Ferroelectric higher-order topological insulator in two dimensions

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