Plasmon-enhanced Faraday rotation in thin films

We have analyzed analytically the Faraday rotation of an electromagnetic wave for a magnetoactive thin metallic film with a nanostructured surface profile. Periodic as well as random surface profiles were considered. The plasmon contribution to the Faraday angle was studied. For the periodic grating case, we have shown that the maximum rotation angle is achieved when the surface plasmon wave number coincides with one of the wave numbers of the inverse lattice. Enhancement of the Faraday angle at plasmonic band edges is predicted. In the case of a random surface profile, it is shown that the diffusion of surface magnetoplasmons gives a dominant contribution to the Faraday rotation. Comparison with experiments is carried out.