Interaction of low-energy electrons with surface polarity near ferroelastic domain boundaries

Abstract

The authors derive surface polarity at and near ferroelastic domain boundaries from molecular dynamics simulations based on a mechanical ball-and-spring model with ionic charges. Force gradients lead to flexoelectricity generating polarity at the surface and inside twin boundaries. Using this model, they simulate electron scattering in low energy electron microscopy based on Coulomb interactions. Point charges at the surface, physical topography and polarity all determine the intensity contrast in the electron images. The results provide a framework for understanding the contrast observed at the surface and at the polar twin boundaries of nonpolar, ferroelastic CaTiO3 illustrated in the 75 \ensuremath{\mu}m image.