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 (M_C) 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.

Keywords:

• Polarization rotation
• dielectric property
• monoclinic structure
• epitaxial strain
• ferroelectric thin film

Funding

The financial support from the National Natural Science Foundation of China (NSFC) and the Program for New Century Excellent Talents in University (NCET) is gratefully acknowledged.