  Faraday rotation is a fundamental property present in all non-reciprocal
optical elements. In the THz range, graphene displays strong Faraday rotation;
unfortunately, it is limited to frequencies below the cyclotron resonance. Here
we show experimentally that in specifically design metasurfaces,
magneto-plasmons can be used to circumvent this limitation. We find excellent
agreement between theory and experiment and provide new physical insights and
predictions on these phenomena. Finally, we demonstrate strong tuneability in
these metasurfaces using electric and magnetic field biasing.
