TOPO2D - Quantum Hall effect in graphene

Contacts: Rebeca RIBEIRO-PALAU

The understanding of matter in its deepest form is one of the most fundamental issues of solid state physics. Different states of matter are found to be distinguished by their internal structure, called orders. There exists a special kind of orders, called topological orders, which are universal, meaning that they are robust to arbitrary perturbations. The most common example of this is the quantum Hall effect (QHE), where the topology of the Landau levels leads to the formation of edge states that circulate along the edges of a two-dimensional electron gas. In the edge states, the backscattering between carriers is highly suppressed and therefore, within the channels, charge carriers can be transported without dissipation. The insensitivity of the Hall quantization to fabrication-dependent details and defects is a consequence of the topological properties of the band structure. The QHE is so robust against arbitrary perturbation that is globaly used as the resistance standard of the international SI (systeme international d'unites). 

In this part of our research we investigate the QHE in new materials such as graphene. The interst of the QHE in graphene goes from the understanding of fundamental phenomena (e.g., elecron solid versus electron liquid) to practical applications (e.g., graphene-based quantum Hall resistance standards).