EFFECT OF CONTROLLED DEFECTS ON THE MICROWAVE TRANSPORT AND DIELECTRIC-CONSTANT OF TETRATHIOFULVALENE-TETRACYANOQUINODIMETHANE

The introduction of controlled disorder in TTF‐TCNQ through irradiation provides information on the transport mechanism. The large changes in the magnitude and temperature dependence of the conductivity in the conducting regime are consistent with either 1d localization or pinning of CDW fluctuations by impurities. However, studies at low temperatures appear to be inconsistent with the localization ideas. Furthermore, the frequency dependence in the conducting regime at microwave frequencies suggests a substantial contribution of fluctuating CDW's to the low frequency transport. The introduction of controlled defects allows a separation of the low temperature conductivity into an intrinsic contribution plus a second contribution of impurity origin. Information on the frequency dependence of the intrinsic conductivity is obtained from comparison of the dc and microwave data. The results are interpreted in terms of soliton transport inhibited by the Larkin‐Lee tunneling. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA