Eur. Phys. J. B 15, 649-656 (2000)
https://doi.org/10.1007/s100510051168

Magnetism and superconductivity in Sr₂YRu_1-uCu_uO₆ and magnetism in Ba₂GdRu_1-uCu_uO₆

¹ Physics Department, University of Notre Dame, Notre Dame, IN 46556, USA
² Physics Department, Arizona State University, Tempe, AZ 85287-1504, USA
³ Physikon Research, Inc. P.O. Box 2421 Blaine, WA 98231, USA
⁴ Physics Department, Buffalo State College, Buffalo, NY 14222, USA
⁵ Department of Physics and Materials Science Center, National Tsing Hua University, Hsinchu, Taiwan
⁶ Physics Department, Tamkang University, Tamsui, Taiwan
⁷ Physics Department, College of William and Mary, Williamsburg, VA 23185, USA
⁸ Physics Department, Gonzaga University, Spokane, WA 99258, USA
⁹ Physics Department, Virginia State University, Petersburg, VA 23806, USA
¹⁰ Physics Department, University of British Columbia, Vancouver, B.C., Canada V6T 1Z1
¹¹ TRIUMF, Vancouver, B.C., Canada V6T 2A3
¹² Nuclear Medicine Department, State University of New York, Buffalo, NY 14260, USA

Received: 30 September 1999
Published online: 15 June 2000

Abstract

We report magnetization, surface resistance (), and electron spin resonance (ESR) for non-superconducting Ba₂GdRu₂Cu_uO₆, and find that all three magnetic ions (Gd, Ru, and Cu) are ordered at low temperatures. Both ESR (Gd sublattice) and weak ferromagnetic resonance (dopant Cu) are observed, while no magnetic resonance due to either paramagnetic or ordered Ru is detected. In addition, for superconducting ( K) Sr₂YRu_1-uCu_uO₆, resistivity, muon spin rotation (µ⁺SR), and ⁹⁹Ru Mössbauer absorption are reported. None of the O₆ materials (e.g., Sr₂YRu_1-uCu_uO₆) have cuprate planes, although Cu is employed as a dopant. In Sr₂YRu_1-uCu_uO₆, the Ru moments order at a temperature (∼23 K) below that for the resistive onset of superconductivity, while the Cu orders at a higher temperature, ∼86 K. Therefore at low temperatures, this material exhibits magnetic order, coexisting with diamagnetism. The only non-magnetic layers in the superconducting O₆ structure, the SrO layers, carry holes and exhibit diamagnetic screening characteristic of type-II superconductivity.