Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 3: Magnetic Semiconductors
MA 3.5: Vortrag
Montag, 25. Februar 2008, 11:15–11:30, H 1012
Element specific investigations of the strutural and magnetic properties of Co-doped ZnO — •Katharina Ollefs1, Shuangli Ye1, Verena Ney1, Tom Kammermeier1, Andreas Ney1, Fabrice Wilhelm2, Andrei Rogalev2, Tiffany Kaspar3, and Scott Chambers3 — 1Fachbereich Physik, Universität Duisburg-Essen, Duisburg, Germany — 2Pacific Northwest National Laboratory, Richland, Washington, USA — 3ESRF, Grenoble, France
Element specific structural and magnetic properties of the dilute magnetic semiconductor (DMS) Co:ZnO were studied using synchrotron radiation in the hard x-ray regime. It was shown by means of x-ray linear dichroism (XLD) measurements at the Co and Zn K-edge that the local crystallographic environment of both Cobalt and Zinc is the wurtzite structure of the ZnO bulk material, and virtually all Co dopant atoms are incorporated on cation lattice sites. The respective XLD spectra were simulated employing the FDMNES code [1] using the multiple scattering formalism within the muffin tin approximation. Various samples fabricated with different preparation methods display significant differences in the local structural quality. X-ray magnetic circular dichroism (XMCD) and the corresponding element specific hysteresis at the Co K-edge reveal pure paramagnetic behaviour for samples of high structural quality. This is corroborated by SQUID measurements. Similar results are known for the DMS Cr:TiO2 [2].
Supported by the EU, 6. FP, Grant No. MEXT-CT-2004-014195.
[1] Y. Joly, Phys. Rev. B 63, 125120 (2001)
[2] T.C. Kapar et al., Phys. Rev. Lett. 95, 217203 (2005)