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MA: Fachverband Magnetismus

MA 51: Magnetic Half-metals and Oxides II

MA 51.3: Talk

Thursday, March 17, 2011, 11:30–11:45, HSZ 401

The influence of the disorder on the electronic states of the Heusler compound Co₂FeAl_0.3Si_0.7 studied by ARUPS and tunnelling spectroscopy. — •Elena Arbelo Jorge, Christian Herbort, Michaela Hahn, Gerd Scönhense, and Martin Jourdan — Institute of Physics, Johannes-Gutenberg University, Staudinger Weg 7, 55099 Mainz, Germany

Heusler compounds have attracted much interest based on their half metallic properties predicted by band structure calculations. However, a direct comparison of the theoretical predictions with experiments remains difficult, even if the spin degree of freedom is averaged. Additionally, the influence of atomic disorder on the band structure is of major interest and is in general expected to result in a broadening of the electronic states. We present in-situ spin averaged angular resolved UV-photoemission spectroscopy (ARUPS) of rf-sputtered Heusler thin films. Additionally, tunnelling spectroscopy on planar junctions of Heusler thin films with AlO_x barrier is performed. Samples of the compound Co₂FeAl_0.3Si_0.7 with different degrees of disorder (B2 and L2₁) are studied. The ARUPS results at energies close to the Fermi edge are compared to measurements of the bias voltage dependent tunnelling conductivity of Co₂FeAl_0.3Si_0.7/AlO_x/Ag and Co₂FeAl_0.3Si_0.7/AlO_x/CoFe junctions. Whereas the ARUPS shows clear correlations with the degree of disorder of the Heusler compound, the interpretation of the tunnelling spectroscopy results in terms of the density of states is challenging.