Depinning of CHARGE-DENSITY WAVES BY TUNNELING

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Abstract
A semiconductor model has been used to calculate the current associated with motion of CDW's by Zener tunneling through a small pinning gap. Introduction of a correlation length gives a threshold field for the tunneling current. Application of Tucker's theory gives a scaling relation between the dc and ac conductivities. There is an additional contribution to [sgrave](ω) from oscillations of the pinned wave. Excellent agreement with experiment is obtained for both transitions in NbSe3 and for the commensurate transition in TaS3. However, the model with Tucker's theory fails to account for effects of combined ac and dc fields. Reasons for the failure and possible ways to develop a satisfactory theory will be discussed.