Dresden 2003 – wissenschaftliches Programm
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MA: Magnetismus
MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)
MA 14.130: Poster
Dienstag, 25. März 2003, 15:15–19:15, Zelt
Magnetic Carbon: Ferromagnetism in Graphite-Silicon Composites — •U. Schaufuß1, R. R. da Silva2, A. Setzer1, R. Höhne1, P. Esquinazi1, and Y. Kopelevich2 — 1Department of Superconductivity and Magnetism, University of Leipzig, D-04103 Leipzig, Germany — 2Instituto de Fisica, Universidade Estadual de Campinas, 13083-970 Campinas, Brasil
Recently published reports on ferromagnetism in graphite [1], graphite-sulphur composites [2] and polymerised fullerene [3], indicate that under certain circumstances carbon may be ferromagnetic. Possible origins for this ferromagnetism are discussed in the literature: from magnetic impurities to topological defects, sp2 and sp3 hybridised carbon atoms in the graphite structure, and edge states. In this work we studied the magnetic properties of graphite-silicon composites (1:1 mass concentration). The pristine graphite and silicon powders showed no detectable ferromagnetic signal. After mixture, however, the composites showed a weak hysteresis loop up to room temperature (Ms ∼ 10−4 emu/g) and an irreversible behaviour between ZFC and FC. We discuss the contribution of magnetic impurities as well as the X-ray characterization results and annealing effects.
[1] P. Esquinazi et al., Phys. Rev. B 66, 024429 (2002).
[2] J. Moehlecke et al., Phil. Mag. B 82, 1335 (2002).
[3] T. Makarova et al., Nature 413, 716 (2001).