  The magnetooptic and magnetic properties of hexagonal arrays of holes in
optically thin iron films are presented. We analyze their dependence on the
hole radius and compare the results to a continuous iron film of same
thickness. We observe a large enhancement of the magnetooptic Kerr rotation
with respect to that of the continuous film, at frequecies where surface
plasmons excitations are expected. Additional simulations are in very good
agreement with the experiment and thus confirm the effect of the surface
plasmons on the Kerr rotation. The altering of the magnetic properties by the
hole array is also visible in the hysteretic behavior of the sample where a
dramatic change is observed.
