Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 36: Magnetic Heusler Compounds II

MA 36.3: Talk

Thursday, March 29, 2012, 10:30–10:45, H 1012

Magnetic anisotropy and magnetization reversal of Co2MnGe-Heusler nanostripes — •Katherine Gross, Kurt Westerholt, and Hartmut Zabel — Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany

We have investigated magnetization reversal and magnetic domain configurations of submicron sized Co2MnGe-Heusler stripes. The magnetic behaviour of this system results from the interplay between the intrinsic magneto-crystalline anisotropy, tuneable growth induced uniaxial anisotropy (1.2x103 J/m3 < KU < 6,1x103 J/m3) and shape anisotropy, as observed by magnetic-force microscopy and longitudinal Kerr hysteresis loop measurements. For sufficiently large KU values, we observe in the remanent state high regular antiparallel domain patterns with the magnetization perpendicular to the long axis of the stripes. By decreasing KU below 4,5x103 J/m3, the demagnetizing energy becomes dominant and the magnetization falls into a flux-closure as well as into dipol structure. A KU=4,5x103 J/m3, which is two orders of magnitude smaller than in Co-nanostripes, seems to be close to a critical lower value for the stabilization of this particular regular domain pattern. The characteristic micromagnetic behaviour, such as coercive, nucleation, and saturation fields can be tailored by varying the aspect ratio length/width, m = 7, 10, 14, 18 of the nanostripes. Weak anisotropy combined with a high degree of spin polarization in Co2MnGe nanostripes is promising for applications related to the control and manipulation of magnetic domain walls by current-driven spin transfer torque.