Tuning the shape of magneto-optical Kerr spectrum by changing the strip width in one-dimensional Ag-Co-Ag magnetoplasmonic nanogratings

Magnetoplasmonic nanostructures have received significant attention as they have the ability to manipulate the magneto-optical response more precisely and efficiently. Here, we report a method to manipulate the shape of the longitudinal magneto-optical Kerr rotation spectrum in one-dimensional magnetoplasmonic nanogratings. It is found that changing the strip width of the nanograting can alter the sign of the maximal Kerr rotation of the two Kerr spectra. Experimentally, we obtained the maximal Kerr rotation angles of 0.30 degrees and -0.18 degrees at the wavelength of 530nm for strip widths of 200nm and 160nm, respectively, in the Ag/Co/Ag grating sample. It has been revealed that the sign change of the two maximal Kerr angles is attributed to the relative contributions of the dipole-dipole interactions. These findings are of potential values for practical applications of magneto-optical devices.