Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Spin dependent Transport Phenomena

MA 35.5: Vortrag

Mittwoch, 9. März 2016, 16:00–16:15, H33

Ab initio investigations on the magneto-thermoelectric properties of the Co₂TiZ (Z= Si, Ge, Sn) Heusler alloys — •Voicu Popescu¹, Peter Kratzer¹, Diemo Ködderitzsch², and Hubert Ebert² — ¹Faculty of Physics and CENIDE, University Duisburg-Essen, 47057 Duisburg, Germany — ²Department Chemie/Physikalische Chemie, Ludwig Maximilian University, 81377 Munich, Germany

The half-metallic ferromagnetic full Heusler alloys Co₂TiZ (Z= Si, Ge, Sn) have been experimentally reported to exhibit a negative Seebeck coefficient with a large absolute value for a metal. Moreover, the temperature dependence of both the resistivity and the Seebeck coefficient display a cusp at the magnetic Curie temperature, a behavior that was so far insufficiently explained by standard band structure approaches.

We investigate, by means of ab initio calculations performed within the framework of the full potential spin-polarized relativistic Korringa-Kohn-Rostoker Green function method, to what extent yet unexplored effects are influencing the magneto-transport properties in these systems. We account for electron correlations (GGA+U), substitutional disorder and temperature dependent scattering of the charge carriers by lattice vibrations and spin fluctuations. Among these, we show that only the last two factors are considerably improving the qualitative and quantitative agreement between the calculated and the reported experimental results.