Field-Dependent Critical Current in Type-II Superconducting Strips: Combined Effect of Bulk Pinning and Geometrical Edge Barrier

TL;DR

This paper models the combined effects of bulk pinning and geometrical edge barriers on the critical current and magnetic field distribution in type-II superconducting strips, revealing new behaviors in the critical current dependence on magnetic field.

Contribution

It provides a theoretical description of current and field distributions considering both bulk pinning and edge barriers, and derives the critical current's dependence on magnetic field and pinning parameters.

Findings

Critical current Ic depends on magnetic field Ha and pinning parameters.

For certain pinning ratios, Ic shows a plateau at low Ha.

At higher Ha, Ic decreases as 1/Ha, indicating a specific field dependence.

Abstract

Recent theoretical and experimental research on low-bulk-pinning superconducting strips has revealed striking dome-like magnetic-field distributions due to geometrical edge barriers. The observed magnetic-flux profiles differ strongly from those in strips in which bulk pinning is dominant. In this paper we theoretically describe the current and field distributions of a superconducting strip under the combined influence of both a geometrical edge barrier and bulk pinning at the strip's critical current Ic, where a longitudinal voltage first appears. We calculate Ic and find its dependence upon a perpendicular applied magnetic field Ha. The behavior is governed by a parameter p, defined as the ratio of the bulk-pinning critical current Ip to the geometrical-barrier critical current Is0. We find that when p > 2/pi and Ip is field-independent, Ic vs Ha exhibits a plateau for small Ha, followed by the dependence Ic-Ip ~ 1/Ha in higher magnetic fields.