  We have analyzed analytically the Faraday rotation of an electromagnetic wave
for magnetoactive thin metallic film with a nanostructured surface profile.
Periodical as well as random surface profiles were considered. The plasmon
contribution to the Faraday angle was studied. For periodical grating case, we
have shown that the maximum of rotation angle is achieved when 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 random surface profile, it is shown that the diffusion of surface
magnetoplasmons gives a dominant contribution to Faraday rotation. Comparison
with the experiments is carried out.
