Doping with Graphitic Nitrogen Triggers Ferromagnetism in Graphene.
Doping with Graphitic Nitrogen Triggers Ferromagnetism in Graphene.
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DOI：
10.1021/jacs.6b12934
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发表时间：
2017-03-01
影响因子：
15
通讯作者：
Zbořil R
中科院分区：
文献类型：
--
作者：
Błoński P;Tuček J;Sofer Z;Mazánek V;Petr M;Pumera M;Otyepka M;Zbořil R
氮掺杂为定制石墨烯的电子性质和带隙提供了可能性，以适应其应用，例如，自旋电子学和光电子学。一个主要障碍是开发具有自旋极化导电行为的磁活性N掺杂石墨烯。然而，氮对石墨烯磁性的影响迄今为止仅在理论上得到解决，并且通过N掺杂引发磁性尚未在实验上得到证明，除了含有大量氧并因此降低电导率的系统之外。在这里，我们报告的第一个例子铁磁石墨烯实现控制掺杂石墨，吡啶，和化学吸附氮。的磁性被发现强烈地依赖于在主机晶格中产生的氮浓度和类型的结构N-图案。石墨烯掺杂低于5原子。%的氮被掺杂;然而，一旦在5.1 at. %的氮，N掺杂的石墨烯在1.69K下表现出向铁磁状态的转变，并且显示出达到1.09emu/g的饱和磁化强度。理论计算被用来阐明个别化学形式的氮的磁性的影响。结果表明，磁性效应是由石墨态氮引发的，而吡啶态氮和化学吸附态氮对整个铁磁基态的贡献要小得多。计算进一步证明了传导电子介导的顺磁中心之间的交换耦合的存在。
Nitrogen doping opens possibilities for tailoring the electronic properties and band gap of graphene toward its applications, e.g., in spintronics and optoelectronics. One major obstacle is development of magnetically active N-doped graphene with spin-polarized conductive behavior. However, the effect of nitrogen on the magnetic properties of graphene has so far only been addressed theoretically, and triggering of magnetism through N-doping has not yet been proved experimentally, except for systems containing a high amount of oxygen and thus decreased conductivity. Here, we report the first example of ferromagnetic graphene achieved by controlled doping with graphitic, pyridinic, and chemisorbed nitrogen. The magnetic properties were found to depend strongly on both the nitrogen concentration and type of structural N-motifs generated in the host lattice. Graphenes doped below 5 at. % of nitrogen were nonmagnetic; however, once doped at 5.1 at. % of nitrogen, N-doped graphene exhibited transition to a ferromagnetic state at ∼69 K and displayed a saturation magnetization reaching 1.09 emu/g. Theoretical calculations were used to elucidate the effects of individual chemical forms of nitrogen on magnetic properties. Results showed that magnetic effects were triggered by graphitic nitrogen, whereas pyridinic and chemisorbed nitrogen contributed much less to the overall ferromagnetic ground state. Calculations further proved the existence of exchange coupling among the paramagnetic centers mediated by the conduction electrons.