  We report strong amplification of photo-magnetic spin precession in Co-doped
YIG employing a surface plasmon excitation in a metal-dielectric
magneto-plasmonic crystal. Plasmonic enhancement is accompanied by the
localization of the excitation within the 300~nm-thick layer inside the
transparent dielectric garnet. Experimental results are nicely reproduced by
numerical simulations of the photo-magnetic excitation. Our findings
demonstrate the magneto-plasmonic concept of subwavelength localization and
amplification of the photo-magnetic excitation in dielectric YIG:Co and open up
a path to all-optical magnetization switching below diffraction limit with
energy efficiency approaching the fundamental limit for magnetic memories.
