Planar hybrid superconductor-normal metal-superconductor thin film junctions based on BaFe1.8Co0.2As2

TL;DR

This study reports on the fabrication and analysis of planar SNS' thin film junctions using BaFe1.8Co0.2As2, revealing transport properties dominated by Andreev reflection and introducing a method to correct electrode influences.

Contribution

We developed a novel junction structure that enables electrode characterization and correction of their influence on conduction spectra in iron-based superconductor junctions.

Findings

Conductivity behavior dominated by Andreev reflection

Electrode properties significantly influence transport measurements

Corrected spectra align with extended BTK-model

Abstract

To investigate the transport properties of iron based superconductors, we prepared planar hybrid superconductor-normal metal-superconductor (SNS') thin film junctions with BaFe1.8Co0.2As2 as base electrode. As counter electrode we used a lead indium alloy, while the normal metal layer was formed by thin gold films. Temperature dependent measurements of the electrical conductivity were strongly influenced by the properties of the electrodes. We developed a junction structure that allows us to characterize the electrodes, too, including the behavior of their normal state resistance in order to correct their influences on the conduction spectra. The corrected conductivity of the junction was described within an extended BTK-model and shows a behavior dominated by Andreev reflexion.