室温斯格明子体系RMn2Ge2单晶的拓扑输运性质及其物理机制

由于蕴含丰富的物理性质和潜在的应用价值，磁性斯格明子等自旋拓扑结构近年来备受关注。然而，自旋拓扑结构与拓扑输运性质之间的关系尚不明确，存在许多相互矛盾的结果亟待澄清。研究表明，稀土磁制冷材料RMn2Ge2具有多种复杂的磁结构，其自旋拓扑结构会随着尺度的变化而改变，同时NdMn2Ge2在室温附近具有巨拓扑霍尔效应。因此，本项目拟以RMn2Ge2(R=La、Ce和Nd)为研究对象，利用助熔剂法制备单晶块体样品，并利用聚焦离子束加工纳米薄片样品；通过磁性、中子衍射和洛伦兹电镜表征，构建完备的不同尺度样品的磁性相图，深入认识其自旋结构随温度、磁场和尺度的演化规律；同时，通过测量不同尺度样品的霍尔电阻与面内霍尔电阻，结合磁性相图，对比分析其拓扑霍尔效应及物理机制，阐明自旋拓扑结构与拓扑输运性质之间的依存关系，为探索和开发新型室温斯格明子材料提供实验和理论支撑，促进我国稀土功能材料的研发与应用。

Spin topological structures have attracted extensive attention and researches due to their rich physical properties and potential application. However, it is not clear to the relationship between spin topological structures and topological transport properties, and there are many contradictory results to be clarified. The previous results show that the rare-earth based magnetic refrigerant materials RMn2Ge2 possess multiple complex magnetic structures, and their topological spin structures change with the dimension. Meanwhile, NdMn2Ge2 presents giant topological Hall effect at room temperature. Therefore, in this project, we intend to prepare RMn2Ge2 single crystals by flux method and the nanoplate samples will be fabricated by the focus ion beam technique. By magnetic measurement, neutron diffraction and Lorentz electron microscopy characterization, the evolution of the spin structures with temperature, magnetic field and dimension will be studied, and the magnetic phase diagrams of bulk and nanoplate samples will be constructed. Furthermore, the Hall resistance and planar Hall resistance of the bulk and nanoplate samples will be measured. Combined with magnetic phase diagrams, the origin of topological Hall effect will be analyzed, so as to deeply understand the mechanism of topological Hall effect, and establish the relationship between the spin topological structures and topological transport properties. This project would provide experimental and theoretical supports for exploring novel room-temperature skyrmion materials, and promote the development of rare-earth functional materials in our country.