Using first-principles density functional theory calculations, we investigated the effect of charge doping in a ${\mathrm{LaNiO}}_3/{\mathrm{SrTiO}}_3$ superlattice. The detailed analysis based on two different doping simulation methods clearly shows that the electronic and structural properties change in a systematic way, and that the orbital polarization (i.e., relative occupation of two $\mathrm{Ni}-e_g$ orbitals) is reduced and the Ni to apical oxygen distance is enlarged as the number of doped electrons increases. Also, the rotation angles of the ${\mathrm{NiO}}_6/{\mathrm{TiO}}_6$ octahedra strongly and systematically depend on the doping. Our results not only suggest a possible way to control the orbital and structural properties by means of charge doping, but also provide useful information for understanding experiments under various doping situations such as oxygen vacancy.

• Received 27 April 2015

DOI:https://doi.org/10.1103/PhysRevB.91.235102