Evidence for Nodal superconductivity in Sr$_{2}$ScFePO$_{3}$

TL;DR

This study investigates the superconducting properties of Sr₂ScFePO₃ using point contact Andreev reflection, revealing a zero bias conductance peak suggestive of nodal superconductivity, consistent with recent theoretical models.

Contribution

It provides experimental evidence supporting the presence of nodal superconductivity in Sr₂ScFePO₃ through detailed spectroscopic analysis.

Findings

Zero bias conductance peak disappears at Tc

Peak survives up to 7T magnetic field at 2K

Observations are consistent with a nodal or d-wave order parameter

Abstract

Point contact Andreev reflection spectra have been taken as a function of temperature and magnetic field on the polycrystalline form of the newly discovered iron-based superconductor Sr2ScFePO3. A zero bias conductance peak which disappears at the superconducting transition temperature, dominates all of the spectra. Data taken in high magnetic fields show that this feature survives until 7T at 2K and a flattening of the feature is observed in some contacts. Here we inspect whether these observations can be interpreted within a d-wave, or nodal order parameter framework which would be consistent with the recent theoretical model where the height of the P in the Fe-P-Fe plane is key to the symmetry of the superconductivity. However, in polycrystalline samples care must be taken when examining Andreev spectra to eliminate or take into account artefacts associated with the possible effects of Josephson junctions and random alignment of grains.