Low-frequency dielectric response in the quasi-one-dimensional organic conductor (TMTSF)2PF6

A unique and rare opportunity of revealing the nature of the spin-density-wave (SDW) fluctuation in the quasi-one-dimensional organic conductor (TMTSF)₂PF₆ has been provided by our AC impedance measurements above the SDW transition temperature. A close resemblance of the low-frequency dielectric response in the range between 20 K and the temperature of maximum resistivity T_max ∼ 80 K to that in the SDW ground state was revealed, with quite compatible exponents for their power law dependencies. The SDW fluctuation has thus been identified in the 2D Fermi liquid regime, which can be regarded as a precursor phase of the SDW ground state.     

Existence of two-dimensional closed orbits and delocalized carriers in the spin-ordered state of quasi-one-dimensional (TMTSF)2PF6

The magnetoresistance in spin-ordered state of quasi-one-dimensional (TMTSF)₂PF₆ has been studied. Both the frequency and anisotropy of the magnetoresistance oscillations are found to be independent of temperature; this proves the temperature independence of the geometry of two-dimensional closed contours at the Fermi level. At the same time, the oscillation amplitude decreases with the temperature, indicating the depopulation of the closed contours in the T = 0 limit. An explanation for the above seemingly controversial results has been proposed.     

Hall effect and conduction anisotropy in the organic conductor (TMTSF)2PF6

Both the Hall effect and the ab(')-plane conduction anisotropy are directly addressing the unconventional normal phase properties of the Bechgaard salt (TMTSF)2PF6. We found that the dramatic reduction of the carrier density deduced from recent optical data is not reflected in an enhanced Hall resistance. The pressure and temperature dependence of the b(')-direction resistivity reveal isotropic relaxation time and do not require explanations beyond the Fermi liquid theory. Our results allow a coherent-diffusive transition in the interchain carrier propagation, however the possible crossover to Luttinger liquid behavior is placed at an energy scale above room temperature.     

Hall effect in the normal phase of the organic superconductor (TMTSF)2PF6

We report accurate Hall effect measurements performed in the normal phase of the quasi-one-dimensional organic conductor (TMTSF)2PF6 at ambient pressure. The Hall coefficient is found to be strongly temperature dependent all the way from 300 K down to the spin density wave onset arising around 12 K. These new results emphasize the existence of a high temperature regime above 130 K where the Fermi liquid model is not satisfactory.     

Microwave transport approach to the coherence of interchain hopping in (TMTSF)2PF6

We report a microwave study of the longitudinal and transverse transport properties of the quasi-one-dimensional organic conductor (TMTSF)₂PF₆ in its normal phase. The contactless technique have provided a direct measurement of the temperature profile of the resistivity along the b' direction and in magnetic fields up to 14 T. A characteristic energy scale ( K) has been observed which delimits a transient regime from an insulating to a metallic behavior. This anomalous profile is discussed in terms of the onset of coherent transport properties along the b' direction below 40 K. This is also supported by the observation of a finite longitudinal and transverse magnetoresistances only below 40 K, indicative of a two-dimensional regime. Below T_x, however, strong deviations with respect to a Fermi liquid behavior are evidenced. Received 27 January 1999     

Low temperature metallic resistivity of the charge-transfer organic conductor (TMTSF)2PF6

The electrical resistivity arising from electron-electron Umklapp scattering is calculated at low temperatures for the anisotropic but two-dimensional charge-transfer complex (TMTSF)₂PF₆. Also, we consider a specular scattering correction to a recent one-phonon scattering mechanism and find a significant change in the temperature dependent behavior of the resistivity. Finally an exact solution is obtained for the resistivity arising from two-libron scattering and is found to give a small contribution at low temperatures. Comparing these results with recent data, we find that the electron-electron mechanism yields the most satisfactory agreement at low temperatures, while contributions from the other two mechanisms may not be negligible at high temperatures.