Topological, Valleytronic, and Optical Properties of Monolayer PbS

Researchers performed first-principle calculations using the more accurate Heyd–Scuseria–Ernzerhof (HSE) hybrid functional to examine the band structures of lead sulfide (PbS) few layers, with a focus on the monolayer. They revealed that the band gaps of few layers exhibited even–odd layer-dependent oscillations without band inversions. They also demonstrated that the uniaxial and biaxial compressive strains can tune the monolayer to a 2D topological insulator (TI) and topological crystalline insulators (TCI).