Intervalley scattering in monolayer MoS2 probed by non-equilibrium optical techniques

Stefano Dal Conte; Federico Bottegoni; E. A. A. Pogna; D. De Fazio; S. Ambrogio; I. Bargigia; C. D'Andrea; A. Lombardo; M. Bruna; F. Ciccacci; A. C. Ferrari; G. Cerullo; M. Finazzi

doi:10.1117/12.2186692

8 September 2015 Intervalley scattering in monolayer MoS₂ probed by non-equilibrium optical techniques

Stefano Dal Conte, Federico Bottegoni, E. A. A. Pogna, D. De Fazio, S. Ambrogio, I. Bargigia, C. D'Andrea, A. Lombardo, M. Bruna, F. Ciccacci, A. C. Ferrari, G. Cerullo, M. Finazzi

Author Affiliations +

Proceedings Volume 9551, Spintronics VIII; 95510W (2015) https://doi.org/10.1117/12.2186692
Event: SPIE Nanoscience + Engineering, 2015, San Diego, California, United States

Abstract

Here we study the exciton valley relaxation dynamics in atomically thin MoS₂ by non-equilibrium optical techniques. A spin polarized excitons population is selectively created in a single valley by circularly polarized ultrashort laser pulses resonant with the optical gap, while the subsequent decay of the valley polarization is measured as a rotation of a linearly polarized probe beam due to a transient Faraday effect. We show that the photoinduced valley polarization in monolayer MoS₂ is quenched after few ps due to an efficient intervalley scattering channel and it displays a peculiar bi-exponential behavior. This rapid time scale is in a good agreement with an intervalley scattering mechanism mediated by an electron-hole exchange interaction. Moreover time resolved circular dichroism experiments performed in the same experimental condition confirms the fast valley relaxation dynamics observed with transient Faraday rotation technique.

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Stefano Dal Conte, Federico Bottegoni, E. A. A. Pogna, D. De Fazio, S. Ambrogio, I. Bargigia, C. D'Andrea, A. Lombardo, M. Bruna, F. Ciccacci, A. C. Ferrari, G. Cerullo, and M. Finazzi "Intervalley scattering in monolayer MoS₂ probed by non-equilibrium optical techniques", Proc. SPIE 9551, Spintronics VIII, 95510W (8 September 2015); https://doi.org/10.1117/12.2186692

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