Electron doping of SmNiO3 via interfacial charge transfer: A first-principles study

Abstract

SmNiO3 is a representative quantum material exhibiting the antidoping behavior, where the conductivity of the material is reduced rather than increased by electron doping. Recent experimental and theoretical works have demonstrated a phase transition of SmNiO3 with large conductance changes via chemical methods. However, the effect of electron doping via interfacial charge transfer in SmNiO3 is much less studied. In this work, the first-principles density functional theory (DFT)+U method is employed to investigate the SmNiO3/YTiO3 superlattice, in which the YTiO3 layer acts as the electron donor. Compared with the chemical doping in SmNiO3, several interesting physical phenomena have been predicted in SmNiO3/YTiO3 superlattices due to the lattice and electronic reconstructions. First, at a doping concentration of 1e− per Ni, i.e., (SmNiO3)1/(YTiO3)1 superlattice, all Ni3+ are converted to Ni2+, resulting in a Mott-insulating phase, similar to the chemical doping in the pristine material. Interestingly, such a Mott gap can be efficiently modulated by tuning the stacking orientation. Second, at a doping concentration of 12e− per Ni, i.e., [001]-orientated (SmNiO3)2/(YTiO3)1 superlattice, the electronic structure associated with charge ordering depends on the concrete magnetic order, giving rise to magnetism-dependent electronic behavior. In addition, as the doping concentration further decreases (i.e., a doping concentration of 13e−/Ni), a metallic state is predicted in a [001]-orientated (SmNiO3)3/(YTiO3)1 superlattice, which is quite different from the case of chemical doping.