Regensburg 2004 – wissenschaftliches Programm
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O: Oberflächenphysik
O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)
O 28.83: Poster
Mittwoch, 10. März 2004, 16:00–19:00, Bereich C
Resonant X-Ray scattering from TbBaCo2O5.5 — •N.V. Kasper1, P. Wochner1, G. Carbone1, A. Vigliante2, D. Mannix3, and G. Jakob4 — 1Max-Planck-Institut für Metallforschung, Stuttgart, Germany — 2Bruker AXS, Karlsruhe, Germany — 3European Synchrotron Radiation Facility, Grenoble, France — 4Institut für Physik, Universität Mainz, Mainz, Germany
Resonant X-ray scattering at the Co K-edge from epitaxial films and single crystals of TbBaCo2O5.5 cobaltite with perovskite structure has been studied in insulating and metallic states. Polarization, energy and azimuthal dependences of the intensity of (016), (116), and (310) Bragg peaks were measured. Strong oscillations of the resonantly scattered intensity were observed both in σ’ and π’ channels. The scattered signal changes very weakly during the metal-insulator phase transition.
The azimuthal oscillations of the scattered signal are attributed to the tensor character of the anomalous scattering factor of Co. Using this concept we have developed a model, describing very well the measured azimuthal oscillations. On the basis of the obtained experimental results and literature data it is argued that this anisotropy of the anomalous scattering factor of Co is caused mainly by distortions of the local surrounding of cobalt ions and not by anisotropies due to ordering of electronic orbitals of Co.