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HL: Fachverband Halbleiterphysik
HL 74: Poster IIIA
HL 74.6: Poster
Donnerstag, 19. März 2020, 15:00–17:30, P2/2OG
Probing spin-valley polarization dynamics in MoSe2/WSe2 heterostructures — •Michael Kempf1, Florian Raab2, Markus Schwemmer2, Andreas Hanninger2, Philipp Nagler2, Christian Schüller2, and Tobias Korn1 — 1Institute of Physics, University of Rostock, Rostock, Germany — 2Institute of Physics, University of Regensburg, Germany
Transition metal dichalcogenides (TMDC) have revealed many intriguing properties in recent years. For valleytronics especially, the coupling of spin and valley degree of freedom shows great promise. Combined with valley-selective optical selection rules, a chosen spin polarization can easily be introduced into these systems.
Keeping possible future applications in mind, a long spin polarization lifetime is of great importance, yet in pristine monolayer TMDC this is strongly limited due to ultrafast exciton recombination and electron-hole exchange.
Through two-color time-resolved Kerr rotation and ellipticity measurements we are able to study the spin-valley dynamics in n-doped MoSe2 and compare it to the undoped case. Here we observe a drastic lifetime increase from the order of pico to nanoseconds, significantly exceeding the lifetimes of excitons and trions. This can be attributed to a transfer of spin polarization to resident carriers [1]. Following a similar reasoning we investigate two-dimensional MoSe2/WSe2 heterostructures, electrons and holes are spatially separated. This in turn suppresses their radiative recombination as well as exchange interaction thus leading to an increase of spin polarization lifetime.
[ 1 ] M. Schwemmer et al. Appl. Phys. Lett. 111, 082404 (2017).