Influence of the structural and induced anisotropy in the effective dielectric function

The shape of metallic inclusions may induce anisotropy in the effective dielectric function εe of inhomogeneous media. This anisotropy modifies the effective depolarization factor of the inclusion. This effect is analysed in the framework of the classical mean field theories of Maxwell Garnett and Bruggeman, which have to be re-established due to the fact that the Laplace equation is no more suitable in anisotropic media. Exact tensorial formulations are presented who predict a shift of the different plasma surface modes and a modification of the percolation threshold value in the self-consistent theory of Bruggeman.