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Excitons and emergent quantum phenomena in stacked 2D semiconductors

Abstract

The design and control of material interfaces is a foundational approach to realize technologically useful effects and engineer material properties. This is especially true for two-dimensional (2D) materials, where van der Waals stacking allows disparate materials to be freely stacked together to form highly customizable interfaces. This has underpinned a recent wave of discoveries based on excitons in stacked double layers of transition metal dichalcogenides (TMDs), the archetypal family of 2D semiconductors. In such double-layer structures, the elegant interplay of charge, spin and moiré superlattice structure with many-body effects gives rise to diverse excitonic phenomena and correlated physics. Here we review some of the recent discoveries that highlight the versatility of TMD double layers to explore quantum optics and many-body effects. We identify outstanding challenges in the field and present a roadmap for unlocking the full potential of excitonic physics in TMD double layers and beyond, such as incorporating newly discovered ferroelectric and magnetic materials to engineer symmetries and add a new level of control to these remarkable engineered materials.

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Fig. 1: Excitons in TMD double layers.
Fig. 2: Moiré excitons.
Fig. 3: Many-body physics of IX.
Fig. 4: Correlated states in superlattices.
Fig. 5: Control of superlattice geometry.

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Acknowledgements

N.P.W. would like to thank J. J. Finley for helpful discussions. X.X. and N.P.W. acknowledge support by the US Department of Energy, Office of Science, Basic Energy Sciences, under award number DE-SC0018171. N.P.W. also acknowledges support from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy—EXC-2111—390814868. W.Y. acknowledges support by the Croucher Foundation (Croucher Senior Research Fellowship), and the Research Grants Council of Hong Kong (AoE/P-701/20). J.S. acknowledges support by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under award number DE-SC0019481.

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X.X. and N.P.W. conceived this work. All authors contributed to the writing and preparation of the manuscript, supervised by X.X.

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Wilson, N.P., Yao, W., Shan, J. et al. Excitons and emergent quantum phenomena in stacked 2D semiconductors. Nature 599, 383–392 (2021). https://doi.org/10.1038/s41586-021-03979-1

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