Single layer equivalence of magneto-optic multilayers for oblique incidence (II)

Abstract

The optical and magneto-optical properties of magnetic multilayers are considered in terms of a single isotropic equivalent layer for radiation at both normal and oblique incidence. It is shown that in the case of absorbing materials, where the square of the modulus of the complex refractive index is greater than about 10, any multilayer system can be treated in terms of a single isotropic layer providing individual sublayer thicknesses are very small compared to the wavelength of the radiation being considered. This single-layer equivalence applies to both normal as well as oblique incidence. Expressions for the effective refractive index and magneto-optic parameter are derived in terms of the basic optical and magneto-optical constants of the materials of the sublayers and it is shown that these are the same as those which apply to the special case of normal incidence. It is also emphasised that where one of the layer materials is a dielectric of low refractive index the multilayer cannot, in the general case, be represented by a single isotropic layer.