Effective medium approximation of anisotropic materials with radiative correction

摘要

A measurable magneto-optical activity of nanoparticles made out of noble metals is observed when the localized plasmon waves are excited in the presence of external magnetic field. We confirmed these observations for quite general Au nanostructure on SiO_2/Si substrate theoretically and by experimental way. The heterogeneous layer is formed as a field of cylindrical or spheroidal nanodots of various size having the same height and parallel symmetry axis. These properties enable to apply the Bruggeman's model of effective medium approximation, for which the size of dots (height, diameter) and fill-factor of nanodots were specified using the transmission electron microscopy image processing. Actually, this model is extended about the interaction of magnetic dipole moments simulated using discrete dipole approximation via geometrical averaging. Derived computational algorithm leads to better agreement with experimental data in the form of Kerr angles in polar configuration at visible spectral region. Obtained out-puts also illustrate the fact that extinction peak of plasmon excitation is located at the resonance wavelength of permittivity.