Graphene non-reciprocal electromagnetic activity at microwave frequencies

Magnetically-biased graphene supports strong Faraday rotation at microwave frequencies. Contrary to other gyrotropic media, such as ferrites, Faraday rotation in graphene can be fully controlled via an electrostatic potential between graphene and a parallel electrode, while the static magnetic bias is kept constant. Based on Faraday rotation in graphene, the first graphene-based waveguide isolator is presented. An analytical model is developed and shown to exhibit excellent agreement with experiment. The performance of the isolator, which strongly depends on the mobility of graphene, is acceptable with the existing technology and is expected to satisfy commercial requirements as the quality of grown graphene improves in the future.