Enhanced polarization in strained BaTiO 3 from first principles

The structure, polarization, and zone-center phonons of bulk tetragonal BaTiO 3 under compressive epitaxial stress are calculated using density functional theory within the local density approximation. The polarization, computed using the Berry-phase formalism, increases with increasing tetragonality and is found to be enhanced by nearly 70% for the largest compressive misfit strain considered (-2.28%). The results are expected to be useful for the analysis of coherent epitaxial BaTiO 3 thin films and heterostructures grown on perovskite substrates having a smaller lattice constant, such as SrTiO 3 .