Enhancement of the Curie temperature in NdBaCo$_{2}$O$_{5.5}$ by Ca substitution

ORAL

Abstract

RBaCo$_{2}$O$_{5.5}$ (R=rare earth or Y) undergoes a sequence of magnetic and electronic transitions between antiferromagnetic/ferrimagnetic/paramagnetic and insulating/paramagnetic metallic states with respective transition temperatures T$_{N}$(230-260 K)$<$T$_{C}$(250-290 K)$<$T$_{MI}(\sim $360 K). We have synthesized a Nd$_{1-x}$Ca$_{x}$BaCo$_{2}$O$_{5.5}$ series (0$\le $x$\le $0.2) of cation- [(Nd,Ca)/Ba] and oxygen vacancy ordered materials and investigated them by neutron diffraction, magnetization, electronic and thermal transport. We observe that upon Ca doping T$_{N}$ is decreasing to 0 for x=0.1 and T$_{C}$ is increasing and coincides with T$_{MI}$ for x$>$0.12, which weakly changes with Ca substitution from $\sim $360 to $\sim $340 K. This is the largest enhancement of T$_{C}$ ever observed for these cobaltites. Unlike the hole doping by adding oxygen, the Ca doping does not disrupt the cation and oxygen vacancy orderings up to x=0.2.

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Authors

  • S. Kolesnik

    Physics Department, Northern Illinois University, DeKalb, IL 60115, 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, Department of Physics, Northern Illinois University, DeKalb, IL 60115

  • B. Dabrowski

    MSD, Argonne National Laboratory, and Physics, Northern Illinois University, De Kalb IL, USA, Physics Department, Northern Illinois University, DeKalb, IL 60115, Physics Department, Northern Illinois University, DeKalb, IL 60115 and Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, Department of Physics, Northern Illinois University, DeKalb, IL and Materials Science Division, Argonne National Laboratory, Argonne, IL, Northern Illinois University, Physics Department, Northern Illinois University, DeKalb IL 60115, Department of Physics, Northern Illinois University, DeKalb, IL 60115

  • O. Chmaissem

    MSD, Argonne National Laboratory, and Physics, Northern Illinois University, De Kalb IL, USA, Physics Department, Northern Illinois University, DeKalb, IL 60115, Physics Department, Northern Illinois University, DeKalb, IL 60115 and Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, Department of Physics, Northern Illinois University, DeKalb, IL and Materials Science Division, Argonne National Laboratory, Argonne, IL, Department of Physics, Northern Illinois University, DeKalb, IL 60115

  • K. Swierczek

    Materials Science Division, Argonne National Laboratory, Argonne, IL and University of Science and Technology, Krakow, Poland