$\textit{Ab initio}$ Materials Design of Superconductivity in $d^9$ Nickelates

TL;DR

This study uses advanced calculations to explore superconductivity in nickelates, revealing that their phase diagrams resemble cuprates and highlighting the importance of electron correlations and layer control.

Contribution

It provides the first detailed phase diagram of $d^9$ nickelates using dynamical vertex approximation, showing their similarities to cuprates and the role of electron correlations.

Findings

Superconductivity appears upon hole-doping in nickelates.

The phase diagram exhibits a dome-shaped superconducting transition temperature.

Electron correlations are crucial for superconductivity in nickelates.

Abstract

Motivated by the recent theoretical materials design of superconducting $d^9$ nickelates for which the charge transfer from the NiO$_2$ to the block layer is completely suppressed [M. Hirayama $\textit{et al.}$, Phys. Rev. B $\textbf{101}$, 075107 (2020)], we perform a calculation based on the dynamical vertex approximation and obtain the phase diagram of RbCa$_2$NiO$_3$ and $A_2$NiO$_2$Br$_2$ where $A$ is a cation with a valence of 2.5+. We show that the phase diagram of these nickelates exhibits the same essential features as those found in cuprates. Namely, superconductivity appears upon hole-doping into an antiferromagnetic Mott insulator, and the superconducting transition temperature shows a dome-like shape. This demonstrates that the electron correlations play an essential role in nickelate superconductors and we can control them by changing block layers.