Physics & Astronomy Colloquium

3:30 PM, Friday, September 5, 2008
Room 155, Chem-Phys Building

Dr. Herbert Fertig
Department of Physics
Indiana University

Graphene: A New Two-Dimensional Electron System
Recent experimental advances have led to the laboratory realization of graphene, a two-dimensional honeycomb network of carbon atoms that forms the building block of graphite, carbon nanotubes, and buckeyballs. This development has created tremendous excitement both for proposed applications in devices, and for the very unusual fundamental electron physics that it supports at low energies. Remarkably, the latter is a massless electron theory, reminiscent of simple models for neutrinos. In the first part of the talk I will outline some of the developments that have generated so much interest, both in zero and finite magnetic fields. One of the remarkable properties of the system is the an anomalous quantum Hall effect, particularly when the system is undoped. Experiments show either metallic or insulating behavior, depending on sample quality and strength of magnetic field, and strong signs of a quantum phase transition of the Kosterlitz-Thouless form separating the two regimes. This suggests that some form of one-dimensional physics controls these experiments. I will discuss how such behavior can emerge naturally at the edge of the system if there are magnetic impurities present, and show that the metallic behavior can be interpreted in terms of a superconducting gap in an otherwise insulating one-dimensional system.

Refreshments will be served in CP 155 at 3:15 PM