Design of a ferroelectric/dielectric bilayer structure with switchable hysteresis via voltage control

Multilayer ferroelectric thin films have attracted a lot of research attention in recent years due to their ability to produce topological domain structures and their outstanding energy storage performance. In this study we propose a bilayer thin-film design consisting of a BaTiO₃ ferroelectric layer and a dielectric layer with specifically selected dielectric constant and layer thickness ratio. The hysteresis behavior of this bilayer system can switch among various characteristics by controlling the applied voltage to the system. We quantitatively investigated the effects of the material parameter and the layer thickness ratio on the hysteresis performance of the bilayer system via phase-field simulation. It is demonstrated that one is able to achieve switchable hysteresis with ferroelectric, antiferroelectric-like or relaxor-ferroelectric-like characteristics by assigning various values to the dielectric constant of the dielectric layer. In addition, the switching between antiferroelectric-like and relaxor-ferroelectric-like characteristics can be achieved by adjusting the amplitude of the applied electric field. Remarkable topological domain structures were found in the bilayer system with relaxor-ferroelectric-like hysteresis. One is able to achieve outstanding energy storage density of 123 J/cm³ and energy storage efficiency of 90 % at the amplitude of 10 MV/cm with the antiferroelectric-like hysteresis. This design method may be applied to other multilayer systems to achieve enhanced domain-structure control and energy storage performance.