Valley-addressable polaritons in atomically thin semiconductors

Abstract

The locking of the electron spin to the valley degree of freedom in transition metal dichalcogenide (TMD) monolayers has seen these materials emerge as a promising platform in valleytronics1,2. When embedded in optical microcavities, the large oscillator strengths of excitonic transitions in TMDs allow the formation of polaritons that are part-light part-matter quasiparticles3,4,5,6,7. Here, we report that polaritons in MoSe2 show an efficient retention of the valley pseudospin contrasting them with excitons and trions in this material. We find that the degree of the valley pseudospin retention is dependent on the photon, exciton and trion fractions in the polariton states. This allows us to conclude that in the polaritonic regime, cavity-modified exciton relaxation inhibits loss of the valley pseudospin. The valley-addressable exciton-polaritons and trion-polaritons presented here offer robust valley-polarized states with the potential for valleytronic devices based on TMDs embedded in photonic structures and valley-dependent nonlinear polariton–polariton interactions.

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Figure 1: Spin–valley locking of excitons in MoSe2.
Figure 2: Valley-addressable exciton-polaritons.
Figure 3: Valley-polarized trion-polaritons.
Figure 4: Cavity-modified relaxation dynamics.

References

  1. 1

    Xiao, D., Liu, G.-B., Feng, W., Xu, X. & Yao, W. Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides. Phys. Rev. Lett. 108, 196802 (2012).

    ADS  Article  Google Scholar 

  2. 2

    Mak, K. F., He, K., Shan, J. & Heinz, T. F. Control of valley polarization in monolayer MoS2 by optical helicity. Nat. Nanotech. 7, 494–498 (2012).

    ADS  Article  Google Scholar 

  3. 3

    Liu, X. et al. Strong light–matter coupling in two-dimensional atomic crystals. Nat. Photon. 9, 30–34 (2015).

    ADS  Article  Google Scholar 

  4. 4

    Dufferwiel, S. et al. Exciton–polaritons in van der Waals heterostructures embedded in tunable microcavities. Nat. Commun. 6, 8579 (2015).

    ADS  Article  Google Scholar 

  5. 5

    Flatten, L. C. et al. Room-temperature exciton-polaritons with two-dimensional WS2 . Sci. Rep. 6, 33134 (2016).

    ADS  Article  Google Scholar 

  6. 6

    Sidler, M. et al. Fermi polaron-polaritons in charge-tunable atomically thin semiconductors. Nat. Phys. 13, 255–261 (2017).

    Article  Google Scholar 

  7. 7

    Lundt, N. et al. Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer. Nat. Commun. 7, 13328 (2016).

    ADS  Article  Google Scholar 

  8. 8

    Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010).

    ADS  Article  Google Scholar 

  9. 9

    Berkelbach, T. C., Hybertsen, M. S. & Reichman, D. R. Theory of neutral and charged excitons in monolayer transition metal dichalcogenides. Phys. Rev. B 88, 045318 (2013).

    ADS  Article  Google Scholar 

  10. 10

    Ugeda, M. M. et al. Giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor. Nat. Mater. 13, 1091–1095 (2014).

    ADS  Article  Google Scholar 

  11. 11

    Kasprzak, J. et al. Bose–Einstein condensation of exciton polaritons. Nature 443, 409–414 (2006).

    ADS  Article  Google Scholar 

  12. 12

    Amo, A. et al. Superfluidity of polaritons in semiconductor microcavities. Nat. Phys. 5, 805–810 (2009).

    Article  Google Scholar 

  13. 13

    Amo, A. et al. Exciton–polariton spin switches. Nat. Photon. 4, 361–366 (2010).

    ADS  Article  Google Scholar 

  14. 14

    Marsault, F. et al. Realization of an all optical exciton-polariton router. Appl. Phys. Lett. 107, 201115 (2015).

    ADS  Article  Google Scholar 

  15. 15

    Walker, P. M. et al. Ultra-low-power hybrid light–matter solitons. Nat. Commun. 6, 8317 (2015).

    ADS  Article  Google Scholar 

  16. 16

    Yu, H., Cui, X., Xu, X. & Yao, W. Valley excitons in two-dimensional semiconductors. Natl Sci. Rev. 2, 57–70 (2014).

    Article  Google Scholar 

  17. 17

    Maialle, M. Z., de Andrada e Silva, E. A. & Sham, L. J. Exciton spin dynamics in quantum wells. Phys. Rev. B 47, 15776 (1993).

