SKM 2021 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 4: Poster
DS 4.1: Poster
Dienstag, 28. September 2021, 10:00–13:00, P
Two-color time-resolved Kerr rotation measurements of twisted MoS2/WS2 heterostructures — •Michael Kempf1, Alina Schubert1, Annika Bergmann1, Mustafa Hemeid1, Antony George2, Andrey Turchanin2, Rico Schwartz1, and Tobias Korn1 — 1University of Rostock, Rostock, Germany — 2University of Jena, Jena, Germany
Transition metal dichalcogenides (TMDC) have revealed many intriguing properties in recent years. For valleytronics especially, the coupling of spin and valley degrees of freedom shows great promise. Using valley-selective optical selection rules, a coupled spin-valley polarization can easily be introduced in these systems. Keeping possible future applications in mind, the dynamics of this polarization, especially its lifetime, is of great importance. Yet in pristine monolayer TMDCs this is strongly limited due to ultrafast optical exciton recombination and electron-hole exchange interaction. By contrast, in TMDC heterostructures, ultrafast interlayer charge transfer may circumvent these limits on valley polarization lifetimes.
We use two-color time-resolved Kerr rotation measurements to study the spin-valley dynamics in disulfide-based TMDCs and their heterostructures. The independent tunability of our coupled laser systems allows to selectively pump and probe their excitonic transitions resonantly. We present low-temperature valley dynamics studies on TMDC monolayers and twisted MoS2-WS2 heterostructures fabricated by combining CVD-grown and exfoliated monolayers.