Tunable magnetoplasmonics in lattices of Ni/SiO2/Au dimers

We present a systematic study on the optical and magneto-optical properties of Ni/SiO2/Au dimer lattices. By consideringthe excitation of orthogonal dipoles in the Ni and Au nanodisks, we analytically demonstrate that the magnetoplasmonicresponse of dimer lattices is governed by a complex interplay of near- and far-field interactions. Near-field coupling betweendipoles in Ni and low-loss Au enhances the polarizabilty of single dimers compared to that of isolated Ni nanodisks. Far-fielddiffractive coupling in periodic lattices of these two particle types enlarges the difference in effective polarizability further.This effect is explained by an inverse relationship between the damping of collective surface lattice resonances and theimaginary polarizability of individual scatterers. Optical reflectance measurements, magneto-optical Kerr effect spectra, andfinite-difference time-domain simulations confirm the analytical results. Hybrid dimer arrays supporting intense plasmonexcitations are a promising candidate for active magnetoplasmonic devices.