Enhanced nonreciprocal effects in magnetoplasmonic systems supporting simultaneously localized and propagating plasmons.

Perforated magnetoplasmonic Au/Co/Au multilayers support both localized and propagating surface plasmon resonances. The presence of holes produces an enhancement of the magnetic field modulation of the propagating surface plasmon wavevector with respect to the isostructural continuous film in the spectral region corresponding to the hole associated localized plasmon resonance. This is due to the increased electromagnetic field in the surrounding area of the resonant hole, and the subsequent additional contribution to the magnetic modulation of the continuous film. This novel concept that gives rise to enhanced magnetic field induced nonreciprocal effects can be of interest in the development of innovative platforms for sensing applications, optical isolators and modulators.