利用氟辅助制备氮含量和掺杂形式可调节的石墨烯并调控其磁性

Nitrogen-doping is demonstrated to be an effective way to tailor the magnetic property of graphene, thus making N-doped graphene a promising material for use in spintronics. However, N atoms are usually chemisorbed on the defect sites of graphene sheets, thus, we will tailor the concentration of vacancies to tune the nitrogen-doping level and types for controlling the magnetic properties of graphene. In this project, we propose to introduce various vacancies in graphene by F-assisted method to improve the performance of nitrogen-doping, and realize the controllability in the nitrogen level and types. Thereafter, with the study of the magnetic property of graphene, we will reveal the magnetic contribution of N-doping. Thus, we can increase the spin density of graphene by tuning the nitrogen level and types, and realize high-magnetization and room-temperature ferromagnetic graphene, which will push the way for potential applications in spintronics devices. The combination of theory and experiment is adopted to explore the intrinsic magnetic source and magnetic coupling mechanism, and which will help to provide theoretical suggestions for its experimental study.

通过氮掺杂可以有效调节石墨烯的磁学性质，推动石墨烯在自旋电子学领域的发展潜力。由于氮一般掺杂在石墨烯的缺陷位，因此我们拟通过调节缺陷浓度，实现对氮含量及掺杂形式的调节，进而调控石墨烯的磁学性质。本申请书拟采用氟辅助的方式在石墨烯中引入不同空位形式以促进氮的掺杂，并获得氮掺杂量及形式可调节的石墨烯。通过研究其磁学性质，揭示氮掺杂对石墨烯的磁性的影响，进而通过调节氮掺杂量和掺杂形式来提高石墨烯的自旋浓度，以期获得高磁、室温铁磁性石墨烯。此外，拟采用理论计算和实验相结合，探索石墨烯中本征磁性的来源和磁耦合机制，为其实验研究提供理论依据。

提高石墨烯的自旋浓度并促进自旋耦合是推动石墨烯在自旋电子学领域应用的关键。石墨烯的氮掺杂（NG）可以有效调节石墨烯的磁学性质，推动石墨烯在自旋电子学领域的发展潜力。本项目提出利用氟辅助的方式调节石墨烯的内部缺陷，实现对氮含量及掺杂形式的调节，进而调控石墨烯的磁学性质。本工作揭示了氟含量与氮掺杂量的对应关系、并通过调整氟分布形式调节氮掺杂形式,完成了利用FG制备高含量、掺杂形式可控的NG的目标,获得浓度高达29.82 at.%的NG样品。在此基础上揭示了氮含量、掺杂形式与自旋浓度、自旋耦合的关系。获得了磁矩为2.30 emu/g的NG样品，并通过调整氮掺杂的形式，将NG的铁磁性推高至近室温250K。最后理论计算了NG中的各种掺杂形式的稳定性，显示结构调整的微观机制是F能有效调整N的稳定性。磁性研究的结果也表明结构的转化（i）能有效捕获自由电子，在磁场下促进自旋极化；（ii）增加磁矩间RKKY交换的耦合系数；（iii）有效缩短磁矩间的耦合距离。该工作理论上推动了石墨烯s-p 电子磁性理论，对于传统的 3d、4f 电子体系的基本磁学理论是一个巨大补充。应用上获得自旋浓度高，铁磁耦合强的石墨烯，促进了石墨烯在自旋电子学器件中应用前景。