Visualizing topological edge states of single and double bilayer Bi supported on multibilayer Bi(111) fi lms
Visualizing topological edge states of single and double bilayer Bi supported on multibilayer Bi(111) fi lms
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可视化多层 Bi(111) 薄膜上支持的单双层 Bi 和双双层 Bi 的拓扑边缘态
DOI：
10.1103/physrevb.98.245108
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发表时间：
2018
影响因子：
3.7
通讯作者：
Fu Ying-Shuang
中科院分区：
文献类型：
--
作者：
Peng Lang;Xian Jing-Jing;Tang Peizhe;Rubio Angel;Zhang Shou-Cheng;Zhang Wenhao;Fu Ying-Shuang
独立式单双层 Bi(111) 是一种二维拓扑绝缘体，其边缘态沿其周边传播。鉴于实验上的层间耦合，Bi(111)薄膜的拓扑性质以及支撑衬底对最顶层Bi双层的影响仍然存在争议。在这里，结合扫描隧道显微镜和第一性原理计算，我们系统地研究了在基底上生长的Bi(111)薄膜的电子特性。两种非磁性边缘结构，即传统的锯齿形边缘和2×1重构边缘交替共存于单个双层岛的边界处，其拓扑边缘状态表现出明显不同的能量和空间分布。无论 Bi(111) 薄膜的底层厚度如何，在单双层 Bi 岛和双双层 Bi 岛的边缘都持续可见突出的边缘态。我们对所观察到的边缘态的拓扑起源提供了解释，并通过第一性原理计算进行了验证。我们的论文澄清了有关 Bi(111) 薄膜拓扑的长期争议，并揭示了通过边缘修改拓扑边缘态的可调性。
Freestanding single bilayer Bi(111) is a two-dimensional topological insulator with edge states propagating along its perimeter. Given the interlayer coupling experimentally, the topological nature of Bi(111) thin films and the impact of the supporting substrate on the topmost Bi bilayer are still under debate. Here, combined with scanning tunneling microscopy and first-principles calculations, we systematically study the electronic properties of Bi(111) thin films grown on asubstrate. Two types of nonmagnetic edge structures, i.e., a conventional zigzag edge and a 2 × 1 reconstructed edge, coexist alternately at the boundaries of single bilayer islands, the topological edge states of which exhibit remarkably different energy and spatial distributions. Prominent edge states are persistently visualized at the edges of both single and double bilayer Bi islands, regardless of the underlying thickness of Bi(111) thin films. We provide an explanation for the topological origin of the observed edge states that is verified with first-principles calculations. Our paper clarifies the long-standing controversy regarding the topology of Bi(111) thin films and reveals the tunability of topological edge states via edge modifications.