Comparison of SPR and T-MOKE Effects in Magneto-optic Plasmonic Nanostructures

In this letter, we report on the response of surface plasmon resonance (SPR, reflectance versus incident angle) and transverse magneto-optic Kerr effect (T-MOKE) versus incident angle) in two different magneto-optic-plasmonic (MOP) configurations: Ti/Au/Co/Au (Configuration A) and Ti/Ag/Co/Au (Configuration B) at the excitation wavelength of 780 nm in air. Configuration A includes a 35 nm Au layer and Configuration B includes a 35 nm Ag layer. Both configurations consist of a thin (4 or 8 nm) Co magneto-optic layer and showed an enhancement of the T-MOKE signal over the SPR signal. Configuration B showed higher SPR and T-MOKE responses over Configuration A, possibly due to the low loss and higher plasmonic properties of Ag over Au. The T-MOKE based sensor shows improvements in quality factor by over two times compared to that of SPR. The magneto-optic SPR sensitivity of the sensor obtained shows an improvement by three times over the SPR sensitivity, and this can be further improved by suitably modifying the configuration. These results are of importance to the development of enhanced MOP/plasmonic sensors.