Skyrmions dans la simple couche et la bicouche de graphène
Other titre : Skyrmions in monolayer and bilayer graphene
Graphene, a monolayer of graphite, has been isolated in 2004 by Novoselov et al. . Since then, it has been the subject of intense study both theoretically and experimentally. In this thesis, we study the ground states of the two-dimensional electron gas (2DEG) in graphene and bilayer graphene in a quantizing magnetic field. We first study the liquid phases at filling factors [nu] = 1, 2, 3, 4 including spins and valley pseudo-spins as well as the meron crystal phases with spin and valley pseudospin textures around filling factor [nu] = 1. We then look for single-particle excitations in a bilayer graphene system at the filling factor [nu] = -3. We find that charged pseudo-spin textures do not exist in such a system. The lowest charged excitations are the quasi-hole and quasi-electron states. We conclude that topological excitations do not play a significant role in the conductivity of the bilayer at [nu] = -3.
- Sciences – Mémoires