Phase-field Method of Mesoscale Polar Topological Transformations and Phase Diagrams of Ferroelectric Thin Film Heterostructures

This presentation will discuss the thermodynamic stability and transformations of polar topological structures in ferroelectric thin films and heterostructures. The focus will be on the applications of phase-field method to predicting the mesoscale transformation pathways and mechanisms among the different ferroelectric polar structures such as conventional nanotwins, vortex lattices, skyrmions, supercrystals, etc., under mechanical, electric, and thermal stimuli as well as light. The possibility of establishing the thermodynamic stability and phase diagrams of polar topological structures at different temperature, strain, and film thickness using both classical thermodynamics and phase-field method will be illustrated. One of the main advantages of the phase-field method is the fact that it allows one to analyze the primary strain, electrostatic, and domain wall energy contributions that are responsible for the thermodynamic stability of specific polar structures and thus can be utilized to guide the design and tuning of the polar topological structures and properties.