Topological insulator behavior of WS₂ monolayer with square-octagon ring structure

We report electronic behavior of an allotrope of monolayer WS₂ with a square octagon ring structure, refereed to as (so-WS₂) within state-of-the-art density functional theory (DFT) calculations. The WS₂ monolayer shows semi-metallic characteristics with Dirac-cone like features around Γ. Unlike p-orbital's Dirac-cone in graphene, the Dirac-cone in the so-WS₂ monolayer originates from the d-electrons of the W atom in the lattice. Most interestingly, the spin-orbit interaction associated with d-electrons induce a finite band-gap that results into the metal-semiconductor transition and topological insulator-like behavior in the so-WS₂ monolayer. These characteristics suggest the so-WS₂ monolayer to be a promising candidate for the next-generation electronic and spintronics devices.