Anomalous optical nonreciprocity in magnetic nanoisland arrays

We study the phenomenon of optical nonreciprocity in multilayer systems of magnetic nanoislands [FeNi–Al₂O₃]_N. An anomalously large optical nonreciprocity was observed in these systems. The effect was manifested in nonequivalence of polarization plane rotation of reflected light for the sample in an initial position and rotated by . We assume that the super-vortex magnetization in the FeNi layers is responsible for the optical nonreciprocity effect. It was found that the value of nonreciprocity effect depends on the effective thickness of FeNi island layer and reaches a maximum with the super-vortex magnetization formation. The nonreciprocity magnitude is significantly higher than the values observed recently in systems of specially formed magnetic nanoparticles. Nonreciprocity magnitude is strongly dependent on interlayer interaction between nanoisland layers at large distances. (paper)