Temporal processes in a polymeric anion-based organic superconductor

We have studied the time-dependent resistivity of kappa- (BEDT-TTF)(2)Cu[N(CN)(2)]Br, a high transition temperature organic superconductor (T-c=11.6 K), in the temperature range 60-85 K. Based on these measurements, we identify an important parameter (in terms of time-dependent changes in resistivity) that is directly correlated to the superconducting transition temperature and also to the amplitude of the quantum oscillations associated with the Shubnikov-de Haas effect. This finding sheds new light on mechanisms involving disorder in this material. We describe a two-level model that accounts for the details of the time-dependent changes in resistivity.