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Excitonic Mott insulator in a Bose-Fermi-Hubbard system of moiré WS 2 /WSe 2 heterobilayer.

Beini GaoDaniel G Suarez-ForeroSupratik SarkarTsung-Sheng HuangDeric SessionMahmoud Jalali MehrabadRuihao NiMing XiePranshoo UpadhyayJonathan VannucciSunil MittalKenji WatanabeTakashi TaniguchiAtaç ImamoğluYou ZhouMohammad Hafezi
Published in: Nature communications (2024)
Understanding the Hubbard model is crucial for investigating various quantum many-body states and its fermionic and bosonic versions have been largely realized separately. Recently, transition metal dichalcogenides heterobilayers have emerged as a promising platform for simulating the rich physics of the Hubbard model. In this work, we explore the interplay between fermionic and bosonic populations, using a WS 2 /WSe 2 heterobilayer device that hosts this hybrid particle density. We independently tune the fermionic and bosonic populations by electronic doping and optical injection of electron-hole pairs, respectively. This enables us to form strongly interacting excitons that are manifested in a large energy gap in the photoluminescence spectrum. The incompressibility of excitons is further corroborated by observing a suppression of exciton diffusion with increasing pump intensity, as opposed to the expected behavior of a weakly interacting gas of bosons, suggesting the formation of a bosonic Mott insulator. We explain our observations using a two-band model including phase space filling. Our system provides a controllable approach to the exploration of quantum many-body effects in the generalized Bose-Fermi-Hubbard model.
Keyphrases
  • transition metal
  • molecular dynamics
  • high resolution
  • high intensity
  • single cell
  • solar cells