Research & Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
Sci Rep. 2013;3:2599. doi: 10.1038/srep02599.
The magnetism of graphene has remained divergent and controversial due to absence of reliable experimental results. Here we show the intrinsic magnetism of graphene edge states revealed based on unidirectional aligned graphene sheets derived from completely carbonized SiC crystals. It is found that ferromagnetism, antiferromagnetism and diamagnetism along with a probable superconductivity exist in the graphene with irregular zigzag edges. A phase diagram is constructed to show the evolution of the magnetism. The ferromagnetic ordering curie-temperature of the fundamental magnetic order unit (FMOU) is 820 ± 80 K. The antiferromagnetic ordering Neel temperature of the FMOUs belonging to different sublattices is about 54 ± 2 K. The diamagnetism is similar to that of graphite and can be well described by the Kotosonov's equation. Our experimental results provide new evidences to clarify the controversial experimental phenomena observed in graphene and contribute to a deeper insight into the nature of magnetism in graphene based system.
由于缺乏可靠的实验结果，石墨烯的磁性一直存在分歧和争议。在这里，我们展示了基于完全碳化 SiC 晶体衍生的单向排列石墨烯片揭示的石墨烯边缘态的本征磁性。研究发现，具有不规则锯齿边缘的石墨烯具有铁磁性、反铁磁性和抗磁性以及可能的超导性。构建了一个相图来显示磁性的演化。基本磁序单元（FMOU）的铁磁有序居里温度为 820±80 K。属于不同子晶格的 FMOU 的反铁磁有序尼尔温度约为 54±2 K。抗磁性与石墨相似，可以用 Kotosonov 方程很好地描述。我们的实验结果为澄清石墨烯中观察到的有争议的实验现象提供了新的证据，并有助于更深入地了解基于石墨烯的系统中磁性的本质。
