Depinning of spin-density-wave in (TMTSF)(2)ClO4

We have performed the electric conductivity measurements in the spin-densit y-wave (SDW) phase of (TMTSF)(2)ClO4 to clarify the dynamics of SDW. The te mperature dependence of threshold electric field E-T associated with the de pinning of SDW was investigated with changing the SDW transition temperatur e T-SDW by the control of anion ordering. The steep temperature dependence was observed for the highest T-SDW (6 K) and was explained with the weak pi nning by the impurity. The temperature dependence of E-T becomes moderate w ith decreasing T-SDW. For T-SDW = 4 K, it is understood with the strong pin ning. The crossover of pinning mechanism from the weak pinning to the stron g one was discussed with taking account of the effective impurity concentra tion due to the disordered array of anion orientation.