Structural, Topological, and Superconducting Properties of 2D Tellurium Allotropes from <i>ab initio </i>Predictions

2D Tellurium, will extended the realm of two-dimensional (2D) materials to group-VI elements beyond the discovery of graphene, phosphorene, and borophene, and it will provide new candidates for next-generation electronic and optoelectronic device applications. Through the particle-swarm optimization searches combined with ab initio calculations, we further predict 31 novel stable 2D tellurium allotropes with various geometric structures which sorted by different thickness of atomic layers (termed as M-α, B-α, T-α, T+α, and so on). Their thermodynamic stabilities have been carefully verified by the phonon modes calculations. We show that four (the B-α, B-β, B-γ, and B-η phases) exhibit topological insulators, and three (B-β, B-ε and T-κ phases) are intrinsic superconductors with Tc ~8 K. Interestingly, B-β phase possesses both topological and superconducting properties, which is the 2D monolayer material that have such intrinsic properties and may provide an appealing platform for exploring topological superconductivity in 2D systems.