Upscaling of Thermomagnetic Generators Based on Heusler Alloy Films

Thermomagnetic (TM) generators based on Heusler alloy films have the potential to recover waste heat below 200°C at small temperature differences . Progress in the development of materials that exhibit large abrupt changes in ferromagnetic ordering and in film engineering enable efficient thermomagnetic generation via resonant self-actuation of freely movable film-based devices. Yet, power levels of individual devices are low, and upscaling becomes a key issue of material development and engineering. Here, we address the key question of how film thickness and device footprint affect power and efficiency. We investigate the scaling performance of heat intake, heat dissipation, and resulting local temperature changes. Based on this understanding, the electrical power per footprint could be increased by a factor of 3.4. Maximum values of electrical power per footprint are 50 μW/cm2 at a temperature change of only 3°C, which marks an important milestone in the upscaling of Heusler alloy film-based TM generators.