Dresden 2011 – scientific programme

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KR: Fachgruppe Kristallographie

KR 5: Poster Multiferroics (Joint Session of MA, DF, DS, KR, TT)

KR 5.66: Poster

Tuesday, March 15, 2011, 10:45–13:00, P2

Microstructure of free-standing Ni2MnGa films — •Richard Hausmanns, Tobias Eichhorn, and Gerhard Jakob — Institut für Physik, Johannes Gutenberg-Universität Mainz, Deutschland

One of the interesting properties of the Heusler compound Ni2MnGa is the presence of the magnetic shape memory effect with a maximum length change of 10%. Thin, single crystalline films of this material thus are interesting for miniaturized sensor and actuator applications. The here investigated samples are prepared by dc-magnetron sputter deposition on heated MgO(100) substrates with a Cr buffer layer. The films can be released from the substrate by selective chemical etching of the Cr layer. The complex crystal structure before and after releasing the film is studied by x-ray diffraction in 4-circle geometry. Thereby different orthorhombic variants and modulation (7M/14M) are identified. The crystal structure appears to be unaffected by the removal of the buffer layer.

The presence of steps in the hysteresis loops, measured on free-standing films, indicates that magnetically induced reorientation of variants can occur. To prove that the variant distribution is studied by x-ray diffraction with applied magnetic field.