Berlin 2012 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 45: Joint Session "Magnetic Shape Memory Alloys II" (jointly with DS, MM)
MA 45.13: Vortrag
Donnerstag, 29. März 2012, 18:15–18:30, H 0112
Martensitic and magnetic microstructure of epitaxial Ni-Mn-Ga films — •Anett Diestel1,2, Anja Backen1,2, Volker Neu1, Sandra Kauffmann-Weiß1,2, Ludwig Schultz1,2, and Sebastian Fähler1 — 1IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden, Germany — 2Dresden University of Technology, Department of Mechanical Engineering, Institute of Materials Science, 01062 Dresden, Germany
The modulated 14M martensite phase of the magnetic shape memory (MSM) alloy Ni-Mn-Ga shows huge strains up to 10 % by magnetically-induced reorientation of martensitic variants. The interaction between the crystallographic short and the magnetic easy axis is an essential requirement for the MSM effect. For Ni-Mn-a bulk materials a staircase-like domain pattern with 90∘- and 180∘-domain walls is already known. To understand this interaction in thin films we analyzed the martensitic and magnetic microstructures of epitaxial Ni-Mn-Ga films of different thicknesses by atomic and magnetic force microscopy. The observed domain pattern of thin epitaxial films differs considerably from the bulk concept. Due to the reduced variant width magnetic exchange coupling has to be considered. An interaction between the martensitic microstructure and the magnetic out-of-plane stripe domain pattern was established and a correlation between the domain width periodicity ΛDW and the film thickness d according to ΛDW ∼ d1/2 was identified in good agreement with the theoretical band domain model of Kittel. This work was funded by DFG through SPP 1239.