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 $\alpha \text{−}{\mathrm{In}}_2{\mathrm{Se}}_3$ by reversing the electric polarization of the ferroelectric $\alpha \text{−}{\mathrm{In}}_2{\mathrm{Se}}_3$. The topological switching results from the different charge transfer associated with the two opposite polarization states of $\alpha \text{−}{\mathrm{In}}_2{\mathrm{Se}}_3$. 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.

中文翻译：

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二维异质结构中拓扑状态的非易失性铁电控制

量子自旋霍尔（QSH）绝缘体材料具有受拓扑保护的边缘状态，可以极大地减少耗散，对下一代电子产品很有用。然而，拓扑边缘状态的非易失性控制仍然是一个挑战。在本文中，基于第一性原理计算，在由二维（2D）Bi（111）双层（BL）和B组成的范德华（vdW）异质结构中发现了可切换的拓扑状态。$\alpha \text{-}{在}_2{硒}_3$ 通过反转铁电体的极化 $\alpha \text{-}{在}_2{硒}_3$。拓扑切换是由与电荷的两个相反极化状态相关的不同电荷转移产生的$\alpha \text{-}{在}_2{硒}_3$。这种新的拓扑切换机制具有完全电气和非易失性的独特优势。我们的发现提供了一种前所未有的方法来实现2D材料中拓扑状态的铁电控制，这将在拓扑纳米级电子学中具有巨大的应用潜力。