二维铁磁材料中自旋波行为的铁磁共振和纯自旋调控研究

The discovery of two-dimensional ferromagnetic materials in 2017 is a hot topic in the frontier physics research. The large number of spin waves excited by strong fluctuations in two-dimensional ferromagnetic materials are very easy to destroy the magnetic order, which has caused great obstacles to the research and application. On the other hand, the behavior of spin waves in two-dimensional system is a new field which was previously difficult to enter, and has rich physical content. At present, there is still no much study of spin waves in two-dimensional ferromagnetic materials, providing a broad research space. This project intends to study the spin-wave behavior in two-dimensional ferromagnetic materials through ferromagnetic resonance and spin rectification detection as follows: 1) Systematically measuring the magnetic properties and spin-dynamic parameters of materials, understanding the basic properties of spin-wave from the angle of energy and time, excitation and relaxation processes, and exploring its behavioral characteristics different from traditional three-dimensional magnets; The control of temperature and strong magnetic field reveal the changing law of magnetism, spin wave and other properties and the correlation among them. 3) The key factors and mechanism that affect the magnetic stability and spin wave behavior are further clarified by the direct control of magnetic properties by pure spin injection alone. It provides valuable reference for further understanding the spin dynamics properties of two-dimensional ferromagnetic materials, stabilizing the magnetic order and improving the overall properties of materials.

2017年发现的二维铁磁材料是前沿物理研究中受到极大关注的一个热点。二维铁磁材料中因强涨落激发的大量自旋波极易破坏磁有序，对研究和应用都造成了巨大障碍；另一方面，二维极限下的自旋波行为又是此前难以涉足的一个全新领域，具有丰富的物理学内容。目前对二维铁磁材料自旋动力学的研究尚存在较大空白，具有广阔的研究空间。本项目拟通过铁磁共振并结合自旋整流探测，对二维铁磁材料中的自旋波行为开展如下研究：1）系统测量材料的静磁学性质和自旋动力学参数，从能量和时间角度、激发和弛豫过程理解自旋波的基本性质，并探索其可能存在的新奇效应；2）通过强磁场、电场、温度等整体调控，揭示磁性、自旋波和电学等性质的变化规律和相互间存在的关联；3）通过纯自旋注入单独对磁性质进行直接调控，进一步厘清影响磁稳定性和自旋波的关键因素和作用机制。为深入理解二维铁磁材料的自旋动力学性质，稳定磁有序和提升材料整体性能提供有价值的参考。

申请人主要围绕二维磁性体系开展了前瞻性探索，完成了预定的研究目标，取得了若干创新性成果。项目执行3年间，以（共同）通讯作者发表论文18篇；申请发明专利6项，其中1项授权；培养博士生3名，硕士生12名。申请人通过机械剥离、薄膜生长、二维堆垛等技术，成功制备了单层/少层的WTe2、Fe3GeTe2等多种单一材料和相关异质结，通过电子束曝光、转移技术等手段制备了相关微纳尺度器件，发展了相关自旋探测技术、阴影遮罩技术、接触界面工程、离子液体薄膜等新型技术手段，系统表征了材料和器件的电学、磁学、光学、自旋、能带结构等相关性质，发现了反对称磁电阻、界面电荷转移、各向异性电阻、拓扑平庸-非平庸转换等新奇电荷、自旋性质和物理效应，通过电场调控、层数、离子液体调控等手段，成功实现了对磁性材料磁矩的翻转场、铁磁-非铁磁转换等的有效调控，可以应用于未来基于二维体系的高速、高密度、低能耗的信息技术器件。