Magnetic and Superconducting Properties of Doped and Undoped Double Perovskite Sr2YRuO6

We report here SQUID (magnetization) measurements, along with supporting specific heat, Raman, SEM (scanning electron microscope), EDX (energy dispersive X-ray) and XRD (X-ray diffraction) measurements, on Cu-doped and undoped double perovskite (abbreviated as SrY2116) system grown as single crystal using high-temperature solution growth technique. These measurements show the undoped system to be a nonmetallic (insulating) spin glass (SG) and the similar to 5-30% Cu-doped (i.e. Cu-concentration/(Cu + Ru-concentration) similar to 5-30%) system to be a spin glass superconductor (SGSC) with T (c) (critical temperature) similar to 28-31 K and superconducting volume fraction, f (sc)similar to 2.2-9%. To mention, similar measurements done on undoped and Cu-doped BaY2116 and BaPr2116 systems show for them the same (SG, SGSC) behaviors. However they show a decrease in T (c) and f (sc) when diamagnetic Y3+ ions are replaced by Pr3+ spins, presumably due to enhanced internal pair breaking, and also decreased Cu-O-Cu overlap, owing to Pr3+ presence; these phenomena are known to exist in the Pr123 compound, PrBa2Cu3O7-delta (delta similar to 0), due to similar to 10% of Pr3+ ions having tendency to occupy Ba2+ sites. Measurements done on undoped and Cu-doped SrHo2116 show similar SG and SGSC properties. Further, the undoped and Cu-doped SrY2116 crystals grown by hydrothermal growth technique (i.e., grown using lower temperature and high pressure) show same behaviors. From these investigations it can be said that the undoped Ru-double perovskites (A(2)BB'O-6, B'=Ru) are SG systems and that Cu-doped Ru-double perovskites (A(2)BB'O (delta) , delta similar to 6, B'=Ru1-x Cu (x) , 0 < xa parts per thousand(2)0.3) are SG superconductors (SGSCs). Results are discussed.