    ADS  Article  Google Scholar 

  18. 18

    Glazov, M. M. et al. Exciton fine structure and spin decoherence in monolayers of transition metal dichalcogenides. Phys. Rev. B 89, 201302 (2014).

    ADS  Article  Google Scholar 

  19. 19

    Yu, H., Liu, G.-B., Gong, P., Xu, X. & Yao, W. Dirac cones and Dirac saddle points of bright excitons in monolayer transition metal dichalcogenides. Nat. Commun. 5, 3876 (2014).

    ADS  Article  Google Scholar 

  20. 20

    Whittaker, D. M. et al. Motional narrowing in semiconductor microcavities. Phys. Rev. Lett. 77, 4792–4795 (1996).

    ADS  Article  Google Scholar 

  21. 21

    Wang, G. et al. Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers. Appl. Phys. Lett. 106, 112101 (2015).

    ADS  Article  Google Scholar 

  22. 22

    Trichet, A. A. P. et al. Topographic control of open-access microcavities at the nanometer scale. Opt. Express 23, 17205–17216 (2015).

    ADS  Article  Google Scholar 

  23. 23

    Rapaport, R. et al. Negatively charged polaritons in a semiconductor microcavity. Phys. Rev. B 63, 235310 (2001).

    ADS  Article  Google Scholar 

  24. 24

    Kavokin, A., Malpuech, G. & Glazov, M. Optical spin Hall effect. Phys. Rev. Lett. 95, 136601 (2005).

    ADS  Article  Google Scholar 

  25. 25

    Dufferwiel, S. et al. Strong exciton-photon coupling in open semiconductor microcavities. Appl. Phys. Lett. 104, 192107 (2014).

    ADS  Article  Google Scholar 

  26. 26

    Godde, T. et al. Exciton and trion dynamics in atomically thin MoSe2 and WSe2: effect of localization. Phys. Rev. B 94, 165301 (2016).

    ADS  Article  Google Scholar 

  27. 27

    Moody, G. et al. Intrinsic homogeneous linewidth and broadening mechanisms of excitons in monolayer transition metal dichalcogenides. Nat. Commun. 6, 8315 (2015).

    ADS  Article  Google Scholar 

  28. 28

    Bleu, O., Solnyshkov, D. & Malpuech, G. Optical valley Hall effect based on transitional metal dichalcogenide cavity polaritons. Preprint at http://arXiv.org/abs/1611.02894 (2016).

  29. 29

    Sarkar, D. et al. Polarization bistability and resultant spin rings in semiconductor microcavities. Phys. Rev. Lett. 105, 216402 (2010).

    ADS  Article  Google Scholar 

  30. 30

    Kretinin, A. V. et al. Electronic properties of graphene encapsulated with different two-dimensional atomic crystals. Nano Lett. 14, 3270–3276 (2014).

    ADS  Article  Google Scholar 

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Acknowledgements

We thank the financial support of the Graphene Flagship under grant agreement 696656, the Engineering and Physical Sciences Research Council (EPSRC) grants EP/M012727/1 and EP/J007544/1, European Research Council (ERC) Advanced Grant EXCIPOL no. 320570, and Marie Sklodowska-Curie network Spin-NANO under grant agreement 676108. A.A.P.T., D.N.K. and J.M.S. acknowledge support from the Leverhulme Trust. F.W. acknowledges support from the Royal Academy of Engineering, and K.S.N. from the Royal Society, EPSRC, US Army Research Office and ERC Grant Hetero2D.

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Contributions

S.D, and T.P.L. carried out optical investigations with a contribution from S.S. A.A.P.T. designed and fabricated the concave mirrors. F.W. fabricated the MoSe2 samples. D.D.S. and G.M. carried out theoretical analysis. S.D. analysed the data and prepared the manuscript with contributions from all co-authors. J.M.S., K.S.N., M.S.S., D.N.K. and A.I.T. provided management of various aspects of the project. D.N.K. proposed the idea of using an open-access microcavity system, developed by his group, for polariton studies with TMD monolayers. S.D. and A.I.T. conceived the project. A.I.T. oversaw the project.

Corresponding authors

Correspondence to S. Dufferwiel or A. I. Tartakovskii.

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The authors declare no competing financial interests.

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Dufferwiel, S., Lyons, T., Solnyshkov, D. et al. Valley-addressable polaritons in atomically thin semiconductors. Nature Photon 11, 497–501 (2017). https://doi.org/10.1038/nphoton.2017.125

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