Non-reciprocal faraday rotation in graphene: Just a unique phenomenon or even more?

Faraday rotation observed in magnetically biased graphene is reviewed. For the best quality of CVD grown graphene to date and a magnetic field of 1 T a Faraday rotation around 10° is estimated. In contrast to other gyrotropic materials such as ferrites where rotation direction can only be controlled by the magnetic bias field, the rotation direction in graphene can be reversed by reversing an electric bias voltage applied between graphene and a gate electrode. The rotation angle is proportional to the mobility of graphene, which imposes a practical challenge in achieving rotation angles greater than 15°. However, even angles as low as 10° are enough to design isolators with isolation in the order of 20 dB. Due to the conducting nature of graphene at microwave frequencies, such devices are always accompanied by moderate loss, which however can be considered acceptable accounting advantages of graphene-based devices, such as easy tunability and invunerability to demagnetization effects present in ferrite-based devices.