Magnetism in doped infinite-layer NdNiO₂ studied by combined density functional theory and dynamical mean-field theory

Abstract

The recent observation of superconductivity in infinite-layer nickelates has brought intense debate on the established knowledge of unconventional superconductivity based on the cuprates. Despite many similarities, the nickelates differ from the cuprates in many characteristics, the most notable of which is the magnetism. Instead of a canonical antiferromagnetic (AFM) Mott insulator as the undoped cuprates, from which the superconductivity is generally believed to arise upon doping, the undoped nickelates show no sign of magnetic ordering in experiments. Through a combined density functional theory, dynamical mean-field theory, and model study, we show that although the increased energy splitting between O-p orbital and Cu/Ni-d orbital (Δdp) results in a larger magnetic moment in nickelates, it also leads to stronger AFM/ferromagnetism competition and weaker magnetic exchange coupling. Meanwhile, the self-doping effect caused by Nd-d orbital screens the magnetic moment of Ni. The Janus-faced effect of Δdp and self-doping effect together give a systematic understanding of magnetic behavior in nickelates and explain recent experimental observations.