Dresden 2011 – scientific programme
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MA: Fachverband Magnetismus
MA 36: Micro- and Nanostructured Magnetic Materials III
MA 36.2: Talk
Wednesday, March 16, 2011, 15:00–15:15, HSZ 103
Reversible tuning of the magnetic moment of nanocrystalline maghemite/platinum composites by electrochemical charging — •Thomas Traußnig1, Stefan Topolovec1, Kashif Nadeem2, Dorothée Vinga Szabo3, Heinz Krenn2, and Roland Würschum1 — 1Inst. f. Materialphys., TU Graz, Petersgasse 16, 8010 Graz, Austria — 2Inst. f. Physik, Univ. Graz, Graz, Austria — 3Inst. f. Materialforschung III, KIT, Karlsruhe, Germany
Recent studies on nanocrystalline metals demonstrated that their physical properties, such as magnetic moment or conductivity, can be reversibly tuned by electrochemical charging owing to the high interfacial charge carrier densities and the high surface-to-volume ratio. In the present work this concept of charge-induced property tuning is extended to nanocrystalline metal oxides. Reversible variations of the magnetic moment of up to 10.4% could be achieved by making use of a γ-Fe2O3/Pt nanocomposite. The maghemite nanocrystallites with a small crystallite size and a narrow size distribution were prepared by microwave plasma synthesis. Intermixing the ferrimagnetic maghemite nanocrystallites with paramagnetic Pt nanocrystallites results in a conductive porous network which can be charged electrochemically upon immersing in 1-M KOH electrolyte. Magnetic measurements were performed in-situ by SQUID magnetometry. The reversible variations of the magnetic moment in the 10%-regime are considered to arise from surface modifications of the maghemite nanoparticles due to reversible oxygen adsorption/desorption processes. Financial support by the FWF Austrian Science Fund is appreciated (project S10405-N16).