Excess magneto-resistance in multiband superconductors due to the viscous flow of composite vortices

TL;DR

This paper explains the excess magneto-resistance observed in multiband superconductors by modeling vortices as composites of fractional vortices, revealing how their dynamics lead to larger flux-flow resistivity than traditional estimates.

Contribution

It introduces a theoretical framework using time-dependent Ginzburg-Landau theory to account for flux-flow resistivity in multiband superconductors through composite vortices.

Findings

Flux-flow resistivity can significantly exceed Bardeen-Stephen estimates.

Vortex core size to relaxation length ratio varies widely with system parameters.

Electric field stretching outside vortex cores influences magneto-resistance.

Abstract

By using the time-dependent Ginzburg-Landau theory, we show that extremely diverse experimental data on flux-flow resistivity in multiband superconductors can be qualitatively explained by a composite nature of Abrikosov vortices consisting of elementary fractional vortices in different bands. In composite vortices, the ratio of a core size to electric field relaxation length is found to vary in wide limits depending on system parameters. As a result, the flux-flow magneto-resistance can strongly exceed the single-component Bardeen-Stephen estimation provided that moving vortices generate electric field stretching strongly outside the vortex cores.