The spontaneous Hall effect driven by the quantum Berry phase (which serves as an internal magnetic flux in momentum space) manifests the topological nature of quasiparticles and can be used to control the information flow, such as spin and valley1,2. We report a Hall effect of excitons (fundamental composite particles of electrons and holes that dominate optical responses in semiconductors3). By polarization-resolved photoluminescence mapping, we directly observed the Hall effect of excitons in monolayer MoS2 and valley-selective spatial transport of excitons on a micrometre scale. The Hall angle of excitons is found to be much larger than that of single electrons in monolayer MoS2 (ref. 4), implying that the quantum transport of the composite particles is significantly affected by their internal structures. The present result not only poses a fundamental problem of the Hall effect in composite particles, but also offers a route to explore exciton-based valleytronics in two-dimensional materials.
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We thank N. Nagaosa, A. Fujimori, M. Yoshida and F. Qin for helpful discussions. M.O. is supported by Advanced Leading Graduate Course for Photon Science (ALPS). M.O. and Y.Z. were supported by Japan Society for the Promotion of Science (JSPS) through the Research Fellowship for Young Scientists. T.I. was supported by Grant-in-Aid for Research Activity Start-up (No. JP15H06133) and Challenging Research (Exploratory) (No. JP17K18748) from JSPS. This research was supported by Grant-in-Aid for specially promoted research (No. 25000003) from JSPS.
The authors declare no competing financial interests.
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Onga, M., Zhang, Y., Ideue, T. et al. Exciton Hall effect in monolayer MoS2. Nature Mater 16, 1193–1197 (2017). https://doi.org/10.1038/nmat4996
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