  We examine the efficacy of Dark-mode plasmonics as a platform for enhanced
magneto-optics. Dark-mode of a small particle consists of two co-existing
equal-intensity and mutually opposing dipolar excitations. Each of these two
opposing dipoles may even resonate at or near the dark-mode frequency, but the
net dipole moment vanishes due to the mutual cancelation between the opposing
dipoles. We show that application of external magnetic bias may alleviate the
intense destructive interference. Furthermore, under external magnetic bias the
opposing dark-resonances of a plasmonic particle shift in opposite directions
and create a region of extremely sensitive Faraday rotation. We show that the
magnetized dark resonance in lossless Ag-like particle may provide more than 20
degrees rotation under magnetic fields of the order of 1-2 Tesla, exhibiting
magneto-plasmonic activity that is 2-3 orders of magnitude larger than that
observed in conventional plasmonic particle of the same material.

Optics