Evidence of a room-temperature quantum spin Hall edge state in a higher-order topological insulator
Evidence of a room-temperature quantum spin Hall edge state in a higher-order topological insulator
复制标题
高阶拓扑绝缘体中室温量子自旋霍尔边缘态的证据
DOI：
10.1038/s41563-022-01304-3
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发表时间：
2022-07-14
期刊：
影响因子：
41.2
通讯作者：
Hasan, M. Zahid
中科院分区：
文献类型：
--
作者：
Shumiya, Nana;Hossain, Md Shafayat;Hasan, M. Zahid
宏观量子相的室温实现是基础物理(1，2)的主要追求之一。量子自旋霍尔相(3-6)是一种具有二维绝缘体和螺旋边态的拓扑量子相。在这里，我们使用矢量磁场和基于变温的扫描隧道显微镜为高阶拓扑绝缘体Bi4Br4表面的室温量子自旋霍尔边态提供了微观光谱证据。我们发现，原子分辨的晶格显示出200 meV以上的大绝缘带隙，原子锐利的单层阶跃边存在带隙内的无隙状态，这表明拓扑体边界对应。外加磁场可以使边缘状态间隙，这与基本带状拓扑结构中固有的时间反转对称保护一致。我们进一步证明了这种边态的几何杂化，它不仅支持量子自旋霍尔态的Z(2)拓扑，而且可视化了高阶拓扑绝缘体相的构建块。我们的结果进一步鼓励了对这里所报道的假定拓扑相的高温输运量子化的探索。
Room-temperature realization of macroscopic quantum phases is one of the major pursuits in fundamental physics(1,2) . The quantum spin Hall phase(3-6) is a topological quantum phase that features a two-dimensional insulating bulk and a helical edge state. Here we use vector magnetic field and variable temperature based scanning tunnelling microscopy to provide micro-spectroscopic evidence for a room-temperature quantum spin Hall edge state on the surface of the higher-order topological insulator Bi4Br4. We find that the atomically resolved lattice exhibits a large insulating gap of over 200 meV, and an atomically sharp monolayer step edge hosts an in-gap gapless state, suggesting topological bulk-boundary correspondence. An external magnetic field can gap the edge state, consistent with the time-reversal symmetry protection inherent in the underlying band topology. We further identify the geometrical hybridization of such edge states, which not only supports the Z(2) topology of the quantum spin Hall state but also visualizes the building blocks of the higher-order topological insulator phase. Our results further encourage the exploration of high-temperature transport quantization of the putative topological phase reported here.