Coexistence of giant Rashba spin splitting and quantum spin Hall effect in H–Pb–F

Rashba spin splitting (RSS) and quantum spin Hall effect (QSHE) have attracted enormous interest due to their great significance in the application of spintronics. In this work, we theoretically proposed a new two-dimensional (2D) material H–Pb–F with coexistence of giant RSS and quantum spin Hall effec by using the ab initio calculations. Our results show that H–Pb–F possesses giant RSS (1.21 eV⋅Å) and the RSS can be tuned up to 4.16 eV⋅Å by in-plane biaxial strain, which is a huge value among 2D materials. Furthermore, we also noticed that H–Pb–F is a 2D topological insulator (TI) duo to the strong spin–orbit coupling (SOC) interaction, and the large topological gap is up to 1.35 eV, which is large enough for for the observation of topological edge states at room temperature. The coexistence of giant RSS and quantum spin Hall effect greatly broadens the potential application of H–Pb–F in the field of spintronic devices.