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O: Fachverband Oberflächenphysik

O 91: [MA] Poster II

O 91.5: Poster

Freitag, 30. März 2012, 11:00–14:00, Poster A

Direct investigation of the Co₂MnSi/MgO interface by spin-resolved photoemission — •R. Fetzer¹, J.-P. Wüstenberg¹, T. Taira², M. Yamamoto², M. Aeschlimann¹, and M. Cinchetti¹ — ¹Department of Physics and Research Center OPTIMAS, TU Kaiserslautern, Erwin-Schrödinger-Str. 46, D-67663 Kaiserslautern — ²Graduate School of Information Science and Technology, Hokkaido University, Kita 14 Nishi 9, Sapporo 060-0814, Japan

State-of-the-art tunnelling magnetoresistance (TMR) devices based on magnetic full Heusler compounds (e.g. Co₂MnSi) as electrodes and insulating MgO as tunnelling barrier are very promising as advanced spintronic devices [1]. Understanding the spin-dependent electronic properties of Heusler/insulator interfaces is hereby of great importance for further improvement of these multilayer systems. We have studied the Co₂MnSi/MgO (100) interface by means of spin-resolved near-threshold photoemission spectroscopy. The excitation source was laser light with photon energy lower than the MgO band gap width. This allows to investigate directly the spin-dependent electronic properties of the interface as a function of the MgO thickness. We found that the interface spin polarization is positive and can be detected through MgO layers up to 20 ML. Furthermore distinct changes in crystal structure and chemical composition of the epitaxial MgO layer were observed by means of LEED and Auger electron spectroscopy when varying its thickness. We will discuss the connection between the quality of the MgO layer and the detected interface spin polarization.
T.Ishikawa et al., J. Appl. Phys 103, 07A919 (2008)