Coexistence of magnetic fluctuations and superconductivity in the pnictide high temperature superconductor SmFeAsO$_{1-x}$F$_{x}$ measured by muon spin rotation

TL;DR

This study uses muon-spin rotation to investigate the coexistence of magnetic fluctuations and superconductivity in SmFeAsO$_{1-x}$F$_{x}$, revealing that spin fluctuations may play a role in the unconventional superconducting state.

Contribution

It provides experimental evidence of magnetic fluctuations near the superconducting transition in pnictide superconductors, highlighting their potential role in the pairing mechanism.

Findings

Enhanced slow spin fluctuations near superconducting transition

In-plane penetration depth estimated at 190 nm

Pnictide superconductors follow Uemura relation between Tc and lambda^-2

Abstract

Muon-spin rotation experiments were performed on the pnictide high temperature superconductor SmFeAsO$_{1-x}$F$_{x}$ with x=0.18 and 0.3. We observed an unusual enhancement of slow spin fluctuations in the vicinity of the superconducting which suggests that the spin fluctuations contribute to the formation of an unconventional superconducting state. An estimate of the in-plane penetration depth $\lambda_{ab}(0)=190(5)$\thinspace nm was obtained, which confirms that the pnictide superconductors obey an Uemura-style relationship between $T_{\mathrm{c}}$ and $\lambda_{ab}(0)^{-2}$.