Model construction and a possibility of cuprate-like pairing in a new d9 nickelate superconductor (Nd,Sr)NiO2

TL;DR

This paper constructs effective models for the Nd,Sr)NiO2 superconductor, revealing larger interactions than cuprates and suggesting similar dx2-y2-wave pairing with potentially lower transition temperatures.

Contribution

It introduces a multiorbital model for (Nd,Sr)NiO2, highlighting larger effective interactions and the likelihood of cuprate-like superconductivity.

Findings

Effective interactions are larger than in cuprates.

dx2-y2-wave superconductivity is likely.

Transition temperature may be lower than in cuprates.

Abstract

Effective models are constructed for a newly discovered superconductor (Nd,Sr)NiO2, which has been considered as a possible nickelate analogue of the cuprates owing to the d9 electron configuration. Estimation of the effective interaction, which turns out to require a multiorbital model that takes account of all the orbitals involved on the Fermi surface, shows that the effective interactions are significantly larger than in the cuprates. A fluctuation exchange study for the model indicates that dx2-y2-wave superconductivity is likely to occur as in the cuprates, where the transition temperature in the nickelate can be lower from the cuprates due to the larger interaction and narrower bandwidth.