(La,Sr)₂NiO₃: An antiferromagnetic Mott insulator capable of doping

Abstract

The topotactic reduction of (La,Sr)NiO3 to superconducting (La,Sr)NiO2 using CaH2 as a detergent has revealed new routes to synthesize nickelates. Here we look into the possibility of a similar reduction of (La,Sr)2NiO4 to (La,Sr)2NiO3. We perform density functional theory plus dynamical mean-field theory calculations. Our results show that chemical reduction (via, e.g., CaH2) is expected to remove in-plane oxygens instead of the apical ones, leaving vertical planar NiO4 squares that form one-dimensional NiO chains. (La0.5Sr0.5)2NiO3 with a 3d9 electronic configuration is an antiferromagnetic, single-band Mott insulator. Hole doping suppresses this antiferromagnetic order and turns the system metallic. The crystal and electronic structure of (La,Sr)2NiO3 bears quite some similarity with the cuprate superconductor Ba2CuO3+δ.