Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Domaines cond-mat
Date Vendredi 27 Septembre 2019
Heure 13:30
Institut LPENS
Salle Conf IV
Nom de l'orateur Faugeras
Prenom de l'orateur Clément
Addresse email de l'orateur
Institution de l'orateur
Titre Magneto-optics of interlayer excitons in homo- and hetero- bilayers of 2D semiconductors
Résumé Monolayers of semiconducting transition metal dichalcogenides are direct band gap semiconductors. Because of the lack of inversion symetry and of the large spin orbit interaction, the spin and valley degrees of freedom are strongly coupled and a particular valley exciton population can be initialized using circularly polarized light excitation. As two dimensional materials, monolayers can be stacked on top of one another in the form of van der waals heterostructures to create artifical hetero- or homo- bilayers. These artifical structures can host different types of exciton complexes, in particular interlayer excitons for which electrons and holes are in different layers. Recently, it was realized that the twist angle between the two layers can strongly modify the electronic properties of the stack and can also be used to generate a lateral modulatin of the potential through a Moiré pattern. In this talk, I will describe interlayer excitons in homobilayers of 2H-MoS2 and present experimental evidence for such excitons. In a second part, I will describe optical properties of a WSe2/MoSe2 heterobilayer in which the two layers have been aligned with an angle close to 60∞ (2H stacking) to create a well defined band structure together with a moiré potential. I will show how these particular structures, combined with the use of high magnetic fields, allow for a rich spectroscopy of interlayer exciton scattering mechanisms.
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