Abstract
After decades of research, the mechanism for the superconductor to insulator transition (SIT) in highly disordered s-wave superconducting thin films and the nature of the resulting insulator are finally being clarified. Using quantum Monte Carlo and Bogoliubov-deGennes theory we show that, with increasing disorder, pairing in a 2D superconductor become highly inhomogeneous. Remarkably, the energy gap in the single-particle density of states survives across the SIT, but coherence peaks exist only in the superconducting state. A characteristic pseudogap persists above the critical disorder and critical temperature, in contrast to conventional theories. Surprisingly, the insulator has signatures of pairing, with a two-particle gap scale that vanishes precisely at the SIT despite a robust single-particle gap. In this talk, I will explain new microscopic insights into the SIT, compare our theory in detail with existing experiments, and make testable predictions for local spectroscopic probes.
Coffee and tea will be served 20 minutes prior to the seminar.