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arXiv · 1910.02869

Anomalous Interlayer Exciton Diffusion in Twist-Angle-Dependent Moir\'{e} Potentials of WS$_2$-WSe$_2$ Heterobilayers

Long Yuan·Biyuan Zheng·Jens Kunstmann·Thomas Brumme·Agnieszka Beata Kuc·Chao Ma·Shibin Deng·Daria Blach·Anlian Pan·Libai Huang
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Abstract

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 WS$_2$-WSe$_2$ 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.

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Long Yuan, Biyuan Zheng, Jens Kunstmann, Thomas Brumme, Agnieszka Beata Kuc, Chao Ma, Shibin Deng, Daria Blach, Anlian Pan, Libai Huang. 2019-10-07. Anomalous Interlayer Exciton Diffusion in Twist-Angle-Dependent Moir\'{e} Potentials of WS$_2$-WSe$_2$ Heterobilayers. https://doi.org/10.1038/s41563-020-0670-3

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