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