Electronic conductivity and structural distortion at the interface between insulators SrTiO3 and LaAlO3
Résumé
When insulator LaAlO3 is grown by epitaxy onto a TiO2-terminated {100} surface of insulator SrTiO3, the resulting system has a metallic character. This phenomenon has been associated with an electrostatic frustration at the interface, as {100} surfaces of SrTiO3 are neutral while those of LaAlO3 are polar, but its microscopic mechanism is not quite understood. Here, we present a structural characterisation of this in-terface by spherical aberration-corrected transmission electron microscopy. We show that the unit cells at the interface are elongated along the growth direction, and interpret this distortion in terms of Jahn-Teller effect.