Electronic correlations and magnetic interactions in infinite-layer NdNiO$_2$

TL;DR

This study uses advanced quantum chemistry methods to analyze the electronic and magnetic properties of infinite-layer NdNiO$_2$, revealing strong correlations and significant antiferromagnetic interactions that are crucial for understanding its superconductivity.

Contribution

It provides a detailed comparison of electronic correlations and magnetic exchange in NdNiO$_2$ with cuprates, highlighting the stronger dynamical correlations and their impact on magnetic interactions.

Findings

Strong on-site dynamical correlations in NdNiO$_2$

Large antiferromagnetic exchange coupling (J=77 meV)

Similar electronic structure to cuprates but different correlation roles

Abstract

The large antiferromagnetic exchange coupling in the parent high-$T_{\rm c}$ cuprate superconductors is believed to play a crucial role in pairing the superconducting carriers. The recent observation of superconductivity in hole-doped infinite-layer (IL-) NdNiO$_2$ brings to the fore the relevance of magnetic coupling in high-$T_{\rm c}$ superconductors, particularly because no magnetic ordering is observed in the undoped IL-NdNiO$_2$ unlike in parent copper oxides. Here, we investigate the electronic structure and the nature of magnetic exchange in IL-NdNiO$_2$ using state-of-the-art many-body quantum chemistry methods. From a systematic comparison of the electronic and magnetic properties with isostructural cuprate IL-CaCuO$_2$, we find that the on-site dynamical correlations are significantly stronger in IL-NdNiO$_2$ compared to the cuprate analog. These dynamical correlations play a critical role in the magnetic exchange resulting in an unexpectedly large antiferromagnetic nearest neighbor isotropic $J$ of 77 meV between the Ni$^{1+}$ ions within the $ab$-plane. While we find many similarities in the electronic structure between the nickelate and the cuprate, the role of electronic correlations is profoundly different in the two. We further discuss the implications of our findings in understanding the origin of superconductivity in nickelates.