Nonvolatile electric-field control of topological phase transition in a two-dimensional ferroelectric heterostructure

Discovery and design of materials with the coexistence and coupling of different functional properties is extremely attractive for both fundamental physics and technical applications. In this work, we proposed a strategy to realize the coexistence of ferroelectricity, magnetism and topological order in a two-dimensional van der Waals heterostructure composed of a ferroelectric material alpha-In2Se3 and a topological hydrogenated germanene. More importantly, we found the strong coupling of the topological electronic structure and ferroelectric order. Transition from a normal semiconductor to a quantum anomalous Hall insulator can be switched by reversing the polarization direction of alpha-In2Se3. The topological phase transition mechanism is revealed by the interfacial charge transfer and energy band alignment. The difference in the energy band alignment stems from the difference of interfacial potential energy for two opposite ferroelectric phases. So, ferroelectric heterostructure engineering is an effective way to realize band inversion and topological phase transition by the interface effect. Our work is not only of great scientific significance for studying the coupling mechanism of various degrees of freedom through the interface effect, but also provides an effective strategy for realizing nonvolatile topological switches and storage devices in practical applications. Topological phase transitions can be controlled by nonvolatile electric-fields through ferroelectric heterostructure engineering.