Strain-induced large Faraday rotation in graphene at subtesla external magnetic fields

Abstract

It is known that, under the presence of a static external magnetic field Be, an electromagnetic field rotates its polarization axes (Faraday rotation) when transmitted across a graphene single layer. Graphene provides record values of Faraday angle per layer thickness, but at frequencies of the order of the cyclotron frequency. This impedes applications, as fields of the order of 10 T would be required even for terahertz operation. Here we show that this condition is relaxed in strained graphene, where the potentially large induced pseudomagnetic field Bps, when combined with a small Be (needed to break time-reversal symmetry), provides large Faraday rotation at arbitrary frequencies. It is found that the Faraday rotation in this system presents a very rich dependence on all different parameters, being greatly enhanced when the number of occupied Landau levels (governed by Be±Bps) is different in the two graphene valleys.