Modeling ferroelectric domain walls motion and nonlinear dielectric response

Abstract

The dynamics of ferroelectrics domain walls is modeled by the equation of a particle in a force field. It is considered that over the domain walls act the forces due to the interaction with an external electric field $\overrightarrow{E},$ the internal mechanical and electric interactions represented by the effective potential $W(l),$ and the friction force produced by the interaction of domain walls with phonons and point defects. The effective potential is determined assuming that the dielectric permittivity dependence on the electric field is given by the relation $\epsilon \prime \propto 1/(\alpha +\beta E^2).$ Simulations reproduce several important features of nonlinear dielectric behavior of ferroelectrics in good agreement with experimental data. Defects are included in the model introducing a generalized damping force with which it is possible to explain the high losses observed for subswitching electric fields. This theoretical approach can be useful in domain wall engineering and to develop new applications of ferroelectrics.

Keywords:

• Ferroelectric domain walls
• nonlinear dielectric response
• dielectric permittivity
• dielectric dispersion

Acknowledgments

The authors acknowledge financial support from CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico-Brazil) and FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo).