CLASSICAL-MODEL OF CHARGE-DENSITY WAVES APPLIED TO MIXED SAMPLES OF TAS3

In this work we present an application of the classical model of charg e-density waves (CDW) to samples that are a mixture both known polytyp es of TaS3. The proposed model originates a system of differential equ ations that can be solved numerically. The response of the system to a de current bias shows features in the dynamics of both kinds of CDW's in the sample. First, there is an unusual ac-induced depinning of the higher threshold field CDW due to the motion of the lower threshold f ield one. Once both CDW's are depinned they establish consecutive mode -locking states between them. In each state both CDW's move in such a way that the quotient of velocities is an integer number. This integer characterizes each mode-locking stale and we call the whole effect in terference between CDW's, as it resembles the well-known interference between a CDW and an external ac excitation. The transition between tw o consecutive mode-locking states is detected through a strong peak in the differential resistivity characteristics (dV/dI). We are able to test the results of the model on special samples of TaS3. In this samp le we detect the predicted anomalies and peaks in dV/dI characteristic s. We successfully assign to each peak an integer relation between vel ocities of both CDW's of the system, thus confirming the prediction of the model.