title: Polarization instability in polydomain ferroelectric epitaxial thin films and the formation of heterophase structures
abstract: A thermodynamic theory is developed for dense laminar domain structures in epitaxial ferroelectric films. It is found that, at some critical misfit strain between the film and substrate, the 90 degrees c/a/c/a domain structure becomes unstable with respect to the appearance of the polarization component parallel to domain walls, which results in the formation of a heterophase structure. For PbTiO3 and BaTiO3 films, the stability ranges of polydomain and heterophase states are determined. Dielectric anomalies accompanying misfit-strain-driven structural transformations are described.
authors.affiliation: A. F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia.
authors.initials: NA
authors.lastname: Pertsev
authors.initials: VG
authors.lastname: Koukhar