(TM)₂X organic superconductors: interplay between 1-D charge localization and higher dimensionality cross-over

A survey of transport and magnetic properties of the (TM)₂X series together with a recent investigation in high magnetic fields shows that the charge localization occurring at low temperature in a 1-D half-filled band is suppressed by the 1-D to 2-D (3-D) cross-over in selenium compounds. However, a localization around 30 K in the non-ordered phase can be reactivated by the application of a high transverse magnetic field. The intermediate (strong) coupling limit is valid for the spin degree of freedom whereas the charge is governed by the strength of the Umklapp scattering varying by a large factor from sulfur to selenium compounds and under pressure.