Enhancing the magneto-optical Kerr effect through the use of a plasmonic antenna.

We employ an extended finite-element model as a design tool capable of incorporating the interaction between plasmonic antennas and magneto-optical effects, specifically the magneto-optical Kerr effect (MOKE). We first test our model in the absence of an antenna and show that for a semi-infinite thin-film, good agreement is obtained between our finite-element model and analytical calculations. The addition of a plasmonic antenna is shown to yield a wavelength dependent enhancement of the MOKE. The antenna geometry and its separation from the magnetic material are found to impact the strength of the observed MOKE signal, as well as the antenna's resonance wavelength. Through optimization of these parameters we achieved a MOKE enhancement of more than 100 when compared to a magnetic film alone. These initial results show that our modeling methodology offers a tool to guide the future fabrication of hybrid plasmonic magneto-optical devices and plasmonic antennas for magneto-optical sensing.