THERMOPOWER OF DEUTERATED AND ALLOYED CU-DCNQI-CYSTALS - EVIDENCES FOR A QUITE NORMAL REENTRY OF THE CONDUCTIVITY

In Cu(2,5-DMe-DCNQI)(2) (DCNQI: N,N'-Dicyanoquinonediimine) crystals w ith metal-like conductivity, phase transitions (ph.t.) to an insulatin g state can be adjusted. A reentry to the metallic state at lower temp erature is observed in alloyed Cu-DCNQI systems. Correlating the ph.t. of the thermopower S, the conductivity sigma and the ESR-intensity of deuterated and alloyed DCNQI salts, we could proof a model of coexist ing conducting and non-conducting areas in the vicinity of the ph.t. W e could find S(T) similar to T - as known for metals - in the high tem perature range for the examined DCNQI-salts. At low temperatures, in t he range of the reentry of sigma, S(T) reaches again the value accordi ng to a metallic behavior. This low temperature metallic state is iden tified as equivalent to that of the high temperature one.