Superconducting Instabilities in Strongly-Correlated Infinite-Layer Nickelates

TL;DR

This paper investigates the superconducting pairing mechanisms in infinite-layer nickelates, revealing a transition from d-wave to nodal s± symmetry driven by orbital fluctuations, with implications for understanding their unconventional superconductivity.

Contribution

It provides a theoretical analysis incorporating multi-orbital correlations and doping effects, uncovering a transition in pairing symmetry specific to nickelates.

Findings

Transition from d-wave to nodal s± pairing symmetry.

Orbital fluctuations drive the pairing transition.

Results align with recent experimental observations.

Abstract

The discovery of superconductivity in infinite-layer nickelates has added a new family of materials to the fascinating growing class of unconventional superconductors. By incorporating the strongly correlated multi-orbital nature of the low-energy electronic degrees of freedom, we compute the leading superconducting instability from magnetic fluctuations relevant for infinite-layer nickelates. Specifically, by properly including the doping dependence of the Ni $d_{x^2-y^2}$ and $d_{z^2}$ orbitals as well as the self-doping band, we uncover a transition from $d$-wave pairing symmetry to nodal $s_\pm$ superconductivity, driven by strong fluctuations in the $d_{z^2}$-dominated orbital states. We discuss the properties of the resulting superconducting condensates in light of recent tunneling and penetration depth experiments probing the detailed superconducting gap structure of these materials.