Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 61: Caloric Effects
MA 61.5: Talk
Friday, March 20, 2020, 10:30–10:45, HSZ 101
Thermomagnetic properties of Co or Cu doped Ni-Mn-Ga films for mico energy harvesting — •Lukas Fink1,2, Anett Diestel1, Kornelius Nielsch1,2, and Sebastian Fähler1 — 1Leibnitz IFW Dresden, Institute for Metallic Materials, D-01171 Dresden, Germany — 2TU Dresden, Institute of Materials Science, D-01062 Dresden, Germany
Recovery of waste heat is decisive for a more efficient use of primary energy. Furthermore, at the micro scale it enables the Internet of Things without the need for wiring. However, except for thermoelectrics, there is hardly any technology available to harvest low temperature waste heat. As an alternative approach recently first thermomagnetic microsystems were developed, which use magnetocaloric materials as active material. The high surface-to-volume ratio of thin films enables a fast heat transfer, resulting in high cycling frequencies and power densities compared to bulk devices.
For this application we prepare Ni-Mn-based Heusler films by sputter deposition. We focus on Ni-Mn-Ga-X films (X= Cu, Co) and examine the role of the doping elements and chemical order on 1) the transition temperature, 2) hysteresis losses, and 3) difference of magnetization at the martensitic transition, which is the decisive property for thermomagnetic harvesting of low temperature waste heat. We discuss the suitability of these alloys for thermomagnetic harvesting of low temperature waste heat in comparison to magnetocaloric refrigeration.
This work is funded by the DFG (FA453/14).