Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 83: 2D Materials: Electronic Structure and Exitations III (joint session O/HL/TT)

O 83.5: Vortrag

Donnerstag, 20. März 2025, 11:30–11:45, H11

Ultrafast phonons dynamics of monolayer transition metal dichalcogenides — •yiming pan and fabio caruso — Kiel University, Germany

Valley degrees of freedom in transition-metal dichalcogenides influence thoroughly electron-phonon coupling and its nonequilibrium dynamics. Here we present a time-resolved ab-initio study of the ultrafast dynamics of chiral phonons following carrier excitation with circularly-polarized light. By investigating the valley depolarization dynamics of monolayer MoS₂ and WS₂, we find that a population imbalance of carriers distributed at K and K^′ can lead to valley polarized phonons persisting beyond 10 ps, and characterized by a distinctive chirality [1]. Additionally, we find that strain can be exploited as a tool to control the phonon emission and the relaxation channels of hot carriers [2]. Finally, we briefly discuss available opportunities for experimental detection of these phenomena

[1] Y. Pan and F. Caruso, Nano Lett. 23, 7463 (2023)

[2] Y. Pan and F. Caruso, npj 2D Mater. Appl. 8, 42 (2024)

Keywords: ab-initio calculations; ultrafast dynamics; electron-phonon coupling; chiral phonons; transition metal dichalcogenides