Determination of characteristic muon precession and relaxation signals in FeAs and FeAs2, possible impurity phases in pnictide superconductors

Abstract

We report muon-spin relaxation measurements of highly homogeneous samples of FeAs and FeAs2, both previously found as impurity phases in some samples of recently synthesized pnictide superconductors. We observe well defined muon precession in the FeAs sample with two precession frequencies of 38.2(3) and 22.7(9) MHz at 7.5 K, with the majority of the amplitude corresponding to the lower frequency component. In FeAs2 we confirm previous measurements showing that no long-ranged magnetic order occurs above 2 K and measure the muon spin relaxation rate, which increases on cooling. Our results exclude the possibility that previous muon-spin relaxation measurements of pnictide superconductors have been measuring the effect of these possible impurities.

4 pages, 3 figures, corrected Figure 3

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Cited by in corpus (3)

• Enhancement of Superfluid Stiffness, Suppression of Superconducting T_c and Field-induced Magnetism in the Pnictide Superconductor LiFeAs
• Competition/Coexisitence of Magnetism and Superconductivity in Iron Pnictides Probed by Muon Spin Rotation
• Two-dimensional magnetism in the pnictide superconductor parent material SrFeAsF probed by muon-spin relaxation