Distribution of Transport Current in a Type II Superconductor Studied by Small Angle Neutron Scattering

TL;DR

This study uses Small-Angle Neutron Scattering to analyze how surface roughness affects vortex pinning and current distribution in a Type II superconductor, revealing persistent surface currents during flux flow.

Contribution

It demonstrates the use of SANS to probe current distribution and shows how surface roughness influences vortex pinning and surface currents in superconductors.

Findings

Surface roughness causes vortex pinning.

Surface currents persist during flux flow.

Surface treatments alter current distribution.

Abstract

We report Small-Angle Neutron Scattering (SANS) measurements on the vortex lattice in a PbIn polycrystal in the presence of an applied current. Using the rocking curves as a probe of the distribution of current in the sample, we observe that vortex pinning is due to the surface roughness. This leads to a surface current that persists in the flux flow region. We show the influence of surface treatments on the distribution of this current.