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Optical control of the valley Zeeman effect through many-exciton interactions

Nature Nanotechnology volume 16, pages 148–152 (2021)Cite this article

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Abstract

Charge carriers in two-dimensional transition metal dichalcogenides (TMDs), such as WSe2, have their spin and valley-pseudospin locked into an optically addressable index that is proposed as a basis for future information processing1,2. The manipulation of this spin–valley index, which carries a magnetic moment3, requires tuning its energy. This is typically achieved through an external magnetic field (B), which is practically cumbersome. However, the valley-contrasting optical Stark effect achieves valley control without B, but requires large incident powers4,5. Thus, other efficient routes to control the spin–valley index are desirable. Here we show that many-body interactions among interlayer excitons (IXs) in a WSe2/MoSe2 heterobilayer (HBL) induce a steady-state valley Zeeman splitting that corresponds to B ≈ 6 T. This anomalous splitting, present at incident powers as low as microwatts, increases with power and is able to enhance, suppress or even flip the sign of a B-induced splitting. Moreover, the g-factor of valley Zeeman splitting can be tuned by ~30% with incident power. In addition to valleytronics, our results could prove helpful to achieve optical non-reciprocity using two-dimensional materials.

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Fig. 1: Many-exciton exchange interactions among IXs with a WSe2/MoSe2 heterostructure.
Fig. 2: Exchange field-induced splitting in WSe2/MoSe2 heterostructure.
Fig. 3: Equivalence between the exchange field and the external magnetic field.
Fig. 4: Non-linear behaviour of Zeeman splitting under a large circular excitation power.

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Data availability

The authors declare that the data supporting the findings of this study are available within the paper, Supplementary Information and Source Data. Extra data are available from the corresponding authors upon request. Source data are provided with this paper.

References

  1. Wang, G. et al. Colloquium: excitons in atomically thin transition metal dichalcogenides. Rev. Mod. Phys. 90, 021001 (2018).

    Article  CAS  Google Scholar 

  2. 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).

    Article  Google Scholar 

  3. Xiao, D., Yao, W. & Niu, Q. Valley-contrasting physics in graphene: magnetic moment and topological transport. Phys. Rev. Lett. 99, 236809 (2007).

    Article  Google Scholar 

  4. Kim, J. et al. Ultrafast generation of pseudo-magnetic field for valley excitons in WSe2 monolayers. Science 346, 1205–1208 (2014).

    Article  CAS  Google Scholar 

  5. Sie, E. J. et al. Valley-selective optical stark effect in monolayer WS2. Nat. Mater. 14, 290–294 (2015).

    Article  CAS  Google Scholar 

  6. Srivastava, A. et al. Valley Zeeman effect in elementary optical excitations of monolayer WSe2. Nat. Phys. 11, 141–147 (2015).

    Article  CAS  Google Scholar 

  7. Aivazian, G. et al. Magnetic control of valley pseudospin in monolayer WSe2. Nat. Phys. 11, 148–152 (2015).

    Article  CAS  Google Scholar 

  8. Li, Y. et al. Valley splitting and polarization by the Zeeman effect in monolayer MoSe2. Phys. Rev. Lett. 113, 266804 (2014).

    Article  Google Scholar 

  9. MacNeill, D. et al. Breaking of valley degeneracy by magnetic field in monolayer MoSe2. Phys. Rev. Lett. 114, 037401 (2015).

    Article  Google Scholar 

  10. Nagler, P. et al. Giant magnetic splitting inducing near-unity valley polarization in van der Waals heterostructures. Nat. Commun. 8, 1551 (2017).

    Article  Google Scholar 

  11. Wang, T. et al. Giant valley-Zeeman splitting from spin-singlet and spin-triplet interlayer excitons in WSe2/MoSe2 heterostructure. Nano Lett. 20, 694–700 (2020).

    Article  CAS  Google Scholar 

  12. Ciarrocchi, A. et al. Polarization switching and electrical control of interlayer excitons in two-dimensional van der Waals heterostructures. Nat. Photon. 13, 131–136 (2019).

