Low-temperature monoclinic phase in epitaxial (001) barium titanate on (001) cubic substrates

The possibility of the existence of a low temperature monoclinic phase in epitaxial (001) BaTiO3 films on a (001) compressive substrate is analyzed theoretically and compared to recent experimental data from literature. There is good agreement between the theoretical findings and the experimentally observed behavior. The formation of the monoclinic phase arises from the point group reduction due to the rotation of the polarization vector commensurate with the variations in the in-plane strain state.