论文标题
MNBI $ _4 $ TE $ _7 $的两个终止上的不同拓扑表面状态
Distinct Topological Surface States on the Two Terminations of MnBi$_4$Te$_7$
论文作者
论文摘要
最近发现的固有磁性绝缘子MNBI2TE4在托管新兴现象（例如量子异常霍尔效应和轴突绝缘子状态）方面取得了非同寻常的成功。然而，由超晶格样MnBi2Te4/（bi2te3）N（n = 0，1，2，3 ...）分层结构组成的Mn-Bi-Te家族的表面式对应关系，仍然令人兴奋，但难以捉摸。在此，通过使用扫描隧道显微镜（STM）和角度分辨光发射光谱（ARPES）技术，我们明确地将MNBI4TE7（n = 1）的两个不同的表面状态分配给Quintuple-Layer（QL）BI2TE3 TETE3终止和隔层（QL）spleple-Layer（slayer（ql）slayer（ql）slayer（sl）mnbi2te4端子。 A comparison of the experimental observations with theoretical calculations reveals the diverging topological behaviors, especially the hybridization effect between magnetic and nonmagnetic layers, on the two terminations: a gap on the QL termination originating from the topological surface states of the QL hybridizing with the bands of the beneath SL, and a gapless Dirac-cone band structure on the SL termination with time-reversal symmetry.准粒子干扰模式进一步证实了两种终止的表面状态的拓扑性质，持续远高于费米能。 QL终端带有带有六角形翘曲的自旋式狄拉克状态，而在SL终止下，从表面上的强烈倾斜的螺旋状态位于其相邻层的一对rashba-split状态之间。我们的工作阐明了拓扑表面状态的组成部分之间的前所未有的杂交效应，还揭示了磁性拓扑绝缘子中终止依赖的时间反转对称性破坏，并提供了一个理想的平台，以实现半含量的量子量响应量和相关的量子现象。
The recent discovered intrinsic magnetic topological insulator MnBi2Te4 have 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 superlattice-like MnBi2Te4/(Bi2Te3)n (n = 0, 1, 2, 3 ...) layered structure, remains intriguing but elusive. Here, by using scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) techniques, we unambiguously assign the two distinct surface states of MnBi4Te7 (n = 1) to the quintuple-layer (QL) Bi2Te3 termination and the septuple-layer (SL) MnBi2Te4 termination, respectively. A comparison of the experimental observations with theoretical calculations reveals the diverging topological behaviors, especially the hybridization effect between magnetic and nonmagnetic layers, on the two terminations: a gap on the QL termination originating from the topological surface states of the QL hybridizing with the bands of the beneath SL, and a gapless Dirac-cone band structure on the SL termination with time-reversal symmetry. The quasi-particle 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-split states 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, rendering an ideal platform to realize the half-integer quantum Hall effect and relevant quantum phenomena.
