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SYTS: Symposium Interaction Effects and Correlations in twodimensional Systems - New Challenges for Theory

SYTS 1: Interaction effects and correlations in twodimensional systems - New challenges for theory

SYTS 1.2: Hauptvortrag

Mittwoch, 3. April 2019, 15:30–16:00, H1

Dark exciton dynamics in 2D materials — •Ermin Malic — Chalmers University of Technology, Göteborg, Sweden

Transition metal dichalcogenides (TMDs) exhibit a remarkably strong Coulomb interaction giving rise to the formation of tightly bound excitons. In addition to regular bright excitonic states, there is also a variety of dark excitons that cannot be accessed by light due to the required momentum-transfer or spin-flip.

Combining semiconductor Bloch equations and the Wannier equation, we demonstrate time- and momentum-resolved formation, thermalization, and photoemission of bright and dark intra- and interlayer excitons in TMD monolayers and heterostructures. In particular, we reveal the impact of dark exciton states on photoemission and differential absorption spectra. We present in a joint theory-experiment collaboration a direct evidence for the existence of energetically lowest momentum-dark excitons in tungsten-based TMDs. Finally, we show a possible technological application of 2D materials by predicting a novel dark-exciton-based mechanism for optical sensing of molecules and strain.