Ab initio study of ferroelectricity in edged ${\text{PbTiO}}_{3}$ nanowires under axial tension

Ab initio study of ferroelectricity in edged ${PbTiO}_{3}$ nanowires under axial tension

Takahiro Shimada, Shogo Tomoda, and Takayuki Kitamura

Phys. Rev. B 79, 024102 – Published 6 January 2009

Abstract

The atomistic and electronic structures of ${PbTiO}_{3}$ nanowires with characteristic edges consisting of (100) and (010) surfaces and the crucial role of axial tensile strain on ferroelectricity have been investigated by means of ab initio density-functional theory calculations. Ferroelectricity is enhanced at the edge of the PbO-terminated nanowire because the Pb-O covalent bond that predominates ferroelectric distortions is locally strengthened. On the other hand, a considerable suppression is found in the ${TiO}_{2}$ -terminated nanowire, caused by the charge transfer from the Pb-O site to the Ti-O site. Surprisingly, the smallest PbO-terminated nanowire with a cross section of only one-unit cell can possess ferroelectricity while ferroelectricity disappears in the ${TiO}_{2}$ -terminated nanowires with a cross section smaller than four-by-four cells (diameter of about 17 Å). However, ferroelectricity is recovered by axial tension, where smaller nanowires require larger critical strains.