Short note on magnetic impurities in SmFeAsO$_{1-x}$F$_x$ (x=0, 0.07) compounds revealed by zero-field $^{75}$As NMR

TL;DR

This study uses zero-field $^{75}$As NMR to investigate magnetic impurities in SmFeAsO$_{1-x}$F$_x$ superconductors, revealing FeAs clusters and demonstrating NMR's effectiveness in assessing material quality.

Contribution

First zero-field $^{75}$As NMR analysis of SmFeAsO$_{1-x}$F$_x$ compounds, identifying FeAs clusters and establishing NMR as a sensitive quality probe.

Findings

Detection of $^{75}$As resonance at ~265 MHz indicating FeAs clusters

NMR as a tool for evaluating superconductor material quality

Identification of magnetic impurities in the compounds

Abstract

We have performed zero-field $^{75}$As nuclear magnetic resonance study of SmFeAsO$_{1-x}$F$_x$ (x=0, 0.07) polycrystals in a wide frequency range at various temperatures. $^{75}$As resonance line was found at around 265 MHz revealing the formation of the intermetallic FeAs clusters in the new layered superconductors. We have also demonstrated that NMR is a sensitive tool for probing the quality of these materials.