Plasmonic dichroism and all-optical magnetization switching in nanophotonic structures with GdFeCo

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.