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Low-dimensional confinement and reduced Coulomb screening make artificial stacks of transition metal dichalcogenides (TMDs) a prosperous material class for realizing new correlated states of matter. Fundamental to these many-body phenomena is the correlated interaction of Coulomb-bound electron-hole pairs, i.e., excitons. However, the correlated interactions, in particular with respect to momentum- and spin- forbidden optically dark excitons, are still poorly understood. Here we show that femtosecond momentum microscopy enables direct access to correlation effects of bright and dark excitons. For the model system of twisted WSe2/MoS2, we show that the ultrafast transfer of the exciton’s hole across the type-II band- aligned heterointerface leads to an energy upshift of the single-particle photoelectrons being emitted from the two-particle exciton. This is surprising at first, since energy relaxation processes typically lead to an energetic downshift of the spectroscopic signature. However, the spectral function that is measured in pho- toemission is not only sensitive to the single-particle electron that is eventually detected, but also depends on the properties of the correlated excitonic quasiparticle before the photoemission break-up process.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: electron-hole correlation
, twisted semiconductor
, time-resolved photoelectron spectroscopy


Date published: 2024-02-09

Publisher: American Association for the Advancement of Science (AAAS)

Journal:

• Science Advances (ISSN: 23752548) vol. 10 issue. 6 eadi1323

Funding:

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1126/sciadv.adi1323

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Updated at: 2026-02-16 16:30:07 +0900

Published on MDR: 2026-02-16 13:57:34 +0900