Complex cobalt oxide perovskites with general formula RBaCo₂O_5+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 TbBaCo₂O_5.5 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

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/7906 must be provided.

1. Cuprate spin ladder crystals grown by floating zone method under elevated oxygen pressure
2. Layered cobaltites: single crystal growth, structure, transport and magnetic properties
3. Anharmonicity and weak modes assignment in LaSrCuO with oxygen isotopic substitution
4. Giant magnetoresistivity in single crystals of rare earth layered cobaltites