Robust $d_{x^2-y^2}$-wave superconductivity of infinite-layer nickelates

TL;DR

This paper investigates the superconducting properties of infinite-layer nickelates, revealing a dominant $d_{x^2-y^2}$ pairing symmetry similar to cuprates through first-principles, RPA, and t-J model analyses.

Contribution

It introduces and compares single- and three-orbital models for nickelates, demonstrating the robustness of $d_{x^2-y^2}$-wave pairing across different theoretical approaches.

Findings

Superconductivity in nickelates is dominated by $d_{x^2-y^2}$ pairing symmetry.

Both models capture key low-energy physics relevant to superconductivity.

The dominant pairing tendency is consistent across weak and strong coupling regimes.

Abstract

Motivated by the recent observation of superconductivity in strontium doped NdNiO$_2$, we study the superconducting instabilities in this system from various vantage points. Starting with first-principles calculations, we construct two distinct tight-binding models, a simpler single-orbital as well as a three-orbital model, both of which capture the key low energy degrees of freedom to varying degree of accuracy. We study superconductivity in both models using the random phase approximation (RPA). We then analyze the problem at stronger coupling, and study the dominant pairing instability in the associated t-J model limit. In all instances, the dominant pairing tendency is in the $d_{x^2-y^2}$ channel, analogous to the cuprate superconductors.