Professor René Wasserman Award 2021 - Antimo Marrazzo
Electronic Structure and Topology of Novel Materials
EPFL thesis n°7449
Thesis director: Prof. N. Marzari
For charting the topological properties of all exfoliable non-magnetic materials, identifying 2D jacutingaite as the first example of a Kane-Mele quantum spin Hall insulator, and 3D jacutingaite as a dual-topology material - a prediction later confirmed by experiments.
In this thesis, we have studied the electronic structure and its topology in the context of materials design and discovery. In particular, we focused on a specific class of materials, namely two-dimensional topological insulators. By coupling state-of-the-art first-principles simulations with materials’ informatics we have screened materials databases looking for novel two-dimensional topological insulators. In this search, we found novel candidates and provided a picture of the abundance of such materials in nature. In the process, we identified one outstanding candidate, jacutingaite, displaying fairly unique physical properties. We have unveiled the electronic structure of monolayer jacutingaite and showed its strong links with that of graphene. Monolayer jacutingaite in fact realises the topological physics of graphene, but at a much higher and more relevant energy scale, while retaining a richer interplay between spin-orbit coupling, crystal-symmetry breaking and dielectric response, that is potentially relevant for applications. We also studied jacutingaite in its layered three-dimensional bulk form. We showed how bulk jacutingaite is a dual topological insulator, where a non-trivial coupling between graphene-like layers induces an additional topological crystalline order with protected (001)-surface states; this has been confirmed by experiments.