Phase vortices and CDW conduction noise

Abstract

We review a theoretical aspect of the phase vortex model proposed by Ong, Verma and Maki to account for the quasi-periodic voltage oscillation observed in the non-Ohmic regime of the CDW states in NbSe3 and TaS3. Phase conservation requires a train of phase vortices at the domain boundary whenever two adjacent CDW domains move with different sliding velocities. These phase vortices move along the boundary with the number of vortices which sweep the boundary per second being proportional to the difference in the sliding velocities. In addition to conserving phase these vortices convert the CDW current into normal current (i.e. the quasi-particle current). This implies that the sources of the normal current are localized and move with the phase vortices. Therefore a periodic fundamental frequency proportional to the sliding velocity, when the CDW is pinned on one side of the array and moving on the other side.