SKM 2023 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 34: Ultrafast Electron Dynamics at Surface and Interfaces III
O 34.2: Vortrag
Dienstag, 28. März 2023, 10:45–11:00, TRE Phy
Electron dynamics after a spin- and valley-polarized electronic excitation in WS2 — •Lasse Münster1, Sarah Zajusch1, Raul Perea-Causin1, Samuel Brem1, Katsumi Tanimura1, Jens Güdde1, Yaroslav Gerasimenko2, Rupert Huber2, Ermin Malic1, Ulrich Höfer1, and Robert Wallauer1 — 1Fachbereich Physik, Philipps-Universität Marburg, Germany — 2Fachbereich Physik, Universität Regensburg, Germany
The excitonic landscape of monolayer transition metal dichalcogenides (TMDCs) comprises optically accessible bright excitons as well as spin- and momentum-forbidden dark excitonic states. We image the formation process of these states after optical excitation on an ultrashort timescale with time-resolved momentum microscopy.
We excite monolayer WS2 resonantly to the A 1s exciton with circular polarized light. This excitation leads to a population, which is located purely within the K valley for one helicity and in the K’ valley for the other helicity. In the case of an excitation at K, electron scatter to K’ and Σ by spin-conserving processes within a few tens of femtoseconds. Furthermore, we observe the formation of spin-forbidden excitons in the K valley and electron scattering towards Σ’. Both of these processes involve a spin-flip and are significantly slower (50 - 100 fs).