二维高温铁磁体的理论设计与自旋调控

Spintronics, manipulating both charge and spin of electron, offer great opportunities for next generation information technology. However, several technical problems have to be solved in spintronics, such as efficient spin generation and injection, long distance spin transport, and manipulation and detection of spin orientation. The solutions to these issues mainly rely on designing new spintronic materials with specific properties, such as long range ordered magnetic structures, high Curie temperature (Tc), and good compatibility with semiconductors. Since graphene boom, different types of 2D materials with a wealth of physical phenomena have been synthesized, but the realization of intrinsic 2D magnetism at room temperature remains a challenge. Due to their fantastic geometries and excellent conductivity, here we propose to perform high-throughput computation of 2D MXene with a wider range of composition in order to search 2D spintronic materials candidates with good stability and high Tc. We first clarify the correlation between the structural parameters, chemical composition of 2D MXene and the electronic and magnetic characters. Then we illuminate the number of layers, thickness, functional groups, and alloy strategy for spin engineering of 2D MXene materials. Finally, we will discuss the mechanism of ferromagnetism coupling of 2D MXene and propose some ideal prototype spintronic device based on our spin transport simulations. The present project not only build the database of 2D MXene with long range ordered magnetic structures and high Tc, but also shed considerable light on controlling magnetism in 2D materials.

自旋电子学可同时利用电子的自旋和电荷特性对信息进行存储、运输和处理，是下一代信息技术的核心。发展高效的自旋电子学器件面临着尺寸小型化、自旋可控性、制备工艺可行性等难题。这些问题的解决将主要依赖于具有特定电子结构、磁学特性、与成熟半导体工艺兼容的功能材料的研发。二维MXene包含未满d壳层过渡金属，组分灵活可调，结构多样，具有可调控的电学性能和高的电导率，是获得自旋电子学材料的理想选择。本项目借鉴材料基因组学的研究思路，拟对多成分和化学配比下的二维硼基、碳基、氮基MXene开展第一性原理高通量计算搜索，筛选出兼具结构稳定性、铁磁长程序、高居里温度的二维磁体，建立MXene较完整的结构和电学/磁学特性数据库。阐明二维MXene磁性产生机理，探索增强磁矩和居里温度的有效途径。模拟二维MXene异质结界面的自旋电子注入和极化输运行为，为新型二维自旋电子学原型器件的研制提供有价值的理论指导。

通过本项目的研究，在二维磁性材料和自旋电子学器件设计领域取得了一系列具有国际影响力的原创性成果。主要包括：1) 建立了二维MXene材料数据库，获得了系列具有高居里温度的二维磁体；2) 阐明了多种磁耦合机理，提出了应力、功能化、等价电子替换，磁近邻效应等自旋调控机制；3) 基于理论设计的二维磁性材料，提出了多种潜在的自旋电子学新概念器件，包括自旋场效应晶体管、自旋阀、磁场调制的光电器件等；4）开发了基于机器学习算法的二维磁性材料的筛选方法。在Nature Commun.、Appl. Phys. Rev.、Adv. Funct. Mater.、Phys. Rev. B、Appl. Phys. Lett等期刊上发表SCI论文64篇，其中第一标注论文26篇。学术成果被诺贝尔奖获得者R. Hoffmann和H. Kroto教授在内的国际同行在Science、Nature Phys.、Phys. Rep.等权威期刊上引用和正面评价2600余次，二维磁性材料设计方面的多项成果被国际同行的实验直接验证（二维MBene、双层硼烯、二维CrSBr等）。应邀以第一作者为物理学权威期刊Appl. Phys. Rev.撰写系统总结二维磁性材料进展的长篇综述，被标记为“ESI前0.1%热点文章”和“ESI前1%高被引文章”。获河北省自然科学二等奖（排名第2）和大连理工大学自然科学一等奖（排名第2）。入选了大连市高层次人才“高端人才”。