Modification of the Longitudinal Kerr Magneto-Optic Effect by Dielectric Layers

General formulas governing the modification of the longitudinal Kerr magneto-optic effect by dielectric layers deposited on the ferromagnetic surface are simplified by two assumptions justified on experimental evidence. From the resulting formulas it is shown that the change in Kerr rotation σ can be evaluated by means of a simple vector diagram. It follows that the increases in σ due to the dielectric layer are almost unlimited, and that the effect of the dielectric layer in this case can be regarded as an antireflection effect. The improvements of signal-to-noise ratio associated with the Kerr effect are, however, strictly limited, and the function of the dielectric is then partly that of a phase plate. Results much better than have been obtained with single layers of zinc sulfide are not likely to be achieved.