Contribution of the surface plasmon resonance to optical and magneto-optical properties of a Bi:YIG-Au nanostructure.

We have studied the optical and magneto-optical properties of bismuth-substituted yttrium iron garnet (Bi:YIG) films with Au nanoparticles dispersed on their top surfaces. These structures exhibit surface plasmon resonances due to light coupling to Au nanoparticles, showing, for any direction of polarization of the incoming light beam, an absorption band in the spectral range of 500–750 nm. For transmitted light beams with the plasmon-resonant wavelengths, the plane of polarization rotates slightly when the structure is not magnetized. Polarization-resolved transmission spectra show that this rotation is due to anisotropy of light propagation through the array of Au nanoparticles. For the structure comprising the 90-nm-thick Bi:YIG film and the array of Au nanoparticles of several tens of nanometers, the Faraday rotation angle enhances as compared with that for the original Bi:YIG film of the same thickness. [ABSTRACT FROM AUTHOR]