Atomic scale crystal field mapping of polar vortices in oxide superlattices

Polar vortices in oxide superlattices exhibit complex polarization topologies. Using a combination of electron energy loss near-edge structure analysis, crystal field multiplet theory, and first-principles calculations, we probe the electronic structure within such polar vortices in [(PbTiO 3 ) 16 /(SrTiO 3 ) 16 ] superlattices at the atomic scale. The peaks in Ti L -edge spectra shift systematically depending on the position of the Ti 4+ cations within the vortices i.e., the direction and magnitude of the local dipole. First-principles computation of the local projected density of states on the Ti 3 d orbitals, together with the simulated crystal field multiplet spectra derived from first principles are in good agreement with the experiments. The response of the electronic structure to the non-trivial polarization texture in PbTiO 3 /SrTiO 3 superlattices has not been explored. Here, the authors reveal how the peaks of the spectra shift and change their local electronic structure depending on the position of the Ti cation.