Influence of carrier lifetime on quantum criticality and superconducting T c of (TMTSF) 2 ClO 4

This work presents and analyzes electrical resistivity data on the organic superconductor (TMTSF) 2 ClO 4 and their anion-substituted alloys (TMTSF) 2 (ClO 4) 1−x (ReO 4) x along the least conducting c axis. Nonmagnetic disorder introduced by finite size domains of anion ordering on non-Fermi-liquid character of resistivity is investigated near the conditions of quantum criticality taking place at x = 0. The evolution of the T-linear resistivity term with anion disorder shows a limited decrease in contrast with the complete suppression of the critical temperature T c as expected for unconventional superconductivity beyond a threshold value of x. The resulting breakdown of scaling between both quantities is compared to the theoretical predictions of a linearized Boltzmann equation combined to the scaling theory of umklapp scattering in the presence of disorder-induced pair breaking for the carriers. The theory shows that quantum antiferromagnetic fluctuations, which are at the core of unconventional Cooper pairing and inelastic scattering of T-linear resistivity in these systems, are weakly affected by disorder while the phase coherence responsible for a finite T c can be completely suppressed.