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HL: Fachverband Halbleiterphysik

HL 9: 2D Materials and Heterostructures: Interlayer Excitons

HL 9.3: Talk

Monday, March 18, 2024, 15:30–15:45, EW 201

Emergent Trion-Phonon Coupling in Atomically Reconstructed MoSe2-WSe2 Heterobilayers — •P. Parzefall1, S. Meier1, Y. Zhumagulov2, M. Dietl1, N. Meier1, J. Lichtenberger1, M. Kempf1, J. Holler1, P. Nagler1, K. Watanabe3, T. Taniguchi3, P. E. Faria JR.2, J. Fabian2, T. Korn4, and C. Schüller11Institut für Exp. und Angewandte Physik, Uni Regensburg (UR), Germany — 2Institut für Theo. Physik, UR, Germany — 3NIMS, Tsukuba Ibaraki, Japan — 4Institut für Physik, Uni Rostock, Germany

We report about low-frequency Raman studies on atomically-reconstructed MoSe2-WSe2 heterostructures (HS) at cryogenic temperatures. In these experiments, we tune a Ti:Sapphire laser into close resonance to the intralayer excitonic transitions of both, MoSe2 and WSe2, and compare the resulting Raman spectra to the well-known off-resonant case [1]. We detect a low-enery Raman mode, which is observable only at the intralayer trion (X) resonances. The energy of the emergent Raman mode is close to the interlayer shear mode (ISM) of the HS [1] but it exhibits different polarization selection rules and a lineshape, resembling a Fano-profile.
We interpret our results as follows: The X gains an interlayer character via its second electron, which is located in the Q valley and distributed over both layers, and which enables the coupling to the interlayer shear mode. [1] J. Holler et al., APL 117, 013104 (2020) [2] S. Meier et al., Phys. Rev. Res. 5 , L032036 (2023)

Keywords: Trion-Phonon Coupling; Heterobilayers; Atomic Reconstruction; Resonant Raman Spectroscopy; Transition metal dichalcogeniode

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