Theory of Faraday rotation in granular magnetic materials

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Abstract
We present a formalism to treat Faraday rotation (FR) in composite media. The method is not limited to low concentrations of magnetically active inhomogeneities and is thus useful for understanding the magneto‐optical properties of such inhomogeneous media over the whole range of concentrations. It involves the calculation of an effective magnetic‐field‐dependent dielectric tensor εe using a tensor effective‐medium approximation. To illustrate the technique, we present the results of several model calculations involving both paramagnetic and ferromagnetic metals. We find that such materials have strongly enhanced FR over a wide range of frequencies. The effects of particle shapes on FR are discussed.