paper

Effective model and pairing tendency in bilayer Ni-based superconductor LaNiO

arXiv:2306.07275 · doi:10.1103/PhysRevB.111.174506

Abstract

Since the discovery of cuprate, the origin of high-T superconductivity has been an outstanding puzzle. Recently, high-T superconductivity was observed in a bilayer nickelate LaNiO under pressure, whose structure hosts the apical oxygen between two layers, distinct from multi-layer cuprates. Motivated by this discovery, we investigate its electronic structure using first-principle calculations and superconducting instabilities from both weak-coupling and strong-coupling perspective. Based on the first-principle band structures, we construct a bilayer two-orbital model on a square lattice, consisting of and orbitals, which accurately captures the low-energy electronic properties. Within this model, we study pairing instability using both functional renormalization group approach and multi-orbital t-J model. An -wave pairing with sign-reversal gaps on different Fermi surfaces is revealed, reminiscent of iron based superconductors. The Ni- orbital and its associated interlayer and intralayer exchange couplings are found to be crucial for the high-T superconductivity. Our study provides valuable insights into unique nature of electronic structure and superconductivity in LaNiO and contributes to the understanding of unconventional superconductors.

5 pages, 4 figures + SM

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