  Employing plasmonic antennas for subdiffraction focusing of light on
recording media requires to take into account the complete structure of the
medium, including dielectric cover layers. We find, with finite difference time
domain simulations, that optical energy transfer to the magnetic recording
layer is most efficient for an off-resonant antenna. Furthermore, we show that
the focal spot in the magnetic film is well below the diffraction limit, making
nanoscale all-optical magnetic data recording achievable.
