Analogy between Depinning of a Charge Density Wave and Onset of Plastic Deformation of Crystals

The effect of an electric field on a pinned charge density wave (CDW) is considered in analogy with the mechanical deformation of crystals. At low fields, the commensurate CDW is elastically displaced and CDW defects pinned by impurities are distorted, giving rise to large dielectric constants. At the threshold field, CDW defects are nucleated and begin to move, leading to a permanent plastic flow which is identified with the CDW excess current. This interpretation is supported by the striking similarities observed between crystal plasticity and those recently found especially in the blue bronze K0.3MoO3.