Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza , 50009 Zaragoza, Spain.
ACS Nano. 2013 Nov 26;7(11):9780-7. doi: 10.1021/nn403282x. Epub 2013 Oct 4.
A single graphene sheet, when subjected to a perpendicular static magnetic field, provides a Faraday rotation that, per atomic layer, greatly surpasses that of any other known material. In continuous graphene, Faraday rotation originates from the cyclotron resonance of massless carriers, which allows dynamical tuning through either external electrostatic or magneto-static setting. Furthermore, the rotation direction can be controlled by changing the sign of the carriers in graphene, which can be done by means of an external electric field. However, despite these tuning possibilities, the requirement of large magnetic fields hinders the application of the Faraday effect in real devices, especially for frequencies higher than a few terahertz. In this work we demonstrate that large Faraday rotation can be achieved in arrays of graphene microribbons, through the excitation of the magnetoplasmons of individual ribbons, at larger frequencies than those dictated by the cyclotron resonance. In this way, for a given magnetic field and chemical potential, structuring graphene periodically can produce large Faraday rotation at larger frequencies than what would occur in a continuous graphene sheet. Alternatively, at a given frequency, graphene ribbons produce large Faraday rotation at much smaller magnetic fields than in continuous graphene.
当一片石墨烯单原子层置于垂直静态磁场中时，其产生的法拉第旋转角度超过任何已知材料的旋转角度。在连续的石墨烯中，法拉第旋转起源于无质量载流子的回旋共振，这允许通过外部静电或静磁设置进行动态调谐。此外，通过外部电场改变石墨烯中载流子的符号，可以控制旋转方向。然而，尽管有这些调谐可能性，但是大磁场的要求阻碍了法拉第效应在实际器件中的应用，特别是在高于几太赫兹的频率下。在这项工作中，我们证明了通过激发单个 ribbons 的等离子体激元，可以在石墨烯微带阵列中实现大的法拉第旋转，其频率高于回旋共振所决定的频率。通过这种方式，对于给定的磁场和化学势，周期性地结构化石墨烯可以在比连续石墨烯片更大的频率下产生大的法拉第旋转。或者，在给定的频率下，石墨烯 ribbon 在比连续石墨烯小得多的磁场下产生大的法拉第旋转。
