On-demand quantum spin Hall insulators controlled by two-dimensional ferroelectricity

TL;DR

This paper proposes a design principle for 2D heterostructures that combine ferroelectricity and topological order, enabling switchable quantum spin Hall states controlled by electric polarization.

Contribution

It introduces a general method to create 2D ferroelectric topological insulators from trivial building blocks, demonstrating control over topological phases via ferroelectric polarization.

Findings

Identified heterostructures as 2D ferroelectric topological insulators.

Showed electric polarization controls topological phase transitions.

Proposed quantum electronic devices based on these materials.

Abstract

The coexistence of ferroelectric and topological orders in two-dimensional (2D) atomic crystals allows non-volatile and switchable quantum spin Hall states. Here we offer a general design principle for 2D bilayer heterostructures that can host ferroelectricity and nontrivial band topology simultaneously using only topologically trivial building blocks. The built-in electric field arising from the out-of-plane polarization across the heterostrucuture enables a robust control of the band gap size and band inversion strength, which can be utilized to manipulate topological phase transitions. Using first-principles calculations, we demonstrate a series of bilayer heterostructures are 2D ferroelectric topological insulators (2DFETIs) characterized with a direct coupling between band topology and polarization state. We propose a few 2DFETI-based quantum electronics including domain-wall quantum circuits and topological memristor.