Infinite-layer fluoro-nickelates as $d^9$ model materials

TL;DR

This paper theoretically investigates a new series of fluoro-nickelates with a $d^9$ electronic configuration, proposing them as ideal model materials for studying high-temperature unconventional superconductivity.

Contribution

It predicts the structural and electronic properties of fluoro-nickelates, establishing them as novel $d^9$ systems with potential for exploring unconventional superconductivity.

Findings

Predicted Ni$^{1+}$ oxidation state in fluoro-nickelates.

Identified these materials as pure Ni-3$d$ band systems.

Proposed as ideal platforms for high-temperature superconductivity studies.

Abstract

We study theoretically the fluoro-nickelate series $A$NiF$_2$ ($A=$ Li, Na, K, Rb, Cs) in the tetragonal $P4/mmm$ infinite-layer structure. We use density functional theory to determine the structural parameters and the electronic band structure of these unprecedented compounds. Thus, we predict these materials as model $d^9$ systems where the Ni$^{1+}$ oxidation is realized and the low-energy physics is completely determined by the Ni-3$d$ bands only. Fluoro-nickelates of this class thus offer an ideal platform for the study of intriguing physics that emerges out of the special $d^9$ electronic configuration, notably high-temperature unconventional superconductivity.