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Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 8: Magnetic Shape Memory Alloys

MA 8.3: Vortrag

Montag, 22. März 2010, 15:45–16:00, H22

Dynamical properties of Ni-Mn-Ga alloys — •Semih Ener1, Jürgen Neuhaus1,2, Klaudia Hradil2,3, Richard Mole2, Peter Link2, and Winfried Petry1,21Technische Universität München, Physik Department E13, Garching, Germany — 2Technische Universität München, Forschungsneutronenquelle Heniz Maier-Leibnitz (FRM II), Garching, Germany — 3Georg-August-Universität Göttingen, Institut für Physikalische Chemie, Göttingen, Germany

In this work we investigate the vibrational properties of Ni-Mn-Ga alloys by using the Three Axis Spectrometers (TAS) PUMA (for thermal neutrons) and PANDA (for cold neutrons) which are located in FRM II, Garching. To approve the first principle calculations the whole dispersions of stoichiometric sample were measured in high temperature austenite and low temperature martensite phases. The temperature dependence of the vibrational properties in both stoichiometric and off-stoichiometric sample were investigated. In the austenite phase we observe a softening at TA2[q q 0] branch in both stoichiometric and off-stoichiometric samples. In stoichiometric sample the softening is more prominent than the off-stoichiometric one and the minimum of the softening is at 0.33 and 0.27 for stoichiometric and off-stoichiometric samples, respectively. The temperature dependence of vibrational properties of TA2[q q 0] branch in pre-martensitic phase were investigated in stoichiometric sample. The results showed that in the vibrational point of view the 5-layered martensite phase and the pre-martensite phase have the same behavior but it is not the case in low energy excitations.

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