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HL: Fachverband Halbleiterphysik
HL 74: Poster IIIA
HL 74.8: Poster
Donnerstag, 19. März 2020, 15:00–17:30, P2/2OG
Time-resolved Faraday Rotation on single-layer MoSe2 — •Simon Raiber1, Gabriela Hirschinger1, Matthias Dietl1, Tobias Korn2, and Christian Schüller1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg — 2Institut für Physik, Universität Rostock
For an atomically thin layer of MoSe2, a direct band gap emerges at the K points of the hexagonal Brillouin zone. The broken inversion symmetry of the crystal structure gives rise to chiral selection rules, allowing to create a valley polarization. Faraday rotation is sensitive to spin and hence can give direct access to the valley polarization.
We have performed time-resolved Faraday rotation experiments with a femtosecond time resolution on an exfoliated MoSe2 single-layer sample at low temperatures. Measuring the total carrier life time and taking into account direct radiative recombination, dephasing via intervalley exchange interaction and exciton-phonon relaxation processes, we can give a detailed view on the evolution of the valley polarization and determine the corresponding decay times. In the presence of out-of-plane magnetic fields of up to 8 Tesla, it was possible to generate a valley polarization that is independent of the helicity of the incident light. We find that the valley life times exhibit a pronounced magnetic field dependence.