Vortex motion and the Hall effect in type II superconductors: a time dependent Ginzburg-Landau theory approach

TL;DR

This paper develops a complex relaxation time time-dependent Ginzburg-Landau model to analyze vortex motion and the Hall effect in type II superconductors, comparing various models and exploring phenomena like the Nernst effect and vortex fluctuations.

Contribution

It introduces a novel approach using complex relaxation times in TDGL equations to study vortex dynamics and Hall effects, connecting microscopic theory with phenomenological models.

Findings

Vortex velocity component parallel to current due to particle-hole symmetry breaking.

Calculated transport energy, Nernst effect, and thermopower for a single vortex.

Discussed vortex fluctuations and their impact on vortex line motion and wave propagation.

Abstract

Vortex motion in type II superconductors is studied starting from a variant of the time dependent Ginzburg-Landau equations, in which the order parameter relaxation time is taken to be complex. Using a method due to Gor'kov and Kopnin, we derive an equation of motion for a single vortex ($B\ll H_{c2}$) in the presence of an applied transport current. The imaginary part of the relaxation time and the normal state Hall effect both break ``particle-hole symmetry,'' and produce a component of the vortex velocity parallel to the transport current, and consequently a Hall field due to the vortex motion. Various models for the relaxation time are considered, allowing for a comparison to some phenomenological models of vortex motion in superconductors, such as the Bardeen-Stephen and Nozi\`eres-Vinen models, as well as to models of vortex motion in neutral superfluids. In addition, the transport energy, Nernst effect, and thermopower are calculated for a single vortex. Vortex bending and fluctuations can also be included within this description, resulting in a Langevin equation description of the vortex motion. The Langevin equation is used to discuss the propagation of helicon waves and the diffusional motion of a vortex line. The results are discussed in light of the rather puzzling sign change of the Hall effect which has been observed in the mixed state of the high temperature superconductors.