Robustness of superconductivity to competing magnetic phases in tetragonal FeS

Abstract

We have determined the superconducting and magnetic properties of a hydrothermally synthesized powder sample of tetragonal FeS using muon spin rotation ($\ensuremath{\mu}\mathrm{SR})$. The superconducting properties are entirely consistent with those of a recently published study, showing fully gapped behavior and giving a penetration depth of ${\ensuremath{\lambda}}_{ab}=204(3)$ nm. However, our zero-field $\ensuremath{\mu}\mathrm{SR}$ data are rather different and indicate the presence of a small, nonsuperconducting magnetic phase within the sample. These results highlight that sample-to-sample variations in magnetism can arise in hydrothermally prepared phases, but interestingly the superconducting behavior is remarkably insensitive to these variations.