Berlin 2008 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 36: Phase Transitions II
MM 36.4: Talk
Thursday, February 28, 2008, 12:30–12:45, H 0107
Beyond the standard analysis of magnetic shape memory alloys-Comparison of Ni-Fe-Ga and Ni-Mn-Ga single crystals — •Oleg Heczko1, Alexander Vasiliev2, Yuriy Chumlyakov3, and Sebastian Fähler1 — 1IFW Dresden, Institute for Metallic Materials, P. O. Box 27 01 16, 01171 Dresden, Germany — 2Moscow State University, Moscow, 119991, Russia — 3Tomsk State University, Tomsk, 634050, Russia
Some ferromagnetic Heusler alloys exhibiting martensitic transformations are known to change their shape by an external magnetic field (MSM effect). Here we analysed in depth and compared the magnetic properties of Ni54Fe19Ga27 and Ni50Mn29Ga21 single crystals; at low temperature using Bloch spin wave theory, at high temperature in the vicinity of the ferromagnetic transition using the equation of state and Arrot analysis. Temperature dependence of reciprocal paramagnetic susceptibility indicates a ferrimagnetic ordering in Ni-Fe-Ga compound. Magnetic anisotropy is determined from the magnetization curves measured in different temperatures. The transformation to martensitic phase is accompanied by the increase of the spontaneous magnetization and large increase of magnetocrystalline anisotropy in both compounds. The consequences of observed differences of magnetic properties for existence of the MSM effect are discussed.