二维铁磁材料Fe3GeTe2磁学性质的力学调控研究

现代社会信息数据的爆炸性增长，使人们对信息存储介质的密度和容量的要求不断提高。近年随着对二维材料研究的深入，使得在单原子极限厚度的二维材料上实现高密度的磁存储和处理成为可能。但在这种极限厚度下是否存在长程铁磁序一直是科研界讨论的热点。16年以来，实验上相继在单层CrI3二维半导体和单层Fe3GeTe2（FGT）二维金属材料中证实长程铁磁序的存在。通过外磁场、电场以及调节费米面高度对材料的铁磁性质可以进行调控。对于二维铁磁材料，除了层内自旋-自旋交换相互作用外，层间的耦合作用对体系的矫顽场和居里温度有着重要的影响。而二维材料中这种相互作用很容易通过力学手段加以调控。本项目拟通过控制FGT材料层间距离来改变层间耦合强度，利用磁圆偏振二色性光谱技术开展不同温度下材料铁磁性质的研究。意在阐明层间自旋-自旋耦合作用调控铁磁序的机理。有望通过力学手段在二维FGT材料中实现室温下的长程铁磁序。

The explosive growth of information in modern society has led to an increasing demand for storage density and capacity of storage media. In recent years, with the in-depth study in two-dimensional materials, it has become possible to achieve high-density magnetic storage and processing on single-atom-thick two-dimensional materials. However, the existence of long-range ferromagnetic order at such extreme thicknesses has been a hot topic in the research community. Since 2016, it has been demonstrated experimentally layer-dependent ferromagnetism in CrI3 and Fe3GeTe2 (FGT) van der Waals crystals down to the monolayer limit. And the ferromagnetic properties of the materials can be controlled by the external magnetic field, the electric field, and the density states. For two-dimensional ferromagnetic materials, in addition to the intra-layer spin-spin exchange interaction, the spin coupling between the interlayers also plays an important role in the coercive field and Curie temperature of the system. Moreover, this interaction in two-dimensional materials can be easily tuned by mechanical means. In this project, we propose to increase or decrease the interlayer coupling strength by controlling the interlayer distance of the FGT, and detect the ferromagnetism at different temperatures by the magnetic circular dichroism spectroscopy. It is intended to clarify the intrinsic mechanism of tuning of ferromagnetism by controlling interlayer spin-spin coupling. It is expected to achieve the long-range ferromagnetic orders in FGT materials at room temperature by mechanical means.