Observation of an Extensive Curie Temperature Window and Synergic Multicaloric Effects in NiMnCuGaSn Alloys

The study of multicaloric effects in Heusler alloys has attracted increasing research interest, fueled by their potential applications in solid-state refrigeration and energy conversion technologies. Despite the promising aspects, challenges such as the limited operating temperature range and large hysteresis have hindered the optimal device performance. Herein, by introducing a Cu/Sn co-substitution strategy, a Curie temperature window for synergic magnetostructural transformation is extended from 244 K to 313 K in the customized NiMnCuGaSn alloys, along with a substantial increase in transformation entropy change. Crucially, employing a combined approach of magnetic-field-stress loading and zero-field-stress unloading significantly reduces stress hysteresis and enhances the reversibility of the transformation, resulting in a significant adiabatic temperature change of 4.7 K at a relatively low critical stress. This approach underscores an efficient method to enhance caloric responses, paving the way for advances in cooling technologies.