The interpretation of the field angle dependence of the critical current in defect-engineered superconductors

TL;DR

This paper uses the vortex path model to interpret the field angle dependence of critical currents in defect-engineered superconductors, clarifying misconceptions and showing that electron mass anisotropy is not a key factor.

Contribution

It demonstrates that the vortex path model provides a consistent interpretation of experimental data without relying on electron mass anisotropy, and clarifies misconceptions about critical current peaks.

Findings

The vortex path model explains diverse features of critical current data.

Electron mass anisotropy is not a significant factor in the data.

Misconceptions about peaks indicating correlated pinning are corrected.

Abstract

We apply the vortex path model of critical currents to a comprehensive analysis of contemporary data on defect-engineered superconductors, showing that it provides a consistent and detailed interpretation of the experimental data for a diverse range of materials. We address the question of whether electron mass anisotropy plays a role of any consequence in determining the form of this data and conclude that it does not. By abandoning this false interpretation of the data, we are able to make significant progress in understanding the real origin of the observed behavior. In particular, we are able to explain a number of common features in the data including shoulders at intermediate angles, a uniform response over a wide angular range and the greater discrimination between individual defect populations at higher fields. We also correct several misconceptions including the idea that a peak in the angular dependence of the critical current is a necessary signature of strong correlated pinning, and conversely that the existence of such a peak implies the existence of correlated pinning aligned to the particular direction. The consistency of the vortex path model with the principle of maximum entropy is introduced.