Nonlinear Hydrodynamics of Disentangled Flux-Line Liquids

TL;DR

This paper develops a non-Gaussian hydrodynamic model to analyze the magnetic response of flux-line liquids in type-II superconductors, revealing how interactions can enhance the tilt modulus and indicating the presence of a disentangled flux-liquid phase.

Contribution

It introduces a non-Gaussian hydrodynamic framework that accounts for nonlocal vortex interactions, advancing understanding of flux-line behavior in thick superconducting samples.

Findings

Interaction effects can increase the tilt modulus c44 in thick samples.

Nonlocal vortex interactions are essential for the renormalization of c44.

Disentangled flux-liquid fraction emerges due to interaction effects.

Abstract

In this paper we use non-Gaussian hydrodynamics to study the magnetic response of a flux-line liquid in the mixed state of a type-II superconductor. Both the derivation of our model, which goes beyond conventional Gaussian flux liquid hydrodynamics, and its relationship to other approaches used in the literature are discussed. We focus on the response to a transverse tilting field which is controlled by the tilt modulus, c44, of the flux array. We show that interaction effects can enhance c44 even in infinitely thick clean materials. This enhancement can be interpreted as the appearance of a disentangled flux-liquid fraction. In contrast to earlier work, our theory incorporates the nonlocality of the intervortex interaction in the field direction. This nonlocality is crucial for obtaining a nonvanishing renormalization of the tilt modulus in the thermodynamic limit of thick samples.