Shumiya Nana, Hossain Md Shafayat, Yin Jia-Xin, Wang Zhiwei, Litskevich Maksim, Yoon Chiho, Li Yongkai, Yang Ying, Jiang Yu-Xiao, Cheng Guangming, Lin Yen-Chuan, Zhang Qi, Cheng Zi-Jia, Cochran Tyler A, Multer Daniel, Yang Xian P, Casas Brian, Chang Tay-Rong, Neupert Titus, Yuan Zhujun, Jia Shuang, Lin Hsin, Yao Nan, Balicas Luis, Zhang Fan, Yao Yugui, Hasan M Zahid
Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, USA.
Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China.
Nat Mater. 2022 Oct;21(10):1111-1115. doi: 10.1038/s41563-022-01304-3. Epub 2022 Jul 14.
Room-temperature realization of macroscopic quantum phases is one of the major pursuits in fundamental physics. The quantum spin Hall phase 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 BiBr. 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 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.
宏观量子相的室温实现是基础物理学的主要追求之一。量子自旋霍尔相是一种拓扑量子相，其特征是二维绝缘体态和螺旋边缘态。在这里，我们使用基于矢量磁场和可变温度的扫描隧道显微镜，为高阶拓扑绝缘体BiBr表面的室温量子自旋霍尔边缘态提供微观光谱证据。我们发现，原子分辨晶格表现出超过200 meV的大绝缘能隙，并且原子级尖锐的单层台阶边缘存在能隙中的无隙态，这表明了拓扑体-边界对应关系。外部磁场可以使边缘态产生能隙，这与潜在能带拓扑中固有的时间反演对称性保护相一致。我们进一步确定了这种边缘态的几何杂化，这不仅支持量子自旋霍尔态的Z拓扑，还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本文报道的假定拓扑相的高温输运量子化的探索。
