Spatial characterization of the edge barrier in wide superconducting films

TL;DR

This paper investigates the edge barrier effects in wide superconducting films, using a new simple method based on current-voltage measurements to analyze critical states and residual magnetic fields, aiding the development of superconducting detectors.

Contribution

It introduces a straightforward technique to study the critical state at each film edge using current-voltage data, avoiding complex microscopy methods.

Findings

Edge potential barrier influences critical state formation.

A simple method for residual magnetic field estimation was developed.

Insights into edge effects improve understanding of superconducting detector performance.

Abstract

The current-induced destruction of superconductivity is discussed in wide superconducting thin film strips, whose width is greater than the magnetic field penetration depth, in weak magnetic fields. Particular attention is paid to the role of the edge potential barrier (the Bean-Livingston barrier) in critical state formation and detection of the edge responsible for this critical state with different mutual orientations of external perpendicular magnetic field and transport current. Critical and resistive states of the thin film strip were visualized using the space-resolving low-temperature laser scanning microscopy (LTLSM) method, which enables detection of critical current-determining areas on the thin film edges. Based on these observations, a simple technique was developed for investigation of the critical state separately at each film edge, and for the estimation of residual magnetic fields in cryostats. The proposed method only requires recording of the current-voltage characteristics of the thin film in a weak magnetic field, thus circumventing the need for complex LTLSM techniques. Information thus obtained is particularly important for interpretation of studies of superconducting thin film single-photon light emission detectors.