固态制冷是绿色环保、高效节能的新型制冷技术，其原理是利用固态相变材料的热效应进行制冷。多卡效应的提出为固态制冷材料热性能的改善和不同能量形式相互干预空间的扩宽提供了新的途径，因此受到了人们的广泛关注。NiMn基Heusler合金中具有磁结构协同相变特征的NiMnGa基合金在多卡效应研究和固态制冷应用方面具有明显优势。但是相变温度在室温的磁结构协同相变材料体系目前较少且该类材料的多卡效应研究还尚未开展。本项目拟以探索NiMnGa基室温磁结构协同相变材料体系为基础，结合系统的实验表征和唯象的朗道理论模拟深入探究磁结构协同相变材料中相变熵变和磁结构耦合强度的定量关系，为开发多卡性能优异的制冷材料提供理论依据。同时，本项目拟通过研究NiMnGa基合金在偏置磁场下的弹热效应揭示磁结构协同相变材料中磁场对弹热效应的影响机制，积极推动室温磁结构协同相变材料及其多卡效应的研究进展。

Solid-state refrigeration is a new type of eco-friendly and high efficient refrigeration technology. This refrigeration technology is designed based on the caloric effect of solid-state transformation materials. The presentation of multicaloric effect provides a new approach to enhance the caloric properties of solid-state refrigerant and broaden the space for the interaction of different forms of energy. Thus, the multicaloric effect has gained a lot of attention recently. Among NiMn-based Heusler alloys, NiMnGa-based alloys show more advantages in the investigation of multicaloric effect and application in solid-state refrigeration due to the cooperative effect of magnetic and structural transformations. However, NiMnGa-based alloys with such cooperative effect are scarce at room temperature and their multicaloric effect has not been studied. In this project, we propose to explore more systems with such cooperative effect at room temperature. In these systems, the quantitative relation of transformation entropy change and magnetostructural coupling strength will be investigated on the basis of a phenomenological Landau model combined with comprehensive experimental studies. This quantitative relation can provide theoretical basis for developing excellent multicaloric materials. Besides, the elastocaloric effect of NiMnGa-based alloys under bias magnetic fields will be investigated and the influencing mechanism of magnetic field on elastocaloric effect in materials with cooperative effect will be revealed. With the framwork of this project, the develpment of magnetostructural transformation materials with cooperative effect and their multicaloric effect should be actively promoted.