Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 9: FV-internes Symposium "Heusler-Legierungen" (Organizers: B. Hillebrands, H. Zabel)

MA 9.6: Hauptvortrag

Freitag, 4. März 2005, 17:45–18:15, TU EMH225

Magnetic tunnel junctions with Heusler alloy electrode: Interface structure and magnetism in the shine of soft X-rays — •Jan Schmalhorst — University of Bielefeld, Department of Physics, Nano Device Group, P.O. Box 100131, 33501 Bielefeld, Germany

The implementation of half-metallic materials like full Heusler alloys [1] for spintronic applications [2], e.g., as electrode in magnetic tunnel junctions, is of highest technological relevance. The major challenge is the preparation of preferably defect free interfaces. We fabricate Co₂MnSi / AlO_x / Co-Fe MTJs with 95% tunneling magnetoresistance (TMR) at low temperature and low bias voltage [3,4]. However, the TMR bias voltage and temperature dependence is considerably stronger than usually found for optimized MTJs with 3d-alloy electrodes. For explaining this conclusively, knowledge of the structural and magnetic properties of the Co₂MnSi / AlO_x interface is of vital importance. In this talk investigations of the Co₂MnSi / AlO_x interface [5] and the Co₂MnSi bulk material by X-ray absorption spectroscopy will be presented and discussed with respect to the temperature dependent transport properties of the junctions. The author gratefully acknowledge the opportunity to perform soft X-ray absorption spectroscopy at the Advanced Light Source, Berkeley, USA and at the BESSY mbH, Berlin, Germany.

[1] R. A. de Groot et al., Rev. Lett. 50 (1983) 2024

[2] S.A. Wolf et al., Science 294, 1488 (2001)

[3] S. Kämmerer et al., Appl. Phys. Lett. 85 (2004) 79

[4] J. Schmalhorst et al., to be published

[5] J. Schmalhorst et al., Phys. Rev. B 70 (2004) 024426