Surface Influence on Flux Penetration into HTS Bulks

TL;DR

This study investigates how surface treatments affect AC loss in high-temperature superconductor (HTS) bulks, revealing complex behaviors and a dynamic surface barrier related to vortex propagation.

Contribution

It introduces a new understanding of surface influence on flux penetration and AC loss behavior in HTS bulks, highlighting the role of vortex dynamics and surface barriers.

Findings

Surface polishing complicates AC loss amplitude dependence.

A dynamic crossover indicates the emergence of a surface barrier at higher field variation rates.

Surface barrier appearance is explained by along-surface vortex propagation.

Abstract

The influence of surface treatment on AC loss in melt-processed quasi-single crystal HTS was investigated with resonance oscillations technique. We have found that amplitude dependencies of AC loss on magnetic field amplitude become rather complicated after surface polishing. The experimental data show well distinguished dynamic crossover from absence of barrier at low rates of field variation to its appearence at higher rates. An explaination of such a dynamic surface barrier appearance based on consideration of along surface vortex propagation was suggested.