Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe2/MoSe2 bilayers

J. Sung, You Zhou, Giovanni Scuri, Viktor Zolyomi, Trond I. Anderson, Hyobin Yoo, Dominik S. Wild, Andrew Y. Joe, Ryan J. Gelly, Hoseok Heo, Samuel Magorrian, Damien Bérubé, Andres M. Mier Valdivia, Takashi Taniguchi, Kenji Watanabe, Mikhail D. Lukin, Philip Kim, Vladimir Fal'ko, Hongkun Park

Research output: Contribution to journalArticlepeer-review


Van der Waals heterostructures obtained via stacking and twisting have been used to create moiré superlattices1, enabling new optical and electronic properties in solid-state systems. Moiré lattices in twisted bilayers of transition metal dichalcogenides (TMDs) result in exciton trapping2-5, host Mott insulating and superconducting states6, and act as unique Hubbard systems7-9 whose correlated electronic states can be detected and manipulated optically. Structurally, these twisted heterostructures feature atomic reconstruction and domain formation10-14. However, due to the nanoscale sizes of moiré domains, the effects of atomic reconstruction on the electronic and excitonic properties could not be systematically investigated. Here, we use near 0o twist angle MoSe2/MoSe2 bilayers with large rhombohedral AB/BA domains15 to directly probe excitonic properties of individual domains with far-field optics. We show that this system features broken mirror/inversion symmetry, with the AB and BA domains supporting interlayer excitons with out-of-plane electric dipole moments in opposite directions. The dipole orientation of ground-state -K interlayer excitons can be flipped with electric fields, while higher-energy K-K interlayer excitons undergo field-asymmetric hybridization with intralayer K-K excitons. Our study reveals the impact of crystal symmetry on TMD excitons and points to new avenues for realizing topologically nontrivial systems16,17, exotic metasurfaces18, collective excitonic phases19, and quantum emitter arrays20,21 via domain-pattern engineering.
Original languageEnglish
JournalNature Nanotechnology
Publication statusAccepted/In press - 3 Jun 2020

Research Beacons, Institutes and Platforms

  • National Graphene Institute


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