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

被引：96

作者：

Dal Conte, S. ^{[1
,2
]}

Bottegoni, F. ^{[2
]}

Pogna, E. A. A. ^{[2
]}

De Fazio, D. ^{[3
]}

Ambrogio, S. ^{[4
,5
]}

Bargigia, I. ^{[6
]}

D'Andrea, C. ^{[2
,6
]}

Lombardo, A. ^{[3
]}

Bruna, M. ^{[3
]}

Ciccacci, F. ^{[2
]}

Ferrari, A. C. ^{[3
]}

Cerullo, G. ^{[1
,2
]}

Finazzi, M. ^{[2
]}

机构：

[1] IFN CNR, I-20133 Milan, Italy

[2] Politecn Milan, Dipartimento Fis, I-20133 Milan, Italy

[3] Univ Cambridge, Cambridge Graphene Ctr, Cambridge CB3 0FA, England

[4] Politecn Milan, Dipartimento Elettron Informat & Bioingn, I-20133 Milan, Italy

[5] IU NET, I-20133 Milan, Italy

[6] Ist Italiano Tecnol, Ctr Nano Sci & Technol PoliMi, I-20133 Milan, Italy

来源：

PHYSICAL REVIEW B | 2015年 / 92卷 / 23期

基金：

英国工程与自然科学研究理事会;

关键词：

POLARIZATION; LIFETIMES; GRAPHENE;

D O I：

10.1103/PhysRevB.92.235425

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We study the exciton valley relaxation dynamics in single-layerMoS(2) 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.

引用

页数：6

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