磁制冷技术是目前受到国内外广泛重视的一项具有重要应用前景的新技术，然而磁制冷材料相变过程中仍有很多内在的微观过程和物理机理没有被充分地揭示。本课题将以Mn5Ge3基合金为研究对象，采用结构分析、物性测量、模拟和理论计算相结合的方法，在前期研究的基础上，对滞后损耗、电子结构及其场-熵关联性机理等问题进一步的探究。主要通过对相变前后材料内部介观及其以下尺度磁结构变化的对比观察与分析，从相分离和电子向列有序两个模型出发，结合必要的理论分析，澄清在强关联电子体系中轨道自由度所起的作用，以及揭示滞后行为与轨道自由度之间的关联，进而提升对强关联电子体系中存在的复杂相互作用过程与机理的理解；另外，深入了解磁热的内在秉性和更加合理地评估制冷性能，澄清磁熵-外加磁场依赖性物理机制，对理解巨磁熵变效应和进一步寻求新型高效室温磁致冷工质具有重要理论价值和实际意义。

Magnetic refrigeration has been widely considered as a new technology with important application, but many inherent physical processes and mechanisms have not been fully revealed during the phase transition in related materials. Based on the analysis of phase transition, we will systematically study on Mn5Ge3-based alloys and adopt the methods of structural analysis, physical property measurement as well as simulative and theoretical calculation to reveal the relationship between hysteresis loss, electronic structure and magnetic field dependence of the maximum magnetic entropy change will be further studied. The role played by orbital freedom and the origin between the hysteresis and the orbital freedom will be used to enhance the understanding of the complex interaction processes and mechanisms that exist in strongly associated electronic by analyzing the phase transition in mesoscopic structures and the following dimensions combined with phase separation and electronic nematic order. Additionally, the nature of magnetocaloric effect and reasonable assessment of the refrigeration performance.is helpful for clarifying the mechanism of field dependence of magnetic entropy; these results will give theoretical and practical support for understanding the giant magnetocaloric effect and further seeking efficient room-temperature magnetocaloric materials.