Interactions and disorder in 2D graphite sheets

The present work discusses theoretical models which address the effects of electron--electron interactions and disorder in graphene planes. The starting point for the study is a simple tight-binding model for the electronic structure followed by discussion of the interesting features induced by the unscreened Coulomb interaction. The unusual features of the model are emphasized. It is shown that the standard perturbative treatments used in condensed matter theory fail, and a more refined renormalization group approach is required. Then, a theoretical framework which allows us to extend the model to many types of disorder, following an early approach dessigned to treat the fivefold rings of the fullerenes, is discussed. The combined effects of disorder and interactions gives rise to a phase diagram with new strongly interacting phases.