Zhong Jingyuan, Yang Ming, Shi Zhijian, Li Yaqi, Mu Dan, Liu Yundan, Cheng Ningyan, Zhao Wenxuan, Hao Weichang, Wang Jianfeng, Yang Lexian, Zhuang Jincheng, Du Yi
School of Physics, Beihang University, Haidian District, Beijing, China.
Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, and School of Physics and Optoelectronics, Xiangtan University, Hunan, China.
Nat Commun. 2023 Aug 16;14(1):4964. doi: 10.1038/s41467-023-40735-7.
Weak topological insulators, constructed by stacking quantum spin Hall insulators with weak interlayer coupling, offer promising quantum electronic applications through topologically non-trivial edge channels. However, the currently available weak topological insulators are stacks of the same quantum spin Hall layer with translational symmetry in the out-of-plane direction-leading to the absence of the channel degree of freedom for edge states. Here, we study a candidate weak topological insulator, BiBrI, which is alternately stacked by three different quantum spin Hall insulators, each with tunable topologically non-trivial edge states. Our angle-resolved photoemission spectroscopy and first-principles calculations show that an energy gap opens at the crossing points of different Dirac cones correlated with different layers due to the interlayer interaction. This is essential to achieve the tunability of topological edge states as controlled by varying the chemical potential. Our work offers a perspective for the construction of tunable quantized conductance devices for future spintronic applications.
通过堆叠具有弱层间耦合的量子自旋霍尔绝缘体构建的弱拓扑绝缘体，通过拓扑非平凡边缘通道提供了有前景的量子电子应用。然而，目前可用的弱拓扑绝缘体是相同量子自旋霍尔层的堆叠，在平面外方向具有平移对称性，导致边缘态缺乏通道自由度。在这里，我们研究了一种候选的弱拓扑绝缘体BiBrI，它由三种不同的量子自旋霍尔绝缘体交替堆叠而成，每种绝缘体都具有可调的拓扑非平凡边缘态。我们的角分辨光电子能谱和第一性原理计算表明，由于层间相互作用，在与不同层相关的不同狄拉克锥的交叉点处会打开一个能隙。这对于实现通过改变化学势控制的拓扑边缘态的可调性至关重要。我们的工作为未来自旋电子应用中可调量子化电导器件的构建提供了一个视角。
