Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 10: Poster I

MA 10.37: Poster

Tuesday, March 23, 2010, 10:45–13:45, Poster A

Anomalous Hall Effect in Heusler Compounds — •I.-M. Imort¹, G. Reiss¹, A. Thomas¹, A. Krupp², F.D. Czeschka², M. Althammer², R. Gross², and S.T.B. Goennenwein² — ¹Fakultät für Physik, Universität Bielefeld, Bielefeld, Germany — ²Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching, Germany

The anomalous Hall Effect (AHE) is a fundamental but still controversially discussed phenomenon in ferromagnets. Furthermore, it is a volatile characterization tool for magnetic materials. We here report on our magnetotransport experiments and the AHE in the Heusler compound Co₂FeAl. Using rf-magnetron sputtering, 20 nm thick Co₂FeAl thin films were grown on single-crystal MgO(001) substrates. Before patterning into 80µm wide Hall bars, some of the samples were annealed at different temperatures. The Hall resistivity ρ_xy and the magnetoresistivity ρ_xx were measured simultaneously over a temperature range of 3 to 300 K and a magnetic field range of |14| T. For low magnetic fields µ₀H, ρ_xx exhibits typical anisotropic magnetoresistance features, with resistance jumps and a non-linear dependence on H. This behaviour abruptly changes at higher fields: for µ₀H≥1.6 T, ρ_xx scales strictly linearly with H. In contrast, the Hall resistivity always is proportional to |H|, but the slope of ρ_xy abruptly changes sign at µ₀H≈ 1.6 T. We will discuss the impact of temperature, surface roughness and annealing temperature on the magnetotransport properties and compare our results to the literature.

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