Zhang Long, Zhang Zhe, Wu Fengcheng, Wang Danqing, Gogna Rahul, Hou Shaocong, Watanabe Kenji, Taniguchi Takashi, Kulkarni Krishnamurthy, Kuo Thomas, Forrest Stephen R, Deng Hui
Physics Department, University of Michigan, 450 Church Street, Ann Arbor, MI, 48109-2122, USA.
State Key Laboratory of Surface Physics, Department of Physics, Fudan University, 200433, Shanghai, China.
Nat Commun. 2020 Nov 18;11(1):5888. doi: 10.1038/s41467-020-19466-6.
Moiré lattices formed in twisted van der Waals bilayers provide a unique, tunable platform to realize coupled electron or exciton lattices unavailable before. While twist angle between the bilayer has been shown to be a critical parameter in engineering the moiré potential and enabling novel phenomena in electronic moiré systems, a systematic experimental study as a function of twist angle is still missing. Here we show that not only are moiré excitons robust in bilayers of even large twist angles, but also properties of the moiré excitons are dependant on, and controllable by, the moiré reciprocal lattice period via twist-angle tuning. From the twist-angle dependence, we furthermore obtain the effective mass of the interlayer excitons and the electron inter-layer tunneling strength, which are difficult to measure experimentally otherwise. These findings pave the way for understanding and engineering rich moiré-lattice induced phenomena in angle-twisted semiconductor van der Waals heterostructures.
在扭曲的范德华双层中形成的莫尔晶格提供了一个独特的、可调节的平台，以实现以前无法获得的耦合电子或激子晶格。虽然双层之间的扭曲角已被证明是设计莫尔势和在电子莫尔系统中实现新现象的关键参数，但作为扭曲角函数的系统实验研究仍然缺失。在这里，我们表明，不仅莫尔激子在甚至大扭曲角的双层中都很稳健，而且莫尔激子的性质还取决于并可通过扭曲角调谐由莫尔倒易晶格周期控制。从扭曲角依赖性出发，我们还获得了层间激子的有效质量和电子层间隧穿强度，否则这些很难通过实验测量。这些发现为理解和设计角扭曲半导体范德华异质结构中丰富的莫尔晶格诱导现象铺平了道路。
