Effect of x-ray irradiation on anisotropic properties of tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ)

We present the results of the effect of controlled disorder on the electrical resistivity of the one-dimensional conductor TTF-TCNQ. The resistivity was measured, both parallel (σ) and perpendicular (σ) to the TTF-TCNQ chains, as a function of x-ray photon dose Φ. The longitudinal resistivity increases with photon dose, saturates at about twice its original value, and then increases again. The effect of irradiation on the transverse resistivity is much less pronounced. This behavior, as well as the observed dependence of the anisotropy on temperature and defect concentration, is explained within the framework of the theory which takes into account the libron-drag effect on the metallic transport properties of TTF-TCNQ.