Size-dependent ferroelectric-to-paraelectric sliding transformations and antipolar-to-ferroelectric topological phase transitions in binary homobilayers

Abstract: The recent discovery of ferroelectric behavior in few-layer materials, accompanied by the observation of antipolar domains in hexagonal boron nitride and transition metal dichalcogenide moir\'e bilayers, is paving the way for revolutionary advancements in the generation and manipulation of intrinsic electric dipoles through stacking. In addition, these cutting-edge quantum materials are reshaping our comprehension of phase transitions. Within the present study, we unveil a hitherto unreported size-dependent sliding behavior that marks a significant departure from conventional ferroelectrics. We also shed light on thermally induced spontaneous hyperlubric sliding within moir\'e bilayers, which can be used as a signal to distinguish topological phase transitions from an antipolar onto a ferroelectric bilayer. Our findings also suggest that the (topological) pinning of AA nodes in antipolar moir\'e homobilayers prevents the occurrence of an antipolar-to-paraelectric transformation.