Effects of Sr doping on the electronic and spin-state properties of infinite-layer nickelates: Nature of holes

The recent discovery of high-Tc superconductivity in Sr-doped NdNiO2 has sparked a renewed interest in investigating nickelates as cuprate counterparts. Parent cuprates [Cu2+:d9] are antiferromagnetic charge transfer insulators with the involvement of a single dx2-y2 band around the Fermi level and strong p-d hybridization. In contrast, isoelectronic NdNiO2 [Ni+:d9] is metallic with a dx2-y2 band self-doped by Nd-d states. Using first principles calculations, we study the effect of Sr doping in the electronic and magnetic properties of infinite-layer nickelates as well as the nature of holes upon doping. We find that hole doping tends to make the material more cupratelike as it minimizes the self-doping effect, it enhances the p-d hybridization, and it produces low-spin (S=0, nonmagnetic) Ni2+ dopants.