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

TL;DR

This study uses first-principles calculations to analyze the surface polarization effects in polar perovskites BaTiO3 and PbTiO3, revealing ferroelectricity and potential metallic behavior at interfaces, relevant for multiferroic devices.

Contribution

It provides a detailed first-principles analysis of surface polarization effects in BaTiO3 and PbTiO3, highlighting the emergence of ferroelectricity and metallic states at surfaces.

Findings

Most stable TiO-terminated interfaces are ferroelectric.

Topmost layer exhibits metallic behavior due to surface polarization.

Implications for multiferroic tunneling junctions.

Abstract

The (001) surfaces of polar perovskites BaTiO$_3$ and PbTiO$_3$ 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 \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.