Electrical and magnetic properties of DED salts

The temperature dependence of the electrical resistivity of (DED)2PF6(THF)2, where DED is thiadiazoleethylenedithiodiselenadithiafulvalene, is metallic down to ∼20 K. At lower temperatures the resistivity rises proportionally to the logarithm of temperature, followed by a saturation of the resistivity upturn at around 1 K. The magnetic susceptibility exhibits Curie-like behavior down to ∼20 K, and χT suddenly goes towards zero at lower temperatures. Such behaviour indicates that this salt could be a rare example of ‘purely organic’ systems whose electrical behavior at low temperatures might be best explained as a result of Kondo effect.