Limitations of the two-media approach in calculating magneto-optical properties of layered systems

TL;DR

This paper examines the limitations of the two-media approach for calculating magneto-optical properties in layered systems, highlighting its accuracy in certain geometries and its relation to the Fresnel formula, supported by ab-initio calculations.

Contribution

It clarifies the conditions under which the two-media approach is valid and compares it with the matrix technique for magneto-optical calculations.

Findings

Matrix technique accurately accounts for multiple reflections and interferences.

Two-media approach reduces to Fresnel reflectivity for identical layers.

Ab-initio calculations agree well with experimental data for Pt.

Abstract

It is shown that in polar geometry and normal incidence the 2x2 matrix technique - as discussed in detail in a preceeding paper [Phys. Rev. B 65, 144448 (2002)] - accounts correctly for multiple reflections and optical interferences, and reduces only in the case of a periodic sequence of identical layers to the Fresnel formula of reflectivity, which in turn is the theoretical basis of the two-media approach, widely used in the literature to compute magneto-optical Kerr spectra. As a numerical example ab-initio calculations of the optical constants for an fcc Pt semi-infinite bulk using the spin-polarized relativistic screened Korringa-Kohn-Rostoker method show very good agreement with experimental data.