  We study resonant tunnelling effects that can occur in tri-layer structures
featuring a dielectric layer sandwiched between two magneto-optical-metal
layers. We show that the resonance splitting associated with these phenomena
can be exploited to enhance Faraday rotation at optical frequencies. Our
results indicate that, in the presence of realistic loss levels, a tri-layer
structure of sub-wavelength thickness is capable of yielding sensible
(~10{\deg}) Faraday rotation with transmittance levels that are an order of
magnitude larger than those attainable with a standalone slab of
magneto-optical metal of same thickness.
