Surface transport properties of Fe-based superconductors: The influence of degradation and inhomogeneity

TL;DR

This study investigates how surface degradation and inhomogeneity affect the measurement of superconducting properties in Fe-based superconductors, emphasizing the need for fresh surfaces and localized probing for accurate characterization.

Contribution

It provides detailed analysis of surface degradation effects and surface inhomogeneity on spectroscopic measurements of Fe-based superconductors.

Findings

Surface degrades rapidly in air, suppressing gap features in spectra.

Surface inhomogeneity leads to variability in spectroscopic measurements.

Fresh surfaces and localized measurements are essential for accurate property assessment.

Abstract

Surface properties of Co-doped BaFe2As2 epitaxial superconducting thin films were inspected by X-ray photoelectron spectroscopy, scanning spreading resistance microscopy (SSRM), and point contact spectroscopy (PCS). It has been shown that surface of Fe-based superconductors degrades rapidly if being exposed to air, what results in suppression of gap-like structure on PCS spectra. Moreover, SSRM measurements revealed inhomogeneous surface conductivity, what is consistent with strong dependence of PCS spectra on contact position. Presented results suggest that fresh surface and small probing area should be assured for surface sensitive measurements like PCS to obtain intrinsic properties of Fe-based superconductors.