Dresden 2017 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 49: Microstructure and Phase Transformations - shape memory alloys

MM 49.3: Vortrag

Mittwoch, 22. März 2017, 16:15–16:30, IFW B

Impact of doping on the magnetic and structural transformations in magnetocaloric materials — •Biswanath Dutta, Vijaya Begum, Tilmann Hickel, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, D-40237 Düsseldorf, Germany

Understanding the magnetic and the martensitic transformations together with their coupling in magnetocaloric materials (MCMs) is crucial to tailor and optimize them for magnetic refrigeration. Specifically, any application of the MCMs requires a detailed knowledge of their underlying phase transformations. Within this study, we employ density functional theory along with Monte Carlo (MC) simulations to understand the impact of substitutional elements on the phase stability and the transformation behavior in Ni-Mn-based Heusler alloys. Our calculations reveal a reduction in the martensitic transformation temperature accompanied by a metamagnetic transition leading to a large entropy change due to Co substitution. We discuss the results in terms of calculated free energies, magnetic exchange interactions and the magnetic moments. The coupling of the magnetic and the structural degrees of freedom and its influence on the transformation behavior is addressed using MC simulations with the DFT input. Based on the achieved results, we provide new insights into the effect of doping on the martensitic and the magnetic transformations in Heusler alloys.