Spin States Protected from Intrinsic Electron–Phonon Coupling Reaching 100 ns Lifetime at Room Temperature in MoSe2
Year: 2019
Type: article
Abstract: . These long lifetimes are accompanied by an intriguing temperature-dependence of the Kerr amplitude, which increases with temperature up to 50 K and then abruptly switches sign. Using ab initio simulations, we explain the latter behavior in terms of the intrinsic electron-phonon coupling and the activation of transitions to secondary valleys. The phonon-assisted scattering of the photoexcited electron-hole pairs prepares a valley spin polarization within the first few ps after laser excitation. The sign of the total valley magnetization, and thus the Kerr amplitude, switches as a function of temperature, as conduction and valence band states exhibit different phonon-mediated intervalley scattering rates. However, the electron-phonon scattering on the ps time scale does not provide an explanation for the long spin lifetimes. Hence, we deduce that the initial spin polarization must be transferred into spin states, which are protected from the intrinsic electron-phonon coupling, and are most likely resident charge carriers, which are not part of the itinerant valence or conduction band states.
Source: Nano Letters
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Funders: Centres de Recerca de Catalunya, European Commission, Partnership for Advanced Computing in Europe AISBL, Fonds De La Recherche Scientifique - FNRS, Generalitat de Catalunya, Fédération Wallonie-Bruxelles, Forschungszentrum Jülich, Ministerio de Economía y Competitividad, Horizon 2020 Framework Programme
Awards: MAterials design at the eXascale. European Centre of Excellence in materials modelling, simulations, and design, G1473354695, G1819776118, G1844249394, G186625568, G2139942350, G265104915, G2913093573, G3026824933, G3518911933, G353390944, G3583131366, G418748808, G4302515808, G434337789, G4607920683, G4764760277, G4937468798, Graphene Flagship Core Project 2, G56798616, G5745676273, G5769078035, G5913213833, G6489121227, G6501229990, G676850745, G6905955430, G7664062879, G8188878238, PRACE 4th Implementation Phase Project
OpenAlex ID: W2952314541