Regensburg 2019 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 24: Miscellaneous: Biomaterials, Magnetic Shape Memory Alloys, Sensors and Actuators (joint session MM/MA)
MA 24.2: Vortrag
Dienstag, 2. April 2019, 14:30–14:45, H46
Atomic disorder in magnetocaloric materials: A roadmap for achieving better performance — •Biswanath Dutta1,2, Bruno Weise3, Niclas Teichert4, Andreas Hütten4, Anja Waske3, Fritz Körmann1,2, Tilmann Hickel2, and Jörg Neugebauer2 — 1Materials Science and Engineering, Delft University of Technology, Delft, Netherlands — 2Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany — 3Institute for Complex Materials, IFW Dresden, Dresden, Germany — 4Department of Physics, Bielefeld University, Bielefeld, Germany
Understanding and improving magnetic properties of magnetocaloric materials is of great importance for their practical applications. In the quest to enhance these properties, different design strategies have been employed in recent years. Using ab initio calculations, we study the impact of atomic disorder on the martensitic transformation and the magnetic properties in Ni-Mn-based magnetic shape memory alloys (B. Weise et al., Sci. Rep. 8:9147 (2018)). The calculations reveal a remarkable impact of atomic configuration on the structural and magnetic properties of the cubic austenite phase. We also find a delicate interplay of magnetic and chemical orders and the tetragonal distortion during the martensitic transformation, explaining the giant inverse magnetocaloric effect in these alloys. Based on these findings, we qualitatively explain the experimentally observed changes in the magnetocaloric properties after different annealing times. Our investigations thus provide a promising route, i.e., managing disorder with optimal annealing to achieve better magnetocaloric properties.