Kerr Magneto-Optic Effect in Nickel-Iron Films I Experimental

Abstract

An account is given of experiments to determine the magnitude of the Kerr magneto-optic effect in thin films of nickel (83%) iron (17%) alloy and the results discussed with a view to possible applications in computer storage systems. It is shown that the magnitude of the effect in relation to inherent background fluctuations (signal-to-noise ratio) can be appreciably increased by a suitable dielectric (zinc sulfide) layer deposited onto the NiFe films. The improvement, however, is found to depend critically on the thickness of the dielectric layer and on the spectral composition of the illumination in the measuring equipment. These facts, as well as the general lack of agreement in previously published results, are clarified by measurements of the dispersion of the Kerr rotation in NiFe films coated with various thicknesses of ZnS.