Observation of an exciton crystal in a moiré excitonic insulator
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arXiv
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| Autori principali: | , , , , , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| _version_ | 1866912852472758272 |
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| author | Qi, Ruishi Li, Qize Kim, Haleem Nie, Jiahui Zhang, Zuocheng Xia, Ruichen Cui, Zhiyuan Xiao, Jianghan Taniguchi, Takashi Watanabe, Kenji Crommie, Michael F. Wang, Feng |
| author_facet | Qi, Ruishi Li, Qize Kim, Haleem Nie, Jiahui Zhang, Zuocheng Xia, Ruichen Cui, Zhiyuan Xiao, Jianghan Taniguchi, Takashi Watanabe, Kenji Crommie, Michael F. Wang, Feng |
| contents | Strong Coulomb interactions can drive electrons to crystallize into a Wigner lattice. Achieving the bosonic analogue - a crystal of excitons - has remained elusive due to their short lifetimes and weaker interactions. Here, we report the observation of a thermodynamically stable exciton crystal in an excitonic insulator coupled to a moiré potential. Using an electron-hole bilayer composed of a monolayer MoSe2 and a WS2/WSe2 moiré superlattice, we construct a tunable extended Bose-Hubbard model with electrical control over exciton and charge doping in thermal equilibrium. Optical spectroscopy reveals spontaneous crystallization of long-lived excitons at one exciton filling per three moiré sites, evidenced by strong Umklapp scattering peaks in the optical spectrum. Exciton transport measurements further show a pronounced exciton resistance peak at the same filling, consistent with suppressed exciton hopping in a crystalline phase. When doped away from net charge neutrality, this moiré electron-hole bilayer can host new correlated insulating phases where dipolar excitonic insulators form on top of the background of a hole Mott insulator or generalized Wigner crystals in the moiré superlattice. These findings establish moiré excitonic insulators as a versatile platform for realizing correlated crystalline phases of bosons and fermions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_19603 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Observation of an exciton crystal in a moiré excitonic insulator Qi, Ruishi Li, Qize Kim, Haleem Nie, Jiahui Zhang, Zuocheng Xia, Ruichen Cui, Zhiyuan Xiao, Jianghan Taniguchi, Takashi Watanabe, Kenji Crommie, Michael F. Wang, Feng Mesoscale and Nanoscale Physics Strong Coulomb interactions can drive electrons to crystallize into a Wigner lattice. Achieving the bosonic analogue - a crystal of excitons - has remained elusive due to their short lifetimes and weaker interactions. Here, we report the observation of a thermodynamically stable exciton crystal in an excitonic insulator coupled to a moiré potential. Using an electron-hole bilayer composed of a monolayer MoSe2 and a WS2/WSe2 moiré superlattice, we construct a tunable extended Bose-Hubbard model with electrical control over exciton and charge doping in thermal equilibrium. Optical spectroscopy reveals spontaneous crystallization of long-lived excitons at one exciton filling per three moiré sites, evidenced by strong Umklapp scattering peaks in the optical spectrum. Exciton transport measurements further show a pronounced exciton resistance peak at the same filling, consistent with suppressed exciton hopping in a crystalline phase. When doped away from net charge neutrality, this moiré electron-hole bilayer can host new correlated insulating phases where dipolar excitonic insulators form on top of the background of a hole Mott insulator or generalized Wigner crystals in the moiré superlattice. These findings establish moiré excitonic insulators as a versatile platform for realizing correlated crystalline phases of bosons and fermions. |
| title | Observation of an exciton crystal in a moiré excitonic insulator |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2601.19603 |