Valleytronics in 2D materials

Abstract

Semiconductor technology is currently based on the manipulation of electronic charge; however, electrons have additional degrees of freedom, such as spin and valley, that can be used to encode and process information. Over the past several decades, there has been significant progress in manipulating electron spin for semiconductor spintronic devices, motivated by potential spin-based information processing and storage applications. However, experimental progress towards manipulating the valley degree of freedom for potential valleytronic devices has been limited until very recently. We review the latest advances in valleytronics, which have largely been enabled by the isolation of 2D materials (such as graphene and semiconducting transition metal dichalcogenides) that host an easily accessible electronic valley degree of freedom, allowing for dynamic control.

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Figure 1: Valley-dependent carrier transport.
Figure 2: Valley optical coupling of monolayer excitons.
Figure 3: Interlayer valley excitons in 2D semiconductor heterostructures.
Figure 4: Defect-bound valley excitons in monolayer WSe2.
Figure 5: Valley-dependent optoelectronics.

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Acknowledgements

This work is mainly supported by the Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division (DE-SC0008145 and SC0012509). G.C. and P.R. acknowledge support from NSF-EFRI-1433496 and AFOSR FA9550-14-1-0277. H.Y. and W.Y. were supported by the Croucher Foundation (Croucher Innovation Award), and the Research Grants Council (RGC) and University Grants Committee (UGC) of Hong Kong (HKU17305914P, HKU9/CRF/13G, AoE/P-04/08). X.X. acknowledges a Cottrell Scholar Award, support from the State of Washington funded Clean Energy Institute, and support from Boeing Distinguished Professorship.

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Schaibley, J., Yu, H., Clark, G. et al. Valleytronics in 2D materials. Nat Rev Mater 1, 16055 (2016). https://doi.org/10.1038/natrevmats.2016.55

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