告摘要：The response of ultra-relativistic Dirac particles to a Coulomb potential is central to understanding a wide range of electronic phenomena in graphene.  Previously, Coulomb interactions in graphene have been probed by spatially averaged techniques that have not yielded a consistent picture.  In this talk I will discuss recent scanning tunneling spectroscopy measurements around charged and uncharged impurities on a graphene surface.  These measurements show with sub-nm resolution how Dirac fermions screen a Coulomb potential on graphene, and from these measurements we are able to extract useful information about the electron-electron interactions in graphene.  The implications of these measurements to intrinsic graphene properties and to future graphene devices will also be discussed.

报告人简介：Dr. Victor Brar, a.k.a. 韦小宝, received his B.S. degree in physics, mathematics and political science from MIT in 2004, and PhD in physics from UC Berkeley in 2010. His main research direction is on scanning tunneling microscopy studies of 2D systems (especially graphene) and magnetic systems. In 2011 he received the Lars Commins Memorial Award in Experimental Physics from UC at Berkeley and Kavli Nanoscience Institute Postdoctoral Fellowship Award from Caltech.