    Article  CAS  Google Scholar 

  13. Zhang, J. et al. Enhancing and controlling valley magnetic response in MoS2/WS2 heterostructures by all-optical route. Nat. Commun. 10, 4226 (2019).

    Article  Google Scholar 

  14. Sanchez, O. L., Ovchinnikov, D., Misra, S., Allain, A. & Kis, A. Valley polarization by spin injection in a light-emitting van der Waals heterojunction. Nano Lett. 16, 5792–5797 (2016).

    Article  CAS  Google Scholar 

  15. Zhao, C. et al. Enhanced valley splitting in monolayer WSe2 due to magnetic exchange field. Nat. Nanotechnol. 12, 757 (2017).

    Article  CAS  Google Scholar 

  16. Seyler, K. L. et al. Valley manipulation by optically tuning the magnetic proximity effect in WSe2/CrI3 heterostructures. Nano Lett. 18, 3823–3828 (2018).

    Article  CAS  Google Scholar 

  17. Li, W., Lu, X., Dubey, S., Devenica, L. & Srivastava, A. Dipolar interactions between localized interlayer excitons in van der Waals heterostructures. Nat. Mater. 19, 624–629 (2020).

    Article  CAS  Google Scholar 

  18. Kremser, M. et al. Discrete interactions between a few interlayer excitons trapped at a MoSe2–WSe2 heterointerface. npj 2D Mater. Appl. 4, 8 (2020).

    Article  CAS  Google Scholar 

  19. Rivera, P. et al. Valley-polarized exciton dynamics in a 2D semiconductor heterostructure. Science 351, 688–691 (2016).

    Article  CAS  Google Scholar 

  20. Laikhtman, B. & Rapaport, R. Exciton correlations in coupled quantum wells and their luminescence blue shift. Phys. Rev. B 80, 195313 (2009).

    Article  Google Scholar 

  21. Viña, L. et al. Spin splitting in a polarized quasi-two-dimensional exciton gas. Phys. Rev. B 54, R8317 (1996).

    Article  Google Scholar 

  22. Amand, T. et al. Spin relaxation in polarized interacting exciton gas in quantum wells. Phys. Rev. B 55, 9880 (1997).

    Article  CAS  Google Scholar 

  23. Ciuti, C., Savona, V., Piermarocchi, C., Quattropani, A. & Schwendimann, P. Role of the exchange of carriers in elastic exciton–exciton scattering in quantum wells. Phys. Rev. B 58, 7926 (1998).

    Article  CAS  Google Scholar 

  24. Hong, X. et al. Ultrafast charge transfer in atomically thin MoS2/WS2 heterostructures. Nat. Nanotechnol. 9, 682 (2014).

    Article  CAS  Google Scholar 

  25. Zhu, H. et al. Interfacial charge transfer circumventing momentum mismatch at two-dimensional van der Waals heterojunctions. Nano Lett. 17, 3591–3598 (2017).

    Article  CAS  Google Scholar 

  26. Tran, K. et al. Evidence for moiré excitons in van der Waals heterostructures. Nature 567, 71–75 (2019).

    Article  CAS  Google Scholar 

  27. Jiang, C. et al. Optical spin pumping induced pseudomagnetic field in two-dimensional heterostructures. Phys. Rev. B 98, 241410 (2018).

    Article  CAS  Google Scholar 

  28. Tan, L. B. et al. Interacting polaron–polaritons. Phys. Rev. X 10, 021011 (2020).

    CAS  Google Scholar 

  29. Back, P., Zeytinoglu, S., Ijaz, A., Kroner, M. & Imamoğlu, A. Realization of an electrically tunable narrow-bandwidth atomically thin mirror using monolayer MoSe2. Phys. Rev. Lett. 120, 037401 (2018).

    Article  CAS  Google Scholar 

  30. Scuri, G. et al. Large excitonic reflectivity of monolayer MoSe2 encapsulated in hexagonal boron nitride. Phys. Rev. Lett. 120, 037402 (2018).

