Multistep polarization switching and reduced coercive field in lead titanate thin films

Switchable polarization makes ferroelectric materials widely usable in nonvolatile memories and electronic nanodevices. The coercive electric field, determining the polarization switching, is crucially important for the design and usage of ferroelectric devices. To prevent leakage and dielectric breakdown of the devices, it is necessary to reduce the coercive electric field. In this work, we propose a theoretical model to study the domain switching properties of epitaxial PbTiO3 films within the framework of Landau's phenomenological theory, especially the multistep polarization switching in ferroelectric thin films near a phase boundary. Results indicate that substrate strains can significantly affect the domain structures and the domain switching process. Under specific substrate strain conditions (tensile misfit strain of 0%-0.8%), polydomains exist and 180∘ polarization switching can be achieved via a two-step 90∘ switching process. The coercive field required for a multistep switching process can be decreased by about 50% in comparison to that for single domains. The approach of reducing the electric field presents significant opportunities for the design and enhancement of devices based on ferroelectric materials across various applications.