Non-resonant microwave absorption studies on MgB2 thin film

TL;DR

This study investigates weak links in MgB2 thin films using non-resonant microwave absorption, revealing flux trapping, hysteresis, and effects of oxygen content and aging on superconducting properties.

Contribution

It provides new insights into weak link behavior and flux dynamics in MgB2 thin films through detailed NRMA measurements.

Findings

Detection of weak links via low field signals

Observation of hysteresis due to flux trapping

Influence of oxygen content and aging on weak links

Abstract

We report on the presence of weak links in the intermetallic superconductor MgB2 from the non-resonant microwave absorption (NRMA) studies on the MgB2 thin film. The strong low field signal, which is the characteristics of weak links and the presence of hysteresis, which arises due to flux trapping, are observed. The studies are carried out as a function of temperature, microwave power, magnitude of modulation field and the range of field scan. Presence of weak links is discussed in terms of increase in the oxygen content of grain boundaries in the thin film and because of disorder effects arises due to the aging of the sample. The pinning of flux lines with the changes in sweeping direction leads to hysteresis in the NRMA signal and shows the contribution of flux line motion in the power absorption.