AUTHOR=Pathirana W. P. M. R. , Gurevich A. 

TITLE=Superheating field in superconductors with nanostructured surfaces

JOURNAL=Frontiers in Electronic Materials

VOLUME=3

YEAR=2023

URL=https://www.frontiersin.org/journals/electronic-materials/articles/10.3389/femat.2023.1246016

DOI=10.3389/femat.2023.1246016

ISSN=2673-9895

ABSTRACT=<p>We report calculations of a DC superheating field <italic>H</italic><sub><italic>sh</italic></sub> 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 <italic>κ</italic>. Simulations were performed for the material parameters of Nb and Nb<sub>3</sub>Sn at different values of <italic>κ</italic> 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 <italic>H</italic><sub><italic>sh</italic></sub> above the bulk superheating fields of both Nb and Nb<sub>3</sub>Sn. For example, an S-I-S structure with a 90-nm-thick Nb<sub>3</sub>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.</p>