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MM: Fachverband Metall- und Materialphysik
MM 41: Topical Session Diffussionless Transformations II
MM 41.2: Vortrag
Donnerstag, 17. März 2011, 16:30–16:45, IFW D
Smart Heusler materials from first-principles calculations — •Peter Entel, Antje Dannenberg, Mario Siewert, and Markus E. Gruner — Faculty of Physics, University of Duisburg-Essen, 47048 Duisburg, Germany
The interplay of structural and magnetic phase transitions vastly determines the properties of ternary intermetallics such as X2YZ Heusler alloys. Here, X and Y are ransition metal elements and Z is an element from the III-V group. In order to give a precise prescription of the possibilities to optimize the magnetic shape memory and magnetocaloric effects of these alloys, we use density functional theory calculations. From these calculations we can infer the martensitic driving forces and reveal the dominant role of the d-electrons in the formation of both, the different martensitic structures as well as the different magnetic spin orderings as a function of the atomic composition. In particular, we outline how one may find new intermetallics which show higher Curie and martensitic transformation temperatures when compared with the prototypical magnetic-shape memory compound Ni2MnGa. Higher operation temperatures are needed for technological applications. On the other hand, the optimization of the magnetocaloric effect is strongly related to find alloys for which the magnetic and structural phase transitions merge in a narrow temperature interval. This allows for larger adiabatic temperature changes across the transitions in an external magnetic field.