Regensburg 2010 – scientific programme

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KR: Fachverband Kristallographie

KR 10: Poster: Multiferroics (with MA, DF, KR, DS)

KR 10.36: Poster

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

Magnetotransport measurements on Heusler compounds — •A. Krupp¹, F.D. Czeschka¹, M. Althammer¹, S.T.B. Goennenwein¹, R. Gross¹, I.-M. Imort², G. Reiss², and A. Thomas² — ¹Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching, Germany — ²Fakultät für Physik, Universität Bielefeld, Bielefeld, Germany

Magnetic anisotropy (MA) is of fundamental importance in ferromagnets, as it strongly influences their properties. Using magnetotransport measurements, we investigate the MA of the Heusler compound Co₂FeAl. A 20 nm thick Co₂FeAl film on (001)-oriented MgO substrate was patterned into Hall-bar mesa structures with optical lithography and etching. The anisotropic magnetoresistance (AMR) is then measured with the external magnetic field applied in the film plane. The measured longitudinal and transverse resistance show a clear field dependence with distinct steps at small external magnetic fields (µ₀H), indicating abrupt switching of the magnetization orientation. To quantify the MA, we record the angle dependent magnetoresistance (ADMR), i.e. the MR as a function of H-orientation for different magnetic field magnitudes |H|. From the ADMR data taken at high |H|, AMR coefficients are obtained. The MA is then extracted from ADMR at lower |H|. We obtain a cubic MA field of around µ₀H_cub=5 mT and an uniaxial MA field of around µ₀H_uni=1 mT. We also discuss the evolution of MA with temperature and compare our results to literature.