A 2D low-buckled hexagonal honeycomb Weyl-point spin-gapless semiconductor family with the quantum anomalous Hall effect

Abstract

Spin-gapless semiconductors (SGSs), serving as superior alternatives to half-metals, open up new avenues in spintronics. Specifically, Weyl-point SGSs (WPSGSs) with ideal Weyl points at the Fermi energy level represent an optimal amalgamation of spintronics and topological physics. Moreover, considering spin–orbital coupling (SOC), most two-dimensional (2D) WPSGSs undergo transformation into half Chern insulators (HCIs) with the emergence of the quantum anomalous Hall effect (QAHE). The 2D I–II–V half-Heusler compounds, constituting a broad family of narrow-bandgap semiconductors with low-buckled hexagonal honeycomb crystal structures akin to silicene, aptly function as SGSs and serve as nontrivial topological parent materials. Through first-principles calculations, we propose that the Li₁₂X₁₀Cr₂Y₁₂ (X = Mg, Zn, Cd; Y = P, As) monolayers, derived by substituting certain X atoms in the LiXY (X = Mg, Zn, Cd; Y = P, As) monolayers of I–II–V half-Heusler compounds with Cr atoms, emerge as potential candidates for ideal 2D WPSGSs. These monolayers exhibit stable thermodynamic properties and 100% spin polarization. With SOC taken into account, the Li₁₂X₁₀Cr₂Y₁₂ monolayers transition into HCIs with a Chern number of +1, giving rise to the QAHE. These intriguing findings lay the groundwork for a promising material platform for the development of low-power spintronic and topological microelectronic devices.