Structural, Transport and Magnetic Properties of the Doped Magnetic Superconductor Ru-1212

摘要

Single phase materials of RuSr_2Gd_(0.5)Eu_(0.5)Cu_2O_8 (Ru-1212Gd_(0.5)Eu_(0.5)) and Ru(Sr_(1-x)Na_x)_2GdCu_2O_8 (0 ≤ x ≤ 0.10) have been successfully synthesized in oxygen at 1065 °C. DC-resistivity and magnetic susceptibility measurements show a decreases of the superconducting transition temperature T_c from 46 K in the pure Gd compound to 41 K in Ru-1212Gd_(0.5)Eu_(0.5), whereas the magnetic ordering temperature T_M does not change. The influence of the monovalent substitution Na~+ for Sr~(2+) on the properties of Ru-1212Gd is investigated and compared with previous work. Finally, the effects of Cu substituted RuSr_2Gd(Cu_(1-x)M)x)_2O_8 compounds, where M is Co, Ni and Ga for 0 ≤ x ≤ 0.03 are reported and compared with similar doping experiments in other high-T_c superconductors.