Non metal-metal transition in Bruggeman optical theory for inhomogeneous media

Abstract

The Bruggeman optical effective medium theory of the dielectric permeability ε e(ω) of inhomogeneous media is analysed for metal-dielectric compounds in relation to the non metal-metal transition. The influence of the constituent-material parameters (free-electron parameters and bound-state polarization) on both the real and imaginary parts of εe(ω) is investigated in detail for the full range of metal filling factors and for optical to far-infrared wavelengths. A physical interpretation is formulated in terms of bound-state polarization, interfacial polarization and Drude conduction-electrons contributions. The results thus obtained are eventually compared to those of other effective medium theories : Maxwell Garnett modified by Cohen et al., Ping Sheng