Nonvolatile ferroelectric control of topological states in two-dimensional heterostructures

Quantum spin Hall (QSH) insulator materials feature topologically protected edge states that can drastically reduce dissipation and are useful for the next-generation electronics. However, the nonvolatile control of topological edge state is still a challenge. In this paper, based on first-principles calculations, the switchable topological states are found in the van der Waals (vdW) heterostructures consisting of two-dimensional (2D) Bi(111) bilayer (BL) and alpha-In2Se3 by reversing the electric polarization of the ferroelectric alpha-In2Se3. The topological switching results from the different charge transfer associated with the two opposite polarization states of alpha-In2Se3. This new topological switching mechanism has the unique advantages of being fully electrical as well as nonvolatile. Our finding provides an unprecedented approach to realize ferroelectric control of topological states in 2D materials, which will have great potential for applications in topological nanoscale electronics.