Influence of interfacial coherency on ferroelectric switching of superlattice BaTiO₃/SrTiO₃

The switching behavior of a (BaTiO₃)₈/(SrTiO₃)₄ superlattice grown on a SrTiO₃ substrate was simulated utilizing the phase field method. To investigate the effect of the mechanical constraint of the substrate on switching, three types of superlattice/substrate interface mechanical relaxation conditions were considered: (1) fully commensurate, (2) partially relaxed, and (3) fully relaxed. Our simulation results demonstrate that the hysteresis loops under the three types of constraints are very different. The interfacial coherency dramatically affects the coercive field and remanent polarization of the superlattices. The mechanism underlying the hysteresis loop variation with interfacial coherency was investigated by analyzing the ferroelectric domain configuration and its evolution during the switching process. The simulated hysteresis loop of the fully relaxed superlattice exhibits a shape that is potentially relevant to the application of ferroelectrics for energy storage materials.