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Spin and pseudospins in layered transition metal dichalcogenides

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Abstract

The recent emergence of two-dimensional layered materials — in particular the transition metal dichalcogenides — provides a new laboratory for exploring the internal quantum degrees of freedom of electrons and their potential for new electronics. These degrees of freedom are the real electron spin, the layer pseudospin, and the valley pseudospin. New methods for the quantum control of the spin and these pseudospins arise from the existence of Berry phase-related physical properties and strong spin–orbit coupling. The former leads to the versatile control of the valley pseudospin, whereas the latter gives rise to an interplay between the spin and the pseudospins. Here, we provide a brief review of both theoretical and experimental advances in this field.

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Figure 1: 2D hexagonal lattice and valley physics.
Figure 2: Electrostatic charging effects of 2D excitons.
Figure 3: Demonstration of valley polarization and valley coherence.
Figure 4: Spin, valley, and layer pseudospin coupling.
Figure 5: Spectroscopic evidence of coupling between spin and layer pseudospin.

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Acknowledgements

This work was supported by DoE BES DE-SC0008145 and NSF DMR-1150719 (XX), Croucher Foundation under the Croucher Innovation Award, and the RGC (HKU705513P, HKU8/CRF/11G) and UGC (AoE/P-04/08) of Hong Kong (WY), DoE BES Materials Sciences and Engineering Division (DX), and NSF DMR-1106172 (TH).

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X.X. and W.Y. wrote the paper that was examined and improved by all authors.

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Correspondence to Xiaodong Xu or Wang Yao.

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Xu, X., Yao, W., Xiao, D. et al. Spin and pseudospins in layered transition metal dichalcogenides. Nature Phys 10, 343–350 (2014). https://doi.org/10.1038/nphys2942

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