Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.108: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU C

Implementation of Co₂MnSi electrodes in magnetic tunnel junctions: magnetic and chemical bulk properties compared to the interface — •Jan Schmalhorst¹, M. Sacher¹, S. Kämmerer¹, V. Höink¹, G. Reiss¹, A. Hütten¹, D. Engel², A. Ehresmann², and E. Arenholz³ — ¹University of Bielefeld, Department of Physics, Nano Device Group, P.O. Box 100131, 33501 Bielefeld, Germany — ²Department of Physics, Kaiserslautern University of Technology, D-67663 Kaiserslautern, Germany — ³Lawrence Berkeley National Laboratory, Advanced Light Source, Berkeley, CA 94720, USA

The 100% spin polarization predicted theoretically for some Heusler alloys make them attractive for spintronic applications, e.g., as electrode material in magnetic tunnel junctions. The formation of a high quality tunneling barrier without generating defects in the adjacent half-metallic electrode is the crucial preparation step. We have prepared Co₂MnSi / AlO_x / Co₇Fe₃ junctions showing a low temperture / low bias voltage tunneling magnetoresistance of 95% corresponding to an effective spin polarization of 66% instead of the predicted half-metallicity. By comparing soft X-ray absorption in total electron and total fluorescence detection we have determined differences of the chemical and the magnetic properties in bulk Co₂MnSi and at the Co₂MnSi / AlO_x interface. These results show up a way of how to improve the magnetoresistive transport in the future. The authors gratefully acknowledge the opportunity to perform soft X-ray absorption spectroscopy at the Advanced Light Source, Berkeley, USA and at the Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung m.b.H., Berlin, Germany.