Thickness dependence of the critical current density in superconducting films: a geometrical approach

TL;DR

This paper presents a geometrical model to quantify how the thickness of superconducting films affects their critical current density through self-field effects, aiding the development of thicker coated conductors.

Contribution

It introduces an equation linking film thickness to critical current density based on magnetic induction, validated by numerical simulations.

Findings

Critical current density decreases with increasing film thickness due to self-field effects.

The derived equation accurately reproduces simulation results.

The work informs design of thicker superconducting films for technological applications.

Abstract

We analyze the influence of the magnetic field generated by the supercurrents (self-field) on the current density distribution by numerical simulations. The thickness of the superconducting film determines the self-field and consequently the critical current density at zero applied field. We find an equation, which derives the thickness dependence of the critical current density from its dependence on the magnetic induction. Solutions of the equation reproduce numerical simulations to great accuracy, thus enabling a quantification of the dependence of the self-field critical current density with increasing film thickness. This result is technologically relevant for the development of coated conductors with thicker superconducting layers.