Magnetism in superconducting EuFe$_2$As$_{1.4}$P$_{0.6}$ single crystals   studied by local probes
  We have studied the magnetism in superconducting single crystals of EuFe2 As1.4 P0.6 by using the local probe techniques of zero-field muon spin rotation/relaxation and 151 Eu/57 Fe M\"ossbauer spec- troscopy. All of these measurements reveal magnetic hyperfine fields below the magnetic ordering temperature TM = 18 K of the Eu2+ moments. The analysis of the data shows that there is a coexistence of ferromagnetism, resulting from Eu2+ moments ordered along the crystallographic c-axis, and superconductivity below TSC \approx 15 K. We find indications for a change in the dynamics of the small Fe magnetic moments (\sim 0.07 \mu B) at the onset of superconductivity: below TSC the Fe magnetic moments seem to be "frozen" within the ab-plane. 
J. Munevar, H. Micklitz, M. Alzamora, C. Arguello, T. Goko, F.L. Ning,   A.A. Aczel, T. Munsie, T.J. Williams, G.F. Chen, W....
cond-mat.str-el