Modeling of dislocations in a CDW junction: interference of the CDW and the normal carriers

TL;DR

This paper models the behavior of dislocations in a charge density wave junction, revealing how electronic vortices form and evolve under applied voltages, with implications for understanding experimental junctions in NbSe3 and TaS3.

Contribution

It introduces a detailed model that accurately conserves electrons and describes dislocation dynamics in CDW junctions, including the formation of electronic vortices.

Findings

Dislocations form an array near the junction surface with increasing voltage.

Dislocation cores concentrate normal carriers significantly.

Zero CDW amplitude lines act as phase slips across the sample.

Abstract

We derive and study equations for dissipative transient processes in a constraint incommensurate charge density wave (CDW) with remnant pockets or a thermal population of normal carriers. The attention was paid to give the correct conservation of condensed and normal electrons, which was problematic at presence of moving dislocation cores if working within an intuitive Ginzburg-Landau like model. We performed a numeric modelling for stationary and transient states in a rectangular geometry when the voltage V or the normal current are applied across the conducting chains. We observe creation of an array of electronic vortices, the dislocations, at or close to the junction surface; their number increases stepwise with increasing V. The dislocation core strongly concentrates the normal carriers but the CDW phase distortions almost neutralize the total charge. At other regimes, the lines of the zero CDW amplitude flash across the sample working as phase slips. The studies were inspired by, and can be applied to experiments on mesa-junctions in NbSe3 and TaS3 (Yu.I. Latyshev et al in proceedings of ECRYS 2008 and 2011).