Magnetism in superconducting EuFe2As1.4P0.6 single crystals studied by local probes

We have studied the magnetism in superconducting single crystals of EuFe2As1.4P0.6 by using the local probe techniques of zero-field muon spin rotation/relaxation and 151Eu/57Fe Mössbauer spectroscopy. All of these measurements reveal magnetic hyperfine fields below the magnetic ordering temperature TM=18K of the Eu2+ moments. The analysis of the data shows that there is a coexistence of antiferromagnetism, resulting from Eu2+ moments ordered along the crystallographic c-axis, and superconductivity below TSC≈ 10K. We find indications for a change in the dynamics of the small Fe magnetic moments (~0.07 μB) at T⁎≃15K that may be triggering the onset of superconductivity: below T⁎ the Fe magnetic moments seem to be “frozen” within the ab-plane.