Single-layer T′-type nickelates: Ni1+ is Ni1+

The discovery of superconductivity in the infinite-layer nickelates has opened new perspectives in the context of quantum materials. We analyze, via first-principles calculations, the electronic properties of La2NiO3F-the first single-layer T'-type nickelate-and compare these properties with those of related nickelates and isostructural cuprates. We find that La2NiO3F is essentially a single-band system with a Fermi surface dominated by the Ni-3d(x2-y2) states with an exceptional 2D character. In addition, the hopping ratio is similar to that of the highest T-c cuprates and there is a remarkable e(g) splitting together with a charge transfer energy of 3.6 eV. According to these descriptors, along with a comparison to Nd2CuO4, we thus indicate single-layer T'-type nickelates of this class as very promising analogs of cupratelike physics while keeping distinct Ni1+ features.