CUED Publications database

Ultrafast valley relaxation dynamics in monolayer MoS2 probed by nonequilibrium optical techniques

Dal Conte, S and Bottegoni, F and Pogna, EAA and De Fazio, D and Ambrogio, S and Bargigia, I and D'Andrea, C and Lombardo, A and Bruna, M and Ciccacci, F and Ferrari, AC and Cerullo, G and Finazzi, M (2015) Ultrafast valley relaxation dynamics in monolayer MoS2 probed by nonequilibrium optical techniques. Physical Review B - Condensed Matter and Materials Physics, 92. ISSN 1098-0121

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Abstract

© 2015 American Physical Society. We study the exciton valley relaxation dynamics in single-layer MoS2 by a combination of two nonequilibrium optical techniques: time-resolved Faraday rotation and time-resolved circular dichroism. The depolarization dynamics, measured at 77 K, exhibits a peculiar biexponential decay, characterized by two distinct time scales of 200 fs and 5 ps. The fast relaxation of the valley polarization is in good agreement with a model including the intervalley electron-hole Coulomb exchange as the dominating mechanism. The valley relaxation dynamics is further investigated as a function of temperature and photoinduced exciton density. We measure a strong exciton density dependence of the transient Faraday rotation signal. This indicates the key role of exciton-exciton interactions in MoS2 valley relaxation dynamics.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div B > Solid State Electronics and Nanoscale Science
Div B > Photonics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 18:58
Last Modified: 19 Sep 2017 01:30
DOI: