报告题目：Mass generation and interaction-assisted transport in graphene
报告摘要：Graphene, a two-dimensional allotrope of carbon, has drawn much attention since its first experimental isolation. Much of this fascination stems from its exotic low-energy dynamics that is governed by the massless Dirac equation. In this talk I discuss manifestations of this unconventional physics in electron transport. First I will present joint experimental and theoretical work on graphene multilayers grown epitaxially on SiC. STM measurements on this material have revealed a splitting of the zeroth Landau level in high magnetic fields. A phenomenological theory that postulates the emergence of a space-dependent mass term in the Dirac equation fits the experimental data well. I will show how such a mass term is generated microscopically by interlayer interactions. Second, I will talk about the role that the Coulomb repulsion between electrons plays in scattering from one-dimensional defects in graphene. When strain is at the origin of such scattering, the interaction corrections to transport diverge logarithmically at low temperature. This is closely analogous to the one-dimensional Luttinger liquid; the sign of the correction, however, surprisingly is different. The resulting effects are dramatic: the studied scatterers are exponentially renormalized and they effectively disappear at zero temperature. The phenomenology of such scattering is thus more reminiscent of dynamic scatterers in one dimension undergoing the Kondo effect than static scatterers in the Luttinger liquid.