Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Magnetic Half-metals and Oxides I

MA 15.4: Vortrag

Mittwoch, 24. März 2010, 11:00–11:15, H22

Anomalous transport properties of the halfmetallic ferromagnets Co₂TiSi, Co₂TiGe, and Co₂TiSn. — •B. Balke¹, T. Graf¹, J. Barth¹, G.H. Fecher¹, A. Shkabko², A. Weidenkaff², and C. Felser¹ — ¹Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg - University, Mainz, Germany — ²EMPA, Swiss Federal Laboratories for Materials Testing and Research, Solid State Chemistry and Catalysis, CH-8600 Duebendorf, Switzerland

This work reports on the theoretical and experimental investigations of Co₂TiZ (Z = Si, Ge, or Sn) compounds. Band structure calculations predict half-metallic ferromagnetism for all three compounds with only two bands crossing the Fermi energy in the majority channel. The magnetic moments fulfill the Slater-Pauling rule and the Curie temperatures are well above room temperature. All compounds show a metallic like resistivity for low temperatures up to their Curie temperature, above the resistivity changes to semiconducting like behavior. Additionally, we observe a large negative magnetoresistance of 55 % for Co₂TiSn at room temperature. The Seebeck coefficients are negative for all three compounds and reach their maximum values at their respective Curie temperatures and stay almost constant up to 950 K. The combination of half-metallicity and the constant large Seebeck coefficient over a wide temperature range makes these compounds interesting materials for further spincaloric investigations and thermoelectric applications.This work is financially supported by "Stiftung Innovation Rheinland-Pfalz" and by the DfG (P1 and P7, FOR 559).