Mahmud Shoaib, Alam Md Kawsar
Department of Electrical and Electronic Engineering, Bangladesh University of Engineering and Technology Dhaka 1205 Bangladesh
RSC Adv. 2019 Dec 19;9(72):42194-42203. doi: 10.1039/c9ra07531c. eCollection 2019 Dec 18.
Topologically protected edge states of 2D quantum spin Hall (QSH) insulators have paved the way for dissipationless transport. In this regard, one of the key challenges is to find suitable QSH insulators with large bandgaps. Group IV analogues of graphene such as silicene, germanene, stanene, plumbene are promising materials for QSH insulators. This is because their high spin-orbit coupling (SOC) and large bandgap opening may be possible by chemically decorating these group IV graphene analogues. However, finding suitable chemical groups for such decoration has always been a demanding task. In this work, we investigate the performance of a plumbene monolayer with -CX (X = H, F, Cl) chemical decoration and report very large bandgaps in the range of 0.8414 eV to 0.9818 eV with spin-orbit coupling, which is much higher compared to most other topological insulators and realizable at room temperature. The topological invariants of the samples are calculated to confirm their topologically nontrivial properties. The existence of edge states and topological nontrivial property are illustrated by investigating PbCX nanoribbons with zigzag edges. Lastly, the structural and electronic stability of the topological materials against strain are demonstrated to extend the scope of using these materials. Our findings suggest that these derivatives are promising materials for spintronic and future high performance nanoelectronic devices.
二维量子自旋霍尔（QSH）绝缘体的拓扑保护边缘态为无耗散输运铺平了道路。在这方面，关键挑战之一是找到具有大能隙的合适QSH绝缘体。石墨烯的IV族类似物，如硅烯、锗烯、锡烯、铅烯，是QSH绝缘体的有前途的材料。这是因为通过对这些IV族石墨烯类似物进行化学修饰，可能实现其高自旋轨道耦合（SOC）和打开大能隙。然而，找到用于这种修饰的合适化学基团一直是一项艰巨的任务。在这项工作中，我们研究了具有 -CX（X = H、F、Cl）化学修饰的铅烯单层的性能，并报告了在自旋轨道耦合下0.8414 eV至0.9818 eV范围内的非常大的能隙，这比大多数其他拓扑绝缘体要高得多，并且在室温下即可实现。计算了样品的拓扑不变量以确认其拓扑非平凡性质。通过研究具有锯齿形边缘的PbCX纳米带，说明了边缘态的存在和拓扑非平凡性质。最后，证明了拓扑材料对应变的结构和电子稳定性，以扩展这些材料的使用范围。我们的研究结果表明，这些衍生物是自旋电子学和未来高性能纳米电子器件的有前途的材料。
