Department of Quantum Matter Physics, University of Geneva, Geneva 4 CH-1211, Switzerland.
Institute for Quantum Electronics, Department of Physics, ETH Zurich, Zurich CH-8093, Switzerland.
Nat Commun. 2017 Mar 7;8:14626. doi: 10.1038/ncomms14626.
The magnetic circular dichroism and the Faraday rotation are the fundamental phenomena of great practical importance arising from the breaking of the time reversal symmetry by a magnetic field. In most materials, the strength and the sign of these effects can be only controlled by the field value and its orientation. Furthermore, the terahertz range is lacking materials having the ability to affect the polarization state of the light in a non-reciprocal manner. Here we demonstrate, using broadband terahertz magneto-electro-optical spectroscopy, that in graphene both the magnetic circular dichroism and the Faraday rotation can be modulated in intensity, tuned in frequency and, importantly, inverted using only electrostatic doping at a fixed magnetic field. In addition, we observe strong magneto-plasmonic resonances in a patterned array of graphene antidots, which potentially allows exploiting these magneto-optical phenomena in a broad THz range.
磁圆二色性和法拉第旋转是由磁场打破时间反演对称性而产生的具有重要实际意义的基本现象。在大多数材料中，这些效应的强度和符号只能通过场值及其方向来控制。此外，太赫兹范围内缺乏能够以非互易方式影响光的偏振状态的材料。在这里，我们使用宽带太赫兹磁光电光谱学证明，在石墨烯中，磁圆二色性和法拉第旋转的强度都可以被调制，频率可以被调谐，重要的是，在固定磁场下仅通过静电掺杂就可以反转。此外，我们在石墨烯的一个图案化的纳米孔阵列中观察到强烈的磁等离子体共振，这可能使得在很宽的太赫兹范围内利用这些磁光现象成为可能。
