Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 3: Magnetic Semiconductors
MA 3.4: Vortrag
Montag, 25. Februar 2008, 11:00–11:15, H 1012
X-band magnetic resonance investigation of wide band gap dilute magnetic semiconductors — •Tom Kammermeier1, Verena Ney1, Shuangli Ye1, Subhabrata Dhar2, Klaus Ploog2, Fang-Yuh Lo3, Andreas Wieck3, Tiffany Kaspar4, and Scott Chambers4 — 1Experimentalphysik, Universität Duisburg-Essen, Duisburg — 2Paul-Drude-Institut, Berlin — 3Angewandte Festkörperphysik, Ruhr-Universität Bochum — 4Pacific Northwest National Laboratory, Richland, Washington USA
ZnO and GaN are the most prominent wide band gab semiconductors expected to show ferromagnetic behaviour when doped with transition metals or rare earths. Although intensely studied by several groups the experimental results are inconsistent up to now [1,2]. We present electron paramagnetic resonance (EPR) studies on Co:ZnO, Gd:ZnO and Gd:GaN, respectively. Different growth techniques enable investigations of magnetic resonance properties in relation to structural quality and dopant content. Here we discuss magnetic anisotropies caused by crystal fields and/or phase separation as well as temperature dependencies. As EPR is a very sensitive technique for investigation of any kind of paramagnetic impurities, we can compare our findings with models favouring an interplay of the dopant with defects as the origin of ferromagnetic like behaviour in these materials [3].
[1] S. Dhar et al, Appl. Phys. Lett. 89, 062503 (2006) [2] A. Ney et al., Appl. Phys. Lett. 90, 252515 (2007) [3] S. Dhar et al., PRL 94, 037205 (2005)