Effects of surface magnetism on optical second harmonic generation.

We report on the first experiments showing the influence of surface magnetization on optical second harmonic generation in reflection at a Fe(110) surface. The magneto-optical Kerr erect modifies the hyperpolarizability of the surface in the optical field, leading to a dependence of the second harmonic yield on the direction of magnetization relative to the light fields. For the clean surface an erect of 25% was determined, which decays exponentially with surface contamination by the residual gas, thus demonstrating the high surf'ace sensitivity of this technique