Regensburg 2010 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 21: Magnetic Materials
MA 21.2: Vortrag
Mittwoch, 24. März 2010, 15:30–15:45, H23
Investigations of highly ordered, half-metallic Co2FeSi single crystals — •C. G. F. Blum1,2, S. Wurmehl1, G. Behr1, C. Hess1, B. Büchner1, J. Barth2, C. A. Jenkins2, C. Felser2, S. Riegg3, A. Reller3, and J. T. Kohlhepp4 — 1Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Helmholtzstraße 20, D-01069 Dresden — 2Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-University, Mainz — 3Universität Augsburg, D-86159 Augsburg — 4Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
In this presentation the properties of highly ordered, halfmetallic Co2FeSi single crystals will be shown. A wide variety of properties, such as half-metallicity and semiconductivity, is found among the Heusler compounds. In order to separate intrinsic and extrinsic properties, high quality single crystals are required. Here we report on crystals of the half-metallic ferromagnet Co2FeSi [1], grown with different techniques. All crystals show excellent ordering, probed by XRD and NMR, resulting in outstanding electrical behavior. Low residual resistivity and high residual-resistivity-ratio is found. All Co2FeSi crystals show a plateau in resistivity below 50 K, which might point to half-metallic ferromagnetism. The cross-over from this unusual to more conventional transport (T2 dependence) around 50 K indicates the onset of spin flip scattering and thus is indispensable for understanding the strong temperature dependence of Co2FeSi tunneling magnetoresistance-devices. The authors gratefully acknowledge financial support by the DFG (Research Unit 559). [1] Blum et al. Appl. Phys. Lett. 95 161903 (2009).