Microscopic understanding of the orbital splitting and its tuning at oxide interfaces

Abstract

By means of a Wannier projection within the framework of density functional\ntheory, we are able to identify the modified c-axis hopping and the energy\nmismatch between the cation bands as the main source of the $t_{2g}$ splitting\naround the $\\Gamma$ point for oxide heterostructures, excluding previously\nproposed mechanisms such as Jahn-Teller distortions or electric field\nasymmetries. Interfacing LaAlO$_3$, LaVO$_3$, SrVO$_3$ and SrNbO$_3$ with\nSrTiO$_3$ we show how to tune this orbital splitting, designing\nheterostructures with more $d_{xy}$ electrons at the interface. Such an\n"orbital engineering" is the key for controlling the physical properties at the\ninterface of oxide heterostructures.\n