Band Topology of Bismuth Quantum Films
Band Topology of Bismuth Quantum Films
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DOI：
10.3390/cryst9100510
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发表时间：
2019-10-01
期刊：
影响因子：
2.7
通讯作者：
Bian, Guang
中科院分区：
文献类型：
--
作者：
Chang, Tay-Rong;Lu, Qiangsheng;Bian, Guang
铋是发现和发展拓扑绝缘体材料的关键元素。先前的理论研究表明，铋是拓扑平凡的，它可以通过与Sb合金化而转变为拓扑相。然而，最近的高分辨率角分辨光电发射光谱（ARPES）测量强烈表明纯铋具有拓扑能带结构，这与理论结果相矛盾。为了解决这个问题，我们用ARPES和第一性原理计算研究了Bi和Sb薄膜的能带结构。量子约束有效地扩大了Bi薄膜能带结构中的能隙，使Bi的Z2拓扑不变量能够直接可视化。我们发现拓扑平凡相和非平凡相的Bi量子膜对表面扰动的响应不同。这样，我们建立了用光谱方法检测铋带拓扑的实验准则。
Bismuth has been the key element in the discovery and development of topological insulator materials. Previous theoretical studies indicated that Bi is topologically trivial and it can transform into the topological phase by alloying with Sb. However, recent high-resolution angle-resolved photoemission spectroscopy (ARPES) measurements strongly suggested a topological band structure in pure Bi, conflicting with the theoretical results. To address this issue, we studied the band structure of Bi and Sb films by ARPES and first-principles calculations. The quantum confinement effectively enlarges the energy gap in the band structure of Bi films and enables a direct visualization of the Z2 topological invariant of Bi. We find that Bi quantum films in topologically trivial and nontrivial phases respond differently to surface perturbations. This way, we establish experimental criteria for detecting the band topology of Bi by spectroscopic methods.