Ferroelectricity in BaTiO3 nanoscopic structures

The ground-state polarization of BaTiO3 nanosized films and cells is studied using an atomic-level simulation approach based on a shell model with parameters obtained from first-principles calculations. We demonstrate that the critical thickness for ferroelectricity in a free-standing BaTiO3 stress-free film is 3.6 nm, and a decrease in lateral size to nanometric dimensions does not spoil the ferroelectric properties of the film. Nanocells with different lateral faces, BaO or TiO2 planes, present a different domain structure and polarization due to a strong surface effect. (C) 2004 American Institute of Physics.