关于线缺陷诱导的石墨烯一维手征性电子态的理论研究

It is one of the main research directions of graphene to realize the applications in information storage and processing by manipulating multiple electronic degrees of freedom in graphene, such as the electronic spin, pseudospin(sublattices) and valley. Within the current experimental technique, one can control the crystallographic orientation and the size of an extended line defect during the growth of graphene. This kind of line defect can induce the so-called valley chiral one-dimensional electronic state, whose electronic momentum and valley degree of freedom are locked to each other. Therefore, this one-dimensional electronic state can be used in the field of valleytronics. Motivated by the one-dimensional chiral electronic state in graphene caused by the line defect, in this project we will investigate the following aspects theoretically: We will focus on the electronic structure of the composite structures formed by various types of line defect embedded in various graphene structures. Furthermore, we will also consider these composite structures in the presence of heavy adatoms along the line defect with strong spin-orbit coupling. Meanwhile, we will pay attention to the chirality of the electric states induced by the line defect, namely, the correlations of electronic momentum, spin, psudospin and valley degrees of freedom. We also study the influence of the some tunable factors including the number of layers, stacking order, lattice boundary type of graphene, and the external field on the chiral electronic state. Thus, the one-dimensional chiral electronic state induced by line defect can be revealed comprehensively. And based on our results, we can propose some practical device prototypes based on the line defect embedded graphene structures.

将石墨烯中电子的自旋、赝自旋（子晶格）和谷自由度用作信息储存和处理的载体是石墨烯研究的主要努力方向之一。目前的实验技术可将一种线缺陷结构以可控的方式嵌入石墨烯晶格中。这种线缺陷可以诱导所谓的谷手征性一维电子态，其特征是电子动量方向与其谷自由度互相锁定。利用这种电子态可实现“谷电子学”的器件功能。以线缺陷可诱导石墨烯一维手征性电子态为切入点，本课题拟开展如下理论研究：以各种类型线缺陷嵌入石墨烯结构所形成的复合结构为研究对象，研究其电子结构,进而考虑线缺陷吸附重原子以引入较强自旋-轨道耦合的情况。关注线缺陷诱导的电子态的各种手征性，即：电子的动量方向、自旋、赝自旋和谷自由度之间的相互关联。考察石墨烯的层数、堆栈序、晶格边界类型以及外场等可控因素对这类手征性电子态的影响。完成本项目的研究工作，可以较全面地揭示线缺陷诱导的一维手征性电子态，并在此基础上提出一些具体可行的石墨烯电子器件原型。

本项目旨在较全面地揭示石墨烯线缺陷可诱导的一维手征性电子态，并以此为基础提出一些具体可行的石墨烯电子器件原型。主要研究内容包括：（1）通过研究嵌有各种线缺陷的石墨烯结构的电子结构，并考虑外场的影响，揭示了石墨烯线缺陷能够诱导的手征性电子态，设计了一个能实现谷过滤功能以及谷阀门功能的器件原型；（2）通过研究线缺陷和拓扑绝缘体相共存的双层石墨烯结构的能带结构和电子态特征，揭示了线缺陷诱导的手征性电子态和拓扑相边界处的螺旋边态之间的相互影响规律；（3）通过研究石墨烯的三维类似物-拓扑半金属在磁场下的朗道谱，全面地揭示了包括Weyl半金属，Dirac半金属和nodal line半金属在内的拓扑半金属的朗道谱的独有特征以及其中存在的一维手征性电子态，并通过波包演化证实了Weyl半金属中新颖的电子回旋模式；（4）通过研究三维拓扑绝缘体量子线的朗道谱和电子态特征，解释了实验观测的偶数的量子霍尔电导平台而不是像石墨烯的奇数的量子霍尔电导平台，揭示了量子线侧表面态的重要作用。本项目的研究成果对石墨烯纳米电子器件的研发以及新型材料的应用开发提供了有价值的理论信息，对材料科学领域有一定的科学指导意义。