Elemental Ferroelectric Topological Insulator in $ψ$-bismuthene

• DOI: 10.48550/arxiv.2310.01027
• Publication Date: 2023-01-01
• Authors: Yan Liang; Xuening Han; Thomas Frauenheim; Fulu Zheng; Pei Zhao
• Keywords: Topological insulator

Ferroelectric quantum spin Hall insulator (FEQSHI) exhibits coexisting ferroelectricity and time-reversal symmetry protected edge states, holding fascinating prospects for inviting both scientific application advances, especially in two dimensions. However, all of the previously demonstrated FEQSHIs consist or more constituent elements. We herein propose $\psi$-bismuthene, an uncharted allotrope bilayer Bi (110), to be first example 2D elemental FEQSHI. It is that $\psi$-bismuthene harbors measurable ferroelectric polarization nontrivial band gap with moderate switching barrier, which are highly beneficial detection observation topologically insulating states. In addition, all-angle auxetic behavior giant negative Poisson's ratio controllable persistent helix also discussed. The emergent FEQSHI represents a novel domain fundamental physics technological innovation.