Ferroelectric higher-order topological insulator in two dimensions

TL;DR

This paper demonstrates that two-dimensional ferroelectric materials can host higher-order topological insulator states with controllable corner states, linking ferroelectricity and topology for potential electronic applications.

Contribution

It reveals the coupling of ferroelectricity and higher-order topological states in 2D materials, identifying real materials as candidates for ferroelectric higher-order topological insulators.

Findings

Identification of 2D ferroelectrics as topological insulators with corner states

Demonstration of electric control over topological states via ferroelectricity

Proposal of specific materials like In2Se3, BN bilayers, and SnS as candidates

Abstract

The interplay between ferroelectricity and band topology can give rise to a wide range of both fundamental and applied research. Here, we map out the emergence of nontrivial corner states in two-dimensional ferroelectrics, and remarkably demonstrate that ferroelectricity and corner states are coupled together by crystallographic symmetry to realize the electric control of higher-order topology. Implemented by density functional theory, we identify a series of experimentally synthesized two-dimensional ferroelectrics, such as In$_2$Se$_3$, BN bilayers, and SnS, as realistic material candidates for the proposed ferroelectric higher-order topological insulators. Our work not only sheds new light on traditional ferroelectric materials but also opens an avenue to bridge the higher-order topology and ferroelectricity that provides a nonvolatile handle to manipulate the topology in next-generation electronic devices.