Structure and dielectric characteristics of epitaxially strained BaTiO3 thin films

Abstract

The structure and static dielectric permittivity of BaTiO3 thin films as a function of epitaxial strain are determined by using first-principle density functional theory calculation based on pseudopotentials and a plane-wave basis. It is found that BaTiO3 thin films under compressive misfit strain can be grown more easily than those under tensile misfit strain. The static dielectric permittivity of BaTiO3 thin films under different misfit strain is obtained by calculating optical phonon frequencies and Born effective charges using density functional perturbation theory. The zero-temperature dielectric permittivity of e 33 increases to the maximal value under compressive misfit strain, while the e 11/22 reaches to its maximal value under tensile misfit strain. This unsymmetrical dielectric behavior caused by strain is attributed to soft phonons in BaTiO3 films.