Charge dynamics across the disorder-driven superconductor-insulator transition

While insensitive to weak non-magnetic disorder, an s-wave superconductor can be driven insulating by strong disorder. Using a scheme that captures the correct ground state, and fully retains thermal amplitude and phase fluctuations, we describe the disorder-driven superconductor-insulator transition at finite temperature. Our results on the resistivity suggest that beyond moderate disorder the low-temperature superconducting state can arise out of an "insulating" normal state. We also find that the low-frequency weight in the density of states and optical conductivity are non-monotonic in disorder, with a maximum near critical disorder, and their high-temperature values correlate with the superconducting fraction in the disordered ground state. Copyright (c) EPLA, 2014