室温斯格明子的新型材料，拓扑物理以及原型器件的基础研究

As the emerging topic in nanomagnetism, the objective of topological magnetism is to explore novel topological spin textures, magnetic skyrmion in particular. Due to its topological protection that results in quasiparticle behaviors, magnetic skyrmion can be driven very efficiently by electrical current induced spin transfer torque. As a result, magnetic skyrmions has been envisioned as the perfect candidate for the future high density, high speed, low-power consumption and nonvolatile spintronic logics and memories. Furthermore, the real space spin topology of magnetic skyrmion gives rise to many interesting topological transport phenomena such as topological Hall effect, emergent electro/magneto-dynamics, and most recently skyrmion Hall effect. These motivate the present proposal in which the main objective is to study novel skyrmion material system, real-space topological spin transport and prototypical memory and logic devices. Our research is facilitated by utilizing spin sensitive imaging techniques including magneto-optical kerr effect microscope, magnetic force microscope and Lorentz transmission electron microscope, and ultra-high vaccum magnetron sputtering technique, SQUID, micromagnetic simulation, micro/nanofabrication and spin transport techniques. The outcome of this proposal could pave the pathway towards the next generation skyrmion based topological spintronics.

拓扑磁学是纳米磁学领域内近年来衍生出的一个新兴学科，它以探究磁性材料中的新型具有拓扑特性的磁结构为核心，其典型研究对象为磁性斯格明子。由于受到拓扑保护，微纳米级(1-1000 纳米)磁斯格明子可以非常高效地被电流产生的自旋转矩驱动，因而被业界认为是下一代高密度、高速度、低耗能、非易性自旋存储及逻辑器件的优良信息载体。同时，这种实空间自旋拓扑态也给予了许多丰富的拓扑自旋输运物理现象，譬如拓扑霍尔效应、新兴磁电动力学、斯格明子的霍尔效应等等。本项目将以自旋相关成像技术为特色(包括分辨磁光克尔效应显微镜、磁力显微镜、洛伦兹透射电子显微镜等)，结合超高真空磁控溅射薄膜制备技术、磁学性能表征、微磁学模拟、微纳米器件加工以及自旋动力学输运等手段，探索室温亚100纳米斯格明子的新颖材料体系，拓扑自旋物理以及原型功能器件。本项目的顺利实施能为下一代基于磁性斯格明子的拓扑自旋存储器件做好知识与技术储备。

执行期间内，完成了如下研究：（A）探究具有室温300 nm左右斯格明子的磁性超薄膜体系的可控生长。（B）完成手性磁结构的自旋相关成像实验。利用洛伦兹透射电子显微镜，获得斯格明子的精准拓扑相、动力学行为、在外加磁场影响下的完整相图等等。（C）进一步优化界面手性DM相互作用以及自旋霍尔效应，找到具有室温下亚20 nm的斯格明子的新材料体系。（D）探索斯格明子的热电技术方法。项目进行过程中发表14篇高质量学术论文，培养博士后2名。