|
|||||
|
|
Response of La0.8Sr0.2CoO3-δ to perturbations on the CoO3 sublattice |
|
| Authors: | Z Németh Z Homonnay F Árva Z Klencsár E Kuzmann A Vértes J Hakl S Mészáros K Vad P F de Châtel G Gritzner Y Aoki H Konno J M Greneche |
| Institution: | 1. Department of Nuclear Chemistry, E?tv?s Loránd University, P.O. Box 32, Budapest, 1518, Hungary 2. Department of Mathematics and Physics, University of Kaposvár, Guba Sándor u. 40., Kaposvár, 7400, Hungary 3. Research Group of Chemical Research Center Hungarian Academy of Sciences at ELTE, P.O. Box 32, Budapest, 1518, Hungary 4. Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, 4001, Debrecen, Hungary 5. Institut für Chemische Technologie Anorganischer Stoffe, Johannes Kepler Universit?t, 4040, Linz, Austria 6. Division of Materials Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, 060-8628, Japan 7. Laboratoire de Physique de l'état Condensé, UMR CNRS 6087 Université du Maine, 72085, Le Mans Cedex 9, France |
| Abstract: | Emission and transmission M?ssbauer studies of La0.8Sr0.2CoO3-δ perovskites doped with ∼0.02 stoichiometric units of oxygen vacancy or 2.5% iron corroborate the occurrence of electronic phase separation in these systems. The effect of the small perturbation of the CoO3 sublattice with either iron ions or oxygen vacancies on the bulk magnetization as well as on the M?ssbauer spectra is in good agreement with the double exchange based cluster model. The magnetoresistance does not show any peak near the Curie temperature, but reaches -84% in a field of 7.5 T at T = 8 K. Below TC ≈ 180 K the M?ssbauer spectra distinctly include the contribution from paramagnetic and ferromagnetic regions, providing direct evidence for phase separation. No contribution to the spectra from Fe4+ ions can be observed, which is an unambiguous evidence that at low concentration iron (either directly doped or formed from 57Co by nuclear decay) is accommodated in the cobaltate lattice as Fe3+ ion. |
| Keywords: | 75 47 Gk Colossal magnetoresistance 75 30 Kz Magnetic phase boundaries 75 10 Nr Spin-glass and other random models 71 30 +h Metal-insulator transitions and other electronic transitions 76 80 +y Mossbauer effect other gamma-ray spectroscopy |
| 本文献已被 SpringerLink 等数据库收录！ | |