Dark mode enhancing magneto-optical Kerr effect in multilayer magnetoplasmonic crystals

Magnetic materials in metallic nanostructures allow an external magnetic field to easily control surface plasmon polaritons and surface lattice modes (SLMs), which enhances the value of magneto-optical response. The present paper demonstrates both experimentally and numerically that the inherently different radiative damping of dark and bright SLMs in one-dimensional low-loss multilayer Au/Ni/Au magnetoplasmonic crystals can alter the resonant enhancement of the transverse magneto-optical Kerr effect (TMOKE). As the quality factor of dark SLMs goes up, the maximum TMOKE values increase as well. The spectral range of TMOKE enhancement broadens at small incident angles since dark and bright SLMs overlap each other. The Fano resonance model shows that the wavelength shift of the dark and bright modes results in the resonant enhancement of TMOKE.