自旋轨道力矩驱动的亚铁磁超快磁动力学研究

近年来，利用自旋转移力矩和铁磁材料的磁随机存储器技术不断取得突破，有望实现统一存储架构。为了实现超快磁矩翻转以及更低功耗器件，研究团队开始探索具有强交换耦合的亚铁磁材料。在兼具铁磁和反铁磁特性的基础上，亚铁磁具有自聚焦斯格明子轨道等独特的性质。结合自旋轨道力矩等高效的驱动方式，亚铁磁有望成为实现超快自旋电子器件的理想材料。然而，有关亚铁磁物理的研究目前尚处于起步阶段，特别是近期在实验中观测到了很多与理论相矛盾的结果。针对这些科学问题，本项目将建立适用于亚铁磁的数值和解析模型，从第一性原理研究亚铁磁中自旋轨道力矩的微观物理、建立系统的自旋动力学模型，进而阐明自旋轨道力矩在亚铁磁中的作用、理解亚铁磁超快自旋动力学，并实现连续太赫兹信号的激发和调控。我们希望这些研究能深化对亚铁磁物理的理解，推动基于亚铁磁材料的存储与计算器件的研究。

Recently, there are significant breakthroughs in the ferromagnet-based MRAM driven by the spin transfer torque, making it an ideal candidate for constructing the universal memory hierarchy. The further requirement of ultrafast switching and low power consumption leads to the increasing interests of ferrimagnets (FiM) which possess strong exchange coupling. Having the characteristics of both ferromagnets (FM) and antiferromagnets (AFM), FiMs have many unique properties, such as the self-focusing skyrmion racetracks and the fast domain wall motion without Walker breakdown. Driven by the efficient spin-orbit torque, FiM becomes a promising candidate for the ultrafast spintronic devices. Although there are many exciting experimental findings in this emerging area, the underlying physics is not well understood and many scientific questions require further studies. Aiming to answer these questions, in this project, we will study the microscopic origin of spin-orbit torque (SOT) from the first principle and build up a systematic model to describe spin dynamics. Based on these, we then try to understand the effect of SOT on FiM sublattices, study the origin of ultrafast spin dynamics in FiM and explore the electrical generation of continuous THz signals. We hope our study could improve the understanding of FiM physics, therefore advancing the development of FiM-based storage and computing devices.