Soutenance de thèse d'Abderrezak Torche

Abderrezak Torche, doctorant dans l'équipe Théorie quantique des matériaux, soutient sa thèse lejeudi 5 octobre 2017 à 14 h.

UPMC - 4 place Jussieu - 75005 Paris - Atrium Salle de visioconférence - R-d-C, entrée 2 (porte jaune)

Ab-initio resonant Raman simulations in graphene, few layer graphene, and graphite

Abstract

Multi-layer graphene with rhombohedral ABC stacking is considered as a promising carbon phase possibly displaying correlated states like magnetism or high-T c superconductivity due to the occurrence of an ultraflat electronic surface band at the Fermi level. Despite Bernal graphite being the most stable form of graphite, three and four layers graphene samples with rhombohedral stacking can be synthesized. Recently, flakes of thickness up to 17 layers were tentatively attributed ABC sequences although the Raman fingerprint of rhombohedral multilayer graphene is currently unknown and the 2D two-phonon resonant Raman spectrum of Bernal graphite not completely theoretically understood. Here we provide a complete first principles description of the 2D Raman peak in three and four layer graphene for all possible stackings, as well as for bulk Bernal, rhombohedral and an alternation of Bernal and rhombohedral graphite, that can be seen as a periodic sequence of ABA and ABC trilayers. Calculations for several laser energies are performed and we give practical prescriptions are proposed to identify long range sequences of ABC multi-layer graphene flakes. Our work is a prerequisite to experimental nondestructive identification and synthesis of rhombohedral multi-layer graphene and graphite.

Jury

• M.      Valentin POPOV                                Rapporteur
• M.      Laurent ALVAREZ                              Rapporteur
• M.      Fabio FINOCCHI                                Examinateur
• Mme. Marie-Aude MEASSON                    Examinateur
• M.      Gian-Marco RIGNANESE                 Examinateur
• M.      Jean-Christophe CHARLIER             Directeur de thèse
• M.      Matteo CALANDRA                           Directeur de thèse