Linear-T scattering and pairing from antiferromagnetic fluctuations in the (TMTSF)_2X organic superconductors

TL;DR

This paper investigates the electrical transport and superconductivity in (TMTSF)_2X organic superconductors, revealing a connection between antiferromagnetic fluctuations, linear resistivity, and superconducting transition temperature, supported by both experimental data and theoretical modeling.

Contribution

It provides a comprehensive experimental and theoretical analysis of the resistivity behavior and its relation to antiferromagnetic fluctuations and superconductivity in (TMTSF)_2X compounds.

Findings

Linear resistivity correlates with antiferromagnetic fluctuations.

Resistivity behavior changes with pressure and temperature.

Theoretical model explains linear resistivity via electron-electron scattering.

Abstract

An exhaustive investigation of metallic electronic transport and superconductivity of organic superconductors (TMTSF)_2PF_6 and (TMTSF)_2ClO_4 in the Pressure-Temperature phase diagram between T=0 and 20 K and a theoretical description based on the weak coupling renormalization group method are reported. The analysis of the data reveals a high temperature domain (T\approx 20 K) in which a regular T^2 electron-electron Umklapp scattering obeys a Kadowaki-Woods law and a low temperature regime (T< 8 K) where the resistivity is dominated by a linear-in temperature component. In both compounds a correlated behavior exists between the linear transport and the extra nuclear spin-lattice relaxation due to antiferromagnetic fluctuations. In addition, a tight connection is clearly established between linear transport and T_c. We propose a theoretical description of the anomalous resistivity based on a weak coupling renormalization group determination of electron-electron scattering rate. A linear resistivity is found and its origin lies in antiferromagnetic correlations sustained by Cooper pairing via constructive interference. The decay of the linear resistivity term under pressure is correlated with the strength of antiferromagnetic spin correlations and T_c, along with an unusual build-up of the Fermi liquid scattering. The results capture the key features of the low temperature electrical transport in the Bechgaard salts.