Zhao Chenxiao, Li Leiqiang, Zhang Liying, Qin Jin, Chen Hongyuan, Xia Bing, Yang Bo, Zheng Hao, Wang Shiyong, Liu Canhua, Li Yaoyi, Guan Dandan, Cui Ping, Zhang Zhenyu, Jia Jinfeng
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.
International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Phys Rev Lett. 2022 May 20;128(20):206802. doi: 10.1103/PhysRevLett.128.206802.
High-quality stanene films have been actively pursued for realizing not only quantum spin Hall edge states without backscattering, but also intrinsic superconductivity, two central ingredients that may further endow the systems to host topological superconductivity. Yet to date, convincing evidence of topological edge states in stanene remains to be seen, let alone the coexistence of these two ingredients, owing to the bottleneck of growing high-quality stanene films. Here we fabricate one- to five-layer stanene films on the Bi(111) substrate and observe the robust edge states using scanning tunneling microscopy/spectroscopy. We also measure distinct superconducting gaps on different-layered stanene films. Our first-principles calculations further show that hydrogen passivation plays a decisive role as a surfactant in improving the quality of the stanene films, while the Bi substrate endows the films with nontrivial topology. The coexistence of nontrivial topology and intrinsic superconductivity renders the system a promising candidate to become the simplest topological superconductor based on a single-element system.
人们一直在积极探索高质量的锡烯薄膜，以实现不仅具有无背散射的量子自旋霍尔边缘态，还具有本征超导性，这两个核心要素可能会进一步使系统呈现拓扑超导性。然而，由于高质量锡烯薄膜生长的瓶颈，迄今为止，锡烯中拓扑边缘态的令人信服的证据仍未见报道，更不用说这两个要素的共存了。在这里，我们在Bi(111)衬底上制备了一到五层的锡烯薄膜，并使用扫描隧道显微镜/光谱法观察到了稳健的边缘态。我们还测量了不同层锡烯薄膜上不同的超导能隙。我们的第一性原理计算进一步表明，氢钝化作为一种表面活性剂在提高锡烯薄膜质量方面起着决定性作用，而Bi衬底赋予了薄膜非平凡拓扑结构。非平凡拓扑结构和本征超导性的共存使该系统成为基于单元素系统的最简单拓扑超导体的有前途的候选者。
