二维磁性材料的磁相变及演变规律的拉曼光谱测量

本项目中，拟借助低波数变温磁场微区拉曼光谱技术对二维磁性材料的磁性相变性质及其演变规律进行系统研究。通过测量各种二维磁性材料（如FeOCl、CuCrP2S6等）的变温偏振拉曼光谱，分析其拉曼特征峰的峰强、峰位以及偏振依赖性随温度的变化关系，从晶体结构和磁性对称性的角度对其相转变过程进行研究，利用外加磁场改变二维磁体的电子自旋态，结合偏振和旋光拉曼的特征变化，探究其磁光相互作用和自旋声子耦合的物理机制。系统研究不同层数的二维磁性材料拉曼光谱的温度、偏振、旋光以及外加磁场依赖性，分析其相变温度和磁滞行为，绘制磁性相变的相图和磁滞回线，磁性相变对其层数依赖的演变规律进行探究。利用电场、应力以及与其他二维材料异质结的构建对二维磁性材料的电子自旋进行调控，结合拉曼光谱研究其磁性相变的外场调控规律和表界面效应。

In this project, we intend to systematically study the magnetic phase transition properties and evolution rules of two-dimensional (2D) magnetic materials on a low wavenumber, variable temperature, magnetic Raman system. By measuring the temperature-dependent polarized Raman spectra of various 2D magnetic materials, such as FeOCl, CuCrP2S6, etc., the phase transition process is studied from the perspective of crystal structure and magnetic symmetry on the basis of the relationship between the Raman peak intensity, peak position and polarization dependence with temperature. Applied a external magnetic field to change the electron spin state of two-dimensional magnet, the physical mechanism of magneto-optical interaction and spin-phonon coupling is explored using the polarized and helicity-resolved Raman Spectroscopy. Through study the temperature, polarization, helicity and magnetic dependence of Raman spectra for 2D magnetic materials with different thicknesses, the phase transition temperature and hysteresis behavior are resolved, and the phase diagram and hysteresis loop of magnetic phase transition are drawn, and then the evolution rules of magnetic phase transition with layer number are explored. The electron spin state of 2D magnet is modulated by applied gating, strain and fabracation the heterostructure with other 2D materials. Combining the Raman characterization, the external field modulation and surface effect are investigated.