铁镓金属间化合物自旋涨落作用机理与物性调控方法研究

The strong electronic correlations among low-temperature magnetic metallic material led to many fascinating properties, which has drawn extensive attention in the field of fundamental theoretical studies, as well as advanced technical applications. The intermetallic FeGa3 belongs to the rare examples of substances of iron based metals where diamagnetic and semiconducting behaviors are found. Chemical substitution and doping or application of some external parameter such as high magnetic field or pressure for FeGa3 turn the diamagnetic insulating mother compound into a weakly, nearly ferromagnetic metal. Novel physical properties are also aroused by the complex competition among electronic correlations, which are beyond the predictions of the theories based on Stoner and Landau model. When electron correlation effects become strong, the long-range spin-spin interactions have to be considered in general, and the wave-number- and frequency-dependent spin fluctuations should be taken into account in explaining properties of magnetic metal at finite temperature. In this project, we plan to synthesize a series of Fe-Ga intermetallic compounds with different compositions by electron and hole doping method, and investigate its properties of 3d electron at the intermediate range between local and itinerant range through magnetic, calorimetric, and transport measurements at finite temperature. The novel properties will be analyzed in terms of self-consistent renormalization theories of spin fluctuations and related approximations. The investigation performed in this project on the mechanism and functions of spin fluctuations is of fundamental and practical significance for the rational design and construction of novel magnetic materials.

低温磁性金属体系中复杂的电子关联作用使其展现出丰富的物理性能，在基础理论研究和前沿应用领域受到了广泛关注。在铁基金属化合物中，FeGa3显示了稀有的抗磁性半导体行为，对FeGa3进行化学取代和掺杂或施加高压、强磁场等物理变化可诱发体系的电子关联改变，使化合物由抗磁性半导体转变为弱、近铁磁性金属，并在转化中伴随新奇的磁、热和电学物性特征。然而铁镓金属间化合物的物性无法由斯通纳、朗道等经典理论诠释，这是由于经典理论模型忽视了波数自旋涨落和频率依赖自旋涨落的作用，而自旋涨落对铁镓金属间化合物随温度依赖的物理性质有着显著影响。本项目拟以镓化铁为基础，系统地对FeGa3的Fe和Ga位点进行取代和电子、空穴参杂，制备出系列磁性铁镓金属间化合物，研究铁镓金属间化合物中3d电子体系由较强自旋涨落交互作用引发的新奇物性，揭示其本征特征与物性之间的内在联系，为宏观调控出新型磁学功能材料奠定理论基础和技术支撑。

巡游电子体系中自旋涨落作用对材料的物性具有重要影响。弱铁磁、近铁磁电导材料体系因其中的巡游电子和自旋涨落耦合效应，常可调控出奇特的磁有序结构，磁感应强度和磁相变现象，同时常展现出特定的电输运特性。本课题以自旋涨落对物性影响的作用为主要研究内容，着重选择了巡游电子体系为研究对象，通过电子、空穴掺杂等为物性参数调控手段，诱发研究体系因较强自旋交互作用诱导的新奇物性，研究3d电子体系自旋交互作用规律，解释其本征特征与物性之间的内在联系。并对所合成出的材料进行了技术应用方面的进一步探索。.主要的研究内容包括：通过对抗磁性半导体母体材料FeGa3的化学取代和掺杂，制备出弱铁磁、近铁磁半导体转化的系列晶体材料Fe1-xCoxGa3, Fe1-xMnxGa3, FeGa3-yZny；巡游体系石墨烯等体系中大pi键关联的自旋及d0抗、顺磁性客体交互作用下的物性；理论计算预期下可诱发磁有序系统硒化锡基，钴氧化物基晶体体系的物性及其应用；大pi键阳离子络合体系的磁性增强材料物性及其技术应用。.项目执行以来已发表SCI论文3篇（Journal of Alloys and Compounds, Colloids and Surfaces B: Biointerfaces, 和ACS Applied Materials & Interfaces），申请专利1项。部分研究内容因疫情延误正在进一步通过国家大平台测试中心获取超强脉冲、恒定磁场及利用高能量X射线等辅助分析磁结构和自旋耦合等作用整理总结论文。.