Elastic interaction between 90° domain walls and misfit dislocations in epitaxial ferroelectric thin films

Abstract

The elastic interaction between 90° domain walls and misfit dislocations in epitaxial ferroelectric thin films is studied theoretically for the first time. The interaction energy is evaluated via the calculation of a work done by the dislocation stress field during the development of spontaneous strains in a polydomain film. For a single wall separating c and a domains, the energy and force of the interaction with individual misfit dislocations and periodic dislocation arrays are computed as a function of the wall position in a film. The results obtained are used to describe the pinning of 90° walls by misfit dislocations in epitaxial films. The critical electric field Ec , which is necessary for the motion of domain walls through the potential relief created by misfit dislocations, is evaluated and compared with the observed coercive fields of ferroelectric thin films.