The nanoscale periodic potentials introduced by moir\'{e} patterns in semiconducting van der Waals (vdW) heterostructures provide a new platform for designing exciton superlattices. To realize these applications, a thorough understanding of the localization and delocalization of interlayer excitons in the moir\'{e} potentials is necessary. Here, we investigated interlayer exciton dynamics and transport modulated by the moir\'{e} potentials in WS2-WSe2 heterobilayers in time, space, and momentum domains using transient absorption microscopy combined with first-principles calculations. Experimental results verified the theoretical prediction of energetically favorable K-Q interlayer excitons and unraveled exciton-population dynamics that was controlled by the twist-angle-dependent energy difference between the K-Q and K-K excitons. Spatially- and temporally-resolved exciton-population imaging directly visualizes exciton localization by twist-angle-dependent moir\'{e} potentials of ~100 meV. Exciton transport deviates significantly from normal diffusion due to the interplay between the moir\'{e} potentials and strong many-body interactions, leading to exciton-density- and twist-angle-dependent diffusion length. These results have important implications for designing vdW heterostructures for exciton and spin transport as well as for quantum communication applications.
@article{arxiv.1910.02869,
title = {Anomalous Interlayer Exciton Diffusion in Twist-Angle-Dependent Moir\'{e} Potentials of WS$_2$-WSe$_2$ Heterobilayers},
author = {Long Yuan and Biyuan Zheng and Jens Kunstmann and Thomas Brumme and Agnieszka Beata Kuc and Chao Ma and Shibin Deng and Daria Blach and Anlian Pan and Libai Huang},
journal= {arXiv preprint arXiv:1910.02869},
year = {2020}
}