Observation of an Excitonic Mott Transition through Ultrafast Core-cum-Conduction Photoemission Spectroscopy
- Dendzik, M.
- Xian, R.
- Perfetto, E.
- Sangalli, D.
- Kutnyakhov, D.
- Dong, S.
- Beaulieu, S.
- Pincelli, T.
- Pressacco, F.
- Curcio, D.
- Agustsson, S.
- Heber, M.
- Hauer, J.
- Wurth, W.
- Brenner, G.
- Acremann, Y.
- Hofmann, P.
- Wolf, M.
- Marini, A.
- Stefanucci, G.
- Rettig, L.
- Ernstorfer, R.
Publication date
August 2020
DOI Publisher
American Physical Society (APS) Language
EnglishAbstract
Time-resolved soft-X-ray photoemission spectroscopy is used to simultaneously measure the ultrafast dynamics of core-level spectral functions and excited states upon excitation of excitons in WSe$_2$. We present a many-body approximation for the Green's function, which excellently describes the transient core-hole spectral function. The relative dynamics of excited-state signal and core levels reveals a delayed core-hole renormalization due to screening by excited quasi-free carriers, revealing an excitonic Mott transition. These findings establish time-resolved core-level photoelectron spectroscopy as a sensitive probe of subtle electronic many-body interactions and an ultrafast electronic phase transition
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