Article (Scientific journals)
Intravalley Spin-Flip Relaxation Dynamics in Single-Layer WS2
Wang, Zilong; Molina-Sanchez, Alejandro; Altmann, Patrick et al.
2018In NANO LETTERS, 18 (11), p. 6882-6891
Peer reviewed
 

Files


Full Text
ZWang2018a.pdf
Publisher postprint (3.22 MB)
Request a copy

All documents in ORBilu are protected by a user license.

Send to



Details



Keywords :
Transition metal dichalcogenides; transient absorption spectroscopy; spin and valley dynamics; layered materials; optoelectronics
Abstract :
[en] In monolayer (1L) transition metal dichalcogenides (TMDs) the valence and conduction bands are spin-split because of the strong spin-orbit interaction. In tungsten-based TMDs the spin-ordering of the conduction band is such that the so-called dark excitons, consisting of electrons and holes with opposite spin orientation, have lower energy than A excitons. The transition from bright to dark excitons involves the scattering of electrons from the upper to the lower conduction band at the K point of the Brillouin zone, with detrimental effects for the optoelectronic response of 1L-TMDs, since this reduces their light emission efficiency. Here, we exploit the valley selective optical selection rules and use two-color helicity-resolved pump-probe spectroscopy to directly measure the intravalley spin-flip relaxation dynamics in 1L-WS2. This occurs on a sub-ps time scale, and it is significantly dependent on temperature, indicative of phonon-assisted relaxation. Time-dependent ab initio calculations show that intravalley spin-flip scattering occurs on significantly longer time scales only at the K point, while the occupation of states away from the minimum of the conduction band significantly reduces the scattering time. Our results shed light on the scattering processes determining the light emission efficiency in optoelectronic and photonic devices based on 1L-TMDs.
Disciplines :
Physics
Author, co-author :
Wang, Zilong;  Politecn Milan, Dept Phys, Piazza Leonardo Vinci 32, I-20133 Milan, Italy.
Molina-Sanchez, Alejandro;  Univ Valencia, Inst Mat Sci ICMUV, Catedrat Beltran 2, E-46980 Valencia, Spain.
Altmann, Patrick;  Politecn Milan, Dept Phys, Piazza Leonardo Vinci 32, I-20133 Milan, Italy.
Sangalli, Davide;  CNR, ISM, Div Ultrafast Proc Mat FLASHit, Area Ric Roma 1, Monterotondo, Italy.
De Fazio, Domenico;  Univ Cambridge, Cambridge Graphene Ctr, 9 JJ Thomson Ave, Cambridge CB3 0FA, England.
Soavi, Giancarlo;  Univ Cambridge, Cambridge Graphene Ctr, 9 JJ Thomson Ave, Cambridge CB3 0FA, England.
Sassi, Ugo;  Univ Cambridge, Cambridge Graphene Ctr, 9 JJ Thomson Ave, Cambridge CB3 0FA, England.
Bottegoni, Federico;  Politecn Milan, Dept Phys, Piazza Leonardo Vinci 32, I-20133 Milan, Italy.
Ciccacci, Franco;  Politecn Milan, Dept Phys, Piazza Leonardo Vinci 32, I-20133 Milan, Italy.
Finazzi, Marco;  Politecn Milan, Dept Phys, Piazza Leonardo Vinci 32, I-20133 Milan, Italy.
Wirtz, Ludger ;  University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
Ferrari, Andrea C.;  Univ Cambridge, Cambridge Graphene Ctr, 9 JJ Thomson Ave, Cambridge CB3 0FA, England.
Marini, Andrea;  CNR, ISM, Div Ultrafast Proc Mat FLASHit, Area Ric Roma 1, Monterotondo, Italy
Cerullo, Giulio;  Politecn Milan, Dept Phys, Piazza Leonardo Vinci 32, I-20133 Milan, Italy.
Dal Conte, Stefano;  Politecn Milan, Dept Phys, Piazza Leonardo Vinci 32, I-20133 Milan, Italy.
More authors (5 more) Less
External co-authors :
yes
Title :
Intravalley Spin-Flip Relaxation Dynamics in Single-Layer WS2
Publication date :
November 2018
Journal title :
NANO LETTERS
ISSN :
1530-6984
Publisher :
Amer Chemical Soc, Washington, Unknown/unspecified
Volume :
18
Issue :
11
Pages :
6882-6891
Peer reviewed :
Peer reviewed
Focus Area :
Physics and Materials Science
FnR Project :
FNR7731521 - #4;modelling Of Carrier Dynamics And Ultra-fast Spectroscopy In Two-dimensional Materials, 2014 (01/12/2014-31/03/2017) - Alejandro Molina-sánchez
Funders :
FNR - Fonds National de la Recherche [LU]
Juan de la Cierva Program
Early Postdoc Mobility program of the Swiss National Science Foundation
EU Graphene Flagship
ERC grant Hetero2D
EPSRC - Engineering and Physical Sciences Research Council [GB]
EU project MaX Materials design at the eXascale [H2020-EINFRA-2015-1]
Nano science Foundries and Fine Analysis-Europe H2020-INFRAIA-2014-2015
Available on ORBilu :
since 14 January 2019

Statistics


Number of views
149 (9 by Unilu)
Number of downloads
0 (0 by Unilu)

Scopus citations®
 
79
Scopus citations®
without self-citations
65
OpenCitations
 
62
WoS citations
 
78

Bibliography


Similar publications



Contact ORBilu