Probing Sub-Critical and Super-Critical Impurities in Graphene
Date: Thursday, April 6th, 2017
Speaker: Victor Watson Brar, University of Wisconsin – Madison
Graphene, an atomically thin sheet of carbon atoms, is a two dimensional semi-metal in which the electrons behave as massless Fermions. Because it is extremely thin and has a low carrier density, the local electronic structure of graphene can be strongly modified by impurities found either in the nearby environment, or introduced via intentional doping. This talk will discuss several impurity related phenomena that are observed in graphene and how they can modify the macroscopic properties that are observed in graphene devices. By using a scanning tunneling microscope to construct, atom-by-atom, different species of impurities, we will show that phenomena can be realized that are analogous to as-of-yet unobserved high energy physics effects. Namely, it will be shown that ‘super-critical’ impurities can be created in graphene, which demonstrate how electrons and positrons would behave around a nuclear core with Z > 173, where the binding energy of the electron exceeds 2mec2.
Host: Benjamín Alemán
Location: 100 Willamette Hall