Superheating field in superconductors with nanostructured surfaces

• Published in: Frontiers in Electronic Materials 2023-09, Vol.3
• Main Authors: Pathirana, W. P. M. R., Gurevich, A.
• Format: Article
• Language: English
• Subjects: Ginzburg–Landau theory; multilayered superconductors; superconductors; superheating field; vortices
• ISSN: 2673-9895; 2673-9895
• DOI: 10.3389/femat.2023.1246016

We report calculations of a DC superheating field H sh in superconductors with nanostructured surfaces. Numerical simulations of the Ginzburg–Landau (GL) equations were performed for a superconductor with an inhomogeneous impurity concentration, a thin superconducting layer on top of another superconductor, and superconductor–insulator–superconductor (S-I-S) multilayers. The superheating field was calculated taking into account the instability of the Meissner state with a non-zero wavelength along the surface, which is essential for the realistic values of the GL parameter κ . Simulations were performed for the material parameters of Nb and Nb 3 Sn at different values of κ and the mean free paths. We show that the impurity concentration profile at the surface and thicknesses of S-I-S multilayers can be optimized to enhance H sh above the bulk superheating fields of both Nb and Nb 3 Sn. For example, an S-I-S structure with a 90-nm-thick Nb 3 Sn layer on Nb can boost the superheating field up to ≈500 mT, while protecting the superconducting radio-frequency (SRF) cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.