    Article  CAS  Google Scholar 

  31. Barachati, F. et al. Interacting polariton fluids in a monolayer of tungsten disulfide. Nat. Nanotechnol. 13, 906–909 (2018).

    Article  CAS  Google Scholar 

  32. Wang, G. et al. Magneto-optics in transition metal diselenide monolayers. 2D Mater. 2, 034002 (2015).

    Article  Google Scholar 

  33. Stier, A. V., McCreary, K. M., Jonker, B. T., Kono, J. & Crooker, S. A. Exciton diamagnetic shifts and valley Zeeman effects in monolayer WS2 and MoS2 to 65 Tesla. Nat. Commun. 7, 10643 (2016).

    Article  CAS  Google Scholar 

  34. Lyons, T. P. et al. The valley Zeeman effect in inter- and intra-valley trions in monolayer WSe2. Nat. Commun. 10, 2330 (2019).

    Article  CAS  Google Scholar 

  35. Wang, Z., Mak, K. F. & Shan, J. Strongly interaction-enhanced valley magnetic response in monolayer WSe2. Phys. Rev. Lett. 120, 066402 (2018).

    Article  CAS  Google Scholar 

  36. Smoleński, T. et al. Tuning valley polarization in a WSe2 monolayer with a tiny magnetic field. Phys. Rev. X 6, 021024 (2016).

    Google Scholar 

  37. Jiang, C. et al. Microsecond dark-exciton valley polarization memory in two-dimensional heterostructures. Nat. Commun. 9, 753 (2018).

    Article  Google Scholar 

  38. Wang, Z. et al. Evidence of high-temperature exciton condensation in two-dimensional atomic double layers. Nature 574, 76–80 (2019).

    Article  CAS  Google Scholar 

  39. Tang, Y. et al. Simulation of Hubbard model physics in WSe2/WS2 moiré superlattices. Nature 579, 353–358 (2020).

    Article  CAS  Google Scholar 

  40. Regan, E. C. et al. Mott and generalized Wigner crystal states in WSe2/WS2 moiré superlattices. Nature 579, 359–363 (2020).

    Article  CAS  Google Scholar 

  41. Shimazaki, Y. et al. Strongly correlated electrons and hybrid excitons in a moiré heterostructure. Nature 580, 472–477 (2020).

    Article  CAS  Google Scholar 

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Acknowledgements

We acknowledge many enlightening discussions with A. Imamoğlu. A.S. acknowledges support from the NSF through the EFRI program, grant no. EFMA-1741691, and from NSF DMR award no. 1905809.

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Author notes

  1. These authors contributed equally to this work: Weijie Li, Xin Lu, Jiatian Wu.

Authors and Affiliations

  1. Department of Physics, Emory University, Atlanta, GA, USA

    Weijie Li, Xin Lu, Jiatian Wu & Ajit Srivastava

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  1. Weijie Li
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  2. Xin Lu
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  4. Ajit Srivastava
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Contributions

W.L., X.L. and J.W. contributed equally to this work. A.S., W.L. and X.L. conceived the project. W.L., X.L. and J.W. carried out the measurements. J.W. prepared the samples. A.S. supervised the project. All the authors were involved in the analysis of the experimental data and contributed extensively to this work.

Corresponding author

Correspondence to Ajit Srivastava.

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The authors declare no competing interests.

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Nature Nanotechnology thanks the anonymous reviewers for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Notes 1–7 and Figs. 1–14.

Source data

Source Data Fig. 1

Numerical data used to generate graphs in Fig. 1.

Source Data Fig. 2

Numerical data used to generate graphs in Fig. 2.

Source Data Fig. 3

Numerical data used to generate graphs in Fig. 3.

Source Data Fig. 4

Numerical data used to generate graphs in Fig. 4.

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Li, W., Lu, X., Wu, J. et al. Optical control of the valley Zeeman effect through many-exciton interactions. Nat. Nanotechnol. 16, 148–152 (2021). https://doi.org/10.1038/s41565-020-00804-0

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