Liu Hongjun, Chen Jinglei, Yu Hongyi, Yang Fang, Jiao Lu, Liu Gui-Bin, Ho Wingking, Gao Chunlei, Jia Jinfeng, Yao Wang, Xie Maohai
Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong.
Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong.
Nat Commun. 2015 Sep 1;6:8180. doi: 10.1038/ncomms9180.
The extraordinary electronic structures of monolayer transition metal dichalcogenides, such as the spin-valley-coupled band edges, have sparked great interest for potential spintronic and valleytronic applications based on these two-dimensional materials. In this work, we report the experimental observation of quasi-particle interference patterns in monolayer WSe2 using low-temperature scanning tunnelling spectroscopy. We observe intervalley quantum interference involving the Q valleys in the conduction band due to spin-conserving scattering processes, while spin-flipping intervalley scattering is absent. Our results establish unequivocally the presence of spin-valley coupling and affirm the large spin splitting at the Q valleys. Importantly, the inefficient spin-flipping scattering implies long valley and spin lifetime in monolayer WSe2, which is a key figure of merit for valley-spintronic applications.
单层过渡金属二硫属化物的非凡电子结构，如自旋-谷耦合能带边缘，引发了人们对基于这些二维材料的潜在自旋电子学和谷电子学应用的极大兴趣。在这项工作中，我们报告了使用低温扫描隧道光谱对单层WSe2中准粒子干涉图案的实验观察。我们观察到由于自旋守恒散射过程，导带中的Q谷之间存在谷间量子干涉，而不存在自旋翻转谷间散射。我们的结果明确证实了自旋-谷耦合的存在，并肯定了Q谷处的大自旋分裂。重要的是，低效的自旋翻转散射意味着单层WSe2中谷和自旋的寿命较长，这是谷自旋电子学应用的一个关键品质因数。
