The metallic transport of (TMTSF)_2X organic conductors close to the superconducting phase

TL;DR

This study investigates the metallic transport properties of quasi-one-dimensional (TMTSF)_2X organic conductors near their superconducting phase, revealing a unified scattering mechanism and a correlation between T-linear resistivity and superconductivity.

Contribution

It demonstrates a common scattering time governing transport along different axes and links T-linear resistivity to the suppression of superconductivity in these materials.

Findings

A low temperature regime with a single scattering time for both axes.

T-linear resistivity correlates with the suppression of superconducting Tc.

Pressure significantly affects interlayer coupling and anisotropy.

Abstract

Comparing resistivity data of quasi-one dimensional superconductors (TMTSF)_2PF_6 and (TMTSF)_2ClO_4 along the least conducting c*-axis and along the high conductivity a -axis as a function of temperature and pressure, a low temperature regime is observed in which a unique scattering time governs transport along both directions of these anisotropic conductors. However, the pressure dependence of the anisotropy implies a large pressure dependence of the interlayer coupling. This is in agreement with the results of first-principles DFT calculations implying methyl group hyperconjugation in the TMTSF molecule. In this low temperature regime, both materials exhibit for rc a temperature dependence aT + bT^2. Taking into account the strong pressure dependence of the anisotropy, the T-linear rc is found to correlate with the suppression of the superconducting Tc, in close analogy with ra data. This work is revealing the domain of existence of the 3D coherent regime in the generic (TMTSF)_2X phase diagram and provides further support for the correlation between T-linear resistivity and superconductivity in non-conventional superconductors.