Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Domaines cond-mat
Date Lundi 5 Juin 2023
Heure 13:30
Institut LPENS
Salle L382
Nom de l'orateur Ojeda
Prenom de l'orateur Claudia
Addresse email de l'orateur
Institution de l'orateur California State University Long Beach
Titre Probing quantum phase transitions in molecular crystals and topological Dirac semimetals through Angle Resolved Photoemission Spectroscopy ARPES
Résumé ARPES is a useful tool to study a variety of phenomena in quantum materials, as it directly probes the momentum-resolved electronic structure, revealing band dispersions, Fermi surface topology and electron self-energy in materials. In this seminar, I will talk about two different systems studied through this technique. The first addresses a molecular thin crystal of C60, where in contrast to an expected single-molecule- dominated electronic structure, we find that long range interactions between the molecules have a profound effect shaping the electronic structure of this material. Additionally, we find that upon in-situ potassium (K) doping, the C60 thin film undergoes a Mott transition from a molecular insulator to a correlated metal, which challenges the commonly accepted band-filling picture as the explanation for K3C60 metallicity. In the second part of the talk, I will show preliminary studies of type-II Dirac semimetals that present a ferromagnetic order upon magnetic element substitution. Our ARPES measurements on the parent topological Dirac semimetal PtTe2 show a clear signature of type-II fermions, in consistency with theoretical calculations. Upon Cr substitution, we observe the evolution of the electronic structure of this topological material as magnetism is introduced, where signature of type-II excitations disappears but a metallic topological surface state endures the presence of a magnetic moment in the material. The use of ARPES to study these materials is motivated by the idea of using ARPES data to inform electronic transport measurements on similarly prepared samples. Examples of this approach will be presented.
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