Local control of the excitation of surface plasmon polaritons by near-field magneto-optical Kerr effect

We investigate local control of the excitation of surface plasmon polaritons by a magnetic scatterer placed in the vicinity of a metallic surface. We show that under those conditions a change of about 27% in the surface plasmon intensity can be achieved by flipping the external magnetic field. The magnitude of this phenomenon is given by the magneto-optical Kerr effect (MOKE). A qualitative analysis of our numerical results, based on a perturbative approach, lead to simple analytical expressions for the longitudinal MOKE when the scatter is in close proximity to the surface. These results provide physical insight into the problem and may lead to the design of useful devices.