Surface and substrate effects on the ferroelectric properties of PbTiO3 ultrathin films.

M. SEPLIARSKY; M. G. STACHIOTTI; R. L. MIGONI

Foz do Iguazu

Congreso; 11th International Meeting of Ferroelectricity; 2005

Universidad Federal de San Carlos (Brasil) y Un. Nac. de La Plata (Argentina)

The effects of the antiferrodistortive surface reconstruction and the interface with a SrTiO3 substrate on the ferroelectric properties of PbTiO3 ultrathin films are investigated using an interatomic potential approach with parameters computed from first-principles calculations. First we show that a shell model developed for the bulk describes properly the surface properties of PbTiO3, in particular the antiferrodistortive surface reconstruction recently observed from X-ray scattering. We investigate also the effects of the surface reconstruction on the polarization behavior of ultrathin films under open-circuit electrical boundary conditions, showing that the surface layer participates in the ferroelectricity. Finally, film-substrate interface effects on the critical thickness for ferroelectricity are investigated simulating PbTiO3 ultrathin films on SrTiO3.