Reference : Intravalley Spin-Flip Relaxation Dynamics in Single-Layer WS2
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Physics
http://hdl.handle.net/10993/38243
Intravalley Spin-Flip Relaxation Dynamics in Single-Layer WS2
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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 mailto [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.]
Nov-2018
NANO LETTERS
Amer Chemical Soc
18
11
6882-6891
Yes (verified by ORBilu)
International
1530-6984
Washington
[en] Transition metal dichalcogenides ; transient absorption spectroscopy ; spin and valley dynamics ; layered materials ; optoelectronics
[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.
Fonds National de la Recherche - FnR ; Juan de la Cierva Program ; Early Postdoc Mobility program of the Swiss National Science Foundation ; EU Graphene Flagship ; ERC grant Hetero2D ; EPSRC ; EU project MaX Materials design at the eXascale [H2020-EINFRA-2015-1] ; Nano science Foundries and Fine Analysis-Europe H2020-INFRAIA-2014-2015
Researchers ; Professionals ; Students
http://hdl.handle.net/10993/38243
10.1021/acs.nanolett.8b02774
FnR ; FNR7731521 > Alejandro Molina-Sánchez > FAST-2DMAT > Modelling of carrier dynamics and ultra-fast spectroscopy in two-dimensional materials > 01/12/2014 > 31/03/2017 > 2014; FNR7490149 > Ludger Wirtz > NANOTMD > 20 Electric transport and superconductivity in TransitionMetal Dichalcogenides nanolayers > 01/02/2014 > 31/01/2019 > 2013

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