Ferromagnetism and superconductivity in RuSr2RCu2O8 (R = Sm, Eu, Gd)

Polycrystalline single phase RuSr2RCu2O8 (R = Sm, Eu, Gd) samples have been synthesized by a new solid state reaction. We found superconductivity in t wo rare earths R = Sm and Eu with T-s(R=0) = 12 and 17 K, whereas ferromagn etism occurs at T-c = 146 and 139 K in these samples, respectively, in addi tion to the previously reported RuSr2GdCu2O8 with T-s = 36 K and T-c = 136 K. Huge resistivity broadening phenomena common to the high T-c superconduc tors were observed in magnetic fields. which suggest that strong enhancemen t of superconducting fluctuations due to magnetic field, suppresses the occ urrence of superconducting phase coherence in these compounds. (C) 2001 Pub lished by Elsevier Science B.V.