Ferroelectric quantum spin Hall effect in two-dimensional In2TeS2

Ferroelectricity and band topology are hot topics in condensed matter physics, and the nonvolatile regulation of topological orders through ferroelectric properties is crucial for the design of next-generation miniature electronic devices. Here, using first-principles calculations, we demonstrate the coexistence of intrinsic ferroelectric and topological properties in two-dimensional (2D) In2TeS2. Interestingly, in single-layer In2TeS2, the spin flipping of chiral edge states occurs when the direction of ferroelectric polarization is reversed. While for In2TeS2 homobilayers, we find that the topological properties are stacking-dependent, and the ferroelectric order can be served as an effective means to achieve topological phase transition between trivial and nontrivial states. Our work not only shed light on the intrinsic 2D ferroelectric topological insulator but also put forward it as a promising candidate for high-efficiency and low-energy consumption electronic devices.