Relaxation times in incommensurate phases with defects

Critical dynamics of the commensurate-incommensurate phase transition (T = T c ) in defect crystal is studied. It is shown that the relaxation time goes to infinity as exp(const/T(T-T c ) p ). We calculated also the temporal dependence of the critical pinning force at T ≠ O. It is demonstrated that for the long times there is only effective pinning barrier. Its parameters depend on the period of the incommensurate phase. Similar results are applied to the mixed state of type-two superconductors.