Influence of dipolar defects on switching behavior in ferroelectrics

By including the contributions of dipolar defects in the time-dependent Ginzburg-landau theory, we have simulated the domain switching process in ferroelectrics. The model incorporates elastic effects in the form of an anisotropic long-range interaction that is obtained gy integrating out the strain fields, subject to the elastic compatibility constraint. The defects are simulated by considering an inhomogeneous electric field due to randomly placed coarse-grained dipoles. It is shown that these defects act as nuclei for the formulation of 90 degrees twinned structures, resulting in a lower coercive field compared to the defect-free case. Due to these defects, the simulated polarization switching occurs by two successive 90 degrees rotations, rather than a single 180 degrees flipping as in the defect-free case.