Seminários

Título: 

Phase transitions of disordered graphene in the quantum Hall regime

 

Resumo: 

In this presentation, I will talk about our recent studies on the magneto-transport properties of disordered graphene samples in the quantum Hall (QH) regime. Despite the QH effect in graphene has been known for a while, having received a huge attention in the past decade, there are still open questions about the effects of the disorder on the transition states between the Hall plateaus, especially regarding scaling properties. Such transition states have been intensively studied in the context of two-dimensional electron gases and found to exhibit universal scaling behavior. However, the situation is less clear in graphene, which displays an anomalous quantum Hall effect as a consequence of its valley degeneracy. To elucidate this issue, we address the problem by calculating the longitudinal and Hall conductivities of graphene systems up to 10^5 atoms in a Hall bar geometry via the Landauer-Büttiker formalism using scattering matrix methods. We consider two classes of disorder, scalar and chiral, with different disorder correlation lengths.