Ab initio study of the phase diagram of epitaxial BaTiO3

O. DIÉGUEZ; S. TINTE; A. ANTONS; C. BUNGARO; J. B. NEATON; K. M. RABE; D. VANDERBILT

PHYSICAL REVIEW B

AMERICAN PHYSICAL SOCIETY

Lugar: New Yori; Año: 2004 vol. 69 p. 212101 - 212104

1098-0121

Using a combination of first-principles and effective-Hamiltonian approaches, we map out the structure of BaTiO3 under epitaxial constraints applicable to growth on perovskite substrates. We obtain a phase diagram in temperature and misfit strain that is qualitatively different from that reported by Pertsev, Zembilgotov, and Tagantsev [Phys. Rev. Lett. 80, 1988 (1998)], who based their results on an empirical thermodynamic potential with parameters fitted at temperatures in the vicinity of the bulk phase transitions. In particular, we find a region of "r phase" at low temperature where Pertsev have reported an " ac phase." We expect our results to be relevant to thin epitaxial films of BaTiO3 at low temperatures and experimentally achievable strains.