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

Abstract

The (001) surfaces of polar perovskites $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_3$ and $\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_3$ have been studied from first principles at $T=0\mathrm{K}$. For both cases of polarization, the most stable TiO-terminated interfaces show intrinsic ferroelectricity. In the topmost layer, where the O atoms are $>0.1\mathrm{\AA }$ above Ti, this leads to metallic instead of the insulating behavior of the electronic states that may have important implications for multiferroic tunneling junctions.