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

The elastic interaction between 90 degrees 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 cand 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 degrees walls by misfit dislocations in epitaxial films. The critical electric field E-c, 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.