Electrical transport in the organic superconductor β-(BEDT-TTF)2AuI2 [with BEDT-TTF≡bis(ethylenedithio)tetrathiafulvalene] : influence of x-ray-induced defects on the normal phase and superconducting ground state

Abstract

We have measured the in-plane and out-of-plane resistivities of the organic superconductor β-(BEDT-TTF)2AuI2 with disorder introduced by x-ray irradiation. [Here BEDT-TTF is bis(ethylenedithio)- tetrathiafulvalene]. For defect concentrations less than 0.15% per mole, Matthiessen’s rule is obeyed at all temperatures and a T2 term in the resistivity is found in the temperature region between 5 and 20 K. The long-range superconducting order is destroyed by 0.1% per mole and the transition is completely smeared out above 0.2% per mole of defects. The overall temperature behavior of the resistivity is discussed and the possible importance of the electron-electron interaction and two-dimensional localization for the stabilization of the superconducting ground state is emphasized.