Transmission x-ray microscopy at low temperatures - analyzing supercurrents with high spatial resolution

TL;DR

This paper presents a novel low-temperature transmission x-ray microscopy technique that images supercurrents in superconducting films with high spatial resolution, enabling detailed analysis of local supercurrent behavior and its correlation with microstructure.

Contribution

The study introduces a new method combining transmission x-ray microscopy with magnetic mapping to analyze supercurrents at nanometer resolution in superconducting films.

Findings

Achieved magnetic resolution below 100 nm.

Enabled analysis of supercurrents across various temperatures and magnetic fields.

Correlated supercurrent distribution with micro- and nanostructure of the film.

Abstract

Scanning transmission x-ray microscopy has been used to image electric currents in superconducting films at temperatures down to 20 K. The magnetic stray field of supercurrents in a thin YBaCuO film is mapped into a soft-magnetic coating of permalloy. The so created local magnetization of the ferromagnetic film can be detected by dichroic absorption of polarized x-rays. To enable high-quality measurements in transmission geometry the whole heterostructure of ferromagnet, superconductor and single-crystalline substrate has been thinned to an overall thickness of less than 1 micron. With this novel technique local supercurrents can be analyzed in a wide range of temperatures and magnetic fields. A magnetic resolution of less than 100nm together with simultaneously obtained nanostructural data allow the correlation of local supercurrents with the micro- and nanostructure of the superconducting film.