Determination of Superconducting Gap of SmFeAsFxO1-x Superconductors by Andreev Reflection Spectroscopy

TL;DR

This study measures the superconducting gap in SmFeAsFxO1-x superconductors using Andreev reflection spectroscopy, revealing a BCS-like temperature dependence and providing insights into the gap's intrinsic properties.

Contribution

It presents the first detailed measurement of the intrinsic superconducting gap in SmFeAsFxO1-x using Andreev reflection spectroscopy, highlighting its contact independence and BCS-like behavior.

Findings

Superconducting gap value of 13.34 meV for x=0.15

Gap decreases with temperature and vanishes at Tc

Gap behavior is similar to BCS superconductors

Abstract

The superconducting gap in FeAs-based superconductor SmFeAs(O1-xFx) (x = 0.15 and 0.30) and the temperature dependence of the sample with x = 0.15 have been measured by Andreev reflection spectroscopy. The intrinsic superconducting gap is independent of contacts while many other "gap-like" features vary appreciably for different contacts. The determined gap value of 2D = 13.34 +/-0.47 meV for SmFeAs(O0.85F0.15) gives 2D/kBTC = 3.68, close to the BCS prediction of 3.53. The superconducting gap decreases with temperature and vanishes at TC, in a manner similar to the BCS behavior but dramatically different from that of the nodal pseudogap behavior in cuprate superconductors.