Distinct Topological Surface States on the Two Terminations of MnBi4Te7
Distinct Topological Surface States on the Two Terminations of MnBi4Te7
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MnBi4Te7 两个末端的不同拓扑表面态
DOI：
10.1103/physrevx.10.031013
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发表时间：
2020
影响因子：
12.5
通讯作者：
Liu
中科院分区：
文献类型：
--
作者：
Wu Xuefeng;Li Jiayu;Ma Xiao-Ming;Zhang Yu;Liu Yuntian;Zhou Chun-Sheng;Shao Jifeng;Wang Qiaoming;Ha Yu-Jie;Feng Yue;Schwier Eike F.;Kumar Shiv;Sun Hongyi;Liu Pengfei;Shimada Kenya;Miyamoto Koji;Okuda Taichi;Wang Kedong;Xie Maohai;Chen Chaoyu;Liu Qihang;Liu
最近发现的本征磁性拓扑绝缘体在承载诸如量子反常霍尔效应和轴子绝缘体态等突发现象方面取得了不同寻常的成功。然而，由超晶格（）层状结构组成的Mn-Bi-Te家族的表面-体对应关系仍然是有趣但难以捉摸的。通过扫描隧道显微镜和角度分辨光谱学技术，我们明确地将（）的两种不同表面状态分别分配给五层（QL）端和七层（SL）端。实验结果与理论计算结果的比较表明，在两个端点上存在不同的拓扑行为，特别是QL和SL之间的杂化效应。我们在QL端发现了一个间隙，这是由于QL的拓扑表面态与下面的SL带之间的杂化引起的，并且在SL端发现了一个具有时间反转对称性的无间隙的狄拉克-锥带结构。准粒子干涉模式进一步证实了两个端点表面态的拓扑性质，继续远远高于费米能量。QL端携带一个具有六边形翘曲的自旋螺旋狄拉克态，而在SL端，一个来自表面的强倾斜螺旋态位于其邻近层的一对类似rashba的分裂带之间。我们的工作阐明了拓扑表面态构建块之间前所未有的杂化效应，并揭示了磁性拓扑绝缘体中终端相关的时间反转对称性破缺。
The recently discovered intrinsic magnetic topological insulatorhas been met with unusual success in hosting emergent phenomena such as the quantum anomalous Hall effect and the axion insulator states. However, the surface-bulk correspondence of the Mn-Bi-Te family, composed by the superlatticelike() layered structure, remains intriguing but elusive. Here, by using scanning tunneling microscopy and angle-resolved photoemission spectroscopy techniques, we unambiguously assign the two distinct surface states of() to the quintuple-layer (QL)termination and the septuple-layer (SL)termination, respectively. A comparison of the experimental observations with theoretical calculations reveals diverging topological behaviors, especially the hybridization effect between the QL and SL, on the two terminations. We identify a gap on the QL termination, originating from the hybridization between the topological surface states of the QL and the bands of the SL beneath, and a gapless Dirac-cone band structure on the SL termination with time-reversal symmetry. The quasiparticle interference patterns further confirm the topological nature of the surface states for both terminations, continuing far above the Fermi energy. The QL termination carries a spin-helical Dirac state with hexagonal warping, while at the SL termination, a strongly canted helical state from the surface lies between a pair of Rashba-like splitting bands from its neighboring layer. Our work elucidates an unprecedented hybridization effect between the building blocks of the topological surface states and also reveals the termination-dependent time-reversal symmetry breaking in a magnetic topological insulator.