Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 32: Postersession II: Spinstruct./Phase Trans. (1-10); Spinelectronics (11-15); Thin Films (16 - 36); Particles/Clusters (37-45); Multiferroics (46-54); Spindynamics/Spin Torque (55 - 76); Post Deadlines (77-79)

MA 32.15: Poster

Freitag, 29. Februar 2008, 11:15–14:00, Poster E

On the influence of bandstructure on transport properties of magnetic tunnel junctions with Co₂Mn_1−xFe_xSi single and multilayer electrode — Jan Schmalhorst¹, •Daniel Ebke¹, Alexander Weddemann¹, Andreas Hütten¹, Andy Thomas¹, Günter Reiss¹, Andrej Turchanin², Armin Gölzhäuser², Benjamin Balke³, and Claudia Felser³ — ¹Thin Films and Physics of Nanostructures, Department of Physics, Bielefeld University, 33501 Bielefeld, Germany — ²Department of Physics, Bielefeld University, 33501 Bielefeld, Germany — ³Institut für Anorganische und Analytische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany

The transport properties of magnetic tunnel junctions with different (110)-textured Heusler alloy electrode such as Co₂MnSi, Co₂FeSi or Co₂Mn_0.5Fe_0.5Si, AlO_x barrier and Co-Fe counter electrode are investigated. The bandstructure of Co₂Mn_1−xFe_xSi is predicted to show a systematic shift of the position of the Fermi energy E_F through the gap in the minority density of states, while the composition changes from Co₂MnSi towards Co₂FeSi. Although, this shift is indirectly observed by X-ray photo emission spectroscopy, all junctions show a large spin polarization of around 70% at the Heusler alloy / Al-O interface and are characterized by a very similar temperature and bias voltage dependence of the tunnel magnetoresistance. This suggests, that the transport properties of all junctions are dominated by inelastic excitations and not by the electronic bandstructure.