Infinite-layer fluoro-nickelates as d 9 model materials

We study theoretically the fluoro-nickelate seriesANiF(2)(A = Li, Na, K, Rb, Cs) in the tetragonalP4/mmminfinite-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 modeld (9)systems where the Ni(1 + )oxidation is realized and the low-energy physics is exclusively determined by the Ni-3dbands. Fluoro-nickelates of this class thus offer an ideal platform for the study of intriguing physics that emerges out of the speciald (9)electronic configuration, notably high-temperature unconventional superconductivity.