Superconductivity in the spin-state crossover materials: Nickelates with planar-coordinated low-spin Ni${}^{2+}$ ions

Jiří Chaloupka, Giniyat Khaliullin

We theoretically study quasi-two-dimensional nickel compounds, where the nickel ions assume Ni${}^{2+}$ $d^8$ valence state and feature a low-spin $S=0$ ground state quasidegenerate…