Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 51: Magnetic Shape Memory Alloys (Joint Session with MM)

MA 51.6: Vortrag

Freitag, 20. März 2015, 10:45–11:00, H 0112

Coupling of Structural and Micromagnetic Properties in Twinned Epitaxial Ni-Mn-Ga films — •Aleksej Laptev¹, Mikhail Fonin¹, Yuansu Luo², Konrad Samwer², Gesa Welker³, and Kristof Lebecki⁴ — ¹Fachbereich Physik, Universität Konstanz, 78457 Konstanz — ²I. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen — ³Leiden University, Leiden Instute of Physics, 2333 CA Leiden, Netherlands — ⁴Nanotechnology Centre, VSB-TU Ostrava, 70833 Ostrava-Poruba, Czech Republic

Isothermal and temperature-dependent magnetization properties for (010)-oriented Ni-Mn-Ga epitaxial films deposited on MgO(001) substrates have been studied. In particular, the pronounced abrupt changes in slope of the magnetization loop near ± 0.06 T found in these films have been addressed. The mechanism of this characteristic hysteretic behavior could be understood with the help of micromagnetic simulations, which have been compared to experimental data. The results suggest that the abrupt changes in slope, which could be observed down to 10 K, can be attributed to the movement of 180^∘ magnetic domain walls within one of four existing twin variant orientations. The occurrence of such specific hysteresis loops is facilitated by the specific twinned microstructure, which leads to a periodic orientation change of the magnetic easy axis on micrometer scale.