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=00.3em0exK. For both cases of polarization, the most stable TiO-terminated interfaces show intrinsic ferroelectricity. In the topmost layer, where the O atoms are >0.10.3em0ex above Ti, this leads to metallic instead of the insulating behavior of the electronic states that may have important implications for multiferroic tunneling junctions.