Microwave Vortex Motion Characterization of Nb$_3$Sn Coatings for Applications in High Magnetic Fields

TL;DR

This study uses microwave measurements in high magnetic fields to analyze the vortex dynamics and surface impedance of Nb$_3$Sn superconducting coatings made by different techniques, revealing differences and similarities that inform optimization.

Contribution

It provides a comparative analysis of vortex motion and surface impedance in Nb$_3$Sn coatings deposited by vapor tin diffusion and DC magnetron sputtering, highlighting their distinct superconducting properties.

Findings

Similar surface resistances despite different vortex dynamics

Distinct pinning regimes observed in the two coatings

Potential for film optimization balancing flux-flow resistivity and pinning

Abstract

In this work, microwave measurements carried out in dielectric-loaded resonators exposed to high magnetic fields are exploited to yield the surface impedance of Nb$_3$Sn superconducting coatings deposited via two different techniques: vapor tin diffusion, and DC magnetron sputtering. The obtained data lead to qualitative interpretations on both the Nb$_3$Sn superconducting properties, and vortex-dynamics and pinning, of each coating separately, as well as simple distinctive features when comparing those. When examining the respective surface impedances at varying field, it is expected that the studied films perform at substantially diverse magnitudes of flux-flow resistivity, but also in well-differentiated pinning regimes, yet the obtained surface resistances of both samples are comparable, thus demonstrating that there is room for film optimization at the expense of certain compromise between the parameters involved.