Blackboard talk on dirty Dirac fermions

12/08/2013 @ 11:00 AM – 12:00 PM Asia/Singapore Timezone
S13-M01-11 (Physics Conference Room)

Speaker: Shivaji Sondhi
Affiliation: Princeton
Abstract Details: This blackboard talk is aimed at theoretical condensed matter physicists.  We study three-dimensional Dirac fermions with weak finite-range scalar potential disorder. We show that even though disorder is perturbatively irrelevant at 3D Dirac points, nonperturbative effects from rare regions give rise to a nonzero density of states and a finite mean free path, with the transport at the Dirac point being dominated by hopping between rare regions. As one moves in chemical potential away from the Dirac point, there are interesting intermediate-energy regimes where the rare regions produce scattering resonances that determine the DC conductivity. We also discuss the interplay of disorder with interactions at the Dirac point. Attractive interactions drive a transition into a granular superconductor, with a critical temperature that depends strongly on the disorder distribution. In the presence of Coulomb repulsion and weak retarded attraction, the system can be a Bose glass. Our results apply to all 3D systems with Dirac points, including Weyl semimetals.