Influence of the spreading resistance on the conductance spectrum of planar hybrid thin film SNS' junctions based on iron pnictides

TL;DR

This paper investigates how spreading resistance affects conductance spectra in planar hybrid SNS' junctions with iron pnictides, introducing an empirical correction method for accurate measurements.

Contribution

It presents a novel empirical method to correct for spreading resistance effects in conductance spectra of hybrid SNS' junctions involving iron pnictides.

Findings

Spreading resistance significantly influences conductance measurements.

The empirical correction method effectively isolates the junction's true conductance.

The approach simplifies analysis of superconducting properties in hybrid junctions.

Abstract

To investigate the superconducting properties of iron pnictides we prepared planar hybrid SNS' junctions in thin film technology with a pnictide base electrode, a gold barrier layer and a lead counter electrode. Our design allows characterization of the electrodes and the junction independently in a 4-probe method. We show how both electrodes influence the measured spectra due to their spreading resistance. While the Pb electrode has a constant resistance above its $T_c$, the contribution of the pnictide electrode is clearly current-dependent and thus it needs a more advanced method to be corrected. We present an empirical method, which is simple to apply and allows to deal with the spreading resistance in our junctions to recalculate the actual conductance and voltage of one junction at given temperature.