Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 83: [MA] Focussed Session "X-ray absorption spectra - state of the art of theory and experiment" (jointly with DS, HL, MM, O)
O 83.8: Vortrag
Donnerstag, 17. März 2011, 18:40–19:00, HSZ 403
Co-doped ZnO epitaxial films: signs of phase separation by means of hard x-ray absorption spectroscopy — •Verena Ney, Shunagli Ye, Katharina Ollefs, Tom Kammermeier, and Andreas Ney — Fakultät für Physik and CeNIDE, Universität Duisburg-Essen, 47057 Duisburg, Germany
X-ray absorption spectroscopy (XAS) using linear and circular polarized light offers a powerful toolbox of element-specific structural, electronic, and magnetic probes that is especially well suited for studying Zn1−xCoxO (Co:ZnO) to unravel its intrinsic properties. We demonstrate that as long as phase separation or excessive defect formation is absent, Co:ZnO is paramagnetic [1]. We can establish quantitative thresholds based on four reliable quality indicators using XAS; samples which show ferromagnet-like behaviour fail to meet these quality indicators, and complementary experimental techniques indeed prove phase separation [2]. Careful analysis of XAS spectra is shown to provide valuable information of secondary phases in a highly sensitive, non-destructive manner.
[1] A. Ney et al., Phys. Rev. Lett. 100, 157201 (2008).
[2] A. Ney et al., New J. Phys. 12, 013020 (2010).
This work is supported by the DFG (Heisenberg-Programm) and the EU (MEXT-CT-2004-014195)