  We propose a mechanism to actively tune the operation of plasmonic cloaks
with an external magnetic field by investigating electromagnetic scattering by
a dielectric cylinder coated with a magneto-optical shell. In the long
wavelength limit we show that the presence of an external magnetic field may
drastically reduce the scattering cross-section at all observation angles. We
demonstrate that the application of external magnetic fields can modify the
operation wavelength without the need of changing material and/or geometrical
parameters. We also show that applied magnetic fields can reversibly switch on
and off the cloak operation. These results, which could be achieved for
existing magneto-optical materials, are shown to be robust to material losses,
so that they may pave the way for developing actively tunable, versatile
plasmonic cloaks.
