The nanoscale periodic potentials introduced by moiré patterns in semiconducting van der Waals heterostructures have emerged as a platform for designing exciton superlattices. However, our understanding of the motion of excitons in moiré potentials is still limited. Here we investigated interlayer exciton dynamics and transport in WS2-WSe2 heterobilayers in time, space and momentum domains using transient absorption microscopy combined with first-principles calculations. We found that the exciton motion is modulated by twist-angle-dependent moiré potentials around 100 meV and deviates from normal diffusion due to the interplay between the moiré potentials and strong exciton-exciton interactions. Our experimental results verified the theoretical prediction of energetically favourable K-Q interlayer excitons and showed exciton-population dynamics that are controlled by the twist-angle-dependent energy difference between the K-Q and K-K excitons. These results form a basis to investigate exciton and spin transport in van der Waals heterostructures, with implications for the design of quantum communication devices.

中文翻译：

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扭曲角依赖的层间激子在WS2-WSe2异质双层中的扩散。

莫尔图案在半导体范德华异质结构中引入的纳米级周期性电势已经成为设计激子超晶格的平台。但是，我们对激子在莫尔电位中运动的理解仍然有限。在这里，我们使用瞬态吸收显微镜结合第一性原理计算研究了WS2-WSe2异质双层在时间，空间和动量域中的层间激子动力学和传输。我们发现，激子运动是由约100 meV的扭曲角相关的莫尔电势调制的，并且由于莫尔电势与强激子-激子相互作用之间的相互作用而偏离了正常扩散。我们的实验结果验证了在能量上有利的KQ层间激子的理论预测，并显示了受KQ和KK激子之间依赖于扭转角的能量差控制的激子种群动态。这些结果为研究范德华异质结构中的激子和自旋输运提供了基础，对量子通信设备的设计具有重要意义。