Direction?Sensitive Magnetophotonic Surface Crystals

Nanometer-thin rare-earth-transition metal (RE-TM) alloys with precisely controlled compositions and out-of-plane magnetic anisotropy are currently in the focus for ultrafast magnetophotonic applications. However, achieving lateral nanoscale dimensions, crucial potential device downscaling, while maintaining designable optomagnetic functionality is extremely challenging. Here we integrate nanosized Tb$_{18}$Co$_{82}$ ferrimagnetic alloys, having strong anisotropy, within a gold plasmonic nanoantenna array to design micrometer-scale crystal that exhibit abrupt narrow magneto-optical spectral features both field light incidence direction controlled. The Fano-type resonance arises through interference of individual nanoantenna's surface plasmons Rayleigh anomaly whole array, optical spectra, which demonstrate explain using Maxwell-theory simulations. This robust opens way conceptually new high-resolution sensors, as well building blocks plasmon-assisted all-optical magnetization switching RE-TM alloys.