Electronic and magnetic phase diagram of superconductors, SmFeAsO1-xFx

A crystallographic and magnetic phase diagram of SmFeAsO1-xFx is determined as a function of x in terms of temperature based on electrical transport and magnetization, synchrotron powder x-ray diffraction, Fe-57 Mossbauer spectra (MS), and Sm-149 nuclear resonant forward scattering (NRFS) measurements. MS revealed that the magnetic moments of Fe were aligned antiferromagnetically at similar to 144K (T-N(Fe)). The magnetic moment of Fe (M-Fe) is estimated to be 0.34 mu(B)/Fe at 4.2K for undoped SmFeAsO; M-Fe is quenched in superconducting F-doped SmFeAsO. Sm-149 NRFS spectra revealed that the magnetic moments of Sm start to order antiferromagnetically at 5.6K (undoped) and 4.4K (T-N(Sm)) (x = 0.069). Results clearly indicate that the antiferromagnetic (AF) Sm sublattice coexists with the superconducting phase in SmFeAsO1-xFx below T-N(Sm), while the AF Fe sublattice does not coexist with the superconducting phase.