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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. |
