Effect of charge doping on the electronic structure, orbital polarization, and structural distortion in nickelate superlattice

摘要

Using first-principles density functional theory calculations, weinvestigated the effect of charge doping in a LaNiO$_3$/SrTiO$_3$ superlattice.The detailed analysis based on two different simulation methods for dopingclearly shows that the electronic and structural properties change in asystematic way that the orbital polarization ({\it i.e.} relative occupation oftwo Ni-$e_g$ orbitals) is reduced and the Ni to apical oxygen distance enlargedas the number of doped electrons increases. Also, the rotation angles of theNiO$_6$/TiO$_6$ octahedra strongly and systematically depend on the doping sothat the angle $\gamma$ gradually decreases whereas the $\alpha$ and $\beta$increase as a function of electron doping. Further analysis shows that theelectron (hole) doping can play a similar role with the compressive (tensile)strain for the octahedral rotations. Our results not only suggest a possibleway to control the orbital and structural property by means of charge doping,but also provide useful information to understand the experiments under variousdoping situations such as oxygen vacancy.