Abstract
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 $\mathrm{Sr}-{2}^{2+}\mathrm{Y}^{3+}\mathrm{Ru}^{5+}\ mathrm{O}-{6}^{2-}$ (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 ∼ 5-30% Cu-doped (i.e. Cu-concentration/(Cu∈+∈Ru-concentration) ∼ 5-30%) system to be a spin glass superconductor (SGSC) with T c (critical temperature) ∼ 28-31 K and superconducting volume fraction, f sc∼ 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 Y 3+ ions are replaced by Pr 3+ spins, presumably due to enhanced internal pair breaking, and also decreased Cu-O-Cu overlap, owing to Pr 3+ presence; these phenomena are known to exist in the Pr123 compound, PrBa 2Cu 3O 7-δ (δ∼ 0), due to ∼ 10% of Pr 3+ ions having tendency to occupy Ba 2+ 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 2BB′- O 6, B′=Ru) are SG systems and that Cu-doped Ru-double perovskites (A 2BB′-O δ, δ∼ 6, B′=Ru 1-x Cu x, 0<xâ‰0.3) are SG superconductors (SGSCs). Results are discussed.
Original language | English |
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Pages (from-to) | 1249-1262 |
Number of pages | 14 |
Journal | Journal of Superconductivity and Novel Magnetism |
Volume | 24 |
Issue number | 4 |
DOIs | |
Publication status | Published - 2011 May 1 |
Keywords
- Double perovskite
- Frustration
- High-T superconductivity
- Magnetic superconductor
- Ruthenocuprate
- Spin glass
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics