Structure and properties of high-oxygen-pressure annealed Sr$_{1-x}$La$_{x}$Co$_{0.5}$Fe$_{0.5}$O$_{3-d}$ (0$\le $x$\le $0.5)

ORAL

Abstract

Synthesis, oxygen content, structural, magnetic, and resistive properties will be discussed for the Sr$_{1-x}$La$_{x}$Co$_{0.5}$Fe$_{0.5}$O$_{3-d}$ perovskites. The x=0 sample shows oxygen-vacancy ordered Sr$_{8}$Co$_{4}$Fe$_{4}$O$_{23}$ tetragonal I4/mmm structure. With an increase of the La content the materials became oxygen stoichiometric and a lowering of the crystal symmetry is observed from cubic Pm3m (x=0.1 and 0.2) to tetragonal I4/mcm (x=0.3 and 0.4), and finally to monoclinic I12/c1 (x=0.5). All samples show ferromagnetic ordering with the maximum Curie temperature near 290 K at x=0.2. Conductivity is enhanced and small negative magneto-resistance is observed below T$_{C}$. Transport measurements up to 1100$^{o}$C show high conductivity that is affected by the varying oxygen content. Work at NIU was supported by the NSF (DMR-0706610) and at ANL by the U.S. DOE under contract No. DE-AC02-06CH11357.

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Authors

  • S. Remsen

    • Department of Physics, Northern Illinois University, DeKalb, IL and Materials Science Division, Argonne National Laboratory, Argonne, IL
    • Physics Department, Northern Illinois University, DeKalb, IL 60115

  • K. Swierczek

    • Department of Physics, Northern Illinois University, DeKalb, IL and Materials Science Division, Argonne National Laboratory, Argonne, IL

  • B. Dabrowski

    • Department of Physics, Northern Illinois University, DeKalb, IL and Materials Science Division, Argonne National Laboratory, Argonne, IL
    • Physics Department, Northern Illinois University, DeKalb, IL 60115, Materials Science Division, Argonne National Laboratory, Argonne, IL 60439

  • L. Suescun

    • Department of Physics, Northern Illinois University, DeKalb, IL and Materials Science Division, Argonne National Laboratory, Argonne, IL
    • Facultad de Qu\'imica, Universidad de la Rep\'ublica, Montevideo, Uruguay

  • S. Kolesnik

    • Department of Physics, Northern Illinois University, DeKalb, IL and Materials Science Division, Argonne National Laboratory, Argonne, IL
    • Physics Department, Northern Illinois University, DeKalb, IL 60115