Atomic scale crystal field mapping of polar vortices in oxide superlattices
Sandhya Susarla, Pablo García‐Fernández, Colin Ophus, Sujit Das, Pablo Aguado‐Puente, Margaret R. McCarter, Peter Ercius, Lane W. Martin, R. Ramesh, Javier Junquera
Abstract
Abstract 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 $$L$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>L</mml:mi> </mml:math> -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 $$3d$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>3</mml:mn> <mml:mi>d</mml:mi> </mml:math> orbitals, together with the simulated crystal field multiplet spectra derived from first principles are in good agreement with the experiments.