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MA: Fachverband Magnetismus

MA 15: Magnetic Half-metals and Oxides I

MA 15.3: Vortrag

Mittwoch, 24. März 2010, 10:45–11:00, H22

The surface spin polarization of Co-based Heusler alloys — •Roman Fetzer¹, Jan-Peter Wüstenberg¹, Sabine Neuschwander¹, Martin Jourdan², Christian Herbort², Enrique Vilanova Vidal², Gerhard Jakob², Martin Aeschlimann¹, and Mirko Cinchetti¹ — ¹University of Kaiserslautern, Department of Physics and Research Center OPTIMAS, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern — ²University of Mainz, Institute of Physics, Staudinger Weg 7, 55128 Mainz

Co-based Heusler alloys belong mainly to the family of half-metallic ferromagnets (HMFs). The predicted full spin polarization at the Fermi level due to the minority spin band gap makes this class of materials highly interesting for application in the field of spintronics. Thus, the characterization of the surface of Co-based Heusler compounds is extremely relevant for understanding and improving the performance of Heusler-based spintronics devices, like tunnel-magnetoresistance (TMR) junctions. Using Auger electron spectroscopy (AES) [1] and low energy spin polarized electron photoemission [2], we systematically studied the correlation between chemical composition and spin polarisation of the surface. For various Co-based Heusler alloys, e.g. Co₂CrAl, Co₂MnAl and Co₂FeGa_0.5Ge_0.5, we found different degrees of spin-polarization at the very surface region. Reasons for the distinct deviation from the predicted 100% spin polarization and the dependence on the specific surface preparation procedure will be discussed.

[1] Wüstenberg et al. , J. Phys. D: Appl. Phys. 42 (2009) 084016

[2] Cinchetti et al., J. Phys. D: Appl. Phys. 40 (2007) 1544-1547