QUASI-REGULAR IMPURITY DISTRIBUTION DRIVEN BY A CHARGE-DENSITY-WAVE

The displacive motion of impurities immersed into a one-dimensional (1D) system has been studied in detail previously as one kind of quasiregularity driven by charge-density waves (CDW). As a further investigation of this problem we develop here a microscopic model for a different kind of quasiregular impurity distribution driven by the CDW, consisting of a modulation in the probability of occupied sites. The dependence on impurity concentration and temperature of relevant CDW quantities is obtained. Data reported in the quasi-1D materials NbSe3 and Ta2NiSe7, in particular thermal hysteresis effects at the CDW transition, are interpreted in the framework of the present model. Possible similarities to other physical systems are also suggested.