Molecular dynamics study of ferroelectric switching mechanisms in monodomain and 180° domain walls of BaTiO3 and PbTiO3

Understanding the intrinsic switching mechanisms is essential for controlling polarization domains and enabling their integration into next-generation nanoelectronic devices. In this study, we employ molecular dynamics (MD) simulations to investigate the electric field induced polarization switching behaviors of two representative ferroelectric materials, BaTiO3 and PbTiO3 single crystals, initialized with either monodomain configurations or 180° domain walls. By investigating both macroscopic switching dynamics and microscopic dipolar patterns, we identify distinct switching pathways governed by the initial domain structure and material-specific characteristics. Our results reveal that BaTiO3 exhibits a transition from Kolmogorov–Avrami–Ishibashi (KAI)-type switching to nucleation-limited switching (NLS) at intermediate fields when initialized with domain walls, from the NLS switching to homogeneous switching (HS) at high fields, regardless of the initial configuration. In contrast, PbTiO3 single crystals show a strong dependence on the initial domain state: Systems with pre-existing domain walls follow a KAI-to-HS transition, while monodomain systems follow an NLS-to-HS pathway. These differences are attributed to variations in activation fields associated with nucleation vs domain wall motion. Beyond macroscopic kinetics, our simulations demonstrate complex microscopic features. PbTiO3 exhibits polarization vortices and curved dipolar structures during switching, indicative of non-Ising type behavior. In comparison, BaTiO3 displays anisotropic domain growth and directionally biased anisotropic chain correlations. These results provide a comprehensive view of intrinsic switching mechanisms and offer insight into the design of ferroelectric materials with tailored switching characteristics for advanced nanoelectronic devices.