Doping studies of the ferromagnetic superconductor RuSr2GdCu2O8

• Published in: Journal of material chemistry 2001, Vol.11 (1), p.173-178
• Main Authors: MCLAUGHLIN, A. C, JANOWITZ, V, MCALLISTER, J. A, ATTFIELD, J. P
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Effects of crystal defects, doping and substitution; Exact sciences and technology; Inorganic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Superconductivity; Transition temperature variations
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/b002952l

Solid solutions of the ferromagnetic superconductor Ru1-xMxSr2GdCu2O8 were prepared for M = Sn or Nb. Up to 7.5% Sn and 20% Nb were incorporated into the structure, and powder diffraction and physical measurements showed that substitution occurs at the Ru site. The ferromagnetic moment in the ruthenate layers was suppressed upon Sn and Nb substitution, and the Curie temperature dropped from 136 K in the undoped material to 103 K in Ru0.8Nb0.2Sr2GdCu2O8. The onset of superconductivity increased from 19 K in the 15% Nb doped sample to 38 K in the parent compound and to 50 K in the 7.5% Sn doped sample, showing a tuning of the superconducting transition by charge transfer. Structural changes upon M doping were determined from powder synchrotron XRD and, for one sample, neutron diffraction using the high flux diffractometer GEM to compensate for the high absorption of natural Gd. 19 refs.