SDW CONDENSATE PINNED BY ANION DISORDER IN (TMTSF)2CLO4

The threshold electric field E(T) for the depinning of the SDW was inv estigated in (TMTSF)2ClO4 with varying the degree of anion ordering. I n the rapidly quenched phase, the observed temperature dependence of E (T) was explained by the weak impurity pinning. On the other hand, the strong pinning was found to be effective in the slowly quenched phase . This change of pinning mechanism was attributed to the change of ani on disorder as an impurity potential.