Comparative study of polar perovskite surfaces

A novel model of the "zig-zag" (1 1 0) polar surface termination of ABO(3) perovskites is suggested and analyzed. Classical shell model calculations for BaTiO3, SrTiO3 and LaMnO3 show that such the (1 x 2) (1 1 0) surface reconstruction has the lowest energy, comparable to that for the (1 0 0) surfaces. The calculated surface energy reaches the saturation only when 6-8 atomic near-surface planes are allowed to relax. Surface relaxation leads to the formation of considerable dipole moment perpendicular to the surface. The predicted surface polarization of thin perovskite films, even in the cubic phase, could affect their dielectric properties. (C) 2004 Elsevier B.V. All rights reserved.