Au/NiFe Magnetoplasmonics: Large Enhancement of Magneto-Optical Kerr Effect for Magnetic Field Sensors and Memories

Surface plasmon polariton resonance (SPPR) can be originated from the surface charge oscillation via light localization at the interface of a metal, for example, Au or Ag and a dielectric. Such localization can be implemented to increase the magneto-optical (MO) activity of a magnetic medium while SPPR is fulfilled, which is known as magnetoplasmonics. In this paper, a magnetoplasmonic bilayer of Au/NiFe (Py) sputter deposited on glass is demonstrated. Large enhancement in MO-Ken effedt (MOKE) response due to SPPR effect is observed at different light incident angles. By measuring and analyzing the MO signals from the sample with different thicknesses of Au and Py layers, the optimal thicknesses' range is obtained with the largest MOKE. The large MOKE intensity from ultra-soft magnetic Py layer with low coercivity and small saturation field suggests a weak magnetic field-sensitive MO-based element. Finally, different applications of such structures, for example, weak magnetic field sensors and magnetic multilevel memory elements are demonstrated.