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

Abstract

The recent discovery of high-${T}_{c}$ superconductivity in Sr-doped ${\mathrm{NdNiO}}_{2}$ has sparked a renewed interest in investigating nickelates as cuprate counterparts. Parent cuprates $[{\mathrm{Cu}}^{2+}:{d}^{9}]$ are antiferromagnetic charge transfer insulators with the involvement of a single ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ band around the Fermi level and strong $p\text{\ensuremath{-}}d$ hybridization. In contrast, isoelectronic ${\mathrm{NdNiO}}_{2}$ $[{\mathrm{Ni}}^{+}:{d}^{9}]$ is metallic with a ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ 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 $p\text{\ensuremath{-}}d$ hybridization, and it produces low-spin ($S=0$, nonmagnetic) ${\mathrm{Ni}}^{2+}$ dopants.