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Séminaire Hétérostructures 2D à base de dichalcogénures de metaux de transition (TMDC) : 2/3

Excitons in monolayers of transition metal dichalcogenides - Clément Faugeras - Mardi 14 novembre 2017 à 11 h

INSP - UPMC - 4 place Jussieu - 75005 Paris - Barre 22-32, 2e étage, salle 201

Clément Faugeras, Laboratoire National des Champs Magnétiques Intenses (LNCMI), Grenoble

Abstract

Semiconducting transition metal dichalcogenides MX2 where M= Mo or W and X=S, Se or Te, are layered semiconductors that can be thinned down to the monolayer, showing an indirect to direct band gap transition for monolayers. Excitons in these purely 2D systems have a large binding energy of few hundreds of meV, a non-hydrogenic excitonic energy ladder and interband transitions are governed by chiral optical selection rules, allowing for the initialization of a valley population by a circularly polarized optical exciton.

In this talk I will describe the evolution of optical properties with the number of layers and the details of the band structure of monolayers through optical invetsigations of the low energy excitons and of their excited states. I will present our latest investigations concerning the use of magnetic fields to control intervalley scattering processes, responsible for valley depolarization.

Related publications : http://lncmi-g.grenoble.cnrs.fr/spi...