Zhai Dawei, Yao Wang
Department of Physics, The University of Hong Kong, and HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, China.
Phys Rev Lett. 2020 Dec 31;125(26):266404. doi: 10.1103/PhysRevLett.125.266404.
Periodicity of long wavelength moiré patterns is very often destroyed by the inhomogeneous strain introduced in fabrications of van der Waals layered structures. We present a framework to describe massive Dirac fermions in such distorted moiré pattern of transition metal dichalcogenides homobilayers, accounting for the dynamics of layer pseudospin. In decoupled bilayers, we show two causes of in-plane layer pseudospin precession: By the coupling of layer antisymmetric strain to valley magnetic moment; and by the Aharonov-Bohm effect in the SU(2) gauge potential for the case of R-type bilayer under antisymmetric strain and H-type under symmetric strain. With interlayer coupling in the moiré, its interplay with strain manifests as a non-Abelian gauge field. We show a genuine non-Abelian Aharonov-Bohm effect in such field, where the evolution operators for different loops are noncommutative. This provides an exciting platform to explore non-Abelian gauge field effects on electron, with remarkable tunability of the field by strain and interlayer bias.
在范德华层状结构的制备过程中引入的非均匀应变，常常会破坏长波长莫尔条纹的周期性。我们提出了一个框架，用于描述过渡金属二硫族化物同质双层这种扭曲莫尔条纹中的大量狄拉克费米子，该框架考虑了层赝自旋的动力学。在解耦双层中，我们展示了面内层面赝自旋进动的两个原因：层反对称应变与谷磁矩的耦合；以及在反对称应变下R型双层和对称应变下H型双层的SU(2)规范势中的阿哈罗诺夫 - 玻姆效应。在莫尔条纹中存在层间耦合时，其与应变的相互作用表现为一个非阿贝尔规范场。我们在这样的场中展示了一种真正的非阿贝尔阿哈罗诺夫 - 玻姆效应，其中不同回路的演化算符是非对易的。这为探索非阿贝尔规范场对电子效应提供了一个令人兴奋的平台，通过应变和层间偏压可以对该场进行显著的调控。
