The defence will be in French and slides in English.
In this work, we investigate how a two-dimensional (2D) molecular system organizes on a metal surface. More specifically, using microscopy techniques we image at the molecular scale how fullerenes – football-like molecules made of 60 carbon atoms – arrange onto a copper surface. Surprisingly, we observe the coexistence of various molecular arrangements having distinct properties: some of them order in a common fashion, whereas others are disordered in a non trivial way. We explain this unusual coexistence (physical systems are generally in a single, well-defined state at a given temperature) building a model that accounts for the competing interactions present in the system (molecule/molecule and molecule/substrate interactions may be antagonist). Moreover, we perform a thorough statistical analysis of the disordered phases and reveal strong analogies with disordered states of matter usually found in highly frustrated magnets, despite the fact that magnetism is totally absent in our system!