Oxygen octahedron reconstruction in the SrTiO3/LaAlO3 heterointerfaces investigated using aberration-corrected ultrahigh-resolution transmission electron microscopy

We investigate the LaAlO3/SrTiO3 interface by means of aberration-corrected ultrahigh-resolution transmission electron microscopy allowing us to measure the individual atomic shifts in the interface at a precision of a few picometers. We find that the oxygen octahedron rotation typical for rhombohedral LaAlO3 is across the interface and is also induced in the originally cubic SrTiO3 layer. Octahedra distortion leads to ferroelectricitylike dipole formation in the interface which is in addition modified by cation intermixing