Linear-T scattering and pairing from antiferromagnetic fluctuations in the (TMTSF)2X organic superconductors
Département de Physique and RQMP, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada
2 Laboratoire de Physique des Solides, UMR 8502 CNRS Université Paris-Sud, 91405 Orsay Cedex, France
3 Department of Chemistry, H.C. Ørsted Institute, Copenhagen, Denmark
Revised: 4 September 2010
Published online: 20 October 2010
An exhaustive investigation of metallic electronic transport and superconductivity of organic superconductors (TMTSF)2ClO4 and (TMTSF)2PF6 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 ≈ 20 K) in which a regular T2 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 Tc. 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 Tc, 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.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2010