二维磁性层间转角结构及其界面效应的多尺度理论研究

与传统的磁性薄膜相比，Cr2Ge2Te6和CrI3等二维磁性材料更柔软，易受电场调控，易于表面修饰和功能化。类比其他二维材料，如魔角石墨烯，层间堆叠和取向的调整可以极大地调控二维材料的性质。由于二维磁性材料结构复杂度高，共周期结构尺度大，其层间堆叠尤其是转角的理论研究较为困难。本项目首先采用准确的第一性原理计算，研究二维磁性材料层间转角的有限超结构模型，进一步发展DFTB参数，利用自洽电荷密度泛函紧束缚近似方法实现更广泛、更大尺度的二维磁性材料转角结构的模拟。通过本项目的多尺度研究，我们可以深入认识二维磁性材料的层间作用，丰富转角结构，进一步探索多种二维磁性材料构成的复合层间转角异质结，研究其磁性、电子、光电特性以及层间缺陷影响，为二维磁性材料的性质调控提供有力的理论支持。

In contrast with traditional magnetic thin films, atomic thin two-dimensional (2D) magnetic materials, like Cr2Ge2Te6 and CrI3, are more flexible, easier to be affected by electronic field, easier to be decorated and functionalized on the surface. Analogous to other two-dimensional materials, like magic-angle twisted bilayer graphene, the stacking and orientation between layers can extremely tune the properties of 2D materials. However, the theoretical study of the stacking and especially the rotation between layers of 2D magnetic materials is difficult due to the complex of the structures and the large scale of the twisted structures. In this project, first, we calculate the limited twisted bilayer superstructures by precise first principle calculations. Then, we will develop the DFTB parameters and realize the simlation of twisted bilayer superstructures with a larger scale by self-consistent charge density functional tight binding. Through the multiscale theoretical simulations in this project, we can have a deep insight into the interlayer interaction between 2D magnetic layers and enrich the twisted bilayer structures. Futher more, we will investigate the electronic, magnetic and photoelectric properties and defect effect of twisted heterostructures composed of many different 2D magnetic layers. The study of this project will provide theoretical support for the tuning of properties of 2D magnetic materials.