Magneto-Superconductivity of Rutheno-Cuprates
  We reviewed our various results on rutheno-cuprate magneto-superconductors RuSr2GdCu2O8-d (Ru-1212) and RuSr2(Gd0.75Ce0.25)2Cu2O10-d (Ru-1222) synthesized by NPHT process. Also reviewed are the results for HPHT synthesized various Ln/Ru-1212, 1222 and 1232. Various important results being reported by other international groups are incorporated and discussed critically. It is observed, that it is difficult to control the oxygen content of Ru-1212, though the same is possible up to some extent for Ru-1222.   Samples of both phases exhibited superconductivity, presumably in the CuO2 plane at low temperatures coexisting with magnetic ordering of Ru spins of predominantly antiferromagnetic type below 140 K having a ferromagnetic component appearing below 20 K. Electrical conductivity measurements indicate that the RuO2-d layer takes part in conduction besides the CuO2 plane. The magnetic ordering temperature of Ru spins is seen as a clear hump in the resistivity measurements, establishing the magnetic spins interaction with the conduction carriers. 
V.P.S. AWANA (National Physical Laboratory, New Delhi India)