Electronic conductivity and structural distortion at the interface   between insulators SrTiO3 and LaAlO3
  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 interface by aberration-corrected transmission electron microscopy. The unit cells at the interface appear elongated: we discuss this distortion in terms of electrostatic charge and extra carriers at the interface. 
J.-L. Maurice, C. Carretero, M.-J. Casanove (CEMES), K. Bouzehouane,   S. Guyard, \'E. Larquet (IMPMC), J.-P. Contour