Berlin 2024 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 2: 2D Materials and their Heterostructures I: hBN, WSe2, MoS2
DS 2.3: Vortrag
Montag, 18. März 2024, 10:00–10:15, A 060
Exciton-exciton interactions in heterobilayers of transition-metal dichalcogenides — •Edith Wietek1, Alexander Steinhoff2, Matthias Florian3, Tommy Schulz2, Takashi Taniguchi4, Kenji Watanabe4, Shen Zhao5, Alexander Högele5, Frank Jahnke2, and Alexey Chernikov1 — 1Technische Universität Dresden, Deutschland — 2Universität Bremen, Deutschland — 3University of Michigan, USA — 4NIMS, Ibaraki, Japan — 5LMU München, Deutschland
Vertically stacked heterostructures of transition metal dichalcogenides (TMDCs) offer a versatile platform to study electronic and excitonic many-body effects. In particular, interactions between interlayer excitons are key to understand both non-linear optical and transport phenomena in these systems. Here, we address this topic in a joint experiment-theory study by considering spectrally narrow interlayer excitons in the moiré free limit of atomically reconstructed, hBN-encapsulated MoSe2/WSe2 heterobilayers. While classical dipolar repulsion is broadly assumed to determine exciton-exciton scattering, we demonstrate a major role of additional many-body effects including exchange interaction and dynamic screening. Identified by theory, these contribution compensate dipolar term, accounting for the observed spectral shifts of the interlayer excitons of only a few meV even for high injection densities close to the Mott transition threshold. Our findings challenge the traditional picture of the dipolar repulsion in van der Waals heterostructures, highlighting the major role of exchange and screening for the exciton-exciton interactions.
Keywords: TMDC; interlayer exciton; excitonic many-body effects; atomically reconstructed heterostructure; joint experiment-theory study