Interference Phenomena and Mode Locking in the Model of Deformable Sliding Charge-Density Waves

Abstract
We study how a deformable charge-density wave in the presence of random impurities responds to driving fields with both ac and dc components. Features in the differential resistivity are found when an internal frequency proportional to the velocity is either a harmonic or subharmonic of the driving frequency. Even infinitely large systems can exhibit true mode locking to the driving frequency. The behavior cannot be described by an equation of motion for a single effective degree of freedom.