2017年，二维极限下长程磁有序的发现使以CrXTe3(X=Si, Ge)为代表的van der Waals二维磁性材料成为了凝聚态物理研究中的焦点。已有理论研究指出：该类材料的宏观铁磁性背后还蕴含着多种相互耦合的铁磁、反铁磁交换作用，理解其相互作用的关系是理解二维磁性机理的关键之一。但目前基于平衡态磁性的研究无法对其中的多种交换作用进行有效识别，其相互作用关系及对二维磁有序的影响机制亟待澄清。本项目将在前期工作基础上，利用超快磁光克尔技术对CrXTe3这类二维磁性材料中的自旋波进行可控激发和超快探测，1）利用铁磁、反铁磁自旋波在振荡频率和相位上的差异实现两种相互作用的有效区分；2）通过自旋波时域/频域超快动力学参数的磁场-温度依赖关系分析它们之间的竞争与制约关系。通过该研究，力争阐明二维长程磁有序中的自旋相互作用机制，从磁动力学角度为理解本征二维磁性起源提供实验基础。

In 2017, the discovery of long-range magnetic order under the two-dimensional limit makes the two-dimensional van der Waals magnetic materials, represented by CrXTe3 (X=Si, Ge), become the focus of condensed state physics research. Theoretical studies have pointed out that there are many coupling ferromagnetic and anti-ferromagnetic exchanges behind the macroscopic ferromagnetic of this kind of material, and understanding the relationship between the interaction is key to the understanding of the two-dimensional magnetic mechanism. However, at present, the study based on equilibrium magnetism can not effectively identify many of the exchange interactions, and their interaction relationship as well as the influence mechanism on two-dimensional magnetic order needs to be clarified urgently. On the basis of the previous work, in this project we will use ultra-fast magneto-optical Kerr technology to carry out controllable excitation and ultra-fast detection of spin waves in two-dimensional magnetic materials such as CrXTe3, 1) to realize effective distinction between FM and AFM interactions according to the difference in oscillation frequency and phase of FM and AFM spin waves; 2) to analysis the competition and restriction relationship between them by magnetic field-temperature dependence of time/ frequency domain spin wave ultra-fast dynamic parameters. Through this study, we will strive to elucidate the mechanism of spin interaction in two-dimensional long-range magnetic order, and to provide experimental basis for understanding the two-dimensional magnetic origin of the present characteristics from the perspective of dynamic magnetism.