非公度异质结构的拓扑态和量子输运

Due to the difference of lattice constants between the constituent materials, the interface of the heterostructure (e.g., the grapheme-hBN heterostructure) often forms an incommensurate lattice. The incommensurate lattice is neither translation periodic (in which the electrons obey Bloch theorem), nor completely disordered (in which electrons tend to be localized). Recently, attentions begin to be attracted to the electronic structures (e.g., magnitudes of band gaps) in these incommensurate heterostructures. In this project, we propose to perform systematic investigations on the properties and calculation methods of topological states and quantum transports in such incommensurate heterostructures. We will focus on the following aspects in the incommensurate heterostructures: (1) The characterizations of topological states in the incommensurate heterostructures; (2) The emergence of topological states in the heterostructures and the penetration of topological states between the constituents; (3) The electronic transports; (4) The relaxations and transports of the spin and pseudo-spins; and (5) The effect of lattice relaxation and strain. The results will be beneficial for the experimental realizations and technical applications of topological materials.

由于两种组分的晶格常数不一样，异质结构的界面经常形成非公度结构。非公度结构不满足周期平移对称性（电子满足布洛赫定理），但又不是完全无序（容易导致电子局域化）。最近，这类非公度对电子性质（比如石墨烯-hBN异质结构的带隙）的影响开始引起实验和理论的注意。在本项目中，我们将系统、深入地研究此类异质结构中拓扑态和量子输运的性质特点和计算方法，主要研究内容包括：（一）非公度异质结构中拓扑态的刻画；（二）拓扑态在异质结构中的的出现以及在两种材料间的穿透与消长；（三）非公度异质结构中的电子输运；（四）自旋和赝自旋的输运与迟豫；（五）迟豫和应力的影响。研究结果对新奇材料异质结构的实验实现和技术应用具有指导作用。

由于两种组分的晶格常数不一样，异质结构的界面经常形成非公度结构。非公度结构不满足周期平移对称性（电子满足布洛赫定理），但又不是完全无序（容易导致电子局域化）。在本项目中，我们研究了非公度异质结构中各种物理因素对拓扑态和量子输运的影响。取得的主要成果包括：（i）三维节线半金属中，势垒隧穿的现象和原理。（ii）单层和双层量子反常霍尔系统中，非公度势对轨道磁化、轨道磁电耦合以及电导标度性质的影响。（iii）双层量子反常霍尔系统中，尺寸非公度耦合导致的准扩展态，它们生活在体带隙边缘，具有分形结构。