Suppression of superconductivity by non-magnetic disorder in the organic superconductor (TMTSF)2(ClO4)(1-x)(ReO4)x

We present a study of the superconducting properties (Tc and Hc2) in the solid solution (TMTSF)2(ClO4)(1-x)(ReO4)x with a ReO-4 nominal concentration up to x = 6%. The dramatic suppression of Tc when the residual resistivity is increased upon alloying with no modification of the Fermi surface is the signature of non-conventional superconductivity . This behaviour strongly supports p or d wave pairing in quasi one dimensional organic superconductors. The determination of the electron lifetime in the normal state at low temperature confirms that a single particle Drude model is unable to explain the temperature dependence of the conductivity and that a very narrow zero frequency mode must be taken into account for the interpretation of the transport properties.Comment: Received 26 January 2004 / Received in final form 17 June 2004 / Published online 3 August 200

Coexistence of Superconductivity and Spin Density Wave orderings in the organic superconductor (TMTSF)_2PF_6

The phase diagram of the organic superconductor (TMTSF)_2PF_6 has been revisited using transport measurements with an improved control of the applied pressure. We have found a 0.8 kbar wide pressure domain below the critical point (9.43 kbar, 1.2 K) for the stabilisation of the superconducting ground state featuring a coexistence regime between spin density wave (SDW) and superconductivity (SC). The inhomogeneous character of the said pressure domain is supported by the analysis of the resistivity between T_SDW and T_SC and the superconducting critical current. The onset temperature T_SC is practically constant (1.20+-0.01 K) in this region where only the SC/SDW domain proportion below T_SC is increasing under pressure. An homogeneous superconducting state is recovered above the critical pressure with T_SC falling at increasing pressure. We propose a model comparing the free energy of a phase exhibiting a segregation between SDW and SC domains and the free energy of homogeneous phases which explains fairly well our experimental findings.Comment: 13 pages, 10 figures, revised v: fig.9 added, section 4.2 rewritten, accepted v: sections 4&5 improve

Influence of Quantum Hall Effect on Linear and Nonlinear Conductivity in the FISDW States of the Organic Conductor (TMTSF)_2PF_6

We report a detailed characterization of quantum Hall effect (QHE) influence on the linear and non-linear resistivity tensor in FISDW phases of the organic conductor (TMTSF)2PF6. We show that the behavior at low electric fields, observed for nominally pure single crystals with different values of the resistivity ratio, is fully consistent with a theoretical model, which takes QHE nature of FISDW and residual quasi-particle density associated with different crystal imperfection levels into account. The non-linearity in longitudinal and diagonal resistivity tensor components observed at large electric fields reconciles preceding contradictory results. Our theoretical model offers a qualitatively good explanation of the observed features if a sliding of the density wave with the concomitant destruction of QHE, switched on above a finite electric field, is taken into account.Comment: 8 pages, 6 figures, submitted to EPJ

Nodal Superconducting Order Parameter and Thermodynamic Phase Diagram of (TMTSF)2ClO4

The organic materials (TMTSF)2X are unique unconventional superconductors with archetypal quasi-one-dimensional (Q1D) electronic structures. Here, based on our comprehensive field-angle-resolved calorimetry of (TMTSF)2ClO4, we succeeded in mapping the nodal gap structure for the first time in Q1D systems, by discriminating between the Fermi wavevectors and Fermi velocities. In addition, the thermodynamic phase diagrams of (TMTSF)2ClO4 for all principal field directions are obtained. These findings, providing strong evidence of nodal spin-singlet superconductivity, serves as solid bases for further elucidation of anomalous superconducting phenomena in (TMTSF)2X.Comment: 7 pages, 7 figures, including Supplemental Information added at the end of the manuscrip

Two Intranasal Administration Techniques Give Two Different Pharmacokinetic Results

Minor changes in the administration technique used for intranasal instillation of clonazepam, have been  found to influence the results significantly. A simple study was performed, where rabbits received 0.5 mg  clonazepam intranasally. One group received the drug while fixed in a sitting position, where the other  group was fixed in a supine position. The results show that both techniques where able to provide a rapid  absorption with a tmax around 3-4 min. The Cmax and AUC, however, were very different. The Cmax was found  to be 40 ng/ml and 86 ng/ml, respectively, and the AUC was found to be 891 and 2249 (ng/ml/min), respectively,  for the sitting and the supine position. The relative bioavailability for sitting/supine was found to be  38%. These results show that the administration technique is very important and should not be underestimated.

Mechanism of confinement in low-dimensional organic conductors

Confinement-deconfinement transition in quarter-filled two-coupled chains comprising dimerization, repulsive interactions and interchain hopping has been demonstrated by applying the renormalization group method to the bosonized Hamiltonian. The confinement given by the irrelevant interchain hopping occurs with increasing umklapp scattering which is induced by the dimerization leading to effectively half-filling. It is shown that the transition originates in a competition between a charge gap and the renormalized interchain hopping.Comment: 5 pages, 7 figures, Proc. CREST Int. Workshop, Nagoya 2000, submitted to J. Phys. Chem. Solid