Effect of the surface polarization in polar perovskites studied from first principles

The ( 001 ) surfaces of polar perovskites BaTiO3 and PbTiO3 have been studied from first principles at T = 0 K. For both cases of polarization, the most stable TiO- terminated interfaces show intrinsic ferroelectricity. In the topmost layer, where the O atoms are > 0.1 angstrom above Ti, this leads to metallic instead of the insulating behavior of the electronic states that may have important implications for multiferroic tunneling junctions.