Characterizing the superconducting instability in a two-orbital $d$-$s$ model: insights to infinite-layer nickelate superconductors

TL;DR

This study uses quantum Monte Carlo simulations to explore how inter-orbital hybridization affects superconductivity in a two-orbital model relevant to infinite-layer nickelates, revealing hybridization's complex role in enhancing or suppressing pairing.

Contribution

It provides the first detailed analysis of the impact of $d$-$s$ hybridization on superconductivity in a two-orbital model for nickelates, highlighting conditions that can suppress or enhance pairing.

Findings

Hybridization suppresses $d$-wave pairing at relevant doping levels.

Finite $s$ orbital occupancy can inhibit superconductivity suppression.

Large $d$-$s$ hybridization may enhance superconductivity at strong interactions.

Abstract

Motivated by the recent realization of the infinite-layer nickelate superconductivity (SC), we quantitatively investigate a two-orbital $d$-$s$ model by dynamic cluster quantum Monte Carlo calculations. Focusing on the impact of inter-orbital hybridization on the superconducting properties, our simulations indicate that the $d$-$s$ hybridization strength has a decisive role in the suppression of the $d$-wave pairing in the doping regime relevant to infinite-layer nickelates. Although we confirm on the single-orbital description at weak hybridization, at relatively large hybridization, there exists a constructive effect of the non-negligibly finite $s$ orbital occupancy on inhibiting the suppression of the superconductivity. More strikingly, there exists a possible SC enhancement at large enough Hubbard interaction via large $d$-$s$ hybridization. We further provide some insights on the relevance of $d$-$s$ model to infinite-layer nickelates.