Transition Metal Oxides (TMO) represent an ideal platform to exploit exotic phenomena in solid state physics. In some cases, TMO interfaces host phenomena that are not present in none of the original constituent. Interfacial conductivity in the 2D Electron System (2DES) of LAO3/STO3 (LAO/STO) is one of them.
Despite the origin of this 2DES is still object of debate, there is full agreement on the fact that it is host in the STO part of the interface, in a potential well created by STO band bending. Reduced dimensionality of the host of the 2DES can provide a platform for new exotic phenomena, like quantum well states, or coupling of 2DESs in multilayered samples. In this work we analyze the electronic structure of a LAO/STO interface, where we replaced the bulk STO with a few unit cells STO grown on LAO.
The use of soft X-ray ARPES allowed us to image in a straightforward manner modifications induced by the reduced dimensionality of the STO substrate. The experimental data suggest two non-exclusive scenarios for the observed electronic structure modification: in the first one the enhanced presence of defects in the STO thin film enhances the electron-phonon coupling and the polaronic tail associated with this, in the second the reduced dimensionality of STO induced a quantization of the xz/yz t2g band.