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

• Coexistence of superconductivity and magnetism.
• Study of magnetism using 3 different local techniques.
• Change at Fe magnetic moment dynamics below superconducting transition temperature.

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≈TSC≈ 10 K. We find indications for a change in the dynamics of the small Fe magnetic moments (~0.07 μBμB) 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.