Control of magnetic contrast with nonlinear magneto-plasmonics

The interaction between surface plasmons (SP) and magnetic behavior has generated great research interest due to its potential for future magneto-optical devices with ultra-high sensitivity and ultra-fast switching. Here we combine two surface sensitive effects: magnetic second-harmonic generation (MSHG) and SP to enhance the detection sensitivity of the surface magnetization in a single-crystal iron film. We show that the MSHG signal can be significantly enhanced by SP in an attenuated total reflection (ATR) condition, and that the magnetic contrast can be varied over a wide range by the angle-of-incidence. Furthermore, the magnetic contrast of transverse and longitudinal MSHG display opposite trends, which originates from the change of relative phase between MSHG components. This new effect enhances the sensing of magnetic switching, which has potential usage in quaternary magnetic storage systems and bio-chemical sensors due to its very high surface sensitivity and simple structure.