[PAST EVENT] Physics Colloquium

April 15, 2011
Abstract: Graphene, a single atom-thick plane of graphite, has recently been isolated and studied experimentally. In this two-dimensional hexagonal lattice of carbon atoms, the electrons obey the Dirac equation for massless particles, complete with a two-component spinor degree of freedom that mimics the spin of a relativistic particle. Graphene is also composed entirely of surface atoms, making the techniques of surface science useful in studying its properties. In this talk, I will first discuss the electronic structure of graphene, and its implications for electronic properties. I will then discuss experiments which combine ultra-high vacuum (UHV) surface science with electronic transport measurements. Surface science techniques can be used to controllably modify graphene's properties: potassium atoms can be deposited to form charged impurity scatterers; ice can be deposited to modify the dielectric environment of graphene and tune the electron-electron interaction strength; and ion irradiation can be used to create atomic vacancies which act as Kondo impurities. Graphene is extraordinarily sensitive to surface adsorbates, and can be used to detect e.g. the ordering of potassium atoms, or reaction of potassium with water, both at concentrations below 1/1000th of a monolayer.