Hu Xingkai, Pang Zhaoxia, Chen Xinlian, Ren Miaojuan, Li Ping
School of Physics and Technology, University of Jinan Jinan Shandong China 250022
RSC Adv. 2018 Oct 12;8(61):34999-35004. doi: 10.1039/c8ra06316h. eCollection 2018 Oct 10.
Based on first-principles hybrid functional calculations, we demonstrate the formation of two-dimensional (2D) topological insulators (TIs) of Pb/Sb honeycombs on Ge(111) semiconductor surface. We show that 1/3 Cl-covered Ge(111) surface offers an ideal template for metal deposition. When Pb and Sb atoms are deposited on Cl-Ge(111) surface, they spontaneously form a hexagonal lattice (Pb/Sb@Cl-Ge(111)). The Pb/Sb@Cl-Ge(111) exhibits a 2D TI state with large bulk gap of 0.27 eV for Pb@Cl-Ge(111) and 0.81 eV for Sb@Cl-Ge(111). The mechanism of 2D TI state is the substrate orbital-filtering effect that effectively removes the p bands of Pb(Sb) away from the Fermi level, leaving behind only the p and p orbitals at the Fermi level. Our findings pave another way for future design of 2D topological insulators on conventional semiconductor surface, which promotes the application of 2D TIs in spintronics and quantum computing devices at room-temperature.
基于第一性原理混合泛函计算，我们证明了在Ge(111)半导体表面形成了Pb/Sb蜂窝状二维拓扑绝缘体(TIs)。我们表明，1/3 Cl覆盖的Ge(111)表面为金属沉积提供了理想模板。当Pb和Sb原子沉积在Cl-Ge(111)表面时，它们自发形成六边形晶格(Pb/Sb@Cl-Ge(111))。对于Pb@Cl-Ge(111)，Pb/Sb@Cl-Ge(111)表现出二维TI态，其体能隙为0.27 eV；对于Sb@Cl-Ge(111)，体能隙为0.81 eV。二维TI态的机制是衬底轨道过滤效应，该效应有效地将Pb(Sb)的p带从费米能级移开，仅在费米能级留下p和p轨道。我们的发现为未来在传统半导体表面设计二维拓扑绝缘体开辟了另一条途径，这促进了二维TIs在室温下的自旋电子学和量子计算设备中的应用。
