扭转双层-三层石墨烯中的可调拓扑窄带
Tunable topological narrow bands in twisted bilayer-trilayer graphene
另 1 家 · 查看机构详情
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University（教育部人工微纳结构重点实验室和武汉大学物理科学与技术学院）
- IMDEA Nanoscience（IMDEA纳米科学研究所）
- School of Artificial Intelligence, Wuhan University（武汉大学人工智能学院）
- Wuhan Institute of Quantum Technology（武汉量子技术研究院）
机构由 AI 辅助整理，请以论文原文为准。
浏览论文内容
中文总结 AI 辅助
本研究通过紧束缚和连续介质模型，系统研究了扭转双层-三层石墨烯四种堆叠构型中的平带拓扑性质，发现电场可有效调控窄带的陈数及拓扑相变，为设计可调拓扑窄带提供了理论指导。
中文摘要 AI 辅助
我们研究了具有四种堆叠构型（AB--ABC、BA--ABC、AB--ABA和BA--ABA）的扭转双层-三层石墨烯的低能带结构和拓扑性质。利用紧束缚模型和连续介质模型，我们首先证实了这两种方法在低能区的能带结构上表现出良好的一致性。随后，我们研究了平带及其谷陈数随扭转角、垂直电场和自洽哈特里势的演化。在相对较大的扭转角和电场作用下，我们发现窄带之间发生拓扑相变，平带的总陈数遵循手性极限描述导出的陈数求和规则。我们还观察到当平带与相邻的远程带杂化时出现另一种类型的拓扑相变，其中能隙的闭合和重新打开过程导致陈数和电荷密度的转移。通过构建扭转角和电场空间中的拓扑相图，我们表明垂直电场为控制陈带的稳定性和跃迁提供了有效的调节旋钮。最后，我们发现哈特里势主要引起窄带的微弱能带移动和形变。然而，结合哈特里势和电场，窄带展现出丰富的拓扑相图。我们的结果阐明了堆叠、扭转角和电场在操纵扭转双层-三层石墨烯中窄带及其拓扑性质方面的相互作用，并为在真实扭转多层石墨烯体系中工程化具有可调陈数的拓扑窄带提供了指导。
英文摘要
We investigate the low-energy band structure and topology of twisted bilayer--trilayer graphene with four stacking configurations: AB--ABC, BA--ABC, AB--ABA, and BA--ABA. Using both tight-binding and continuum models, we first establish that the two approaches show good agreement in the band structure in low-energy regime. We then study the evolution of the flat bands and their valley Chern numbers as functions of twist angle, perpendicular electric field, and the self-consistent Hartree potential. At relatively large twist angles and under electric field, we find a topological transition between the narrow bands, with the total Chern number of the flat bands following the Chern number sum rules derived from the chiral-limit description. We also observe another type of topological transition when the flat bands hybridize with adjacent remote bands, where gap closing and reopening processes lead to Chern number and charge density transfer. By constructing topological phase diagrams in the space of twist angle and electric field, we show that the perpendicular electric field provides an efficient tuning knob for controlling the stability and transitions of the Chern bands. Finally, we find that the Hartree potential mainly induce weak band shifts and reshaping in the narrow bands. However, with a combination of Hartree potential and the electric fields, the narrow bands show rich topological phase diagram. Our results clarify the interplay between the stacking, twist angle and electric field in manipulating the narrow bands and their topology in twisted bilayer--trilayer graphene, and provide guidance for engineering topological narrow bands with tunable Chern numbers in realistic twisted multilayer graphene systems.
