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MA: Magnetismus

MA 3: Spin-Dependent Transport Phenomena I

MA 3.6: Vortrag

Montag, 27. März 2006, 11:30–11:45, HSZ 103

Characteristics of the half-metallic character of Co₂MnSi Heusler alloy — •Ning-Ning Liu¹, Daniel Ebke¹, Marc Sacher¹, Jan Schmalhorst¹, Günter Reiss¹, and Andreas Hütten² — ¹Fakultät für Physik, Universität Bielefeld, D-33615 Bielefeld, Germany — ²Institut für Nanotechnologie, Forschungszentrum Karlsruhe GmbH, Hermann-von-Helmholz-Platz 1, D-76021 Karlsruhe, Germany

Co₂MnSi is an attractive material to be used as magnetic electrode in magnetic tunnel junctions (MTJs). This is due to the half metallic character predicted by band structure calculation and to its high Curie temperature of 986K, indicating the potential for future magnetoelectronic and spintronic applications. A tunnel magnetoresistance (TMR) of currently 108% at 20K has been achieved, and is associated with a Co₂MnSi spin polarization of 70%. The corresponding room temperature value of TMR is 42%. A new technique has been used in order to relay on a wedge shaped AlOx tunnel barrier. The current limitation to achieve larger TMR has been identified as a direct consequence of the oxygen affinity of the Co₂MnSi - Heusler element Mn. Dependences of annealing temperatures, different oxidation times, and additional interlayers between heusler alloy and tunnel barrier on the TMR behavior have been investigated and will be discussed in detail.