Letter | Published:

Magnetic control of valley pseudospin in monolayer WSe2

Nature Physics volume 11, pages 148152 (2015) | Download Citation


Local energy extrema of the bands in momentum space, or valleys, can endow electrons in solids with pseudospin in addition to real spin1,2,3,4,5. In transition metal dichalcogenides this valley pseudospin, like real spin, is associated with a magnetic moment1,6 that underlies the valley-dependent circular dichroism6 that allows optical generation of valley polarization7,8,9, intervalley quantum coherence10 and the valley Hall effect11. However, magnetic manipulation of valley pseudospin via this magnetic moment12,13, analogous to what is possible with real spin, has not been shown before. Here we report observation of the valley Zeeman splitting and magnetic tuning of polarization and coherence of the excitonic valley pseudospin, by performing polarization-resolved magneto-photoluminescence on monolayer WSe2. Our measurements reveal both the atomic orbital and lattice contributions to the valley orbital magnetic moment; demonstrate the deviation of the band edges in the valleys from an exact massive Dirac fermion model; and reveal a striking difference between the magnetic responses of neutral and charged valley excitons that is explained by renormalization of the excitonic spectrum due to strong exchange interactions.

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We thank X. Li for helpful discussions. This work is mainly supported by the DoE, BES, Materials Sciences and Engineering Division (DE-SC0008145). Z.G. and W.Y. were supported by the Croucher Foundation (Croucher Innovation Award) and the RGC of Hong Kong (HKU705513P, HKU9/CRF/13G). D.C. is supported by US DoE, BES, Materials Sciences and Engineering Division (DE-SC0002197). J.Y. and D.G.M. were supported by US DoE, BES, Materials Sciences and Engineering Division. R-L.C. and C.Z. are supported by ARO (W911NF-12-1-0334) and AFOSR (FA9550-13-1-0045). X.X. acknowledges a Cottrell Scholar Award. Device fabrication was performed at the University of Washington Microfabrication Facility and NSF-funded Nanotech User Facility.

Author information


  1. Department of Physics, University of Washington, Seattle, Washington 98195, USA

    • G. Aivazian
    • , Aaron M. Jones
    • , David Cobden
    •  & X. Xu
  2. Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China

    • Zhirui Gong
    •  & Wang Yao
  3. Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080, USA

    • Rui-Lin Chu
    •  & Chuanwei Zhang
  4. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

    • J. Yan
    •  & D. G. Mandrus
  5. Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA

    • J. Yan
    •  & D. G. Mandrus
  6. Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA

    • D. G. Mandrus
  7. Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA

    • X. Xu


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X.X. and W.Y. conceived the project; G.A. performed the experiment, assisted by A.M.J., under the supervision of X.X.; G.A. and X.X. analysed the data; Z.G. and W.Y. provided the theoretical explanation, with input from R-L.C. and C.Z.; J.Y. and D.G.M. synthesized and characterized the bulk WSe2 crystals; G.A., X.X., W.Y., D.C. and Z.G. wrote the paper. All authors discussed the results.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Wang Yao or X. Xu.

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