High pressure high temperature synthesis and magnetization of magneto-superconducting RuSr2(LnCe2)Cu2O12.25 (Ru-1232) compounds (Ln=Y and Dy)

RuSr2(LnCe2)Cu2O12.25 (Ru-1232) compounds with Ln=Y and Dy being synthesized by high pressure high temperature (6GPa, 1200°C) solid state synthesis route crystallize in space group P4∕mmm in near single phase form with small quantities of SrRuO3 and RuSr2(RE1.5Ce0.5)Cu2O10 (Ru-1222). Both samples exhibit magnetic transitions (Tmag.) at ∼90K with significant branching of zero-field-cooled (ZFC) and field-cooled (FC) magnetization and a sharp cusp in ZFC at ∼70K, followed by superconducting transitions at ∼30K. Both compounds show typical ferromagnetic hysteresis loops in magnetic moment (M) versus field (H) magnetization right up to Tmag. i.e., <90K. To our knowledge these are the first successfully synthesized Ru-1232 compounds in near single phase with lanthanides including Y and Dy. The results are compared with widely reported Gd∕Ru-1222 and Ru-1212 (RuSr2GdCu2O8) compounds. In particular, it seems that the Ru moments magnetic ordering temperature (Tmag.) scales in the c-direction distance between magn...