SKM 2023 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 3: Magnetic Materials for Efficient Energy Conversion

MA 3.10: Vortrag

Montag, 27. März 2023, 12:00–12:15, HSZ 401

Influence of Cu addition and chemical order on the thermomagnetic properties of Ni-Mn-Ga-based films — •Lukas Fink^1,2,3, Kornelius Nielsch^2,3, and Sebastian Fähler¹ — ¹Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, D-01328 Dresden, Germany — ²Leibniz IFW Dresden, Institute for Metallic Materials, D-01171 Dresden, Germany — ³TU Dresden, Institute of Materials Science, D-01062 Dresden, Germany

One way to harvest low-grade waste heat is a microscale thermomagnetic generator (TMG), which uses magnetocaloric films as active material. The high surface-to-volume ratio of thin films enables a fast heat transfer, increasing the cycling frequency and power density compared to bulk devices. Selecting the optimal active material is decisive for the efficiency of a TMG since it will determine the temperature regime and the cycling frequency. Recently Ni-Mn-based Heusler alloys were proposed as they can be prepared by standard thin-film technologies.

Here we use combinatorial growth of Cu alloyed Ni-Mn-Ga films and subsequent heat treatment for systematic optimization of thermomagnetic properties. We examine the key thermomagnetic properties like 1) the working temperature T^∗ and 2) the performance Δ M/Δ T and correlate them with common properties like 3) crystal structure, 4) 1st and 2nd order transition and 5) spontaneous magnetization. Within our research, we can disentangle the effects of valence electron number e/a and chemical order. This work is funded by the DFG (FA453/14).