Coexistence of Topological Edge State and Superconductivity in Bismuth Ultrathin Film
Coexistence of Topological Edge State and Superconductivity in Bismuth Ultrathin Film
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铋超薄膜中拓扑边缘态与超导性的共存
DOI：
10.1021/acs.nanolett.7b00365
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发表时间：
2017
期刊：
影响因子：
10.8
通讯作者：
Jia Jin-Feng
中科院分区：
文献类型：
--
作者：
Sun Hao-Hua;Wang Mei-Xiao;Zhu Fengfeng;Wang Guan-Yong;Ma Hai-Yang;Xu Zhu-An;Liao Qing;Lu Yunhao;Gao Chun-Lei;Li Yao-Yi;Liu Canhua;Qian Dong;Guan D;an;Jia Jin-Feng
理论预测超薄铋自支撑膜是一种二维拓扑绝缘体。实验上，铋的拓扑性质强烈依赖于铋膜的情况。薄膜厚度和与衬底的相互作用经常改变Bi薄膜的拓扑性质。利用角分辨光电子能谱、扫描隧道显微镜或能谱和第一性原理计算研究了NbSe_2超导衬底上生长的Bi（111）超导薄膜的性质。我们发现Bi（111）薄膜的能带结构是准自支撑的，并且在薄至三层的Bi（111）薄膜上存在一维边缘态。超导性也被检测到在不同的层的膜和配对电位表现出指数衰减与层的厚度。因此，拓扑边缘态可以与超导性共存，这使得该系统成为探索马约拉纳费米子的一个有前途的平台。
Ultrathin freestanding bismuth film is theoretically predicted to be one kind of two-dimensional topological insulators. Experimentally, the topological nature of bismuth strongly depends on the situations of the Bi films. Film thickness and interaction with the substrate often change the topological properties of Bi films. Using angle-resolved photoemission spectroscopy, scanning tunneling microscopy or spectroscopy and first-principle calculation, the properties of Bi(111) ultrathin film grown on the NbSe2 superconducting substrate have been studied. We find the band structures of the ultrathin film is quasi-freestanding, and one-dimensional edge state exists on Bi(111) film as thin as three bilayers. Superconductivity is also detected on different layers of the film and the pairing potential exhibits an exponential decay with the layer thicknesses. Thus, the topological edge state can coexist with superconductivity, which makes the system a promising platform for exploring Majorana Fermions.