Radio-frequency electromagnetic field and vortex penetration in multilayered superconductors

TL;DR

This paper derives formulas for vortex-penetration fields and magnetic shielding in multilayered superconductors, showing how layer thicknesses and materials influence the maximum achievable surface magnetic field, with results matching experiments.

Contribution

It provides a rigorous theoretical framework for optimizing multilayered superconductor structures to enhance magnetic field limits, including formulas applicable to various materials.

Findings

Derived general formulas for vortex-penetration and shielding fields.

Showed good agreement between calculations and experimental data.

Provided guidelines for layer thickness optimization to improve field limits.

Abstract

A multilayered structure with a single superconductor layer and a single insulator layer formed on a bulk superconductor is studied. General formulae for the vortex-penetration field of the superconductor layer and the magnetic field on the bulk superconductor, which is shielded by the superconductor and insulator layers, are derived with a rigorous calculation of the magnetic field attenuation in the multilayered structure. The achievable peak surface field depends on the thickness and its material of the superconductor layer, the thickness of the insulator layer and material of the bulk superconductor. The calculation shows a good agreement with an experimental result. A combination of the thicknesses of superconductor and insulator layers to enhance the field limit can be given by the formulae for any given materials.