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Layered cobaltites: synthesis, oxygen nonstoichiometry, transport and magnetic properties

Kazimierz Conder 1Andrew Podlesnyak 2Ekaterina Pomjakushina 1Marian Stingaciu 1

1. Paul Scherrer Institut (PSI), WLGA, Villigen PSI 5232, Switzerland
2. Hahn-Meitner-Institute (HMI), Glienicker Str. 100, Berlin D-14109, Germany


Complex cobalt oxide perovskites with general formula RBaCo2O5+x (R=rare earth) have been attracted considerable interests because of their interesting properties: magnetic and metal-insulator transitions, giant magnetoresistance, ionic conductivity and a structural similarity to high temperature superconductors. All the compounds are oxygen non-stoichiometric (0 < x < 1) and the cobalt cations can adopt different oxidation and spin states. Compounds with x ≈ 0.5 display a metal-insulator transition. We have found that this transition is affected by an oxygen isotope substitution [1] and is accompanied by structural changes and melting of the orbital-ordering [2]. Measurements performed on series of polycrystalline samples with different oxygen contents showed that magnetic properties depend not only on oxygen stoichiometry but also on synthesis history. Some preliminary measurements made on TbBaCo2O5.5 crystals grown by Traveling Solvent Floating Zone method will be also presented.

[1] K. Conder, E. Pomjakushina, V. Pomjakushin, M. Stingaciu, S. Streule, A. Podlesnyak, J Phys.: Condens. Matter 17 (2005) 5813

[2] E. Pomjakushina, K. Conder, V. Pomjakushin, Phys. Rev. B 73 (2006) 094203


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Presentation: Invited oral at E-MRS Fall Meeting 2006, Symposium K, by Kazimierz Conder
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 15:34
Revised:   2009-06-07 00:44