2021/10/29 by Fabian Cadiz, Stefan Gerl, Cadiz, Fabian +5
Biochemistry, Genetics and Molecular Biology · Engineering · Materials Science · Physics and Astronomy · #2D Materials and Applications #Advanced biosensing and bioanalysis techniques #Applied Physics (physics.app-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Perovskite Materials and Applications #cond-mat.mtrl-sci #physics.app-ph
paper · pdf · doi:10.48550/arxiv.2110.15791
arxiv created 2021/10/29 · openalex publication_date 2021/10/29 · arxiv updated 2021/11/01 · openalex created_date 2021/11/08 · openalex updated_date 2026/07/30
We have investigated the steady-sate valley polarization and valley coherence of encapsulated MoS2 monolayer as a function of the temperature and the power density with a continuous wave laser excitation. Both valley polarization and coherence exhibit a non-monotonic dependence on sample temperature, attaining a local maximum at T=40 K. This has been recently attributed to a motional narrowing effect: an enhancement of the valley relaxation time occurs when the scattering rate increases. At a fixed temperature of T=6 K, a two-fold increase of the steady-state valley polarization is achieved by increasing the laser excitation power, which we attribute to a local heating induced by the energy relaxation of photoexcited excitons outside the light cone and to an increase in the exciton-exciton scattering rate. In contrast, in the same power range only a moderate enhancement of valley coherence is observed. Further increasing the excitation power leads to a small reduction of valley polarization but a dramatic loss of valley coherence. Supported by spatial imaging of the excitonic luminescence and polarization, we attribute this behaviour to the detrimental role of exciton-exciton interactions on the pure dephasing rate.