First-principles Study of Unusual Behavior in PbTiO3/KTaO3 Superlattice

Abstract

Ferroelectric superlattices have attracted wide attentions and become a research focus due to excellent performance. In order to investigate the effects of polar discontinuity on properties of superlattices. The polarization behavior of PbTiO3/KTaO3 (PKT) superlattices are studied by first-principles calculation in this paper. It is found that the polarization of local layer in PKT superlattices does not keep a constant value through each superlattice and the directions of polarizations of each local layer are all the same, because the residual plane charges in TaO2/PbO and TiO2/KO interfaces provide mask effect. Furthermore, polarization of (PbTiO3)m/(KTaO3)n superlattices decreases as m/n decreasing, (PbTiO3)n/(KTaO3)n superlattices show declining polarization and become more and more conductive with the increase of n.