Muon-spin rotation studies of SmFeAsO_0.85 and NdFeAsO_0.85 superconductors

TL;DR

This study measures the magnetic penetration depth in SmFeAsO_0.85 and NdFeAsO_0.85 superconductors using muon-spin-rotation, revealing their classification as unconventional superconductors within the Uemura scheme.

Contribution

It provides the first measurements of b in these specific Fe-based superconductors and analyzes their placement within the Uemura classification scheme.

Findings

b values are 189(5) nm and 195(5) nm for Sm and Nd samples.

Both materials fall into the same class of unconventional superconductors.

The results support the universality of the Uemura relation for Fe-based superconductors.

Abstract

Measurements of the in-plane magnetic field penetration depth \lambda_{ab} in Fe-based superconductors with the nominal composition SmFeAsO_0.85 (T_c\simeq52K) and NdFeAsO_0.85 (T_c\simeq51K) were carried out by means of muon-spin-rotation. The absolute values of \lambda_{ab} at T=0 were found to be 189(5)nm and 195(5)nm for Sm and Nd substituted samples, respectively. The analysis of the magnetic penetration depth data within the Uemura classification scheme, which considers the correlation between the superconducting transition temperature T_c and the effective Fermi temperature T_F, reveal that both families of Fe-based superconductors (with and without fluorine) falls to the same class of unconventional superconductors.