Plasmon enhanced direct and inverse Faraday effects in non-magnetic nanocomposites

While applications of plasmonics are rapidly growing, magneto-optical effects in nanocomposites are poorly understood. We therefore devote this paper to the theoretical analysis of magneto-optical effects in nanocomposites. Based on the Drude model, we derived the constitutive equation where the dielectric and coupling functions describe the interactions of metal nanoparticles with magnetic field. In the limitation of low volume fraction of metal nanoparticles (i.e., when the material is still transparent), these functions were calculated within the Maxwell-Rayleigh theory of dilute suspensions. We showed that in the absence of external magnetic fields, a non-magnetic nanoparticle can be magnetized in the circularly polarized light beam, and the magnetization depends on the direction of rotation of the light wave. The external magnetic field alters the particle magnetization, and when the fields are weak, this change in magnetization linearly depends on the particular field. The proposed theory was applied to an analysis of the Faraday effect in nanocomposites. We predicted a resonance behavior of the Verdet function in nanocomposites and its dependence on concentration, sample thickness, and external magnetic field. (C) 2010 Optical Society of America