Grazing incidence nanogap resonance in the prism-gap-ferromagnet magneto-plasmonic Otto configuration

In this Letter, we calculate the optical and magneto-optical reflectivity in a dielectric/gap/ferromagnet excited by a p-polarized monochromatic optical beam through the prism (Otto configuration) as a function of the angle of incidence θ and the gap thickness d. Besides the well-known surface plasmon polariton (SPP resonance at d ∼ λ), we find a new, to the best of our knowledge, resonance with a nanometric gap d ∼ 10 nm at a large θ ∼ 80°. Both resonances display pronounced resonant behavior in the transverse magneto-optical Kerr effect (T-MOKE).