@article{arxiv.2306.05121,
title = {Electronic correlations and superconducting instability in La$_3$Ni$_2$O$_7$ under high pressure},
author = {Frank Lechermann and Jannik Gondolf and Steffen Bötzel and Ilya M. Eremin},
journal= {arXiv preprint arXiv:2306.05121},
year = {2023}
}