Nodal superconductivity coexists with low-moment static magnetism in single-crystalline tetragonal FeS: A muon spin relaxation and rotation study

摘要

We report muon spin relaxation and rotation (μSR) measurements on hydrothermally grown single crystals of superconducting tetragonal FeS. which help to clarify the controversial magnetic slate and superconducting gap symmetry of this compound. μSR time spectra were obtained from 280 K down to 0.025 K in zero field (ZF) and applied fields up to 75 mT. In ZF. the observed loss of initial asymmetry (signal amplitude) and increase of depolarization rate A_(ZF)- below 13 K indicate the onset of static magnetism, which coexists with superconductivity below T_c. TF μSR results indicate a linear temperature dependence of the superfluid density at low temperature, consistent with nodal superconductivity. The s+d-wave model gives the best fit to the observed temperature and field dependencies, and yields an in-plane penetration depth value λ_(ab)(T=0) = 241(3) nm.