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The newly developed two-dimensional layered materials provide perfect platform for valley-spintronics exploration. To determine the prospect of utilizing the valley degree of freedom, it is of great importance to directly detect and…

Mesoscale and Nanoscale Physics · Physics 2016-05-10 Tengfei Yan , Xiaofen Qiao , Pingheng Tan , Xinhui Zhang

We have systematically examined the circular polarization of monolayer WSe2 at different temperature, excitation energy and exciton density. The valley depolarization in WSe2 is experimentally confirmed to be governed by the intervalley…

Mesoscale and Nanoscale Physics · Physics 2015-03-12 Tengfei Yan , Xiaofen Qiao , Pingheng Tan , Xinhui Zhang

We measured the lifetime of optically created valley polarization in single layer WS2 using transient absorption spectroscopy. The electron valley relaxation is very short (< 1ps). However the hole valley lifetime is at least two orders of…

Materials Science · Physics 2014-08-06 Cong Mai , Yuriy G. Semenov , Andrew Barrette , Yifei Yu , Zhenghe Jin , Linyou Cao , Ki Wook Kim , Kenan Gundogdu

Monolayer transition metal dichalcogenides offer the possibility of optical control of the valley degree of freedom. In order to asses the potential of these materials in applications, detailed knowledge of the valley dynamics is essential.…

Mesoscale and Nanoscale Physics · Physics 2015-07-03 A. A. Mitioglu , L. Klopotowski , D. K. Maude , G. Deligeorgis , S. Anghel , L. Kulyuk , P. Plochocka

Semiconducting transition metal dichalcogenide monolayers have emerged as promising candidates for future valleytronics-based quantum information technologies. Two distinct momentum-states of tightly-bound electron-hole pairs in these…

Mesoscale and Nanoscale Physics · Physics 2017-03-16 Gerd Plechinger , Tobias Korn , John M. Lupton

Coupling between exciton states across the Brillouin zone in monolayer transition metal dichalcogenides can lead to ultrafast valley depolarization. Using time- and angle-resolved photoemission, we present momentum- and energy-resolved…

In this letter, we address the chiral properties of valley exciton-polaritons in a monolayer of WS2 in the regime of strong light-matter coupling with a Tamm-Plasmon resonance. We observe that the valley polarization, which manifests in the…

Mesoscale and Nanoscale Physics · Physics 2017-12-13 N. Lundt , S. Stoll , P. Nagler , A. Nalitov , S. Klembt , S. Betzold , J. W. Goddard , E. Frieling , A. V. Kavokin , C. Schüller , T. Korn , S. Höfling , C. Schneider

In single-layer WSe$_2$, a paradigmatic semiconducting transition metal dichalcogenide, a circularly polarized laser field can selectively excite electronic transitions in one of the inequivalent $K^{\pm}$ valleys. Such selective valley…

Mesoscale and Nanoscale Physics · Physics 2017-08-23 Alejandro Molina-Sánchez , Davide Sangalli , Ludger Wirtz , Andrea Marini

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…

Materials Science · Physics 2021-11-01 Fabian Cadiz , Stefan Gerl , Takashi Taniguchi , Kenji Watanabe

Monolayer transition metal dichalcogenids (TMDs) feature valley degree of freedom, giant spin-orbit coupling and spin-valley locking. These exotic natures stimulate efforts of exploring the potential applications in conceptual spintronics,…

Mesoscale and Nanoscale Physics · Physics 2017-06-28 Tengfei Yan , Siyuan Yang , Dian Li , Xiaodong Cui

We investigate valley exciton dynamics in MoSe2 monolayers in polarization- and time-resolved photoluminescence (PL) spectroscopy at 4K. Following circularly polarized laser excitation, we record a low circular polarization degree of the PL…

Materials Science · Physics 2015-03-19 G. Wang , E. Palleau , T. Amand , S. Tongay , X. Marie , B. Urbaszek

By pumping nonresonantly a MoS$_2$ monolayer at $13$ K under a circularly polarized cw laser, we observe exciton energy redshifts that break the degeneracy between B excitons with opposite spin. The energy splitting increases monotonically…

Mesoscale and Nanoscale Physics · Physics 2020-01-07 Yao Li , G. Li , Xiaokun Zhai , Shi Fu Xiong , Hongjun Liu , Xiao Wang , Haitao Chen , Ying Gao , Xiu Zhang , Tong Liu , Yuan Ren , Xuekai Ma , Hongbin Fu , T. Gao

We investigate exciton dynamics in 2H-WSe2 bilayers in time-resolved photoluminescence (PL) spectroscopy. Fast PL emission times are recorded for both the direct exciton with $\tau_{D}$ ~ 3 ps and the indirect optical transition with…

Materials Science · Physics 2014-11-07 G. Wang , X. Marie , L. Bouet , M. Vidal , A. Balocchi , T. Amand , D. Lagarde , B. Urbaszek

We present a theoretical model that allows us to describe the dynamics of exciton polaritons in the strong-coupling regime in a monolayer WS2 based semiconductor microcavity. Numerical simulations using Boltzmann equations give an overall…

Mesoscale and Nanoscale Physics · Physics 2018-06-12 Mohamed Herira , Hela Boustanji , Sihem Jaziri

We develop a model, which incorporates both intra- and intervalley scatterings to master equation, to explore exciton valley coherence in monolayer WS$_2$ subjected to magnetic field. For linearly polarized (LP) excitation accompanied with…

Mesoscale and Nanoscale Physics · Physics 2023-08-09 Kang Lan , Shijie Xie , Jiyong Fu , Fanyao Qu

We investigated the valley depolarization and carrier relaxation process of monolayer and bilayer WS2 at 10 K by using time-resolved Kerr rotation (TRKR) and differential reflectance measurement simultaneously. Two decay processes extracted…

Mesoscale and Nanoscale Physics · Physics 2018-03-28 Huimin Su , Aiying Deng , Zhiheng Zhen , Jun-Feng Dai

Using time-resolved optical Kerr rotation, we measure the low temperature valley dynamics of resident electrons and holes in exfoliated WSe$_2$ monolayers as a systematic function of carrier density. In an effort to reconcile the many…

Materials Science · Physics 2021-04-14 Jing Li , M. Goryca , K. Yumigeta , H. Li , S. Tongay , S. A. Crooker

Since the discovery of semiconducting monolayer transition metal dichalcogenides, a variety of experimental and theoretical studies have been carried out seeking to understand the intrinsic exciton population decay and valley relaxation…

Mesoscale and Nanoscale Physics · Physics 2016-05-04 Galan Moody , John Schaibley , Xiaodong Xu

Optical interband transitions in monolayer transition metal dichalcogenides such as WSe2 and MoS2 are governed by chiral selection rules. This allows efficient optical initialization of an electron in a specific K-valley in momentum space.…

Mesoscale and Nanoscale Physics · Physics 2014-09-09 G. Wang , L. Bouet , D. Lagarde , M. Vidal , A. Balocchi , T. Amand , X. Marie , B. Urbaszek

The valley pseudospin in monolayer transition metal dichalcogenides (TMDs) has been proposed as a new way to manipulate information in various optoelectronic devices. This relies on a large valley polarization that remains stable over long…

Mesoscale and Nanoscale Physics · Physics 2017-12-22 Fahad Mahmood , Zhanybek Alpichshev , Yi-Hsien Lee , Jing Kong , Nuh Gedik
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