Study of inversion symmetry breaking in a ferroelectric/insulating K0.5Na0.5NbO3/SrTiO3 2DEG

First principle calculations predict the formation of a 2D-electron gas (2DEG) at the (001) interface between SrO-terminated SrTiO3 and ferroelectric (FE) KNN, which has the peculiar property to be on/off switchable by the direction of the KNN FE-polarization. This is very promising in view of non-volatile electronic applications. Recently we were able to realize such 2DEG by a epitaxial engeneering. We propose total electron yield x-ray absorption spectroscopy and x-ray linear dichroism at the Ti L3,2 and Nb M3,2 -edges to establish the oxidation state and the crystal-field splitting of the Ferroelectric/insulator 2DEG formed at the KNN/STO interface. The results will provide crucial details concerning the electronic properties of the system, including the crystal field splitting and valence of Nb-4d and Ti-3d states, the latter possibly giving clues about the filling of Nb-related and Ti-related bands contributing to the 2DEG.