Electric field-induced polarization rotation and dielectric tunability of strained PbTiO3 epitaxial thin films

Abstract

Polarization rotation and dielectric property of epitaxial PbTiO3 thin films have been investigated using a phenomenological approach. Occurrence of monoclinic and triclinic structures is determined by electromechancial boundary conditions. With increasing temperature and strain anisotropy, monoclinic structure (MC) becomes more favorable than triclinic structure on the polarization path. In general, high permittivity can be obtained around monoclinic-orthorhombic transition. Strain anisotropy may have a significant impact on the dielectric response. Critical field for monoclinic-orthorhombic transition decreases with decreasing strain magnitude or increasing strain anisotropy. Under equal but opposite in-plane strain, rather high dielectric tunability can be obtained at medium electric field.