Atomic-resolution study of charge transfer effects at the LaTi O 3 / LaFe O 3 interface

Charge transfer effect can give rise to exotic two-dimensional phenomena at not only polar-nonpolar interfaces but also isopolar interfaces in complex oxides. Here, we investigate the valence state changes of both Ti and Fe at the $\mathrm{LaTi}{\mathrm{O}}_{3}/\mathrm{LaFe}{\mathrm{O}}_{3}$ interface by a combination of density functional theory calculations, molecular beam epitaxy, and aberration-corrected scanning transmission electron microscopy. We demonstrate that the charge transfer from Ti to Fe occurs near the interface. The majority of the transferred charge is located within 1 unit cell from the interface. Our results present a detailed understanding of the interfacial charge transfer effect upon the design of functional oxide heterostructures.