Lai Junwen, Liu Xiangyang, Zhan Jie, Yu Tianye, Liu Peitao, Chen Xing-Qiu, Sun Yan
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China.
Research (Wash D C). 2024 Aug 22;7:0439. doi: 10.34133/research.0439. eCollection 2024.
Topological insulating states in 2-dimensional (2D) materials are ideal systems to study different types of quantized response signals due to their in gap metallic states. Very recently, the quantum spin Hall effect was discovered in monolayer TaIrTe via the observation of quantized longitudinal conductance that rarely exists in other 2D topological insulators. The nontrivial topological charges can exist at both charge neutrality point and the van Hove singularity point with correlation-effect-induced bandgap. On the basis of this model 2D material, we studied the switch of quantized signals between longitudinal conductance and transversal Hall conductance via tuning external magnetic field. In topological phase of monolayer TaIrTe, the zero Chern number can be understood as 1 - 1 = 0 from the double band inversion from spin-up and spin-down channels. After applying a magnetic field perpendicular to the plane, the Zeeman split changes the band order for one branch of the band inversion from spin-up and spin-down channels, along with a sign charge of the Berry phase. Then, the net Chern number of 1 - 1 = 0 is tuned to 1 + 1 = 2 or -1 - 1 = -2 depending on the orientation of the magnetic field. The quantized signal not only provides another effective method for the verification of topological state in monolayer TaIrTe but also offers a strategy for the utilization of the new quantum topological states based on switchable quantized responses.
二维（2D）材料中的拓扑绝缘态由于其能隙中的金属态，是研究不同类型量子化响应信号的理想体系。最近，通过观察在其他二维拓扑绝缘体中很少存在的量子化纵向电导，在单层TaIrTe中发现了量子自旋霍尔效应。在电荷中性点和具有关联效应诱导能隙的范霍夫奇点处都可以存在非平凡拓扑电荷。基于这种模型二维材料，我们通过调节外部磁场研究了纵向电导和横向霍尔电导之间量子化信号的切换。在单层TaIrTe的拓扑相中，零陈数可以从自旋向上和自旋向下通道的双能带反转理解为1 - 1 = 0。施加垂直于平面的磁场后，塞曼分裂改变了自旋向上和自旋向下通道能带反转的一个分支的能带顺序，以及贝里相位的符号电荷。然后，根据磁场方向，净陈数从1 - 1 = 0调整为1 + 1 = 2或 -1 - 1 = -2。这种量子化信号不仅为验证单层TaIrTe中的拓扑态提供了另一种有效方法，还为基于可切换量子化响应的新型量子拓扑态的利用提供了一种策略。
