We show that the NiO6 crystal field energies can be tailored indirectly via heterovalent A cation ordering in layered (La,A)NiO4 Ruddlesden–Popper (RP) oxides, where A = Sr, Ca, or Ba, using density functional calculations. We leverage as a driving force the electrostatic interactions between charged [LaO]1 + and neutral [AO]0 planes to inductively tune the Ni–O bond distortions, without intentional doping or epitaxial strain, altering the correlated d-orbital energies. We use this strategy to design cation ordered LaCaNiO4 and LaBaNiO4 with distortions favoring enhanced Ni e g orbital polarization, and find local electronic structure signatures analogous to those in RP La-cuprates, i.e., parent phases of the high-temperature superconducting oxides.
Balachandran, P. V., Cammarata, A., Nelson-Cheeseman, B. B., Bhattacharya, A., & Rondinelli, J. M. (2014). Inductive crystal field control in layered metal oxides with correlated electrons. APL Materials, 2, 076110. https://doi.org/10.1063/1.4890544