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TT: Fachverband Tiefe Temperaturen

TT 32: Correlated Electrons: Poster Session

TT 32.31: Poster

Thursday, February 28, 2008, 14:00–18:00, Poster B

Preparation and Characterization of BaCoO2 and Sr-doped EuCoO3 — •Marco Reuther, Kerstin Dönecke, John Mydosh, Thomas Lorenz, and Martin Valldor — II. Physikalisches Institut, Universität zu Köln, Germany

We have prepared polycrystals of BaCoO2 and (Eu,Sr)CoO3. BaCoO2 is an air sensitive material whose physical properties are hardly explored. The structure of BaCoO2 is trigonal with Co2+ ions in tetrahedral coordination [1]. Our magnetization measurements suggest a canted antiferromagnetic order with TN≈370 K.

EuCoO3 is insulating with Co3+ ions in the nonmagnetic low spin state up to about 400K [2]. Already small amounts of Sr induce a ferromagnetic order with TC≈160 K due to the presence of Co4+ ions. Because of Co3+ remains in the low spin state we can observe the pure magnetic moment of Co4+ by Sr-doping. The electrical resistivity decreases with Sr but remains insulating.

[1] U. Spitsbergen et al., Acta Cryst. 13, 197 (1960).

[2] J. Baier et al., PRB 71, 014443 (2005)

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