Effect of irradiation-induced disorder on the conductivity and critical temperature of the organic superconductor κ-(BEDT-TTF)2Cu(SCN)2

We have introduced defects into clean samples of the organic superconductor kappa-(BEDT- TTF)(2)Cu(SCN)(2) in order to determine their effect on the temperature dependence of the interlayer conductivity sigma and the critical temperature T-c. We find a violation of Matthiessen's rule that can be explained by a model of sigma involving a defect-assisted interlayer channel which acts in parallel with the bandlike conductivity. We observe an unusual dependence of T-c on residual resistivity, inconsistent with the generalized Abrikosov-Gor'kov theory for an order parameter with a single component, providing an important constraint on models of the superconductivity in this material.