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MA: Fachverband Magnetismus

MA 45: Joint Session "Magnetic Shape Memory Alloys II" (jointly with DS, MM)

MA 45.11: Vortrag

Donnerstag, 29. März 2012, 17:45–18:00, H 0112

Influence of the addition of platinum on the magnetic shape memory alloy Ni₂MnGa — •Mario Siewert, Markus E. Gruner, Heike C. Herper, and Peter Entel — University of Duisburg-Essen, Faculty of Physics

We have studied the influence of the addition of platinum on the magnetic shape memory alloy Ni₂MnGa by means of ab initio calculations. In particular, the quaternary system Ni_2−xPt_xMnGa was studied for 0≤ x≤ 2. As a main result, the preference of a tetragonal distortion increases with the amount of Pt that is added to the system. The increased preference of the tetragonal L1₀-structure goes hand in hand with the onset of antiferromagnetic tendencies in the Pt-rich alloys. The martensitic trends which are observed in the phase diagram of Ni-Mn-Ga are also observed for the alloy systems containing platinum. In particular, the transformation temperature can be further increased when substituting Ga by Mn which introduces additional antiferromagnetic tendencies. The modulated 14M structure which is responsible for the magnetic shape memory effect in Ni₂MnGa, also appears in systems with excess Pt. It turns out that the shape memory effect is about 14% and therefore larger than in Ni₂MnGa.