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Intravalley Spin-Flip Relaxation Dynamics in Single-Layer WS2.

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cam.issuedOnline2018-10-16
dc.contributor.authorWang, Zilong
dc.contributor.authorMolina-Sánchez, Alejandro
dc.contributor.authorAltmann, Patrick
dc.contributor.authorSangalli, Davide
dc.contributor.authorDe Fazio, Domenico
dc.contributor.authorSoavi, Giancarlo
dc.contributor.authorSassi, Ugo
dc.contributor.authorBottegoni, Federico
dc.contributor.authorCiccacci, Franco
dc.contributor.authorFinazzi, Marco
dc.contributor.authorWirtz, Ludger
dc.contributor.authorFerrari, Andrea C
dc.contributor.authorMarini, Andrea
dc.contributor.authorCerullo, Giulio
dc.contributor.authorDal Conte, Stefano
dc.contributor.orcidMolina-Sánchez, Alejandro [0000-0001-5121-4058]
dc.contributor.orcidSangalli, Davide [0000-0002-4268-9454]
dc.contributor.orcidFerrari, Andrea C [0000-0003-0907-9993]
dc.contributor.orcidCerullo, Giulio [0000-0002-9534-2702]
dc.contributor.orcidDal Conte, Stefano [0000-0001-8582-3185]
dc.date.accessioned2018-12-11T00:31:34Z
dc.date.available2018-12-11T00:31:34Z
dc.date.issued2018-11-14
dc.description.abstractIn 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.
dc.format.mediumPrint-Electronic
dc.identifier.doi10.17863/CAM.33957
dc.identifier.eissn1530-6992
dc.identifier.issn1530-6984
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/286645
dc.languageeng
dc.language.isoeng
dc.publisherAmerican Chemical Society (ACS)
dc.publisher.urlhttp://dx.doi.org/10.1021/acs.nanolett.8b02774
dc.subjectTransition metal dichalcogenides
dc.subjectlayered materials
dc.subjectoptoelectronics
dc.subjectspin and valley dynamics
dc.subjecttransient absorption spectroscopy
dc.titleIntravalley Spin-Flip Relaxation Dynamics in Single-Layer WS2.
dc.typeArticle
dcterms.dateAccepted2018-09-28
prism.endingPage6891
prism.issueIdentifier11
prism.publicationDate2018
prism.publicationNameNano Lett
prism.startingPage6882
prism.volume18
pubs.funder-project-idEPSRC (via University of Manchester) (R119256)
pubs.funder-project-idEuropean Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (785219)
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/K017144/1)
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/K01711X/1)
rioxxterms.licenseref.startdate2018-11
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.typeJournal Article/Review
rioxxterms.versionAM
rioxxterms.versionofrecord10.1021/acs.nanolett.8b02774

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