  Plasmonic Faraday rotation in nanowires manifests itself in the rotation of
the spatial intensity distribution of high-order surface plasmon polariton
(SPP) modes around the nanowire axis. Here we predict theoretically the giant
Faraday rotation for SPP propagating on graphene-coated magneto-optically
active nanowires. Upon the reversal of the external magnetic field pointing
along the nanowire axis some high-order plasmonic modes may be rotated by up to
~ 100 degrees on scale of about 500 nm at mid-infrared frequencies. Tuning
carrier concentration in graphene by chemical doping or gate voltage allows for
controlling SPP-properties and notably the rotation angle of high-order
azimuthal modes. Our results open the door to novel plasmonic applications
ranging from nanowire-based Faraday isolators to the magnetic control in
quantum-optical applications.
