Stabilizing Phosphorene‐Like Group IV–VI Compounds via van der Waals Imprinting for Multistate Ferroelectricity and Tunable Spin Transport

Abstract

AbstractLayered group IV–VI compounds (i.e., SnSe, SnS, GeSe, and GeS) in the puckered structure resembling black‐phosphorene (BlackP) have attracted increasing interest because of their intriguing ferroic orders and outstanding thermoelectric properties. By invoking the guiding principles of isovalency and isomorphism for promoting van der Waals epitaxy, and based on comprehensive first‐principles calculations, here it is shown that the typically metastable BlackP‐like GeTe can be readily stabilized on the (001) surface of isostructural SnSe. Importantly, the ferroelectricity of such a BlackP‐like GeTe monolayer can be substantially enhanced compared to the freestanding state, due to the substrate enlarged in‐plane polar displacements. The GeTe/SnSe heterobilayer exhibits multiple ferroelectric/ferrielectric polarization states, which can be exploited for high‐density memory devices. These mutually switchable polarization states are also shown to be internally locked with the spin polarization of the valence/conduction bands with pronounced Rashba spin‐orbit splitting and Berry curvature dipole. These findings highlight the intuitive yet enabling power of van der Waals imprinting in growing novel 2D materials for enriched functionalities.