  We report on a phenomenon of plasmonic dichroism observed in magnetic
materials with the transverse magnetization under the excitation of the surface
plasmon polariton waves. The effect originates from the interplay of the two
magnetization-dependent contributions to the material absorption, both of which
are enhanced under plasmon excitation. Similar to the recently discovered
effect of a all-optical helicity-dependent magnetization switching, this effect
provides a possibility to perform a deterministic magnetization switching to
the desired state. We show by electromagnetic modeling that laser pulses
exciting counter-propagating plasmons can be used to write +M or -M state in a
deterministic way independent on the initial magnetization state. The presented
approach applies to various ferrimagnetic materials exhibiting the phenomenon
of all-optical switching of thermal nature and broadens the horizons of their
applications in data storage devices.
