MuSR studies of RE(O,F)FeAs (RE = La, Nd, Ce) and LaOFeP systems:   possible incommensurate/stripe magnetism and superfluid density
  Muon spin relaxation (MuSR) measurements in iron oxy-pnictide systems have revealed: (1) commensurate long-range order in undoped LaOFeAs; (2) Bessel function line shape in La(O0.97F0.03)FeAs which indicates possible incommensurate or stripe magnetism; (3) anomalous weak magnetism existing in superconducting LaOFeP, Ce(O0.84F0.16)FeAs, and Nd(O0.88F0.12)FeAs but absent in superconducting La(O0.92F0.08)FeAs; and (4) scaling of superfluid density and Tc in the Ce, La, and Nd-FeAs superconductors following a nearly linear relationship found in cuprates. 
J.P. Carlo, Y.J. Uemura, T. Goko, G.J. MacDougall, J.A. Rodriguez, W.   Yu, G.M. Luke, Pengcheng Dai, N. Shannon, S. Miyasak...