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O: Fachverband Oberflächenphysik
O 45: Ultrafast Electron Dynamics at Surfaces and Interfaces IV
O 45.4: Talk
Wednesday, March 20, 2024, 11:15–11:30, MA 041
Effect of dynamical screening on the exciton-phono coupling in a layered semiconductor — •Selene Mor1,2, Valentina Gosetti1,2,3, Alejandro Molina-Sanchez4, Davide Sangalli5, Simona Achilli5, and Stefania Pagliara1,2 — 1Università Cattolica del Sacro Cuore, Brescia, Italy — 2I-Lamp Research Center, Brescia, Italy — 3KU Leuven, Leuven, Belgium — 4University of Valencia, Valencia, Spain — 5University of Milan, Milan, Italy
The light-mediated interaction of fermionic and bosonic excitations governs the optoelectronic properties of condensed matter systems. In photoexcited semiconductors, the coupling of electron-hole pairs (excitons) to coherent optical phonons enables a modulation of the excitonic resonance on the picosecond timescale [1]. At the same time, due to the Coulombic nature of excitons, their dynamics are sensitive to transient changes in the screening by the photoexcited carriers. Interestingly, the effect of interplay between exciton-phonon coupling and dynamical screening is still elusive. By means of broadband transient reflectance spectroscopy, we set the spectral evidences of either the breaking or the activation of exciton-phonon coupling in a layered semiconductor, and we reveal that dynamical screening can favor the phonon-mediated modulation of the excitonic resonance. These findings move a step forward on the path towards the optical control of fundamental interactions on the ultrafast timescale. [1]Mor, S. et al., Phys. Rev. Research 3, 043175 (2021)
Keywords: exciton; exciton-phonon coupling; ultrafast optical spectorscopy; layered material; coherent optical phonons