Dresden 2011 – scientific programme
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MA: Fachverband Magnetismus
MA 37: Magnetic Semiconductors II
MA 37.5: Talk
Wednesday, March 16, 2011, 15:45–16:00, HSZ 401
Defect induced ferromagnetic and metallic character of ZnO single crystals — •Khalid Muhammad1, Pablo Esquinazi1, Daniel Spemann2, Wolfgang Anwand3, and Gerhard Brauer3 — 1Division of Superconductivity and Magnetism, University of Leipzig, Germany — 2Division of Nuclear Solid State Physics, University of Leipzig, Germany — 3Institut für Strahlenphysik, Forschungzentrum Dresden-Rossendorf, Dresden, Germany
We investigated the magnetic and electrical properties of H-plasma treated ZnO single crystals. Hysteresis loops taken by SQUID magnetometry at 300 K showed a ferromagnetic behavior with a magnetization at saturation ~ 4 emu/g. A successive chemical etching process showed that the major ferromagnetic contribution comes from the first 10 nm layer. A clear semiconductor-metallic transition is observed in H-ZnO single crystals. The saturation magnetization as well as semiconductor-metallic transition temperature depend on the concentration of defects which is closely related to the exposed time of the sample to H-plasma. We observed a negative and positive magneto-resistance behavior. We attribute the ferromagnetic and metallic behavior of H-ZnO single crystals to hydrogen related defects.