Disorder-tuned quantum phase transitions in superconducting thin films

*Please not the time change*

In two dimensions, as the microscopic disorder is increased, superconducting films evolve toward an insulating state. This change in ground state has commonly been described as a direct Superconductor–to–Insulator Transition (SIT) and results from the competition between disorder-induced Anderson localization and the formation of a macroscopic superconducting coherent state. a-Nb_xSi_1-x thin metal–alloy films are a model system to study the influence of disorder on superconductivity through a modification of composition, thickness or annealing. I will first present low temperature DC transport measurements performed on this material. We have evidenced non-predicted dissipative states resulting from the disorder-induced destruction of the superconducting long range order. Second, I will focus on a broadband microwave experimental setup we have developed, and the first measurements we have performed at low temperature to probe the electrodynamicresponse of disordered thin films.