Heterobilayer with Ferroelectric Switching of Topological State.

Zhang, Jun-Jie; Zhu, Dongyang; Yakobson, Boris I · Nano Lett · 2021

basic_science · Level V

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Abstract

The realization of multifunctional nanomaterials is both fundamentally intriguing and practically appealing to be used in nanoscale devices. Here, a heterobilayer consisting of realistic 2D-material components of matching lattice symmetry, that is, one being the <i>β-</i>phase antimonene β-Sb known for its strong spin-orbit coupling and ferroelectric In<sub>2</sub>Se<sub>3</sub> monolayer, is designed and explored with first-principles density functional theory. The ferroelectric polarization of the In<sub>2</sub>Se<sub>3</sub> layer induces distinctly different electronic properties in the bilayer. With polarization directed "inward", the bilayer is a trivial insulator with spatially-indirect band gap (potentially beneficial for photovoltaics). Surprisingly, when polarized "outward", the bilayer displays nontrivial topological state, <b>Z</b><sub>2</sub> = 1. This suggests that the external electric field can reversibly switch between these two states, inviting potential applications in future multifunctional devices.