Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Domaines cond-mat
Date Lundi 2 Décembre 2019
Heure 13:30
Institut LPENS
Salle Conf IV
Nom de l'orateur Gallais
Prenom de l'orateur Yann
Addresse email de l'orateur
Institution de l'orateur MPQ, Université Paris Diderot, Paris
Titre Electronic Raman scattering in graphene and transition metal dichalcogenides
Résumé In my talk I will review recent progress in the use of Raman scattering as a probe of electronic excitations in two-dimensional crystals. In the first part of my talk I will discuss experiments which aim at directly observing electronic excitations in graphene-based devices [1]. I will show in particular that symmetry-resolved Raman experiments can selectively probe chiral excitations, offering promising venues for this technique as a probe of non-trivial bulk and surface electron states. In the second part of my talk I will present recent Raman results on 2D metallic transition metal dichalcogenides (NbSe2 and TaSe2) in their bulk and few-layer form. I will discuss fingerprints of charge density wave order (CDW) and superconductivity (SC) and I will show that the coupling between CDW and SC orders enables a Raman coupling to the amplitude mode of the superconducting order parameter, a condensed matter analog of the Higgs mode [2]. If time allows I will also present recent THz Kerr and third-harmonic generation experiments which aim at probing the Higgs mode in other superconductors [3]. [1] E. Riccardi et al. Phys. Rev. Lett. 116, 066805 (2016), E. Riccardi et al. Phys. Rev. Mat. 3, 014002 (2019) [2] R. Grasset et al. Phys. Rev. B 97, 094502 (2018), R. Grasset et al. Phys. Rev. Lett. 122, 127001 (2019) [3] K. Katsumi et al. Phys. Rev. Lett. 120, 117001 (2018), H. Chu et al. arXiv : :1901.06675 (2019)
Numéro de preprint arXiv
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